help-with-hw-design

[slow plover]

Unless you mean because they're not PC fans

[cursive sentinel]

In theory, yes. In practice, it depends on the BIOS. They usually have acceptable fan control. Usually.

[supple pollen]

The main advantage the mobo has it the ability to measure the junction temperature on the chips. The main disadvantage is this is normally done indirectly, in software, and if that software has issues, you lose fan control entirely.

[teal fjord]

As someone who has built more computers then I can count and used to own a computer shop. Madbodger is completely correct here. Software control is not better then letting defined engineering of the motherboard do it.

[slow plover]

I have only used the fan controls in the BIOS

[edgy ridge]

Im trying to load circuitpython on a generic esp32 s3 n16 r8 dev board (ordering a metro on friday but i had this and wanted to get started on long weekend)

On the adafruit esptool i am getting the error seen in attached photo. Any guidance would be appreciated. Esp32 does go into boot mode and i am plugged into correct usbc socket.

[supple pollen]

The last time I saw that, I tried lowering the communication speed and it fixed it.

[edgy ridge]

Unfortunately that didnt fix it (was on lowest speed already, tried all available selections though and same error)

[sacred badger]

Not fun @supple pollen lol.

any idea on power rating of this.. ideally 65w

[supple pollen]

Probably depends on the voltage

[sacred badger]

of course -- would use it to charge a power bank inside a waterproof box that'll be used as a ground control station for UAVs

[ocean coyote]

Im looking to connect one of these to a rp2040, afaik i only need to use spi hardware gpio pins for sck and sda right? also whats the best way to connect them? would the led to 3.3v need a series ressistor, or any of the other pins?

[sacred badger]

looks like LED has a resistor on the board -- not sure if both the SD slot and TFT are combined to a single interface, being the pin headers..

[ocean coyote]

yeah your right

didnt even notice that

[sacred badger]

also be aware that SPI SD access isn't particularly fast... it's quick enough for general use, but don't expect it to be blistering

[ocean coyote]

sdio is better aye?

it will only be used to write to bin files 1kb each, reading and writing bytes

[sacred badger]

for what it is, and probably your desired use, it's fine -- im basing that opinion on my RC transmitter that uses SPI for SD access -- 512KB/s max

[ocean coyote]

would the pico limit that speed down further?

[sacred badger]

prob not

[ocean coyote]

will use a rp2350 anyway so 150mhz system clock

[sacred badger]

the radiomaster zorro i'm referencing uses a STMF4 MCU

[ocean coyote]

ah yeah

[ocean coyote]

the PIO usb library i want to use says the system clock speed needs to be a multiple of 12mhz, so the max i can set would be 144mhz if the rp2350 supports 150mhz right?

[sacred badger]

well, my knowledge is and always will be limited -- but i do know there are multiple system clocks

meaning, the clock USB uses may or may not be the main clock

[sacred badger]

for example, from EdgeTX source code--

#elif defined(STM32F4)
#define CPU_FREQ 168000000
#define PERI1_FREQUENCY 42000000
#define PERI2_FREQUENCY 84000000
#define TIMER_MULT_APB1 2
#define TIMER_MULT_APB2 2

for the STM32F4 -- main CPU is 168mhz, peripheral1 is 42MHz, peripheral2 is 84MHz --

bottom left and bottom right are peripheral busses -- 84MHz and 42MHz, respectively

[ocean coyote]

the pico has a usb phy which probably has its own clock but this is basically bit banging USB

[sacred badger]

but if you notice, USB doesn't use peripheral bus -- it's integrated differently.

[ocean coyote]

stm32 will be the same usb PHY

[sacred badger]

https://datasheets.raspberrypi.com/rp2350/hardware-design-with-rp2350.pdf

[drowsy drift]

The engineering diagram on the product page for that SKU says that all the wires are 32 gauge. To me, this says it’s only a data cable and you’ll only be able to get about 1-2 amps through it, which would be 10W (5V) to 40W (20V)

[waxen halo]

At USB2 speeds is it reasonable to have the data lines in parallel to multiple mux ICs?

[sacred badger]

awesome, ty

project evolves by the day -- i've already put a standard 3-prong plug, with a 3-way inside the box for AC PD charger for power bank, and whatever else. would like to simultaneously charge power bank and have the power bank power laptop -- and none of that disconnection tomfoolery bc laptop doesn't have battery

i do have the battery, tho it doesn't hold a charge anymore... can certainly remove the cells from the management board, and then use lipo cells meant for RC vehicles.. but thats more $ 😐

[ocean coyote]

Looking at the datasheet for this display, i see a MIN of 66ns so thats 15.15mhz if im not mistaken, does anyone know how to work out the maximum? or what a good clock freq would be with a sysclock of 144mhz

[supple pollen]

I'll normally just use the default for whatever MCU I have (10MHz for hardware SPI for many of them)

[sacred badger]

i cant brain rn, i have the dumb -- whats the proper way to search for a rp-sma bulkhead connector that's a bit longer to mount to a thick panel

like this -- i guess it's just sma or rp-sma long

[timber portal]

Feed thru?

[unique patio]

how about RP-SMA panel mount, with the mounting plate on the outside? Then the panel thickness doesn't matter:

that is not the right combination, but you get the idea

or how about https://www.datapro.net/products/panel-mount-rp-sma-to-sma-coupler-mf.html

[waxen halo]

I know it's pretty common to make a custom power supply frontend for a computer PSU. I was looking at doing the same, but now I'm exploring doing it with a USB PD supply. The thing with the computer PSU is there are already nicely defined 12v, 5v and 3.3v rails.. but for PD I'd have to break out the rails myself from a variable voltage source. Is this a terrible idea?

[supple pollen]

You only get one rail at a time, are you thinking of having different connectors for each rail and switching between them so only one set of connectors is powered at a time, or what?

[waxen halo]

I was thinking I'd request the highest voltage I could and step down

[supple pollen]

That seems reasonable, could be a compact unit. But if you're already (re)regulating the power, there's not a lot of advantage to starting with USB PD, other than pre-built converters so you don't have to deal with mains.

[waxen halo]

Well the plan is to use the same USB connection to passthrough data lines to connected devices so the custom supply can also act as a programmer

[supple pollen]

Interesting use case

[latent jungle]

That sounds like two completely different goals.

[waxen halo]

Doesn't it describe how most dev boards operate? Plug it into your computer and you get 500ma and a programmer.

[latent jungle]

What do dev boards have to do with PC power supplies?

[waxen halo]

The PC power supply is just the potential supply to the custom front end

[latent jungle]

Okay. Well. USB-PD is negoitated with its own set of signals. So, "passing the data signals" is just a matter of routing D+/D- the board regardless of supply design.
Stepping down an input supply down to multiple rails is pretty much what every device does.

Maybe you can get inspiration from this unique USB Hub design: https://www.crowdsupply.com/aerio-solutions-sas/usb-insight-hub

[ripe dawn]

if I have some buck converters like this (with a 2A limit) and need more current (e.g. 5A), can I just wire three of these in parallel? or is that going to cause all sorts of issues?

[supple pollen]

It's going to cause all sorts of issues. You're much better off getting a buck converter capable of your intended current draw (Pololu offers some nice ones).

[ripe dawn]

ah dang 😔 the prices and sizes definitely don't seem to scale linearly with output power 😭

[latent jungle]

Power output doesn't scale linearly with difficulty.

[inland jungle]

they have this kind:
https://www.amazon.com/10A-5V-Converter-Waterproof-Transformer/dp/B09SD7P92Z/

assuming you want a fixed 5V output

[ripe dawn]

interesting, I see it says

Input range: DC 10V-35V
Input voltage: DC 12V/24V

the first line seems to suggest anything in the 10-35V range, but the second suggests it needs to be 12 or 24V?

Other spots also say things like 12V 24V to 5V 10A Converter Buck Regulator

[sacred badger]

Itd likely take anything from 10-24v and regulate it down to 5v

[gritty sigil]

anyone here ever got a defective usb-c socket on esp32 feather v2? I think I have this here. I have to put pressure with my thumb on the usb-cable for it to make contact with the pcb inside, the minute I stop applying the pressure needed and let the usb-c cable sit on its own in the socket it disconnects. I've tried 3 cables. I'm about to contact my reseller and ask them for a replacement, but curious if anyone here ever had that

[unique patio]

This sounds like a soldering issue. We would be interested in the work order number that is on the bag it came on, if you still have that. Where did you buy it from?

[worldly schooner]

It could also be mechanical damage. I can't speak for USB-C, but I've had similar experiences with older USB ports before, and a slight adjustment of the retaining clips helped it stay connected.

[gritty sigil]

I bought them from one of the french resellers of adafruit, gotronic. I've sent an email to them in case... Not sure how to solve this, if it can be solved at all

[unique patio]

I think ideally they would replace it, but you can write to our support folks too if that is not working. Ping me later for more details if their answer doesn't help.

[gritty sigil]

one reason I bought from them is because they accepted to do the solder job for me. Darn. They did a splandid job, too. They must be so disapointed

also because by avoiding shipping from the US I avoid custom fees and probably big shipping fees :/

[worldly schooner]

@gritty sigil can you take a picture of the connector in question? If you can get a decent shot of the solder joints, maybe we can narrow down the issue.

[gritty sigil]

I could try. I'm blind but I can try to take a picture of the board itself. Should I try to picture it from above, or rather point the usb socket to the camera to do this, so holding it vertically?

[unique patio]

Just from above. Did they solder headers on for you? Is that the only thing they did?

But I would say work with them, since if we did a replacement it would not have headers

[gritty sigil]

yeah they soldered headers on, that's all they did

so I reckon the usb port was most likely already damaged before they worked on it. I doubt that soldering in headers could have damaged the usb-c but what'd I know

[unique patio]

The USB port connection can also get damaged if something pulls hard sideways on the USB cord while it's plugged in. It has to be a pretty strong force, but we've seen that before. We've also seen inadequate soldering.

In any case, let us know what the distributor says.

[gritty sigil]

yep will do 🙂 at the very least I know I was not the one to damage it, because the first time I plugged it in it spewed a bunch of errors at me already

I mean I suppose I can always power it via the 5v pin, but... Meh. That means I need to connect it right away to an sbc in order to use it properly. Not to mention I'm not sure if I can flash anything on it using uart1 ?

[gritty sigil]

I also see no way of working around the current issue and get a functioning usb-c port. At least I contacted the seller soon as I noticed the problem, which lucky for me was on the same day as I received the order

[gritty sigil]

yeah I guess we have to forget the picture idea... I tried at least 30 times with AI to guide me and I just couldn't get the right angle or focus or whatever to show the joints

unless there's a way to do voice chat here somehow and I could use the camera on call to show it live? I don't know

[unique patio]

I'm not sure it's worth it. In order to see an issue we would need a high-magnification picture of the solder joints on the USB jack. Does it feel wiggly?

[gritty sigil]

nop, not one bit wiggly

but inside it the usb-c plug of my cable is wiggly

the cable plugs get to wiggle about in the socket, basically. One tiny little wrong bump and it disconnects if by miracle it stuck on when I plugged it in. But most of the time I have to apply some force on where the plug meets the socket for it to connect

[unique patio]

That's true of my good plugs as well. It may be that the fingers inside the jack got damaged somehow.

[gritty sigil]

if that is it then I reckon the only fix is to solder on a new usb-c socket, right?

that's assuming of course that one would have what is needed to even do that... Board swap's more likely in my case seeing my disability

[gritty sigil]

so I've gotten a friend to take a video of the board when I'm trying to demonstrate the issue. I get that there should be some wiggling going on, but that much? Suspicious to me. Also took a picture of the board

hopefully that showcase the problem good enough... Sorry for the awful quality but couldn't do better

[unique patio]

nothing obvious, but I hope the distributor is able to help. Otherwise you can post in https://forums.adafruit.com which is the official channel for replacements.

[gritty sigil]

yeah. But do we at least agree on the fact it should have a bit of wiggle room but not SO much?

or am I insane?

because right now if I plug it in, a lot of the time my pc just doesn't enumerate it. As in, it's not even trying to. I might get it enumerated sometimes byt it's very rare. If I put it on my esd mat when it is connected, poof it's gone

[unique patio]

I think it is broken, somehow. I am not sure how. It could be the soldering, or it could be inside the jack. Either way, it deserves replacement. This is not common: there is something wrong with this particular one.

[gritty sigil]

it's a relief to know that I wasn't imagining it 😄

thanks for the help, really appreciate it. I'm very curious what the folks at gotronic will say about this one. I've sent them the video and picture, so they can be sure I'm not making it up 😉

[ripe dawn]

I would check that it's not the cable that's the loose/wiggly part (I've had that issue in the past). Also personally I'd buy a new one of these boards before attempting to solder a new connector on it 😅

[lilac pecan]

was no one gonna tell me that the nrf52840 would struggle with HD video?

[knotty tiger]

you're putting a live bare PCB on a ESD mat? maybe don't do that. it might be conductive enough to short things out, or at least make them misbehave

[lilac pecan]

is the m4 express still top of the line for feather form compute?

[unique patio]

The Espressif chips can have more RAM (in the form of PSRAM). THere will be a Feather RP2350, of course. Depends on the capabilities and capacities you want

[lilac pecan]

hmm, i want to make a action cam esque thing, considering teensy, or raspberry pi pico idk, but I might just continue with my nrf52840 sense in low res

[unique patio]

do you want to record video? That's a tall order. There is native camera support on various Espressif builds: https://learn.adafruit.com/search?q=camera%2520circuitpython

[lilac pecan]

yes, I would also like video stabilization, but maybe after the fact because extra processing, since I have sensors from nrf; but that would also require writing the sensor data, and idk if that would bottleneck there

and the memento is a little big for my goal

[hasty solar]

trying to troubleshoot some indicator LEDs in a circuit driving a relay. subset of the current schematic attached - left LED indicates "voltage supplied from timer pin," right LED indicates "transistor closed and supplying power to relay," but the issue i'm hitting is that the voltage sent to the relay is dropping due to the current splitting off to supply the LEDs, and it doesn't end up high enough to activate the relay. the only way i can see to increase the voltage back toward Vcc is to reduce the resistance toward the coil, but that puts the current over the rated current for my relay. am i missing a better way to set up these indicator LEDs?

i could just throw more transistors at it ig

[knotty tiger]

what's driving the transistor base?

[hasty solar]

op-amp wired up as a voltage comparator

[hasty solar]

hmm, seems like the op-amp might be sinking the voltage somehow. increasing resistance on the op-amp's inputs reduces the voltage drop i'm seeing in the output circuit

specifically it looks like the ratio between the resistance on the input and the resistance on the output was causing issues. putting 100k ohms on the inputs and 1k ohms on the output virtually eliminated the voltage drop across the transistor

[supple pollen]

My guess would be the current is dropping due to the 100Ω series resistor

[hasty solar]

sure, but the current dropping is what I want - it keeps it within spec for the relay. the trouble was that the voltage was dropping.

[sacred badger]

anyone experienced with re-using laptop parts -- namely keyboard/touchpad

if so, can we agree Elan is a crappy corporation

i'd love to reuse the gigantic touchpad of the Dell XPS 9500/9700, tho idk if i'm missing something such as I2C drivers being built in to the BIOS, or it totally not being plug n play with an FT260, requiring some sort of further driver to init it and present it's descriptors to the OS

furthest I got was i2cdetect -- finding address 2c -- then i2cdump the address, first 2 words showing 00 00 -- dump again, everything FF FF or 00 00 -- i assume it expects some sort of write to function, but i'm not a software guy

[sacred badger]

$35 each is steep -- would need 4, and $140 is outrageous. $60 more and I could finally FPV my drone

wonder just how difficult it is to assemble some RG174 W.fl or MHF4 pigtails and some elongated RP-SMA bulkheads

[gritty sigil]

I mean I posted a video that shows that even when it's not resting on any surface it misbehaves 🙂 I have to hold the usb-c socket against the cable otherwise things go crazy

[gritty sigil]

I've tried a good 4 cables by now, so it's definitely not the cable. As for soldering anything, out of the question for me since I'm blind, either way

[supple pollen]

That can be a bit of a balancing act, but it's a consequence of Ohm's law: changing the voltage changes the current, and vice versa.

[supple pollen]

Dell is notorious for using nonstandard cost-optimized parts for which drivers and documentation are difficult to impossible to find. The laptop parts I most often re-use are the displays, as they're generally the most valuable remaining part, after the other parts have become less relevant.

[hasty solar]

what determines whether the current or voltage changes? i was picturing current being the only thing that changes, given a constant voltage source and varying resistance

[supple pollen]

The difference is that the voltage is now split across the 100Ω resistor and the relay coil (possibly in parallel with some LEDs)

[hasty solar]

oh this simplifies things dramatically actually. i had the coil resistance set to 100 ohms in the simulator but the datasheet puts it at 720 ohms at ambient temperature. makes the voltage/current swings much less dramatic.

[coarse lark]

does anyone know of a good NRF52840 module thats similar to the ESP WROOM's or what the itsy bitsy uses?

[unique patio]

do you want the module only? You can get the RAYTAC module by itself. We sell the Feather one separately: https://www.adafruit.com/product/4078

and there are plenty of other distributors of the Raytac modules

[coarse lark]

yeah thats what ive been lokking for, thanks

im looking into these modules for a future board im planning

another module i found was one made by minewsemi which also looked promising

[unique patio]

https://www.raytac.com/product/

[coarse lark]

ill look into these

[winter lake]

Hello yall, I was wondering if someone could help me with an issue I'm having. Essentially I am trying to make a vaping device with adustable voltage based on an rpi pico, I achieved this through PWM, but the only problem is that the current the pico outputs is only 12mA whereas I need 1.5-3A of current. My current circuit is: 3.7V battery w/ 750 mAh capacity, this is connected to a 5V boost board that I use to power the pico (don't know it's current output, but it's sufficient enough to power the pico so take from that what you will), the pico then has PWM, and I also have an NTE2987 mos laying around but I am confused on how to implement it. Sorry for the long paragraph but I've been asking all the AI's and searching all the forums to no avail.

[supple pollen]

NTE2968 maybe?

Normally for a MOSFET, you'd connect the source to ground, the drain to your load (and the other end of your load to its power supply), and the gate to a GPIO pin. Unfortunately, the Pico only produces a 3.3V output, which is insufficient to drive that MOSFET into sufficient conduction. You'll probably need either a different MOSFET that can be controlled with such a low gate voltage, or a bipolar transistor (along with a base current limiting resistor).

[sacred badger]

i mean, i did manage to externalize a 7370 3200x1800 touchscreen.. given the touch controller is USB based

i can tell the touchpad uses both I2C and PS/2, along with im guessing palm detect and an i2c interrupt

though, there may be a pullup resistor needed on some particular pin

maybe on TP_LOCK, PTP_DIS#, or even TP WAKE need those pull up/down resistors

which, to me, it should work with PS/2 alone, though I went down a BIOS disassembly (non-dell, HP) rabbit hole and couldn't really find i2c touchpad drivers, but did see touchscreen relevant things, along with various i2c drivers

[sacred badger]

thank heavens for thetechstall for schematics..

[sweet cairn]

Something I'm curious about - why have 'Do Not Place' footprints like R9 here?

Is it a case of 'I might need it later but I'm not sure so I will leave space for it'?

[sacred badger]

you ever see PCBs with pads placed, but no components?

[gritty sigil]

just wanted to let you know gotronic replied and sent a replacement, free of charge, and let me keep the original defective board at the same time. Maybe I can still make something with it, who knows? Using the 5v vbus gpio and programming via uart1 for example, rather than uart0

[unique patio]

Glad to hear!

[sacred badger]

dan, i think i'll go with some flange mount rp-sma connectors, hopefully they're small enough for my use-case.

[gritty sigil]

is my idea of programming over uart1 doable? I think so, but not sure. Like for example if I connect a ftdi usb to ttl adapter on uart1 pins, I can just specify this in arduino ide for flashing,? I don't think uart0 is special in this regard

[sacred badger]

i presume uart0 is for exactly that purpose

[gritty sigil]

yes. But it's broken on this board they let me keep

[unique patio]

uart0 pins are also broken besides the USB jack? I would say the amount of time you are going to spend on this is not worth your time.

[gritty sigil]

no no they are not broken. But I thought uart0 was accessed via usb-c only

[sacred badger]

i assume theres some sort of usb ~> serial converter

would cutting this like it's cropped be ok?

[unique patio]

that should be ok if necessary

[unique patio]

there are no pads that are easy to get to, right

[sweet cairn]

No actually 😅

[worldly schooner]

It looks like a pad meant for custom filter adjustments. I can’t say exactly how it should be used, but I could see someone using it to adjust the band or add attenuation?

[sweet cairn]

I think I understand, but still not fully sure 😅

Not sure if they check mentions but maybe @floral viper can help, they designed this revision of the adafruit macropad I think

[floral viper]

i actually didn't design it, i just posted the files 🙂 this would be a great question to post for AAE though!

[knotty tiger]

yeah, it does kind look like a place to adjust the input filter to the amp without revising the board

[sweet cairn]

Oh I see, apologies for the ping then 😅

I've already asked questions related to this a bunch of times but I haven't really fully understood. Hope it will be ok if I ask there

[sweet cairn]

Got it, so it'd be another capacitor then right?

[knotty tiger]

could be a resistor or capacitor; not sure what makes the most sense here. i'm kind of rusty on filter fundamentals at the moment. basically, if the filter doesn't behave as expected, they can add a part there by reprogramming the pick-and-place without having to revise the board (and order a new batch)

[sweet cairn]

Makes sense. Does make it difficult for me to reproduce if they fitted it out on a production model but not on the schematic lol

[knotty tiger]

yeah, that's plausible. i think back-annotating a schematic for a last-minute engineering change doesn't always happen (in general, not just at Adafruit), and even if it does, the published version might not get the update until later (if at all)

[sweet cairn]

That's a bit of what happened here actually!

Not sure if it's relevant info but the original Amp IC used in the Macropad got discontinued so they had to switch to a different one, but the schematics weren't updated. Thankfully adafruit and its members on this server were kind enough to help out

Anyhow, I'll get a breadboard and the datasheet and start experimenting stuff until it works ig.

I had made a circuit design based on the amp's datasheet but that didn't work and I've been unable to figure out why, so looking to adafruit's board for reference

[supple pollen]

How didn't it work? Output too quiet? Output distorted? No output? Flames?

[sweet cairn]

There was no buzzer output. Based on what I could make out with some limited testing with a multimeter, the buzzer wasn't receiving any power, and I think amp IC wasn't either, not sure though it's been a while. And I am not sure if my testing was accurate either, so will be breadboarding my original design too

This is my implementation. You might remember having seen it since you have helped me out quite a bit with it in the past 😅

[supple pollen]

Yeah, that does look familiar.

[worldly schooner]

What is the purpose of the caps to ground on the speaker side of the amp? oh I found the amplifier you referenced.

Also, why are there polarized caps on the input side?

[sweet cairn]

Datasheet had mentioned using tantalum caps for better performance so went ahead with it. I didn't really have to care about cost or practicality on this project and so just went ahead with whatever seemed fancy 😅

[gritty sigil]

indeed no. I just had a friend checking over https://github.com/adafruit/Adafruit-ESP32-Feather-V2-PCB and uart0 is not exposed anywhere else than usb-c

I tried to get a basic sketch with OTA going, but the tiniest shake of my finger holding down the usb-c cable into the socket would cause it to fail

[rancid lagoon]

Don’t know where to ask so i’ll ask here, could a pico do 1.8v I2C

[unique patio]

It will run at 1.8v if you power it at VSYS with 1.8v.
an nrf52840 is more flexible. you can power it at a higher voltage but set its pins to use a lower voltage

[rancid lagoon]

Then i’ll use a level shifter

[sacred badger]

slippery slope…

before long youll be modding aliexpress chinesium

[sacred badger]

THERES A FREAKIN STRING TO SEPARATE LCD FROM BACK?!?

[supple pollen]

Now THAT's a nice touch!

[ripe dawn]

well that would certainly up the repairability score!

[sacred badger]

dell xps 13 9350 btw

[rich sorrel]

Hey are there any footprint files for the Feather RP2040? I found the PCB files but I'm looking for a footprint I can use to attach it to another board, and I'd like it to be more accurate than just using two header components to simulate it.

[worldly schooner]

What software are you using? I believe there exists a generic Adafruit_Feather footprint for KiCAD in the Module folder.

[rich sorrel]

KiCad, I couldn't find it but I'll check again

[rich sorrel]

Ah, I am just an idiot, and found it immediately. Thank you for the help.

[worldly schooner]

Don’t beat yourself up, there are a lot of parts in a lot of folders and it’s easy to miss haha

[gritty sigil]

well I am either cursed or I use a cable that displeases the feather for whatever reason. Absolutely insane! All of my cables are the same, I've always used those before, the 5a one meter long cable from adafruit. I have 6 of them. My new esp32 feather v2 has exactly the same issue. I've managed to flash esphome on it by being extremely careful and avoiding touching the breadboard on which it is connected, otherwise instant disconnect

either the cables are all wrong, or both of the feather boards are broken in exactly the same way, or... I honestly have no clue what's going on

never seen something like this, pun intended 😉

right. Just placing a finger on the breadboard is enough to disconnect the whole thing. Holy wow

gotronic assured me they tested the board before sending it over and I see no reason they would have lied about that. Plus I don't believe that getting two defective boards in a row is this common, let alone two with exactly the same issue

so if anyone has any ideas here I'm all for that, because I have no clue what to even do anymore

[hushed ermine]

maybe you are extremely conductive

[gritty sigil]

heh, maybe? But I have an esd mat, the dissipative kind, and I ground myself on it using a wristband. My mat has a connector for the wristband

and I make a point to never touch a pcb without wearing it

[unique patio]

so you are not touching the USB cable itself, just the breadboard?
If you put your finger on the USB jack on the feather, with nothing plugged in, does it feel like it's wiggling?

[gritty sigil]

nop it's stable

and yes only the breadboard. I can only assume by touching the breadboard, I moved it a few milimeters and poof it went

fwiw the usb cables I use are these ones here https://www.adafruit.com/product/4199

[gritty sigil]

so I tried the usb cable that came with my anker battery just for the giggles. Same issue

so that means the adafruit cables are not the problem

[unique patio]

does it feel like the plug is seated all the way in to the socket? It is very strange. Did Gotronic send you a new board and you still have the old one?

I have one of these, and it's fine. Do you have the original bag with the work order number on it?

The still photo is very dark, but I was enable to enhance it. I don't see anything wrong. However, it is very low resolution. If the original is higher resolution, could you post that?

also does it make any difference if you turn the USB plug upside down, since it's reversible?

One theory is that one of your cable plugs may be damaged, and because of that it's damaging the socket in these boards. But then it would damage other board sockets too. If you are not seeing that, then that would eliminate that theory.

[gritty sigil]

hm yeah I know the still is very low resolution. I had to do it with the help of a friend, they literally took a screenshot of the video call we were in while we were trying to check out the board for issues. I still have the original board, gotronic let me keep it instead of making me go through the hassle of return and all that.
As for the usb cables, I can definitely tell you that I used it with other boards, including seeduino xiao, and even a zoom f3 field recorder, with no problem. I can try to reverse the cable and see if it does anything, too.

I needed to be guided to be sure the still would show the board properly, so kind of why I couldn't take a high resolution picture at the same time since I was in a video call

the easieest way I can reproduce this now is just lifting the breadboard away from the desk, which forces the usb cable to angle up or down, it's game over

I just tried another cable, usb-a to usb-c this time around. Didn't expect different, but tried regardless. So that's 8 problematic cables. I reckon by now it's far more likely to be the board having a problem, as insane as it sounds

[gritty sigil]

I so wish I was tiny enough to explore the usb socket lol

[dim sapphire]

I’m looking at the page for the esp32 feather v2 (https://www.adafruit.com/product/5400?gad_source=1&gclid=EAIaIQobChMI3YGv6oK-iAMV9h-tBh0BFDdTEAAYASAAEgJkiPD_BwE) and it says there’s two i2c ports but “only one is configured by default in the Feather Arduino IDE support”… can anybody tell me the implications of this? Would I be able to configure the chip to use both i2c ports for peripherals, using either arduino or circuitpython?

[gritty sigil]

I believe so, but don't quote me on it. I think pinmux lets you configure any gpio as i2c or uart or whatever on the board, if I'm not mistaken. Plus, the pinout on the adafruit guide for the feather v2 does talk about i2c afaik

as for how to configure the pins, not sure about that myself given I couldn't even really get started with mine as I keep having issues

[regal crater]

Good Evening/Morning All! I'm new to h/w coming from a software design background and I'm having heaps of fun! I've gotten stuck into kicad and I was hoping to work out what might go into getting the ADA1385 UBEC DC/DC onto my pcb instead of adding a couple of plugs and wiring in and out.

I can see the active chip for v in -> v out is an MP2307 but I'm struggling to work out what's on the rest of the device being new to h/w and all. I was planning on making a custom symbol and step file eventually as I haven't found one

https://www.adafruit.com/product/1385 I was hoping for some help working out what else is on it

[supple pollen]

My first stop when investigating a new chip is to go to its manufacturer's site. Normally there will be a data sheet which will include a description and some example circuits. Often there will be an evaluation board too. While you don't need to buy the evaluation board, the manufacturer's description generally includes a full PCB layout, parts list, and explanation.

In this case: https://www.monolithicpower.com/en/mp2307.html

In this case, the MP2307 is an older chip, not recommended for new designs, so you might consider the updated MP2393 https://www.monolithicpower.com/en/mp2393.html if you're designing your own board.

[unique patio]

I discussed your USB jack problem internally. We have no previous record of such a problem with the USB jacks. This is the same jack we use on many, many other boards. We are willing to replace the board from Adafruit directly, but it will not have soldered headers. You could also ask Gotronics to test some of their stock and see if it has the problem. (Maybe they are testing the board after soldering on the headers, and by chance they are testing with a cable that damages the plug. But that is an unlikely explanation.)

Perhaps it's worth giving one of the boards to a friend for further trials.

If you open a thread in our Forums, say in, https://forums.adafruit.com/viewforum.php?f=57, we can get you in contact with Adafruit support for a direct replacement and further discussion.

[gritty sigil]

I thought of them damaging the port too, I don't see what else it could have been, even if it's unlikely. I have no more ideas right now. I'm guessing a further step might be to examine the port via a microscope or something, but I don't know for sure. I wouldn't mind talking of this further in forum, but having a replacement without headers would be useless to me. I've got noone close to here who can solder, and that's the entire reason why I asked gotronic to solder this in for me

I even tried with a psu from anker just to see if it would behave differently than with my pc, but nop. Lift the breadboard away from my desk a little and the esp32 instantly stops responding to ping, which suggests it lost power

[unique patio]

I discovered we do sell it with headers: https://www.adafruit.com/product/5900

[gritty sigil]

do we at least know if there'd be any custom fees?

[unique patio]

I have no idea. You'd have to ask support that question.

[gritty sigil]

would make sense there is, though

[unique patio]

It depends on your timelines. You could mail one to someone to check it, or mail it back to gotronics. Gotronics could order some headered ones on its next distributor order.

But I think they need to check their stock, and check one of the ones they did for you.

If they have a batch of bad ones, they need to know that. Or they need to know it got damaged later.

[gritty sigil]

ironically I asked them if they could get me id 5900. They said they could but it would take several weeks for it to get to them and then for them to send it over, so we settled on them soldering in headers for 5400

yeah adafruit would have custom fees to france, likely

VAT 20% of total cost

there's a ddp option for dhl express, that said. Might cost more shipping but honestly if it avoids the stress and hasle of duty tax after

[gritty sigil]

I'm not sure what to post in forum exactly though? But I suppose I could ask for a 5900 as replacement, because really no headers in is a problem... But also 44 usd of shipping with dhl express or 20 usd of shipping with usps is kind of ouch

[unique patio]

You can have that conversation with support by email. The only reason to post in the forums is to establish a thread there where I authorize a replacement.

that is our standard procedure

[gritty sigil]

I see. I'm still unsure tough given it would cost me $44 usd shipping with dhl express (probably ddp but unsure as well about that), or $20 usd with usps and who knows how much custom fees... Ugh.

[unique patio]

no, it would not cost you. We are replacing it.

[gritty sigil]

ahh so free shipping too... Aside from customs I guess, cause adafruit has no control over this

[unique patio]

there may be some way around that, since it's a warranty replacement. Support would know

[gritty sigil]

alright. So what should I write in the email to support essentially?

[fervent lance]

I have a problem. Basically I made a riser of s camera module to extend it out from the main board. The thing does not work. Connections are fine. What worries me is that it may be something from signal integrity, and if that's the case, I really don't know how to fix it without lots of trial and error

[unique patio]

open a thread in the forum. Post the link to the thread here and ping me. I will answer, authorize a replacement, and then you will email support.

[gritty sigil]

okay. Gosh, sorry for all the questions, I'm a bit of a mess after two failed boards. I'll also try and do my best to arrange shipping back to gotronic at the same time. They were really nice to send one over without me having to return the first board, because returning for me is a nightmare. The post office opens at ridiculous hours where everyone works and closes exactly when people get off work, and the entire thing's touchscreen driven. And the staff is heavy handed with discrimination and telling me to bring a friend along to help because they have better things to do

[unique patio]

I am sorry you have to put up with that. We could veer off into disability rights but we're talking different countries here.

I agree, our replacement procedure is a bit unintiuitive. discord is an unofficial support channel; the forums are the official channel, so we do stuff like that through the forums

[gritty sigil]

yeah, figured it was something like that. I'm a bit stressed and confused also honestly so it didn't help me catch up

[unique patio]

I have no idea what gotronics wants to do but a phone call or and email exchange may resolve that. I wonder if you can get a prepaid mailing label or something.

[gritty sigil]

yeah I'll ask them, worth a try

[gritty sigil]

I also tried to get the order number that was on the bag just in case, but I kept messing up with AI hallucinating things

[cold path]

anyone skilled with PCBs have a question. Am just really starting to build and design them so my knowledge is very low, and learning a lot as I go.

I am making a PCB with a Pi Zero W mounted onto it. However, I want to have the SD card available in a different place than where it will be mounted. Can I put an SD reader on a different part of my board and run traces back to the Pi? But then, how would I connect the Pi to the traces? Would I then have to desolder the SD reader from the Pi and patch wire from the trace ends to the desoldered points on the Pi?

I know I could get an SD extender and run it over, but I am trying to do it as neatly (and cool) as possible!

If I am trying to do something stupid, please call me a dufus and point me in the right direction. 🙂

[gritty sigil]

okay posted topic asking for replacement but also recap of the whole deal, in case it ever affect others

while writing this I was thinking about soldering... Could that have damaged the pads of the usb-c jack ? I don't know enough about soldering and electronics over all to say, but it's a thought that came to my mind

[shy spear]

Hi, Im posting today because after attempting to get feedback on r/PrintedCircuitBoard either no one responds or the mod gets mad at me for having to many tiny subcircuits... Is he in the right, I really dont know and am hoping for some honest feedback when it comes to my pcb design. Please let me know if im posting in the wrong channel or if there are other discords more suited to pcb design review.

[supple pollen]

It might be worth trying a cord and board and firmly pushing the USB connector into place. Some of them seem to seat, but just barely make connection, but some more pressure causes them to pop in another millimeter or so and provide a solid connection.

[supple pollen]

You're trying to parallel two buck converters, that is not a good idea. I'm guessing the motors are servos – if so, a 3.3V signal should control them directly, no level shifter needed. And the commenter is right, it is hard to follow the circuitry with everything split up like that.

[shy spear]

So to what degree should I have my subcircuits, if possible an example would be great. I will look into either an IC buck converter or just a slightly bigger buck converter module that can handle all the 10 amps that I need (realistically never going over 6). I thought I might as well use the level shifter for the servos because the motor controller requires 5v signal for control. Other than those errors are my resistor and capacitor placement good?

[shy spear]

I would also like to thank you for a very nice and informative reply, im relatively new to pcb design and my only previous experience with it is from a short segment of highschool.

[supple pollen]

How to divide things into subcircuits is a matter of taste, but if a couple of devices mostly connect to each other, I just put them next to each other and connect them. Note that 10A is a lot for a PCB trace, you'll want wide traces, and possibly omit soldermask and add solder or even a bus wire to improve their current carrying capability.

[worldly schooner]

I can’t speak for the zero W as I don’t have one on hand to compare, but the 2W has test pads underneath that allow access to the sd card port. The proper way to connect to them would be with pogo pins, but you’d need some means of ensuring secure mechanical mounting to the pcb for that to work.

[unique patio]

If the soldering was done with any skill, it shouldn't make any difference. I do that kind of header soldering all the time. But to check for an issue, the board really needs to be inspected. An experienced friend would be able to tell and would be a neutral party, but that requires mailing one of the boards.

[gritty sigil]

yeah I tried that tons of times. It's really going as deep as it can, pushing further just makes the usb jack even more mad and reconnects/disconnects tons of time

[obsidian dove]

I'm using the matrix portal S3 with an Adafruit 64X64 RGB display. My text or bmps are always split in half, half on the upper and half on the lower of the display. I cannot figure out how to fix this. The board is already E addressed for this display, per Adafruit. I need help.

[gritty sigil]

aye, makes sense... Thanks so much for the help btw, appreciate it a lot

[cold path]

That's really useful thanks

[urban cypress]

hello i have a power only type-c extension cable and i'm trying to convert it with a toggle switch.

thing is i can't seem to get any power from it i tried multiple type-c power sources.

i tried checking for continuity on red and black including flipping it over. it's ok too.

[urban cypress]

ugh nevermind i found reference that these don't work on the raspberry pi 5 https://thepihut.com/products/usb-c-cable-with-switch. nor any other of my type c devices. shop i bought it from didn't have that notice but they were recommended for the raspberry pi.

[dry ember]

does anyone know the exact connecter on the Lithium Ion Polymer Battery - 3.7v 1200mAh?

Attempting to order the corresponding jack on Digikey, can't tell which one it is for the life of me

https://www.adafruit.com/product/258

i think this is the correct jack, but i might be completely off

https://www.digikey.com/en/products/detail/jst-sales-america-inc/S2B-PH-K-S/926626

[rancid lagoon]

they're https://adafru.it/1769 if it helps

[dry ember]

oh fantastic

didn't realize adafruit sold em

[ornate carbon]

Hi -- not to sure where to ask this. Anyway, does anyone know if this USB to Serial cable is 5V compliant? I.e. I know it sends 3.3 V logic, but if I feed it 5 V logic will I kill it? https://www.adafruit.com/product/954

(There's other USB to TTL things on the website that are explicitly 5 V compliant, but the way this is broken out is particularly convenient)

[latent jungle]

Based on this note, the corresponding data sheet says RXD is 5V tolerant

After July 1, 2014 we changed to a violet body and the PL2303TA chipset.

footnote 2

[ornate carbon]

Ah, I see there's this note: "As of Dec. 21, 2016 we will be shipping cables with SiLabs CP2102 chipset instead of Prolific." Looking at the CP2102 datasheet it lists 5.8 V on the absolute max on "any I/O" pin so it looks like it will be happy with 5 V.

[latent jungle]

lol. I remember seeing the second bullet point on the page, but I read it as "2006" not "2016. 🙂 Good catch.

[jade wedge]

So, I want a switch to control power, which may be as high as 1A, but I want a small switch as it's a small board, so a 1A capable switch is out. Obviously, use the switch to control a MOSFET.
N channel, in enhancement mode so it's normally off, but a positive gate voltage turns it on.
The positive of my power source should connect to the Source pin, while my load connects to the Drain pin... Right?

Also, pin 2 is the Source, right?

[supple pollen]

Nope, the positive of your power source should connect to one side of your load and one side of your switch. The other side of your load connects to the drain. The other side of your switch connects to the gate. The source connects to the negative of your power source.

Note you probably want a pull-down resistor from gate to source to turn off the MOSFET when the switch is off.

[jade wedge]

Figures I'd get it backwards. Also, I realized how I got mixed up. In collecting information one of the examples I was looking at had the configuration I described. It's for a P channel though.

Also the gate goes to ground instead.

So if I use a P channel instead, and ground out the gate, it should work how I originally was hoping, right? I think I'd rather switch the positive incoming line simply because this is hopefully going to be able to run off either battery or USB.
Let me hammer out a schematic

Is this better if I the switching done on the positive side, rather than negative/ground side?

[supple pollen]

I usually switch the negative, but that works too

[jade wedge]

For some reason I feel more comfortable switching the positive. Conceptually I understand the effect will be the same either way, but disconnecting the positive just makes me feel better. Also there will be a battery as well, and that will be switched via the boost circuit, and therefore cutting off the battery's positive. So in my mind disconnecting both positives makes sense.

[supple pollen]

I don't understand what you mean by the battery and boost circuit and both positives, but that's okay I don't have to.

[jade wedge]

For battery power there's going to be a boost converter to bring it up to 5v, and the converter chip has its own enable pin that I plan to switch with the same switch (Double pole double throw switch). The converter chip will only disconnect from its input source. It can't disconnect the ground as that goes straight from the battery to the load.

[supple pollen]

If you can disable the converter, I don't see why you have to switch the load too.

[jade wedge]

Because it will be able to power from either battery or USB, and I don't want to have to unplug it to turn it off since it will also be able to charge.

The charger will of course be unaffected by the switch entirely.

You'll see when I get a proper design worked out.
Or I'll make a complete hash of things. One or the other. All part of learning.

[supple pollen]

Heh, the "all part of learning" is a bit I know well!

[jade wedge]

Heh. I assure you though, it all makes sense in my head.

Except for the FET part. Which should be straightened out now.

[dry ember]

anyone know if there is a datasheet or a footprint for the adafruit vibration sensor?

https://www.adafruit.com/product/2384

[supple pollen]

Here's a similar part: https://soldered.com/productdata/2016/02/Soldered_SW-18020_datasheet.pdf

Here's another one that covers that specific part: https://www.robotpark.com/image/data/PRO/91469/shake_switch_sw180.pdf

[teal siren]

Hello. I'm trying to figure out what I would need to get this to work: https://www.adafruit.com/product/413

what specific diode / transisitor / power supply configuration is correct? Any help is greatly appreciated 😉

is 1A power supply ok? do I need 5A ?

[supple pollen]

You'll want a 12VDC supply capable of at least 250mA. You can use a bipolar or MOSFET transistor to switch it, and a protection diode is a good idea.

1A is plenty

[teal siren]

is this a good transistor: https://www.adafruit.com/product/355

[supple pollen]

Yes, that one is a good choice.

[teal siren]

thank you for your help. this is where I get confused. then I see something like this and don't get the difference: https://www.adafruit.com/product/976

[supple pollen]

Those will work too. The first one is a MOSFET (which is controlled by voltage), the second one is bipolar (which is controlled by current). Both will work well in this application. Note that if you're controlling it with 3.3V logic, the MOSFET may not conduct fully and might generate some heat, but in this case (where it's only conducting 250mA to the solenoid), it should be fine.

[teal siren]

if you had to pick between the two which one would you suggest?

[sacred badger]

sir, this is an Arby's

[teal siren]

Haha.. At this arby's, I don't want to make a mistake that would do more damage than necessary

[supple pollen]

It would depend on what I'm driving it with. I might opt for the TIP-120 as it can be driven easily from 5V or 3.3V logic, and is pretty robust.

Note that the MOSFET has a "parasitic" body diode that will act as a protection diode, but with either transistor, I would use a separate protection diode.

[dry ember]

I'm trying to power a NodeMCU ESP8266 board, which requires 4.5V~7V. My current plan was to use a 3.7 V LiPo battery (as it has a fantastic form factor), and a AP3602AKTR voltage regulator, which outputs 5V at 100mA. The problem is, while the operating current of the NodeMCU board is ~80mA, there is a massive current spike at startup up to 300mA.

Is there any easy way to deal with this current spike? Or is it far easier to just find a different battery?

[inland jungle]

MOSFET body diodes aren't quite the same as protection diodes, right? They're in a different place in the circuit...

[blissful frigate]

Even if the spike wasn't there your 100mA converter is likely gonna run very very hot

the datasheet does mention that it can take 250mA for 100ms

Efficiency isnt great either, below 60% if your battery is fully charged

[supple pollen]

You're right that they're not quite the same. There are a few different ways to place protection diodes.

[rancid lagoon]

i'd get a different voltage booster that can give a bit more juice

[dry ember]

yeah, looking at the LM5002

i don’t really understand how to set it up, but i guess i need to do some research on boost converters

[dry ember]

if anyone has any boost converter suggestions, lmk

[worldly schooner]

The easier and possibly more efficient option would be to use a low-dropout regulator to feed the system directly via the 3v3 pin. Do note that this makes backpowering a concern, so I’d advise not connecting the board over usb while the battery is connected in this way.

[rancid lagoon]

what are the dimensions (mainly diameter) of the raspberry pi 5 RTC battery

[latent jungle]

designing a SMPS is non-trivial, especially their PCB layout. It might be better to use an off-the-shelf module, depending on your load requirements.

if I need more than 10 W, I rarely do my own. And for less, I carefully follow the ref design, especially for PCB.

[dry ember]

thats what im currently doing

microchip was VERY kind and made example circuits, one of which was exactly what i need

[latent jungle]

again. the PCB layout is way more critical then the application circuit values

[dry ember]

currently looking at this guide by TI for pcb layout

https://www.tij.co.jp/jp/lit/an/snva731/snva731.pdf?ts=1726513046733&ref_url=https%253A%252F%252Fwww.google.com%252F

any other suggestions of places i could find info about pcb design for boost convertors?

[latent jungle]

Now I’m confused. You said Microchip had good circuit examples and then you linked TI resources.

You need to follow the layout recommendations of the manufacturer for the SMPS controller.

[dry ember]

I was more looking at the general PCB layout tips in the TI resource, which seem to be consistent with other information I have found online about PCB design with Boost Convertors

Actually, thank you for pushing me to look, as I have now found an actual example layout for the MIC2288 which i could not find before

[latent jungle]

Unless you are a power converter expert, you should follow the manufacturer’s guidelines for the SMPS

Connecting components with thin traces isn’t going to turn out well

[dry ember]

Thanks for the advice. I'm still on the hunt for any information from Microchip about the MIC2288 other then an example PCB they put together a sheet on, and a data sheet that does not bring up PCB design.

[sick glacier]

Hey guys, if anyone has any spare time and experience with single-cell LiPo charging, I was wondering if this schematic for a 2 amp charging circuit and power path would work. It uses a switch-mode battery charger instead of linear to handle the 2 amps properly. Thank you so much. Obviously, feel free to use it in your designs if it works lol (I don't take responsibility though, this is my first battery charging circuit)

[surreal tangle]

Is this LiPo a protected cell? If not, you may want to add a low voltage disconnect, otherwise your boost converter could drain the battery too low....

[gritty sigil]

@unique patio I got my replacement today 🙂 it is as we thought. id 5900's usb-c jack works perfectly fine. Whatever it is, the blame is with gotronic most likely when they soldered. I see no other possibility to be honest

now that I have a board that isn't defective on the usb-c jack front, there's somthing I noticed on the two others. It might be unrelated and not the cause, but... There is a miniscule crack at the back of each usb-c jack

the non defective board does not have it

[unique patio]

I'm glad you got a working one. When you say "crack", what to do you mean?

[gritty sigil]

the crack runs vertically from the back of the usb ports all the way down to where it meets the pcb. Almost like the usb jack has been split in two

it's large enough that I can comfortably move a fingernail along the length of the crack

I'm not exactly sure how to describe it

mmh

[unique patio]

there is a piece of plastic there. The same piece of plastic, I think, is also the middle "finger" that can be felt at the front of the jack. The contacts for the plug are on the lower half of the finger. So if the plastic finger is cracked at the back, I think that would explain the erratic operation

can you feel a crack on the finger?

there is no visible seam on the back that could turn into a crack

[gritty sigil]

I think so, yes. It's very hard to say. But there's something off with the back of those two usb-c ports compared to the functioning one

[unique patio]

it's hard to see how that would get cracked.If you have a bad USB-C cable, I could imagine pressing very hard might fracture the plastic. It could also be that there are multiple versions of this, and some of them are two-piece. But I don't see any like that on the boards I have.

[gritty sigil]

yeah. Like I said, random thing I've noticed

doesn't mean it's the reason for the failure

[unique patio]

Thanks very much for the observation. But it's an interesting correlation. We'll keep this in mind if we have other reports of flaky USB jacks.

[gritty sigil]

I'm not sure if it would be easier to get what I mean and if it's just a quirk that shouldn't matter with a video call somehow. If so I'd be happy to set that up with you, if you're interested. It's very hard to describe for me, and it is also rather difficult to take a picture that would show the issue on my own since I can't see

so maybe with a live showing you would have a better idea of what it might mean or not

[unique patio]

sure, pick your video. you can DM me if you wish with that. Main thing is if you can get close enough. Also, put a bright light on it

[gritty sigil]

in case it matters, the serial numbers are as follows:

• good board: 5799004490
• bad board 1: 54B0006616
• bad board 2: 54B0007382

[unique patio]

The most interesting numbers are the work order numbers on the Adafruit fresh-from-the-factory bags. You may not have those for the Gotronics boards.

[gritty sigil]

probably not

I'll try and do my best to see if a video with a better resolution would capture what I mention. It'll take a bit of time since I'll have to find a way to take the video and have my friend look at it to see if it is visible or not, but I'll send it over in dm asap

[unique patio]

I thought you meant a video conference with me. That is OK too. If you are just recording a video, show the back and the front of the jack.

I was suggesting a DM in case you did not want to share the video conferencing link

ok to post recorded videos here in public

[gritty sigil]

oh. Huh. I misunderstood your previous message then, sorry! Since you mentioned taking your pick

yeah dm for conference sounds better to me since we can adjust the orientation and angle in realtime. I'm unsure if quality on something like google meet would be good enough for it?

[unique patio]

that should be fine

illumination and focusing is more important

[gritty sigil]

alright. You available atm?

[unique patio]

yes

[unique patio]

ok, great, thanks for the video!
Here are some of the terminal block products I was talking about. Unfortunately, they are relatively expensive, but they might be good for more secure connections when you are making a permanent project.
https://www.adafruit.com/product/3173
https://www.adafruit.com/product/2926
https://www.adafruit.com/product/5907
https://www.adafruit.com/product/5095
https://www.adafruit.com/product/5096

[gritty sigil]

that sounds cool indeed. I guess for my use I'd take the second link then? The first one requires soldering but the second appears to be the equivalent if id 5900, that is comes pre-soldered, unless I misread

[unique patio]

Unfortunately, all of these require headers to be attached to the Feather or the Pi Pico.
We have these press-fit headers: https://www.adafruit.com/product/5938. Note the caveats in the product description. I wonder if you could push these on using a metal tube or similar that would fit over the board from the top so you could push down on the board around the top part of the pin.
What these look are regular headers, but with the top part having a press fit piece that fits tightly in the board hole, from the bottom. The top part of the header pin starts out normally, and then splits into two "legs" that squeeze together to fit into the hole.

A different thing that might be useful are these snap-action terminal blocks, to connect wires to wires. You insert wires and flip a lever down for each wire which holds it in place. https://www.adafruit.com/search?q=snap-action

I think these might be easily found at the hardware store.

"Connecteurs électriques avec levier de commande, Rapide Connecteur de Fil de Câble, Bornes de Connexion Automatique"

exemple: https://www.amazon.fr/dp/B0D83S58K9

[sick glacier]

Yes, it's protected. Does everything else look ok? I recently added a enable and disable for the charger too, since most computers can't output 3 amps even out of their USB-C ports, so that I can turn off the charger when programming.

[shy spear]

Is my revised version, decided to keep the buttons and uart port separate but removed alot of the subcircuits. I also am switching to an external dc to dc converter simplifying the circuit further

[teal harness]

Does anyone have a tip for a compact 5V-powered LED driver to supply 500-1000mA to 3V LEDs? Right now I am just using a resistor rated for 4W but it gets way too hot for my taste.
Sparkfun has a really nice board (“Femtobuck”) but it needs >6V supply voltage

[teal harness]

After some more searching on Digikey I have found drivers by Recom (“Lightline” series) and LEDdynamics (“BuckPuck” series) that should work. They are however quite pricey ($10-20 a piece)

[supple pollen]

That's easier to follow. Note that your cooler transistor is going to need an emitter reference to work.

[supple pollen]

It depends somewhat on what sort of LED driver you want. Do you need regulated voltage or regulated current or something else? Does it need to be adjustable?

[teal harness]

I am driving some LED filaments so I was planning on keeping current to 100mA per filament and regulating brightness using PWM. But regulating current would also be an option

[shy spear]

So in this instance would it be okay to connect it to the 3.3v ground and the signal gnd pin 2 on the cooler sw

[supple pollen]

I'd probably just connect the emitter to ground, if it's acceptable to have pin 2 of your connector grounded

[shy spear]

pin 2 is the cars ground. 12v is flowing through the transistor at a very low amperage thats why I have it connected back to pin 2, the signal wire already grounds itself it was just a physical switch before. Im assuming I need to connect it to the microcontrollers ground so the sitching part of the transistor actually works

but I dont think I can connect it straight to the microcontroller ground unless I also connect the cars ground to the microcontrollers ground

[supple pollen]

Right, and I don't know if that's likely to be a problem

If it is, you may need a more complicated isolated switching arrangement

[tulip swift]

Not sure I understand your problem with the 4W resistors. If you put a current limit resistor inline with each LED (running each LED+R in parallel to each other) to limit it to 100ma then your power across each of those resistors should be (5V-3V) x 100mA = 0.2W, which means you can get away with quarter-watt resistors running the Rs at 80% of that rating. Then you only need a power supply rated high enough for however many of those you put in parallel.

[indigo ether]

Hello! So I've got a m4 express, and I recently ran into an issue where someone plugged in a second power supply (of unknown voltage/polarity, etc) to my circuit, which seemed to have caused an issue with some of the outputs on the m4 express... The m4 express python seems to work fine (outputs to the serial interface just fine). If I am using circuitpython to drive some neopixels off of one of the pins, is there a way, with a multimeter, to test whether the pin is working?

[supple pollen]

Yeah, set the pin as an output, set the level high, and look for about 3.3V on that pin. Set the level low, and look for about 0V. If it does both of those, it's likely capable of driving NeoPixels.

[indigo ether]

Excellent, thank you

[indigo ether]

Woo! It is working...

[shy spear]

Here are the PCB Routes from the previous schematic, I make sure that the 10A routes were thick enough and the servos max draw is 3A so the small split going off to them is thick enough aswell (1oz copper spread accrost bottom and top layer)

[sweet cairn]

Any recommendations for a logic level shifter IC - which one do you guys use? Looking for one for 3.3v to 5v and vice versa

[supple pollen]

Totem pole logic, resistor pull-up logic (I2C), or analog?

[latent jungle]

how many bits/channels

[torpid trout]

For the attiny mcus (attiny412) - a sanity check: the updi pin (assuming it's being configured as such) can be left floating, is that correct? It looks like it has an internal pullup.

[tulip swift]

For general purpose 1-bit use, I find the SN74LV1T34 is a great choice. Does both 3.3V to 5V and 5V to 3.3V plus others if you have something like 1.8V logic in your design.

[teal harness]

I was hoping to get away with only one resistor. I am essentially building a smart light bulb with visible LED filaments so having one resistor per filament would make it difficult to keep it neat

[unreal bay]

how many filaments? resistor pack?

[unique patio]

you can't share a single resistor among multiple LED's if they are indivdually controlled. The total current will vary because they are individually turned on and off.

[teal harness]

No individual control, just (at the moment) six filaments in parallel that are in series with a single 3.9 Ohm resistor. All powered off of 5.1V and PWM using a single MOSFET. It works well except for the temperature of the resistor. I figured 1.4W of power to dissipate would not heat up a resistor rated for 4W quite as much. I could add a 3.3V buck converter and swap out the resistor for 1 Ohm but at that point I thought I might as well use a proper LED driver

[unique patio]

have you looked at https://learn.adafruit.com/noods-uberguide

[teal harness]

I have, definitely some good tips in there. The AW9523 breakout would probably work but looking at the datasheet it seems to max out at 37mA per channel so 592mA in total. The TLC5947 seems to be able to handle a little more (720mA) and is a little smaller. But both seem way more sophisticated then necessary for my use case of one regulated channel

https://www.digikey.com/en/products/detail/recom-power/RCD-24-0-70/2256303

I have ordered one of these to test. I chose the standard version but the Vref version might have been better since PWM frequency is a little limited

[knotty tiger]

if you’re connecting LEDs in parallel, separate series resistors for each are a good idea, so that they share current equally (you can probably use small-value “ballast” resistors if using a shared current source driver)

[tulip swift]

Six LEDs in parallel without resistors is not usually a great idea. For one, they all get the same voltage applied across them. If it is close to the Vf voltages the LEDs then often one will conduct, clamping the voltage to its Vf, while others do not turn on if their Vf is a bit higher. And if the voltage is well above the Vf for all of them, while they will all turn on, it is likely one or more of the will be conducting the majority of the current. Short term it appears to work, but long term is the one conducting the most will burn out early and then the next one will begin its early demise. With individual resistors you do not need big power resistors like you are tring to use now. Instead you can get away with thin quarter watt resistors which should be very easy to keep it neat and hidden.

[teal harness]

That makes sense. I was worried about something along those lines but thought it should be fine since the filaments are (as far as I know) also just a bunch of LEDs in parallel. But I guess I might have to adjust my design then

[rich sorrel]

Is the diode symbol at A5 on this adafruit schematic supposed to be the red LED or is there supposed to be a diagram of the red LED under the RED LED text? GF checked the Eagle files (in KiCAD, so maybe it's a rendering glitch?) and it looks the same.

EDIT: https://learn.adafruit.com/assets/101678

[rich sorrel]

Actually, my gf is curious about the use of thermal reliefs in unexpected places like the ground pad of a QFN; is this a rendering glitch in the KiCAD conversion or is this a practice she could be learning from?

[tulip swift]

I don't think that board has a red LED and that might be a copy and paste error when making the new Qt Py RP2040 board. That text should be removed I think. The diode you refer to is a schottky protection diode. It is not a light emitting diode. I can't help you on the thermal relief question. Sorry,

[knotty tiger]

the thermal pad is considerably larger than a signal pad, so thermal relief seems like a good idea

[knotty tiger]

hm, it might depend on the design of the particular LED filament. it might internally consist of LEDs in parallel, with individual ballasting resistors (or equivalent). but then you'd be depending on different filaments in parallel having nearly identical internal ballasting

[rich sorrel]

lemme just add her to the discord instead of typing out replies via verbal instruction lmao

[west cloud]

i'm curious why an imbalance in pad size would be an issue here, since in this case the imbalance is radial, so i don't see how it could lead to tombstoning during cooling. especially since thermal pads are typically designed with the intent of providing a low-thermal-impedance pathway out of the package (datasheets for more thermally intensive QFN parts often recommend vias on the thermal pad and a solid connection to the surrounding plane), i assume this can't be too much of a concern. My understanding is that the main uses of thermal reliefs are for thermal balancing of small SMT parts, and improving solderability of thru-holes. but all my knowledge is self-taught so i'm probably missing things

is it a matter of a trade-off, where these thermal measures reduce yield but are necessary for power-hungry parts? if this is a choice to sacrifice unneded thermal performance to eke out a few fractions of a % yield, that makes total sense (and is also exactly the kind of thing i'd love to learn about as i don't have experience designing hardware for mass production)

(i also assumed there were signal integrity / EMC reasons to have the large ground pad's connection to the surrounding plane be solid, although i'm realizing the RP2040 HW design guide is a bit unclear on this)

apologies, last second edit (appended to the first paragraph)

[knotty tiger]

i don't know the specific details here. i would look to the device manufacturer's datasheet for guidelines for a specific device. there will probably be tradeoffs for thermal and electrical performance vs assembly/process issues, some of which might be empirically determined. ease of rework might also be a factor for prototypes

[west cloud]

that's fair. i think ease of rework is a big factor i'm missing, adafruit does their assembly in house right? i imagine there's an extra motivation to dial in the finer aspects of DFM if you personally know the assembly techs

(i'm curious if ease of rework is a consideration in production, i'm guessing for anything but like an expensive motherboard, rework is unlikely?)

[west cloud]

that's fair, i guess i was just curious if there was some general principle i was missing, makes sense that it's "one of those difficult tradeoff situations"

[knotty tiger]

for info about specific Adafruit design considerations, Ask an Engineer might be a good place (you can now submit questions in advance via Discord)

[west cloud]

oh thanks i was not aware of that

[unique patio]

or via an issue here: https://github.com/adafruit/Ask_An_Engineer/issues, but the Sept 25 issue has not been created yet

[unique patio]

post for AAE questions for this Wednesday is now open, here: https://discord.com/channels/327254708534116352/1287789615146864712

[burnt spear]

Can someone help me read this type of capacitor?

[latent jungle]

Those look like (molded) tantalums. The top side usually has laser marks. If there was a clear picture of those marks, then yes.

[burnt spear]

Is that better?

Mine don't have any markings but have leakage but super tiny so hard to take a pic

[latent jungle]

Those are ceramics, MLCCs. Completely different from the previous picture.

MLCCs rarely have markings.

If they’re in a circuit, you would need to remove them and use a LCR or capacitance meter.

[burnt spear]

So it's an Snes game. I have a second copy same board but some have the same readings

So I get like 68 ohms but there's no 70 ohms capaciters like that

That I can find a replacement for

[latent jungle]

Capacitors aren’t measured in ohms. However, Their insulation resistance is specified in ohms. But for ceramics it should be Mega or Giga ohms. If you’re seeing 70, when it is out of the circuit, it is damaged.

[burnt spear]

It's out of the system no running power

The working one is 70 ohms

Or 68.something

[latent jungle]

As in, remove the capacitor from the circuit.

[burnt spear]

Measure it using what?

Ohms?

[latent jungle]

It’s a capacitor. You need to measure the capacitance.

Anyway. A surface mount MLCC from that era would only be 100nF to 1uF. So, replace it with a 10V (or higher), 1uF X5R or X7R.

[burnt spear]

Ok

[inner monolith]

Hey! I have a custom board i'm trying to use but I cant find the right size connecters. Can someone look at this and tell me what size connectors I need for "Cell-con", "UPDI", and "I2C?"

https://www.altium.com/viewer?token=YHimXFQAN0mN520AvyeO3H7A

There are so types of connectors out there. It's extremely confusing for me.

[supple pollen]

It's your board, you can use any connectors you like. STEMMA style connectors are one possibility for I2C, but hardly the only option.

[green wigeon]

i'd like to dip my toes into learning how to get some boards fabricated on pcbway or jlpcb or whatever people like but i don't have much design experience or formal electronical knowledge. i learn best by doing or hacking/modifying existing things so I was thinking i'd benefit from getting all the files for an existing board, modifying it slightly and then getting it printed up to learn how to go through the whole process end to end, then i can start iterating and playing with different components and options, etc

[supple pollen]

That's a good idea. There are lots of open source boards out there (including AdaFruit ones). However a lot of us used Eagle until recently, but many of us are moving to KiCAD, so if you're just starting out, you may as well start with KiCAD. While it can import Eagle designs, there can be some sticking points, so look for open source KiCAD designs to begin with.

I'd share my first one, but a) it's pretty special purpose, b) it uses some expensive parts, c) it's my first one and probably contains a lot of less than ideal decisions and practices, and d) was designed as a test board, so has lots of breakout points and extra traces to cut to separate systems if they don't work.

[inland jungle]

is adafruit going to transistion its PCB layouts to KiCAD?

[rich sorrel]

Is there anything I need to worry about when stacking a MIDI featherwing, a Music Maker featherwing, and an RP2040 Feather?
Do I need to worry about any collisions on the UART pins, especially when a MIDI IN device is connected?

Is it possible to add a switch to the MIDI synth pads on the Music Maker featherwing so I can switch between sample playback and synth mode on the fly?
If so, should I power down the device before flipping the switch?
What dangers should I be aware of if I bridge the pads while the device is turned on?

Is it possible to add a power switch to the Feather RP2040?
My thought was to add a switch on the battery line, but if it's plugged in via USB it will still turn on. Do I have any other options?

[inner monolith]

Thanks for your response! I don't think I wrote my question clearly. I have a board i'm trying to connect to but the connecters I have are too small (https://www.amazon.com/gp/product/B07PDQKHJ2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1). I was wondering if anyone was able to take a look at the board and tell me what style and size connectors would work. https://www.altium.com/viewer?token=YHimXFQAN0mN520AvyeO3H7A

[rancid lagoon]

What pin count do you need

4? Those are identical to stemma QT cables/connectors (adafruit sells the connectors btw), JST-SH 1mm pitch

[sacred badger]

also be aware that the autoroute function leaves a lot to be desired

[dry ember]

As a sanity check before I order 20 ICs that don't have the pins I need, this board (the ATTiny404) only has 9 pins I can write, PA4 PA5 PA6 PA7 PA3 PA2 PA1 PB0 PB1, correct? It doesn't seem as though i can write PB3 and PB2 from the diagram, and PA0 is UPDI/RESET so I don't think I can write from that pin either

[rancid lagoon]

If you enabled the internal clock i believe you could use PB2/3 as GPIO

But if you’re using an external clock yeah nah you can’t use them as GPIO

To use reset as GPIO you have to do some funky stuff like disabling reset, if you don’t need to I wouldn’t recommend using it as GPIO

[dry ember]

Oh sick, i only need the internal clock. I knew about the reset GPIO thing, but i’d rather not futz around with that

thank you

[dry ember]

has anyone run the neopixels off of 3V before? The datasheet says they can be run lower then 5V, not sure if 3V is too low. looking to run a few off a coin cell

not worried about battery life, just care about whether they show up at all

[marsh zinc]

@dry ember - some/many neopixels will run [out of spec] at 3.3V. You will have 2 problems with a coin cell battery.

1. A 3V coin cell quickly drops to 2.9V and will hang there for a while. This is too low.
2. A coin cell has limited peak current of about 15-20mA. By the time you power a microcontroller, the amount left is barely enough for 1 or 2 neopixels.

@dry ember - the ATtiny404 has 11 GPIO pins (and under a few restrictions you can use the UPDI as a 12th and it's relatively easy to use it as an input pin without any funky configuration).
It really depends on what you need the pins to do as some pins have specials capabilities in addition to being general IO.
As @rancid lagoon mentioned, you often don't need an external clock crystal. The internal clocks on the AVR architecture are pretty good and even have clock compensation values (for some additional accuracy) stored in the chip from the manufacturer.

@inland jungle - I have seen some live streams with LadyAda working with KiCAD. That said, they publish high resolution images of their boards (but I have not see design files). I often reference their schematic images.

@green wigeon - do you have an idea of what type of board you want to start with for learning PCB design? If the board has a particular chip or microcontroller, you could then search GitHub for that part to find an open source design.
Like @supple pollen mentioned, KiCAD is a good place to start if you think you will want to use and share open source projects. If this is a "dip your toe" level of commitment, then you might try EasyEDA which can be used in a browser and integrates easily with JLCPCB.

[dry ember]

gah! of course. i am still new to working with electronics without a bench power supply. completely just looked at the voltage and thought it would be good enough. thank you

[marsh zinc]

No worries. I only know this because I tried it 🫣. I make lots of mistakes.

[edgy ridge]

If you needed to you could use a lm317 and some passives on a breadboard till you get a bench power supply, just watch current and how much input voltage you are giving it because of heat dissipation

[dry ember]

voltage isn’t my problem, its that i am working in a super small form factor and no one makes small batteries that can put out any amount of current

[edgy ridge]

https://www.ti.com/product/LM317

[edgy ridge]

Look into drone batteries or small ones used in the ear buds that have a wire connecting both earbuds. How small do you need yo go?

[dry ember]

im looking to keep things credit card sized, and around 1.6 mm thick

thus the CR2016

interesting, ill give those a look

[edgy ridge]

https://www.amazon.com/dp/B07BTHQ872/ref=sspa_mw_detail_2?ie=UTF8&psc=1&sp_csd=d2lkZ2V0TmFtZT1zcF9waG9uZV9kZXRhaWwp13NParams

Check that out and see if it meets spec

Oh 1.6mm is pretty thin

Ceramic battery maybe?

[dry ember]

i might just tone down the leds, though it will be less cool

[edgy ridge]

Idk where to buy them though https://m.youtube.com/watch?v=kJXRyWQgOY4

[marsh zinc]

With a CR2016 (which is really cool when embedded “in” a 1.6mm PCB) you will need to pay attention to every component of your design. A few suggestions:

1. use discreet LEDs (these can be single color or have R-G-B diodes within a single package)
2. use PWM to manage brightness and consider using charlieplexing to reduce GPIO requirements
3. reduce microcontroller clock as much as possible (an AVR chip running at its default of 20mhz uses about 10ma but at 5mhz it is using about 2.5mhz and at 2mhz it’s down to about 1ma)

I have made a lot of projects which run from the CR2032. It has the same current limits as the CR2016 but about twice the total capacity.

[dry ember]

gpio is not an issue, using solid red leds (was considering the neopixels because i found a great deal), planning on running at 32KHz, which if the spec sheet of the ATTiny404 is correct puts me at about 10 uA for the microcontroller

[marsh zinc]

So charlieplexing and timers are your next step

[dry ember]

im finding VERY conflicting info on continuous current limits with the CR2016. Any idea as to what it is actually around? some sources say 0.1 mA, some say 10 mA

well, my next step is going to bed, but after that yeah

[marsh zinc]

The 0.1ma is the constant drain value used for testing. The 10ma is the peak current drain.

[dry ember]

my gut says closer 10mA, as i’ve seen a CR2032 power multiple LEDs, but i’m a little confused

[dry ember]

ah! thank you

[marsh zinc]

No worries. I’ve don’t a lot of coin cell projects so I have had to find this data (multiple times).

Btw: charlieplexing results in only some less being active at any moment in time so the peak load is never all the leds

[dry ember]

then do you happen to know the current the battery can rest at? As per my limited understanding peak current can’t be maintained for long without issues

is that the 0.1 mA figure? if so that seems near useless

[marsh zinc]

Peak current can be maintained based on the discharge graph. It can be maintained … but it will drain the battery and the voltage will drop over time.

BTW: here is a video of a design using the ATtiny1616 (which has the same power usage as the attiny404) …https://vimeo.com/797188382

This has 42 LEDs which are charlieplexed. At any given time, no more than 6 LEDs are active.

My eChallengeCoin designs average about 6ma when running and 400na when in deep sleep.

[dry ember]

interesting. so are you just turning the leds on and off very quickly to get the effect that there are more then 6 on at once?

[marsh zinc]

Basically yes. If you want to read up about charlieplexing, here is a link: https://gitlab.com/bradanlane/avrcoding101/-/blob/main/documentation/lesson3.md?ref_type=heads#charlieplexing-leds

Here is a link to an example using R-G-B discreet LEDs: https://vimeo.com/818182827

[dry ember]

that would be super helpful. understanding charlieplexing was my homework for myself this weekend

[unique patio]

and also @KevinT: The board design files are published in repos, e.g.: https://github.com/adafruit/?q=pcb&type=all&language=&sort=

@inland jungle 👆

[woven bluff]

has any one done diy AC UPS before? is it feasible ?

[uneven cloak]

Can it be done maybe. Can it be done as cheap and safe as one purchased NO! If you have to ask questions related to mains in a discord then you should not be doing it!

[marsh zinc]

@woven bluff - good question and I will give my personal thoughts.

As @uneven cloak mentioned, dealing with mains power requires a healthy attention to details.

I don't know that I would tackle a mains powered UPS. I have purchased a few UPS over the years. Many were used and inexpensive and just needed new batteries (which are easy to source and install).

I would shop around for a new or used UPS with the power capacity you need. If you find an affordable used one, factor in that you may need to replace batteries (sooner or later).

[woven bluff]

I know how mains work, and I have dealt with things far more powerful than mains, marx generator, railgun, coilgun etc. I'm here to ask about SMPS.

[supple pollen]

UPS or SMPS?

[orchid galleon]

I'm having trouble finding specific electrical information, but is the HSTX peripheral outputting +3.3V/0V or +3.3V/-3.3V on the differential lines? And how should I have found this information? =)

[flat vigil]

I assume 3.3/0. The datasheet's electrical characteristics says output voltage low is 0 - 0.5 V

section 14.9.4

[knotty tiger]

differential isn't necessarily symmetric around ground; it depends on the specific protocol

[orchid galleon]

True, diff does not have to be symmetric, that was mostly my frustration with documentation generally.

[latent jungle]

HSTX is differential?

[flat vigil]

It outputs DVI signals to plus and minus pins

[hollow flame]

Any pro tips for determining pin spacing without any kind of datasheet? I can try some cheap digital calipers I have but I’m not too confident in my ability or the tools precision

[latent jungle]

Ah, this is what I was missing from the rp2350 datasheet:

The HSTX balances all delays to GPIO outputs within 300 picoseconds, minimising common-mode components when using neighbouring GPIOs as a pseudo-differential driver

[latent jungle]

If you don't have a datasheet then you have to measure them. Create a footprint based on what you think the spacing is and then print it out 1:1 on paper to verify if it is correct.

[marsh zinc]

Here is a trick ...

Use the caliper to measure the diameter of one pin and then zero your calipers. Now measure the distance from the extreme of the first pin to the extreme of the last pin. Finally divide by the number of pins. You have the pin spacing with pretty good accuracy as any measurement error has been divided across all the pins.

eg: you measure the diameter of a pin and its 0.8mm, then you zero your calipers and measure the width of all the pins and get 10.2mm, and you divide 10.2 by 8 and get 1.275mm the odds are good the pin spacing is 1.27mm

[hollow flame]

Thanks guys!

[twin parcel]

I need to measure linear distance in a tube (20mm diameter) of about 100mm long, at a high update rate but accuracy isn't that important, how would I go about doing that? Magnets don't seem to be strong enough, a sliding potentiometer doesn't really fit and a distance sensor has to wide of an angle, so it would detect the inside walls of the tube

[supple pollen]

Most distance sensors (both light and sound) react more to a perpendicular surface than a glancing angle, so the inside walls may not be a significant problem, depending on the characteristics of the surface to which you are measuring the distance (if it's a flat plate, it should work well, if it's a diffuse ball of fuzz, it's harder)

[twin parcel]

I had tought of using something like the Vl53l0x but it has too slow of a update speed i think, the thing I'm trying to measure can move trough the entire tube in 0,5 seconds, I feel like there is a better way, maybe a rack and pinion and a rotary encoder?

or maybe a lead screw with a rotary encoder

or this weird lead screw with a higher thread angle:

[drowsy drift]

What about the VL53L1X? It has a 50 Hz update rate https://www.adafruit.com/product/3967

[ionic wigeon]

Hey everyone, what are some good methods to securely attach two PCBs together?

I'm working on a design for a pretty large PCB, but the manufacturing costs are not cheap at that size.
So I realized it would be more cost-effective to go modular and connect smaller boards since the design repeats anyway.
Here's the single-board version: https://imgur.com/8iniUS5
and the modular version I'm considering: https://imgur.com/RJj6niI

That said, what’s the best way to attach these smaller boards together so they hold up well, and to be as stiff as a single board.
I was thinking of using pads on the edges, but I’m worried solder alone might be too brittle for a strong connection. Any ideas?

[marsh zinc]

@ionic wigeon - how many traces will traverse from module to module?

TBH: any method of connecting the modules will have negatives.

If I were designing a module solution of repeating boards, I would probably use a traditional connection - something like right angle 0.1" headers - and then have mounting holes for every module such that the mechanical mounting to the case is what issues no movement.

[ionic wigeon]

well idk about data signals even, thats not that big of an deal and can be solved later. but i need the boards connected stiffly to oneanother. a primitive idea i have is to simply put pads on the edges and solder resistorlegs or similare kind of wire ontop of them on both sides of the pcbs, like that:

i guess this could work, but perhaps there are more elegant ways

[marsh zinc]

If you need a rigid solution, design it as one board. Your alternatives will all be substandard.

It comes down to priorities.

Does rigidity rank higher than the cost savings?

Does thickness matter? If not then you can use connectors and mount the modules to a substructure.

[knotty tiger]

the traditional solution often involves smaller boards and a rigid chassis to mount them to, rather than one large PCB

i’ve also used an old stage light control board with a single PCB design. coincidentally, i had to repair a broken trace on the board in the middle of a show

[woven bluff]

I want to make an at least 10000RPM ESC, is there specialized IC for ESC, or I have to use 3 channel PWM IC with 3 gate drivers?

[clear matrix]

Any of you guys who are used to deal with heat parameters who will venture a guess about how much effect my NSI50350AST3G can dissipate without a heatsink, assuming 25 degrees C ambient?
https://www.ledsales.com.au/pdf/NSI50350AS-D.pdf

[supple pollen]

There are CPU chips optimized for ESC duty, but as far as I know, they all use external MOSFETs and gate drivers. You'll need 6 gate drivers (3 high side), and they'll have to be seriously beefy ones that can slam several amperes in and out of the gates in order to switch fast enough to go that speed.

[inland jungle]

There are bldc controller chips with built in mosfets up to about 8A

Mcf8361

[supple pollen]

Let's see, it would need to dissipate about 0.63 watts in operation, and with the minimum PCB area of 400mm² of 2oz copper, the thermal resistance is 48.2°C/W, so 0.63W*48.2°C/W is a 31°C rise. That seems suitable, but that isn't "no heatsink", that's using PCB copper as a heatsink. Unfortunately the data sheet doesn't specify the thermal resistance with no heatsink at all.

The MCF8361 is more of an FOC controller than an ESC. It doesn't have enough slew rate to manage high speeds.

[clear matrix]

Hmm, very interesting. Thank you for your interpretation. Still useful knowledge since the two I'm using are mounted on top of some chunky ground planes. I'll pwm them a little and see what I can get away with.

[supple pollen]

"Try it and see" is a valuable and reasonable approach

[coarse lark]

This is a WIP of a robot board im making based on the ESP32S3, any comments or suggestions?

[unique patio]

When the batteries are switched on, 5V will be applied to the USB ports, which will backpower the host computer or whatever is plugged into USB. This could damage the upstream USB ports. Use diodes or some other circuitry to prevent this.

What use does the 5v supply have besides supplying the 3.3V regulator?

I don't know what (if any) decoupling caps are recommended for the module, but follow the datasheet guidance on that. Controlling motors can create a lot of electrical noise, so be liberal with decoupling caps, and keep the motor circuitry away from the MCU, etc.

[coarse lark]

Thanks for the comment dan

1. Yes, if the robot is turned on and its connected via usb it will fry my computer, my solution was to power off the robot before connecting it to usb, if its not hard to do ill follow your suggestion and see how i can avoid backfeeding with diodes.
2. The system runs on 2 14500 batteries in series, so 7.4v total, my idea was to use the two regulators because if i put the 7.4v directly on the 3.3v regulator a ton of power would be lost as heat, so i added 2 of them, in addition this lets me power 5v modules and servos.
3. I based the motor controller design off the sparkfun TB6612FNG module, it uses the same capacitors

[coarse lark]

Ah i replied to my own message on accident, see my reply above

[coarse lark]

Oh yeah and motors are 6v

[latent jungle]

I'm surprised ERC didn't catch this extra junction, but probably worth cleaning up

VO / Pin 2

[coarse lark]

Huh, ill clean it up later

[woven bluff]

is there a part number for horizontal stemmaqt socket?

[inland jungle]

SM04B-SRSS-TB I believe

[sturdy shoal]

Is this the right place to ask a PSpice related question?

[unique patio]

it's the best place to do so

[obsidian scaffold]

Hi guys, have a relay question, I’ve got an arcade game that I tapped into via the switches with 4 12v automotive relays, whole system runs on 12v with a common ground, 3 of the relays are 12v powered and grounded on the NO sides of the switches, and 1 relay is 12v powered by a light that the game board turns on after a coin is inserted/game is ready to play, grounded to its ground, that all said, would a 4 channel relay be a good replacement?

[supple pollen]

I'm unsure what you mean by a 4 channel relay here. Do you want to activate everything at once?

[pale grove]

Maybe a stupid question but is it possible to spot weld a wire onto a PCB?

[marsh zinc]

@pale grove - Typically the heat of a spot weld will vaporize the very thin copper.
Is traditional solder not an option?

[pale grove]

It's a very thin wire from a lipo battery (on there it's spot welded and very strong).

Once soldered on the PCB it seems to become more fragile or somehow gets loose

[marsh zinc]

A solder connection should not get loose unless maybe it is a cold solder joint?

The one situation I have encountered fragile/loose solder joints was when I used a low temp solder with bismuth on a pad which had leaded solder. This comb8nation is known to have poor tensile strength.

[pale grove]

It's not that the solder comes off - but the wire kind of tears off from the sodler joint?

[marsh zinc]

Tears off / out? or does the wire break?

Does the solder bond to the wire? or does it appear to bead up?

[unique patio]

if the stranded wires got nicked when stripping the insulation, they would not survive a few bends

or you are not making a good solder joint and the strands are on the very top of the solder blob. They should be well covered

[marsh zinc]

I have seem wire which has oxidized (even under the insulation). In this case, no amount of flux or heat will get the solder to bond to the wire.

[unique patio]

consider attaching pins or screw terminals to the battery connections so you can make a mechanical connection, if it's under stress. Then it will be easie to change the battery too

[marsh zinc]

another possibility is if it is enamel coated wire - often a reddish clear coat. The coating needs to be removed at the end for the solder to bond.

[pale grove]

it's a stranded wire.
Solder joint looks fine at the beginning. But after a bit of handling and moving the PCB around it comes off

but on the battery side it never comes off even if I wiggle it around a lot

[unique patio]

i would say solde a header pin there. You can cut it short if it would get in the way. Then strip the wire longer and wrap it around and make a good mechanical joint.

what kind of solder are you using, and what kind of soldering iron do you have?

does it take a long time to meld the solder?

a picture would be good

if the ring around the pin has gotten damaged or mostly removed, then there is very little trace to solder to

are you putting the wire through the hole?

[marsh zinc]

If it “comes off” rather than breaking, then it sounds like a cold solder joint. If the wire breaks and the end is still in the solder, then it’s just fatigue. Some form of strain relief is one option if you don’t want to use a connector.

[pale grove]

Soldering iron: YiHua 8766D
Solder: I don't remember - it's a generic spool that came with it I believe.
Solder melds pretty much instantly

[pale grove]

Yes the end is still in the solder - so I guess fatigue

But what I don't understand is that it stays on the spot welded battery without strain relief

[marsh zinc]

The difference between the PCB and the battery connection is likely the extent of the “wiggling”. If the solder joint is good, then even a spot weld in the same location will suffer the same fate.

I’ve used a blob of hot glue over a soldered wire to act as strain relieve. It moves the “wiggling” away from the solder joint and has a little give to it.

[unique patio]

maybe attach the battery to the board with sponge tape (or other insulating material) or otherwise prevent strain on the joints

[worldly schooner]

Any stress on the wire at the solder joint will strain the wire much more than it would further up the wire where the strands have more freedom to move relative to each other. I’d strongly recommend using some sort of strain relief for any connection involving solder and stranded wires.

[thorny dirge]

I'm not sure if this is the correct channel for this, but here goes.
The first thing you need to know is that I am a 68 year old retiree with some arthritis in my hands.
I want to add a 8MB PSRAM Chip to my Teensy 4.1 board, and also to a Adafruit Feather RP2350 and, Eventually a Metro RP2350.
Can any of you fine people provide me with some tips, and equipment recommendations?
Thank you

[drowsy drift]

Welcome! There are some good smt soldering tutorials on YouTube. Here’s one of my favorites and they do the exact kind of chip as the PSRAM https://youtu.be/fYInlAmPnGo?si=nh_2D0D3tB9232XN

Apart from that, having a good soldering iron makes things a lot easier. The Hakko ones are good.

I often brace my palm against the table to help stabilize my hand holding the iron

[marsh zinc]

@thorny dirge - I am an outlier when it comes to soldering irons. I use one of the USB-C powered "soldering pencil" types exclusively. Whatever you choose, you want controllable temperature. Before I switched to a pencil, I used an old Weller WES51. In both cases, being able to control the temperature is what's important.

Keep the tip clean and tinned with solder. Flux and good solder will make life easier. I cheat and use a flux "pen" - it looks a lot like a chisel tip marker. A flux paste is better.

I don't skimp on heat and that is partly because a small tipped soldering iron will give up its heat quickly. For a chip with legs, I set my iron to 300C. I tin one pad of the PCB and then place the chip while applying heat. Once that leg is secure (and the chip is square to the other pads) then it's easier to solder the other pads because the chip isn't going anywhere.

I don't have arthritis but my hands are a bit shaky. I keep a pretty clean and open bench surface so both of my hands can rest on the bench top.

If you have an old PCB or have some new perf-board, practice with those. Once you feel you have the practices the peocess of "solder on the pad, placing a part (even a wire) and adding more heat" then you can tackle your Teensy.

[thorny dirge]

Todbot and bradanlane,
Thank you for the advice.
It looks like I need a fine tipped soldering iron, and some tinning paste.

[unique patio]

The toothpick jig shown here: https://electronics.stackexchange.com/a/154550/101049 I think is interesting. I've seen that several times over the years, but I haven't tried it myself. The whole Q/A is worth looking at.

[marsh zinc]

@thorny dirge - tinning paste is really only needed to salvage an abused tip. (and yes, I have it for just that reason).

I suggest a decent 63/37 or 60/40 leaded solder. I like KESTER SOLDER 24-6040-0027 Wire Solder, 0.031"Dia which is pretty fine diameter.

Some people like the "wire pad" for cleaning the tip. I tried it. I went back to my old-school wet folded paper towel.

[latent jungle]

As Bradan said, you don't need/want "tinning paste." But you do want a good quality flux. I am a fan of Chip Quik's SMD291 because it is tacky. It stays where you put it. BUT, it does require a lot of cleaning after you're done.

[sacred badger]

^^ yes, messy, but the satisfaction when surface tension pulls components in to place, and no bridges, i'll gladly sop it all up with alcohol

[woven bluff]

my convergence meter broke, I feel like a chunk of my bring is missing

HV and isolated SMPS broth broken

[supple pollen]

My divergence meter still seems to be working

[coarse lark]

I made this circuit for driving a small 3v passive electromagnetic buzzer, will it werk?

buzzer is an MLT-8530

[supple pollen]

Seems reasonable, if the buzzer will work on 3.3V (I haven't looked it up)

[unreal bay]

Actually a bit less than 3.3V, due the voltage drop across Q1. Also if SPKR is standard audio, it may or may not fully turn on Q1. Is SPKR a DC level signal? You may need to insert a capacitor and bias resistor.

Breadboard it for testing.

[supple pollen]

I'm assuming it's a signal from a GPIO or somesuch. 1k should dump about 2.3mA into Q1, which should be a fairly low voltage drop for reasonable current.

[clear matrix]

Anyone who can help me identify this component?

[coarse lark]

SPKR is connected to IO 2 of an ESP32S3, im only going to play beeps and tones with it, so DC only

[rare roost]

Hi all, I'm working on my first SMT PCB and I was wondering if anyone would have the time to give it a quick once over to see if I'm making any glaring mistakes. I'm not sure what the best way to share it is since a screen shot likely wont give enough info.

[rare roost]

any chance thats in a usb charging brick? best could find is this

[clear matrix]

I could be. I expected it to be a processor because while it does charge a small battery, it also handles a few IOs. Or so I thought.. Maybe its done by hardware elsewhere on the board.

[lime cobalt]

I am designing a 9V battery powered stereo audio effect that uses a 1/4" jack. Typically (with a mono effect), you would use the ring and sleeve of a stereo input to connect & disconnect the ground of the battery to turn it on when the cable is connected. The direct solution for a stereo input would be to use a TRRS 1/4" jack, but those apparently don't exist. I am thinking that this NPN transistor (max 200mA, only needing ~80-100mA) solution may just work (seems to be okay in the simulator), but it doesn't feel elegant. Would it be better to switch to a MOSFET or some other solution?

[supple pollen]

I think there are TRS jacks available that include an isolated switch

[woven bluff]

I don't understand why efficiency drops so much with only few mA, I'm expecting to get 50mA out

larger FET required?

[sacred badger]

A device will only consume as much current as it's designed for -- open circuit is no current, while shorted circuit is all the current. Also, efficiency is directly relative to amount needed to convert -- exact reason a voltage regulator heats up proportional to the difference between input/output.. the closer the input/output voltages are, the less work needs to be done to adjust differences, and excess is dissipated as heat.

Ohm's law implies that one needs double the voltage for half the current... which is why the power grid operates at many thousands of volts before ultimately getting to the transformer near your home which down converts to your area's specifications

[woven bluff]

so Rds(on) is too large

[woven bluff]

do you isolate your HV part of convergence meter?

I isolated mine, now I want to put isolation into the HV flyback

something like this

bigass logic level FET with <5mOhm RdsON at 5V, channel current >50A

and my tiny transformer can only take 1.8A peak at primary

[supple pollen]

Mine uses a shared zero volt reference so that the current can flow though the display tubes, through the cathode switches, and return to the HV supply, completing the circuit. I am using opto-isolators for anode switching, to isolate the logic from the HV (and also gain the advantage of soft switching as a bonus, as the opto-isolators do not switch too fast). I'm using an off the shelf TaylorEdge supply, as I consider it a solved problem and an optimized module designed by an expert seemed like the right solution for me. You can see the TaylorEdge HV supply as the module plugged into the right end of the control board (marked U1).

[woven bluff]

I can't find ready-made HV supply with isolation

[supple pollen]

That's the other reason I did not use isolation 🙂

While it's conceivably possible to have a fully isolated HV section, with its own separated switching electronics, I don't see the advantage of that complexity.

[woven bluff]

there are no-opto flyback chips

[woven bluff]

what powers the HV side of the isolator?

[supple pollen]

The HV supply itself, basically. The output side of the isolator is just a transistor. I hook the collectors to the positive HV output, and they gate them to the display tube anode resistors.

The HV supply is the box on top

[woven bluff]

I ran out of max1771 and hv diodes....they all exploded by my shakey hands

[sacred badger]

i do not condone alcoholism, however, it is of great assistance to stabilize the hands within I

[woven bluff]

I don't drink

[sacred badger]

or the sniper technique of exhaling and holding, but when sitting here and soldering 300+ SMD components by hand with an iron --

[woven bluff]

my GABAA receptor allustic sites were destroyed long ago

[sacred badger]

😦

[woven bluff]

EtOH does nothing to me, except the acetaldehyde poisoning

[sacred badger]

glad to have subjected and simultaneously ridded the self of potential dependence

[woven bluff]

now I pop clonazepam like candy

[supple pollen]

That's another reason I use an off the shelf module: it's easier

[sacred badger]

theres some miraculous videos out there of neural stimulation instantly disabling the vibrate function of parkinson's patients

[supple pollen]

Yet another reason is mine is battery operated, so I'm looking for a good run time, and the off the shelf module is more efficient than anything I'm likely to build myself.

Then again, the 74141 chips I'm using for cathode switching are energy hogs

[sacred badger]

im saying.

[supple pollen]

If you're curious, the module I'm using is this one: https://www.shop-tes.com/1363-hvps-vertical/

[woven bluff]

will this work if HV is non-isolating

I use a 5V-5V isolation module to power the output side

[supple pollen]

It's not clear to me what is happening here. The spike suppressor makes it look like the input side, but the HV line (unless that's HV enable?) makes it look like the output side.

[woven bluff]

Hv is 170V refenced to ground, yes, I put the TVS on the output side, that connector is going to HV parts

[supple pollen]

I do see you have -Vin tied to -Vout, which makes it non-isolating...

[woven bluff]

in your circuit, everything is referenced to ground

[supple pollen]

I also see -Vin/-Vout is not tied to either GND nor GND1, so I'm not sure it's going to work at all

Yes, my circuit has a single zero volt reference (commonly called "ground", but I try to avoid that terminology)

[woven bluff]

I forgot that, it's a rush make

[supple pollen]

So your notion is to have an entirely isolated HV side, and squirt data to the anode/cathode switches through a serial data stream, which is also isolated?

[woven bluff]

how about this

I use shft registrer specifically designed for HV to drive cathode

[supple pollen]

That seems like it would work, but I'm not sure what advantage there is to isolating everything

Note that many HV shift registers operate on 12V logic signals

[woven bluff]

this one works with 5

I don't want to HV wonder into my logic

[woven bluff]

I don't think this will work, HV is referenced to GND, not GND1, shift registrator wont recognize that

[supple pollen]

What I would do is reference the negative side of your isolated HV supply output to GND1, solving that problem

So the input side (the LT4748) would be referenced to GND, but the output side (C3) would be referenced to GND1.

[woven bluff]

I don't have a isolated HV supply.. still in the schematic

[supple pollen]

Yes, your whole scheme depends on an isolated HV supply. I elected to go the other route, and isolate the positive side with optoisolators, and have the return through the cathodes flow to the (shared) ground via the 74141 chips. However, you could do a hybrid approach with a non-isolated HV supply, and drive your cathode switches through an isolator (as you have now). So while the LV and HV sides would have a shared zero volt reference, the logic would still be isolated from the HV (unless some short circuit bridged HV past your isolator)

[woven bluff]

non-isolated HV supply, as put between +5V and GND1?

[supple pollen]

Since it's non-isolated, you'd just have one "GND" net, no need for GND1

So you'd have 3 power supplies, LV 5V (control logic), HV 5V (HV switching), and HV (anode supply), but all 3 would share the same 0V reference.

So if HV got to the HV switching logic, it would only pollute the HV 5V supply

[woven bluff]

if I tie GND and GND1 together, then the logic isolator is useless

[supple pollen]

Not entirely useless: it still isolates the LV 5V supply from the HV 5V supply. Basically it's choosing some protection (with a non-isolated HV supply) over more protection (requiring an isolated HV supply).

There are, of course, other options. You could replace your 5V isolator with a beefier one, and then run your non-isolated HV supply from an isolated 5V supply, thereby isolating both at once.

[woven bluff]

I thought of that, there is no 5V-5V beyond 5W

[supple pollen]

Hogwash, of course there is

[woven bluff]

before I use 5V-12V iso module

then buck it down to power the HV side of the isolator

[supple pollen]

That's also a valid approach

[woven bluff]

5V-5V iso beyong 5W is only made in USA, and very expensive

[supple pollen]

Yes, it's a specialty product, but it does exist. 12V input converters are cheaper and easier to find.

5W may be enough, depending on the load and efficiency of the HV supply, but I generally prefer running my isolated supplies from the preregulated voltages anyway, to remove that load from my unisolated regulated supply.

[tardy lagoon]

Question about the MOSFET driver (https://www.adafruit.com/product/5648): Does it have an integrated gate driver for high frequency switching or should I plan to add that myself?

[supple pollen]

The schematic is on the learn page https://cdn-learn.adafruit.com/assets/assets/000/117/028/large1024/adafruit_products_schem.png?1670851887 and doesn't show a dedicated gate driver

[woven bluff]

I think I;m gonna do that again, since I already have a 5-12V iso 10W module, and a buck mldule

[oblique vale]

given the rp2040's not really 5V tolerant, is it also a bad idea to apply a fast 5V PWM signal to one of its analog inputs at no more than 50% duty cycle?

I guess a voltage divider would remove the question

[worldly schooner]

Is there a reason you want to put a pwm pin to an analog input? With the right low pass filter you could turn the pwm into an analog voltage.

You’d probably want a voltage divider regardless just to keep the signal within your range of measurement.

[oblique vale]

my 3D printer has a 5V output that can be driven with PWM, and I'd like to read that signal as a percentage.

[worldly schooner]

Using an analog input to read a percentage will require a low-pass filter and a voltage divider. With a voltage divider, though, I believe the rp2040 would be more accurate measuring pwm through a PWM input or PIO.

[oblique vale]

I had resource concerns about reading PWM in software since other code is timing-sensitive. PIO is a cool idea. I wasn't gonna make the code chip-specific, but in this case it might be a good solution. I see a PIO PwmIn library on github, and I'll look up info on low-pass filters. thanks!

[worldly schooner]

A low-pass filter is a very simple way to convert a high frequency square wave into an analog voltage proportional to duty cycle, and can be implemented by a simple RC circuit. Since the voltage divider also uses resistances, these components will affect each others' behaviors. Here's a simple simulation to illustrate this combined effect with some arbitrary values. Feel free to play with the parameters of the square wave to simulate the PWM and adjust the component values to achieve the desired output.

https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWEA2aAWB8CcBmSy0AOBBAdkJE0sskoFMBaMMAKAHkQ0jxlaEwATD1oiWAc07cBhClwo4BIqCwBOnOCjTraYXlBpwWAY0kVdtOSGkURseJAhhoyQqTQu0YfGlLI3OKDtWACVtTRAcBCECfSEvDQFoJESkWwRVMPMwgQRkfXjDAHds3OyZZWK0DSzLLMgWSoTyy2tlAHt9BX0AD0IvQWoYeyxfXJz88BAGMhYACwirCJYgA

It doesn't necessarily have the same precision as digital measurement due to the ripple, but for a rough percentage it should be more than sufficient.

[dim sapphire]

Hey all I’m back with a question about designing a circuit for a group of rotary encoders: When looking up switch matrices I’ve seen how you wire them in rows and columns with diodes, each row/col linked to a gpio pin. However, when I refer to the quad rotary encoder schematic here (https://learn.adafruit.com/assets/122222) I see that one side of each switch (both the encoder push switch and the pair of rotation switches) is going to ground, rather than a GPIO pin. When should I wire both sides of a switch to gpio, and when should I wire one side to ground? I plan to group 8 encoders in a 2x4 pattern if that makes a difference.

[worldly schooner]

The matrix arrangement of keys for a keyboard works because the keypress events are long enough for a controller to poll the button states one row at a time. With rotary encoders, however, the states can switch much faster when you turn the knob, and the polling of states for these switches can result in missed steps. That's why encoders generally use edge detection instead of state polling for accurate readings, so they do require their own GPIO pin for each of the two phases.

[dim sapphire]

Thank you! So I should mirror the quad rotary breakout schematic and send the C pin to ground and A and B to gpio?

[worldly schooner]

Yep.

[dim sapphire]

Awesome thank you

[worldly schooner]

You could also connect to VCC instead of ground, it'll just require the pull direction of the input to be configured differently.

[willow tartan]

Hey guys
I have a issue with a board(mcu STM32U575VGT6) that I made. The schematic looks like this(picture). The issue is with the external oscillator (picture with red line). I put a 16pF capacitor and when I try to run a code an use the external HSE the board freezes, if I use the internal HSE the board works (crystal used https://ro.mouser.com/ProductDetail/732-FA128-48F20X-K0), I use a blinking code to test the board. Is the capcaitor used a good choise(idk what is the Stray Board Capacitance of the board that I made)? Or do I need to change it? Should I try to change the capacitor?

[sick geyser]

By my math you need 16pF total but you've got 2x 16 = 32

[supple pollen]

https://blog.adafruit.com/2012/01/24/choosing-the-right-crystal-and-caps-for-your-design/

[willow tartan]

So my math was correct regarding 16pf but instead of using 2 8pf I used 2 16pf

[willow tartan]

I ordered today some capacitors with the value of 8 10 and 13 , to test out. I will come back with more information's after. Maybe I will buy a oscyloscope too :))

[latent jungle]

FYI. Unless you get an active probe, an oscilloscope's passive probe has about 10 pF of capactiance ...

[marsh zinc]

I had to look up active vs passive probes. It looks like an active probe has about 10x the impedance of a passive probe at 50mhz. Am I reading this correct? I didn’t see (or understand) the effect on capacitance.
Source: https://www.digikey.com/en/articles/understanding-selecting-using-active-oscilloscope-probes

[worldly schooner]

Yes, that is correct. The benefit of an active probe is its ability to read the higher frequencies without being (as) affected by the parasitic capacitance of the probe.

If you have ever seen the effect an RC circuit has on a fast square wave, the filter has a tendency to round the corners of a rising or falling edge. At really high frequencies, there isn’t any avoiding this with a passive probe.

[marsh zinc]

@worldly schooner - thanks. I have seen (and demonstrated) the effect of an RC circuit (and just a cap) on the rise/fall edge.

I demonstrated it when showing hardware debounce of momentary contact switch.

I have also had to deal with it when converting raw phototransistor input to digital data.

[ionic wigeon]

Hey, does anyone know how to make through-holes in EasyEDA with a copper pad on just one side of the PCB?
Or, if that's not possible, how can I manually remove the annular rings from a THT component on one side of a 2-layer PCB?

[latent jungle]

I didn’t see (or understand) the effect on capacitance.
First, I know it is pedantic, but that graph does not go down to 50 mHz. I think you meant 50 MHz, which is a very different frequency.

Next, don't forget that impedance across frequency shows the reactance which is a combination of capacitance, inductance, and resistance.

For reference, a typical active probe has less than 1 pF, sometimes much less, of capactive loading at DC (or 50 mHz...) while a 10:1 passive probe will have 10 pF.

When measuring the crystal of a MCU, the side actively driven by the MCU can handle the loading of a passive probe. (As in, the oscillator will still run, but what you see on the scope isn't valid.) The other side, however, will essentially see an extra capacitor and prevent the oscillator from running.

[marsh zinc]

@latent jungle - thanks for injecting better details. (given the 'H' was not capitalized either, I suspect there was no ambiguity for all but the most specialized RF engineers)
Was the linked DigiKey article accurate?

[latent jungle]

Oh, I missed the link. Yes. Anything about oscilloscopes written by Art Pini is accurate. 🙂

[marsh zinc]

I do my best to include links to source material since a super brief comment will never be sufficient (and quick typing can easily introduce confusing)

[unreal bay]

Not EasyEDA specific. Can you crate a stand alone hole, then add a pad to just one side? How about a thorugh hole that has zero sized pad, then add a pad (as a second part) on just one side? Needing to avoid any design rules checks that might say the copper is too close to a cut edge.

[marsh zinc]

~~ µMerlin~~ @ionic wigeon - Within KiCAD it is possible to create a through hole with different specs for the front and back layers. I have not tried to create an example matching your details.

Can you can you created/edit a picture of what the pad/hole would look like on a PCB?

Some questions to answer in your description:

• is the hole plated or non-conductive?
• does the pad have thermal relief or not?
• while it likely doesn't make a different to the implementation, what is the size of the hole (this will help visualize what you are attempting)
• how will this hole be used in your design?

[unreal bay]

That was not a question for my own use. It was a response to someone else with what I thought might be a path to solve their problem. From your more specific response, it is.

[marsh zinc]

Oops. I just fixed to tag the OP 🫣

[ionic wigeon]

Thanks for the response! While i could do that, would the innerpart of the hole be plated then aswell tho?

[ionic wigeon]

"Can you can you created/edit a picture of what the pad/hole would look like on a PCB?"
here a reallife example what i wanna do

[sacred badger]

What yer gonna do is place a hole, then a pad on top, and adjust diameters accordingly -- then switch to edit the other layer, and make the initial layer non-visible, and place a pad on that side as well, adjusting it's diameter accordingly

[ionic wigeon]

lol you beat me last second, just wanted to post i found the solution :D

make the annular ring on both sides only 0,2mm and then create another flat pad on the backside with the radius 1,5mm. (use the same net aswell, obviously)
with this hack, the topside annular ring is 1,2mm and the backsides annular ring is 0,5mm :)

[sacred badger]

yz

[ionic wigeon]

but still thank you very much for thaking the time to try help me :)

[sacred badger]

you're very welcome -- hope your PCB arrives with no issues!

[ionic wigeon]

thanks :)

[sacred badger]

prob better to use a via instead of a hole, guaranteeing there's continuity between layers -- and as you've learned, place a pad on top and simply adjust it's diameter

[ionic wigeon]

well i did use a multi layer pad with the small annular ring as the hole

and then simple a bigger surface pad on the buttonside

[sacred badger]

ah -- in those images above, it looks like it's a via, but tis just a hole -- and im unaware if jlc would make it a via, or if part of the process would make it a via regardless given there's copper on both sides

[marsh zinc]

@ionic wigeon - I’m still going to see if I can create this with just parameters. If not, then a custom pad is the way to go. (rather than have two pads with the same name, you create a custom “pad”; then it’s one thing if you end up duplicating it) I use custom shaped pads all the time. They are super handy for things like touch pads.

[marsh zinc]

@ionic wigeon - I tested with the 1x3 through hole header connector. I was not able to achieve your desired result with just parameter changes.
I was able to create your result with the following steps:

1. change the tru-hole "pad" to have a 1mm hole and a 1.05mm diameter. (you could have more anular ring if you prefer)
2. create an SMD pad on the front coper with a 2mm diameter (again, you can choose to fit your needs)
3. Position the SMD pad over the thru-hole pad
4. with the SMD pad selected, use "pad edit mode" (CTRL-E on Windows CMD-E on Mac)
5. selected the thru-hole pad
6. exit "pad edit mode"
   Now, there is one "pad" and it is a thru-hole with a large coper area on the front and almost zero copper on the back

[ionic wigeon]

👀

[marsh zinc]

The resulting pad is a single entity and may be moved, copied, etc.

BTW: "pad edit mode" is also how to make oddly shaped pads for things like touch sensors. (useful when integrated touch pads into artistic PCBs)

[ionic wigeon]

uhhhh nice! what rending software ist this? this doesnt look like the easyeda 3d render

[marsh zinc]

I use KiCAD for my electronics work.

[distant raven]

There is a little bit of nuance here that can be important. Higher frequency crystals are going to be more affected by this than lower frequency. Generally I've seen that crystals 16MHz and below typically handle passive probes with only small variances in operation. I've not tried anything between 16-32MHz, though I've found that 32MHz exhibits issues in startup if I'm trying to probe operation. Just some real world nuance. This is also using those cheap probes that come with handheld oscilloscopes so your overall mileage will absolute vary.

[woven bluff]

@supple pollen I got a NCH8200HV, it's advertised 3-15V input and 170V regulated output but when I input 12V, it drops to 150V.

[woven bluff]

My next divergence meter, how you think the big 5V tank?

[pale grove]

Maybe a dumb question - I am trying to open/convert some of the adafruit eagle files into KiCAD.
I was following some guides with mapping layers etc.

I see the board being imported - but when I try to link the schematic and board it does not seem to work. Is there something extra I need to do? Or a better way to import them?

[flat vigil]

I usually do the auto-layer matching. silkscreen doesn't always work but everything else seems to

[unique patio]

https://hakkousa.com/ is having a 20% off various things sale this month, including the new FX-888DX soldering station.

[pale grove]

Tried that but quite a lot missing it seems

[flat vigil]

what file are you trying to load?

[pale grove]

2 different ones.

https://github.com/adafruit/Adafruit-LIS3DH-Breakout-PCB
https://github.com/adafruit/Adafruit-RP2040-Prop-Maker-Feather-PCB

But maybe I am doing something wrong on import? Not sure

Import => eagle
Then I select the auto layer matching

• manually add the milling and images.
  Then hit ok

[flat vigil]

what version of kicad are you using?

[pale grove]

Kicad 8.0

Yes I do see the board

[flat vigil]

and what window did you screen grab?

[pale grove]

When I try to link them

the board and schematic

[flat vigil]

I see three errors and 15 warnings for the feather

I didn't do anything manual

[pale grove]

I just tried a fresh one again

Ok now 21

Those errors/warnings are important or can be mostly ignored?

Or how/where would I start fixing them?

For example

Warning: Via connected to unknown net (USB_D+).

It looks correct but maybe I am missing something?

[ionic wigeon]

Hi everyone,
I’m currently working on a project requiring 4 devices with the same address on a single I2C bus. Since the devices don’t have any address select pins and I have to use these, my only other option is to switch/multiplex the I2C bus itself.

That’s why I searched for suitable ICs and found purpose-built ICs like the PCA9546, which is solely designed for I2C bus switching. However, I do not like the fact that I have to send an I2C command to switch the output channel on the switch itself. So, I googled and found out, that there are also I2C multiplexers, but that got me even more confused since they also control the output channel via a command on the same I2C bus.

This led me to tinker with other ideas, and I found what on paper should be the best solution, but I fear I’m missing something. In theory, a dual 4-channel analog multiplexer with typical <45 ohm impedance and <2 pF output capacitance seems like an easy fit. The datasheet of the random analog multiplexer I chose (SN74LV4052ADR) even has this usage as an application example! But now it begs the question: what about performance?

The purpose-built ICs all list a max frequency of 400 kHz, but my gut feeling tells me that with the parameters of the analog multiplexer, it should easily reach the full 1 MHz my STM32 can output. But if so, why do these purpose-built ICs even exist? Why doesn’t everybody just use the readily available general-purpose ICs?! Or am I missing something? Might there be a problem of crosstalk, its “high” impedance, etc.?

[pale grove]

It seems the imported footprints have some errors within them

But how would I fix them or set them to be ignored?

[worldly schooner]

I can’t claim to have a complete understanding of this, but from my experience the main reason is merely a matter of preference. In the application I used a multiplexer, I was monitoring 6 separate temperature sensors, and didn’t need to poll them more than once a second. That plus the lack of spare pins on my peripheral controller made a specialized ic more appealing than an analog mux.

[unique patio]

Have you looked a these guides https://learn.adafruit.com/search?q=i2c%2520multiplexer, including the overview https://learn.adafruit.com/working-with-multiple-i2c-devices ? The code needed to do the switching is straightforward, and there are libraries to help. This is the standard way to do it.

[worldly schooner]

More often than not it comes down to control scheme and available pins…

Most I2C devices are small sensors that don’t require high poll rates or take up a huge bandwidth, but the ones that do usually don’t like sharing a bus in the first place.

[unique patio]

The advantage of the I2C-controlled I2C multiplexers is that you don't need extra pins. And if you have extra pins available to control a non-I2C mux, then maybe you could use those pins for I2C as well.

[ionic wigeon]

im not keen on bitbanging four I2C-Busses with each controlling a oled display - meaning a pretty high bandwidth

[unique patio]

which controller iC is used for the displays, and what's the microcontroller you are using?

[ionic wigeon]

oh i didnt even mention this

STM32F070 and i think the generic ssd1306 but let me recheck nop, the drive ic is called "ch1115"

https://www.lcsc.com/product-detail/OLED-Display_Newvisio-X050-8848TSWYG02-H14_C18723010.html

[unique patio]

CH1115 according to the datasheet has an "SA0" pin which can change the I2C address by one bit. So you could put two displays on one I2C bus and two on another

[ionic wigeon]

well the driver inside the oled itself sure

but the oled itself doesnt have it in its pinconnector

[unique patio]

actually I'm looking at the ch1115 datasheet

[ionic wigeon]

what what? :o

[unique patio]

I can't find a ch1114

nevermind my typo. It's ch1115

i just typed it wrong above and then read it back. Anyway, maybe they exposed that jumper on this display?

[ionic wigeon]

well im not gonna be able to solder a jumper on the flexcable myself^^

for that i would need to scrape the upper surface of while not damaging anything :D

[unique patio]

it's not exposed on the flex cable, maybe on the board.. I'm looking

[ionic wigeon]

btw while your at it: why does the datasheet claim the VDD2 (for the DC/DC Conv.) must be atleast 3,5V when that thing is inside the driveric, and its datasheet says it works at 2,8 already. that confused the heck out of me :D

[unique patio]

I don't know

are you wedded to this display?

The STM32 has two I2C controllers, so if you were able to find a display board that allowed at least one other I2C address, you'd be home free without any external I2C control logic

is this for a commercial design or homebrew?

[ionic wigeon]

ha, no.

[unique patio]

what are your display requirements

[ionic wigeon]

i kept a secret, i wanna do this 2 times

in total im gonna use 8 of these mini displays

usecase btw:

[unique patio]

ok, then just use a multiplexer IC. Are you writing this in STM SDK or arduino

[ionic wigeon]

stm32 IDE and SDK* for sure, im already familiar with it through my work

but since thats my personnel project, cant use company tools

[unique patio]

really, writing the control stuff is not that hard. The analog mux is just a complication

[ionic wigeon]

well to be fair, both solutions seems pretty doable / not hard. the question is for me, could the analog multiplexer perhaps even be faster?!...

i mean the datasheet of the analog multiplexer does even has this application as an example listed:

[unique patio]

well, that seems fine, if you have the pins. The advantage of the i2C-controlled multiplexers is that it doesn't require any extra pins

[ionic wigeon]

the switch IC does guarantee a functioning speed of 400khz, but the analog mux could perhaps be even faster

[unique patio]

so if you are already short on pins, it's a no-extra pins solution

[ionic wigeon]

since the cheapest stm32 on lcsc with usb is a 64pinner anyway, not a problem at all

[unique patio]

can you run the displays at 1 MHz?

[ionic wigeon]

[unique patio]

I would say just try it. if you need to add a little settling time, that's easy

[ionic wigeon]

fair question, i never checked omg.

and: no

well that solves the question :D

then there really isnt an advanced to using a multiplexer. i throught all of the
X050-... oled displays feature 1mhz as everyone i checked previously did

but OFCOURCE the one i decide to use doesnt arrggghh

but thank you very much @unique patio

[unique patio]

you're welcome 🙂

[pale grove]

Another question - I want to integrate a 18650 battery. The usual battery holder is too big for my enclosure.
I found these boards here - so maybe I can replicate this type of connection? Are there any references on how to make these in KiCad?

Or is it a simple hole with some copper around it?

[latent jungle]

Those are plated slots. One approach would be to make an oval pad with an oval hole.

You'd have to watch the slot requirements of the PCB fab you're using. Otherwise, you could created "holes" and communicate to the fab you want them plated manually.

A custom footprint (so you can add the vias) is probably a better approach. And would probably require communication with the fab to know it needs to be plated.

[sacred badger]

@ionic wigeon that looks p dope tbh

[supple pollen]

What load? Is it adjustable?

[ionic wigeon]

english isnt my first language and google is telling me your either talking about meth or transistor n- and p-doping ahaha but thanks anyway i guess^^

[supple pollen]

I believe it is an abbreviation of an idiomatic phrase. So the long form would be "that looks pretty dope", where "pretty dope" is slang for good, nice, or well done.

[ionic wigeon]

ahhh i see, in that case thanks :D

[elder peak]

I mean, that was confusing for me because I was nerd child and so transistor doping was ... um, the first meaning I knew.

[sacred badger]

thanks madbodger

[clever shadow]

Do you think a 1k resistor is a good value between a MCU logic pin and MOSFET gate? This would be to protect the MCU in the event the MOSFET fails, since they otherwise don't really sink current during normal operation.

[supple pollen]

Depends on the voltages on the drain and source, but in most cases that would be sufficient

[shy spear]

is this a good 3.3v clean PSU (its going in a car)

[uneven cloak]

Have you allowed for the vehicle voltage variations as most vehicles can vary between 10.5 and 13.8 volts. The low side on some can go to 9 and high side can go up to 15 volts.

[shy spear]

Yes I have

[shy spear]

A slight revision to fix some errors that I caught

[spring hornet]

Good morning! 🙂
Can you recommend me a wire like leak sensor that I can wire into an esp32?
That can be a digital sensor right? So no additonal component requred, same as like door sensor.

[hushed ermine]

Does this meet your needs? https://www.adafruit.com/product/4965

[stark arch]

Anyone ever use custom servo horns for their project? Looking for a way to possibly screw something into a horn, but options look limited. Was possibly looking at the following combo, not completely sure if they are compatible:

Servo: https://www.adafruit.com/product/2307

Servo horn: https://www.towerhobbies.com/product/aluminum-servo-horn-20t-grom/LOS-1910.html?srsltid=AfmBOopyOTgkhhA3v4-uSerQm40lb5sWJZ7oIvvXqZWHRQIuuDihb_5lx28

[lyric nymph]

Does anyone know which connector is in use on this Adafruit EyeSpi breakout?
https://www.adafruit.com/product/5613
I plan to pull the connector off that board and use it on my own board, but I need to make sure I get the footprint correct!

[worldly schooner]

I could offer a guess, but honestly all of the 0.5mm FPC connectors of the same pin count basically have the same footprint. The only slight difference is usually the size and position of the support ground pads, but oversizing them like on https://www.adafruit.com/product/1492 can easily compensate for any margin of error.

[ripe dawn]

I'm guessing the answer is "it depends" and "would recommend against", but…

Does anyone know if it's safe to connect 120VAC to perfboard? To clarify, my intent is to immediately pass this into a low current (~2mA) voltage divider to detect the signal, but I want to make sure nothing is going to arc on its own before it gets to the resistors.

I'm planning to run the wires into a terminal block with 0.2in pitch, but want to make sure there's no chance of it "double jumping" through the plating around the holes.

[knotty tiger]

if you have to ask, the answer is no

[dark grail]

i would just plug a cellphone charger into a normal 120 outlet, and then detect if its producing 5v on its usb port

then your only dealing with 5v and its far safer

[ripe dawn]

In this case it's not an outlet though. It's inside an appliance, and one of the two signals I'm trying to register is a buzzer which only rings for about a second. It seems like a lot of wall chargers take at least some time before they're outputting 5V so not sure if it would be enough in this case.

[dark grail]

ah, that complicates it some

[worldly schooner]

The board itself is fine, but the air gaps between solder blobs may not be. I would keep any ac power away from perfboard.

I also would use a transformer instead of a resistive divider to provide some isolation from mains. Just to be safe.

[dark grail]

ah yeah, that would definitely help a lot

[copper lintel]

Does anyone know why my GND symbols get tied to one of my 3.3v nets after I update the board from the schematic? Is it a netclass issue?
Really annoying that all of my GND nets are actually 3.3v for some reason.

this is really weird

[copper lintel]

Nevermind, it was an issue in my custom symbol!
No idea what the issue was, but changing a hidden pin from "power input" (its an unused pin supposed to be tied high) to "passive" seemed to fix it

If someone knows why this happens I would love to know

[unreal bay]

Transformers are bulky. How about a full wave bridge and optoisolator. Not mounted on the perfboard. Output from the optoisolator the only wires to the perfboard. Examples seen when searching for zero-crossing detectors.

[uneven cloak]

Once again if you have to ask DON'T do it. I do believe questions or answering anything about High voltage is against server rules

[ripe dawn]

1. there is no mention about anything involving voltage in #welcome, #code-of-conduct or #announcements
2. what is the cutoff for "high voltage"?

[uneven cloak]

1. If there isn't there should be . 2. Anything where your obvious lack of knowledge and care about physical harm can involve you or others. Generally considered to be anything over 32volts.

[uneven cloak]

How about this * Discussion or promotion of activities or projects that intend or pose a risk of significant harm.

[unique patio]

In this case, it's due to experience and knowledge folks have about working with mains voltage. Mains voltage can easily be fatal. Considerable lengths are taken to make mains voltage terminals inaccessible to you inside electronic equipment, light switches, plugs, bulb sockets, etc. Putting bare mains voltage on a perf board is an example of not taking care to make it very inaccessible

[knotty tiger]

@ripe dawn also there are safety standards for PCBs that carry mains voltage, and a typical perfboard almost certainly doesn’t satisfy them. i’d suggest having a qualified professional do that work

[tulip swift]

So not suggesting anyone add mains voltage to a perf board if they don't have the knowledge or experience, but did want to note, there is no reason, if you did do this, that the two lines HAVE to go in adjacent holes as everyone seems to be suggesting. Spread them out. Sheesh!

[worldly schooner]

I mean there are a number of ways to make it safer. Spreading them out, encapsulating with a nonconductive epoxy, adding fuses, etc. Generally, however, it’s not recommended to play with mains voltages in DIY projects due to high potential current and risk of real bodily harm if proper precautions aren’t taken.

I do some electrical work on my own house on occasion, so I won’t say you absolutely cannot do it, but I’m not qualified enough to make recommendations on how to do such work, let alone teach anyone how to stay safe while doing so.

I did suggest a transformer as an off the shelf option to step the voltage down, but I probably should exercise more caution when offering advice regarding mains…

[tulip swift]

So back to the original problem to be solved, is the buzzer on the appliance run off 120/240V (older or simplier appliances) or is it driven off a lower voltage (newer designs often utilizing MCUs boards to run everything)?

[ripe dawn]

directly off 120V, unfortunately

[tulip swift]

Is it wires? Or soldered to a board? If the former, wires going to the buzzer, then easiest solution would be a non contact current sensor. Basically a clamp around the wire that gives you a voltage proportional to the current running through it. For example https://www.electromaker.io/shop/product/non-invasive-ac-current-sensor-5a-max

[ripe dawn]

Ah yeah I had looked at these and probably need to give them another look. I think there's at least one spot where I could sneak these around a wire instead of tapping into the board. What's the right way to read values from these? I'm seeing a lot of them being sold bundled with an ADS1115, but could I just use the built in ADC on various MCUs if I don't care about a precise current reading, just whether or not there's current?

[worldly schooner]

With a 0-1V output, you're going to need a fairly precise ADC to discern a milliamp current. A typical piezo buzzer draws less than 20mA IIRC, and this current sensor looks like it'll translate current at 0.2V/A. 20mA current is 0.004V, so you may want to consider an amplifier circuit or a different current sensor.

[inland jungle]

also determine whether you can see that above the noise

[uneven cloak]

Depending on the country there are legal requirements on distance of mains cable to data cables and a lot of requirements for isolation and intrusion in most countries. I haven't seen "spreading them out" in any countries legislation. @worldly schooner @tulip swift

[worldly schooner]

This is true under many standards, yes. Please do not sell or distribute anything that could be in violation of these codes.

(With perfboard, I’ve only ever built engineering prototype and proof-of-concepts, neither of which are saleable or intended for a permanent installation.)

[copper lintel]

https://www.digikey.com/en/products/detail/stmicroelectronics/LD57100J330R/21348950
Am I crazy, or is this not possible? I would like to use this part in my design, but have a few questions.

How can it supply 1A, when the balls are just 0.254mm? Can that wide of a trace really do 1A?
Is the dropout voltage really just 40mV, or is there some other catch, like with the Vbias pin?
If I use a LiPoly battery from adafruit, can I just tie the Vbias to the input?
Can I use standard solderpaste for it, or do I need to use balls for it?

[supple pollen]

I think you can use paste. I see two possible gotchas with it: one is it needs a separate bias supply, unlike an ordinary 3-terminal regulator. The other is the 60°C/W thermal resistance, if you're drawing an amp, you'll need to keep the supply voltage near the output voltage to avoid excessive dissipation.

[copper lintel]

Got it, thanks! I only plan to draw about 700mA for short periods of time, but the bias is a deal breaker, as I dont have any other source of power for that

[ionic wigeon]

Does a more accurate clock help the ADC on an STM32(G030) in a noticeable way? I'm thinking of adding an external crystal, but since the 32-pin version doesn’t support HSE crystals, I'd need a full crystal oscillator, which is about 10x the cost. By “noticeable” I mean an actual improvement in accuracy or SNR. I could see more stable timing helping with sampling consistency, but maybe the internal RC oscillator is already good enough for this. Anyone have experience with this?

And yes, i know, a clean supplyrail and the layout itself is probably way more important then the clock, but thats whats interests me... by how much really :o

[supple pollen]

I don't have experience, but my understanding is that the clock has little effect on ADC accuracy. For another project I'm working on that requires clock accuracy (for different reasons), I found that I could get a little packaged 1.5ppm accuracy oscillator for around $7.

[dark grail]

what if the clock frequency is too high? i assume there must be some minimum period time

[ionic wigeon]

what do you mean with that? i could always clock/divide it down but the question was if a more stable external clock would improve the ADC itself or if thats unnecessary

[dark grail]

i was thinking more along the lines of overclocking the adc

[ionic wigeon]

oh no thats not what i had in mind^^

[supple pollen]

I'm making the assumption that the clock used is an appropriate frequency. I figured the question was whether clock accuracy (as opposed to frequency) affected ADC accuracy.

Overclocking the ADC presumably would affect accuracy

[ionic wigeon]

yes it would. 16mhz to be precise.

[gloomy lion]

Making an RP2354 thing for the first time and wanted to double check if my schematic and circuitry look okay - I know the PCB view is a little messy and hard to follow tho

I'm very used to designing for the RP2040 and I just want to be sure that I'm not making any obvious newbie mistakes with the component layout

[sacred badger]

quick question -- trying to wrap my head around how this LED tree from lowes works. it appears there's a central hub at the top that distributes power (5v/G), but all data lines are connected... yet, there's animations that have a spiral effect -- can't be something like ws2812b or whatever, bc if all data lines originate at same place, spiral effect would be impossible(?!) i'd think

it's powered by a STC8H1K08, and has an 8MB 25* flash chip which i dumped with a CH341, and viewing with a hex editor, one can somewhat see the animations

im somewhat assuming it's treated as a panel, of sorts -- 18px wide. was never a software person

[latent jungle]

Voltage (vertical) noise will almost always be higher than time/sampling error.

granted, at 16 millihertz, things can be different. but you probably meant 16 MHz, which is a couple of orders of magnitude faster.

(just worth mentioning because it’s a weird units error to make when the primary concern is timing)

[ionic wigeon]

i though so too^^ but will see how clean i get my voltagerail in the end. And yes, ofcourse i meant 16MHz :D

just wrote that on my phone without much care since in the context only MHz would make sense anyways :D

[supple pollen]

Could be each string is (virtually) offset by one position. GE made some addressable lights a while back, this could be related.

[sacred badger]

thx for that -- done got me lookin at SK9822 strips lmao

[sacred badger]

in fact it is a GE branded tree

wonder if i could replicate it for cheaper

[knotty tiger]

i think Adafruit even sells "fixed address" LED strings that have similar properties

[golden wasp]

Hi, I have bought an Adafruit 128x32 OLED feather wing for an Arduino UNO R4 Minima project. The display is 3.3V and the UNO is 5V so I've bought an Adafruit 4 Bi-Directional Level Shifter (https://www.adafruit.com/product/757). I tried to run the matching ssd1306_128x32_i2c example but the display doesn't do a thing. I've tr ied the display with an Adafruit ESP32 V2 and with that it works. However I need to make this work with the UNO. I've connected the 5V and the ground to the HV side of the level shifter, SDA to B1, SCL to B2, the display to the LV side. This is the way it should work, right? (noob here)

[brave vigil]

https://learn.adafruit.com/adafruit-128x64-oled-featherwing/wiring-to-other-microcontrollers says you also need to connect the RST pin of both the MCU dev board and feather wing together. I'm not sure how to do that with the level shifter.

[worldly schooner]

LV needs to be connected to a 3.3v source. The level shifter does not do this power conversion for you.

The uno should have a 3.3v output next to the 5v output.

Use the breadboard to connect 3.3v to both the display and LV.

[golden wasp]

I think that is only if you want the reset button on the oled wing to work (i.e. you made the reset button on the main feather board unreachable by putting the oled wing on it.

[golden wasp]

Thank you so much 🙏 It works now 🎆

❓ one more question: the display seems to attached to the pcb with a drop of glue. lets say I want to have the display flush with the case. suppose I'm carefull enough not to damage the flex cable, can I pry the display from the board and fold it 180 degrees (thus facing the back of the pcb). It would give me just enough wiggle room to better install the display. or is it a foolish idea?

[unique patio]

I think it's double-stick tape, not glue. Do you see glue ooze?

[worldly schooner]

It is possible to pry the display off the pcb, but I’d say it’s quite risky. Mechanically, the adhesive holding the display also doubles as strain relief for the flex cable, so undoing that would make your assembly that much more fragile.

The typical method of flush mounting is to use the mounting holes on the pcb.

[unique patio]

I agree with Hem.

[pale grove]

are there any "long" USB-C connectors? I need something that's like 20 mm

Or alternatively I would need to add wires to the USB-C connector instead

[brave vigil]

Depending on the connection type (USB host vs device), you could try using a USB Type-A connector with this adapter: https://www.adafruit.com/product/4175

[pale grove]

Ah no I meant for mounting on a PCB

[supple pollen]

It may be possible to put a sort of extension on your PCB to hold the connector out a distance, but I don't know if it would work for your particular use case.

[brave vigil]

An additional USB Type-A port is what would be mounted on the PCB, when using my suggestion.

[latent jungle]

like this? https://www.mouser.com/ProductDetail/Same-Sky/UP20-C-F-G-FL-1-P12-TR

[worldly schooner]

Long that may be, but it isn’t 20mm long. Datasheet suggests closer to 13mm.

[latent jungle]

Then I doubt such a thing exists

[gilded grail]

Not 100% sure if this is the right channel for this... But!
I picked up a KB2040 for this controller project I'm working on. I'm looking for a solution that would kinda be described as a "zero resistance volume knob." So I found some "free spin" potentiometers and the two I've tried so far, just don't really have that zero resistance to them that I'm looking for.
So I knew that logitec has that "free spin" scroll wheel that they market on some of their mice, bought one of those and took it apart to see the magic in the sauce. To me it looks like a IR sensor on a custom PCB, maybe someone here knows more about these mice than I do and could comment on that.
But I bought (picture A/ black PCB) because I thought it would work the same way the scroll wheel on the mouse did, but I can't really get it to read which direction it's rotating in... which is a no go on the controller idea if I can distinguish whether it's spinning left or right...
Soooo.. I thought about getting (Blue PCB) and trying to stick one of those discs from the other sensor in there and go about programming it the way I need it to work. But would just like some input from some more knowledge people before I get 100$ into this project and none of the parts work for what I'm looking to do...
Thanks in advance for any input and can provide more references for things!

[supple pollen]

Basically, you use two sensors per wheel to generate what's known as a "quadrature" signal, which can then be decoded to derive both direction and speed. There are encoders available that integrate the wheel and both sensors.

[gilded grail]

Is there something specific I should be googling here?
Are the encoders your talking about free spinning OR would it be something kind of like the first IR sensor pictured with some custom hardware around it?
Just kind of trying to pick which rabbit hole I'm jumpping into

[gilded grail]

https://www.amazon.com/dp/B081W2TY6Q?ref=ppx_yo2ov_dt_b_fed_asin_title
These are the actual sensors that I bought already, not too sure if I just wired them wrong, or those just don't read directional data.

[unreal bay]

Quadrature encoding is based on the encoding wheel (multiple variations) and dual sensors, to be able to detect both speed and direction. Whether that is free spinning or not is completely separate. That is controlled by the mechanics of how it is mounted.

Do a search on quadrature encoder to see how the 2 sensors allow direction detection.

[pale grove]

Another question - which resistor is meant here that needs to be replaced?

The R3 10k?

[pale grove]

And for the LED - doesn't it need 5V?

[supple pollen]

The resistor connected to the PROG pin (which programs the charge current). R9, in this case.

[supple pollen]

The LED is designed for 5V, but lots of people run them on 3.7V (from a lithium cell) or even 3.3V successfully. You need enough forward voltage to power the bandgap of a blue LED with a little headroom for current regulation (the WS2812 uses current regulation instead of fixed resistors), and 3.3V is (barely) sufficient.

[pale grove]

Ah ok - thanks!

So in theory I could just hook it up to a 5V source too without any extra components?

[supple pollen]

The LED will run well from 5V but a 3.3V signal may not be able to control it reliably.

So you may need a level shifter if your controller is 3.3V

[unique patio]

If this is for an external WS2812, sure, you can try this. If this is for a board you are making (e.g. status indicator), play it safe and drive it with 3.3V.

[pale grove]

It will be for a board but I need 5 LEDs

[unique patio]

that is still OK if your 3.3V regulator can supply the current

or you can add a level shifter

[gilded grail]

I had found a pretty good video explaining it. But all the quadrature encoders I've found on sites make them kind of look like regular old rotary encoders? Is there something I need to be adding to my searches to get closer to what I'm looking for? or are they actually more like rotary encoder and inside the pot it's just the optical disc like I'm looking for?

[supple pollen]

They're all rotary encoders, but you presumably want one without detents so it rotates smoothly

[gilded grail]

so you're saying get an "optical quadrature encoder" and not a "magnetic quadrature encoder"?
Or how can I tell if it has any detents inside of the pot without opening it?

[gilded grail]

https://www.amazon.com/Taiss-Incremental-Encoder-Voltage-Warranty）600P/dp/B07MX1SYXB?dib=eyJ2IjoiMSJ9.y5gXuZk0wI-_INogZdOQ3KYKRy08Qe18EZ0JS35TJJSZTLlTR-jIp3zKaRbk_OXQk2fFBhNCpa3CkJRk4oQvN_Sp625q3AjhhfnSTbShjF0mM9pnVEnowkd4iQz89tIaZGEfILt0ANVVdqmikt-SEPxu9hmFUDbkvVQyVsgvpAnvgg2k1kYcpCtRBmk2E5HzAOZ8Y1-MVx7ZtUMY84fx-7tXOjsokIKLDNX1xktZyp0.MRdx7VDAHUOqUOWj-fIpJh9phr-mzb34rrhqaAQJC7Q&dib_tag=se&keywords=quadrature%2Bencoder&qid=1730949792&sr=8-1&th=1

This is what I was looking at. But I have the adafruit kb2040 and this encoder has a review that says it doesn't work well with anything under 7V.

[unreal bay]

Various sensor technologies can be used for quadrature encoders. Mechanical, magnetic, optional, and anything else that can sense a presence or absence at a scale and resolution to implement that '90°' phase shift needed. With varying resolutions and accuracy. How the shaft that is attached to is mounted determines whether it is 'free turning' or not. If you can find a simple shaft and bearing of the right size, you could mount (for example) an optical encoder wheel on that, then position (either reflective or break beam) sensors to read it. Add a knob of your choice to the shaft, and you are ready to go. For a DIY version like that, the fiddly part is positioning the sensors to get proper 90° phase shift. I have no information about specific products. Just for playing, I have taken apart old optical mice that had a pair of encoder wheels. For detection of X an Y motion.

[gilded grail]

this is esentially what my plan was, but... I bought those speed sensors and they just don't read direction like I thought they did. I'm curious if I get one in a pot like the one I linked above your message would work for how I'm talking about using it. It would make printing housing and the CAD work a lot simpler for that part of the controller. But madbodger had mentioned detents.
Unfortunately I'm only like a couple hours into this over the last month or two. So I'm okay at wiring up controllers and arcade cabs with some simple boards. I'm still really just learning on the custom side of things. 😓

[supple pollen]

Detents are a mechanical feature that simply makes it "click" into a number of positions. Without them, it would turn smoothly. You don't have to open it up, you can easily feel if it has detents by turning it. From your original description, it seemed to me like you wanted smooth rotation. There are several very small magnetic and optical encoders available here https://www.pololu.com/category/157/encoders-for-micro-metal-gearmotors intended to be mounted on motor shafts. There are, of course, stand-alone ones as well.

[orchid galleon]

I was about to ask if 'free spin' meant 'no detent' or if it meant 'very low friction'.

[supple pollen]

Or just continuous rotation, as opposed to an ordinary potentiometer which can only rotate 270° or so.

[pale grove]

Another specific question.

I am working on a custom charging cable for a device.
On that charging cable I want to add some kind of LED indiator so that I know if the device is charging or not.

Is there a simple approach to this without using a microcontroller?

Or do I need one?

I basically have V+ and GND available from a USB-connector