#help-with-hw-design

1 messages · Page 4 of 1

limpid nest
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What's worse for a PCB: smaller power/gnd pours that aren't interrupted or larger pours that are?

unreal flax
limpid nest
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Yeah it's hard for me to put a rule on but I thought there might be one

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I'll just focus on trying to make big pours without interruptions

knotty tiger
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much like in other parts of engineering, "it depends". i think there are broad guidelines about where interrupted pours might get you intro trouble, like where there might be high current flows, or where they're joined with a long trace that has enough inductance to disrupt the circuit

supple pollen
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For high current/high frequency, interruptions are to be avoided. But if you're using the ground pours for heatsinking, larger is better. In cases of both, you tend to end up with lots of via stitching

woven bluff
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OK, CCFL Inverters have high ratio transformers

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they are a bit bulky, but much better than CRT transformer

supple pollen
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Yeah, they're good to 1300V or so which is useful. There are also high ratio transformers available from surplus vendors, places like Information Unlimited, and the far East (such as the popular MP-2057). I have links if you're curious.

pale umbra
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is it a good reflex to be scared when a transformer start ringing/whining loudly and shut off the power going to the appliance it's in ?

woven bluff
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no, transformers whine alot

limpid nest
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Yeah it's part of how they work/a consequence of materials

pale umbra
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what about ringing and the appliance display lcd goes wacky and randomly displaying things turning on/off?

knotty tiger
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sometimes switching power supplies will audibly squeal when overloaded

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the sound in combination with unusual behavior of the device it's powering does suggest some kind of fault condition, which could become hazardous depending on the details of the device

pale umbra
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yeah its fuse was turned off and they came and unplugged it inside the wall but was a bit scary

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but I'm pretty sure the ringing was a feature, as in it was probably not the transfer but the control board having a speaker/ringer

carmine plume
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hey i've got a pcb with pads for a 2.54mm 2-pin header - any suggestions for a good low profile header?

distant raven
pale umbra
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I just sigh loudly and yawn like a lower-pitch chewbacca

supple pollen
carmine plume
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I think I might try and go for a low profile jst connector at right angles

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really any low profile 2.54mm connector will do

pale umbra
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is there something that can sort of analyze PWM if all else fails for my R/C stuff ?

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to trace how it arm (duration/baud rate/etc)

supple pollen
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The traditional tools are things like logic analyzers and oscilloscopes, but you can also use stuff like a "pulse in" function available on many microcontrollers

pale umbra
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are they going to be fast enough for something that last like 1us at 115000 bauds ?

unreal flax
pale umbra
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it's not usb though but custom connectors like XT60, mini-tamiya etc

unreal flax
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No, I mean the logic analyzer hooks up to your PC via USB. It just has wire leads to attach to whatever you're analyzing.

pale umbra
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the reason I haven't gotten an ESC yet is this and because it's hard to tell if the ESC allow for expansion and the connections aren't soldered also all those new connectors (ESC normally need to be connected to the lipoly battery with the same connectors that the receiver use) and bigger connectors are used for bigger loads just like lower AWG are used for bigger loads

supple pollen
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I don't know what you mean by "allow for expansion": most ESCs have fixed programming, but some have the ability to configure various parameters. You could always splice wire or solder new stuff on, but most of them come with wires attached already. Normally the ESC powers the receiver with its on-board regulator, but some builds use a UBEC to power the receiver separately.

pale umbra
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whereas a traxxas xl-5 is expendable but very expensive as well so trying to find a modular one in the 40$ range

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the 1/64 esc are the worst as everything is used

supple pollen
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I still don't know what you mean by "allow for expansion" or what female connectors you want. You can hook an Arduino to the control connection. As for battery connectors, you can use adapters or just cut off the provided connector and replace it (I've standardized on Anderson PowerPole connectors for my builds, so I install them on all my batteries and ESCs)

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Here's one of my Traxxas models, I've replaced the Traxxas battery connector with my usual PowerPole

traxxas-innards.jpg
pale umbra
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well in the case of this one I can't put a 2nd battery

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it has 3 free wires and 1 battery wire

supple pollen
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Why would you want a second battery?

pale umbra
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because Im doing 1:10 and those are pretty powerful

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and the battery will be quickly used (between 9 and 39 minutes)

supple pollen
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You could either use a bigger battery, or (carefully with proper precautions) parallel batteries, or use a series connection if the resulting voltage is something the ESC can accept.

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I do have a pair of paralleled 105Ah AGM batteries, but that's not for a vehicle

pale umbra
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I guess I'll go for the build I said the other day or wait until I have enough money for the SCX10

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it comes with an esc and a receiver/transmitter so it would be kinda useless to buy an esc now just to test if I can interface with one than throw it if I get the scx10...

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Well 105Ah sounds suitable for bigger vehicles

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like scooters or forklifts

pale umbra
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so I'd rather have too much than not enough...

void sentinel
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Is that a three phase rc car?

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sounds efficient. I never thought of applying that to smaller motors. We have been using vfds for decades.

pale umbra
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3 phase motors have been used for a long time in the r/c world

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they are just so far ahead of the general electronics community for motors/mechanics - the best you can get is a terrestial 70$ motor that's like 10W in general electronics while these can go up to ~1400W in burst (120A ESC * 12.2V) and you also don't have to create the mechanical system for a robot etc

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also saw an high-end 12000$ semi-open robot that uses an r/c as the mover

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all they did was reinforce the wheels and shocks

void sentinel
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Um, ping moderators? what is the proper reaction to this?
(besides reposting it in a way that defeats bot scripts?)
More importantly, what was the bad word? The f word?

Screenshot_2022-09-04_110235.png
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Futaba?

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nope...

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must be methane

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weird

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Ok my newest edit. Can I just post the brd files or is that more complicated than a screenshot if it has to be downloaded and ran in special software? Hmmm.

📎 v3.0.brd 📎 v3.0.sch
pale umbra
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it mention something dangerous / discord product that's why it's blocked - at least that is what I was told

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code of conduct mention "Discussion or promotion of activities or projects that intend or pose a risk of significant harm" and that word would fall in it

void sentinel
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the n i t r o?

pale umbra
void sentinel
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It is not their intent to do harm. I am confused.

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ok that sounds good.

woven bluff
vast flume
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Hey guys, posted this to the general channel but meant to post here

alpha.jpg
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Accidentally had my microusb port flipped on my pcb

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Any ideas on how I can surgery this back to life? 🤣

knotty tiger
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oh, is the receptacle opening facing away from the edge of the board?

limpid nest
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Yeah, only thing I can think of is using a R angle piece

vast flume
knotty tiger
# vast flume Yeah

so if you rotated it 180 degrees in the plane, you'd have to swap all the wires (and the stakes would be in the wrong place)?

vast flume
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I think what happened was the datasheet wasn't clear with which orientation the port was supposed to be in

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So I didn't know which way to orient the footprint

pale umbra
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PCB Maker "so user has made error I think they have a usb plug pointing into the board" - not my job print it anyway

limpid nest
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JLC at least does some error checking, as I've gotten feedback from them before, but I doubt they'd go as far as that

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Your board, your error.

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Having made a number of them, I feel the pain

vast flume
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Yeah they actually asked me about the component placement for other components on the board, but not for the single most important thing that I cant fix myself with reworking 🤣

limpid nest
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Ouch! Sorry friend

hollow flame
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any tips for making wire to board connectors? harnesses s i've heard them called. is there a particular molex series thats easiest to crimp? I'm very comfortable doing things like crimping RJ45, is there anything that would be kinda smilar to that?

tough matrix
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do you need something very specific?

hollow flame
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I need to route the individual wires to very different places, but I want a clean connection on the board just cause I think it looks more professional. I've used screw terminals in the past

tough matrix
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if you have freedom to choose your own connectors to place on board, choose something like JST PH connector on the board and then buy cables like this one

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how much current do you need to carry?

hollow flame
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its just 5v logic im basically just running it to different potentiometers

rustic fulcrum
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That said, I did stumble on a huge guide to this a while ago, let's see if I can find it

hollow flame
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this is awesome!

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thanks!

hollow flame
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also found this video that explains things very well

bleak crown
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Hello, (It was suggested I try my question here and not in general tech)
If the ANSI / ESD S4.1 guidelines (section 8.0) resistance-to-groundable point (RTG) test PASSES (including the wrist strap to ground resistance testing in the same range as mat RTG), is the point-to-point (RTT) test necessary? Not for certification, but for a hobbyist using less than 120VAC more like 3.3 to 48 VDC - wrist strap grounded through 2M ohms. What could possibly go wrong? 😩 What is the benefit of the RTT? Seems like I might leak less than 6mA (5 milliAmps using RMS) between components on the mat?

ANSI / ESD S4.1 guidelines (section 8.0) state that point-to-point (RTT) tests should find the mat has greater than or equal to 1 x 10^6 ohms of surface resistance.
A different vendor product -> 2 x 10^4 ohms FAIL

ANSI / ESD S4.1 guidelines (section 8.0) states that resistance-to-groundable point (RTG) tests should find the mat has between 1 x 10^6 and 1 x 10^9 ohms of surface resistance.
A different vendor product -> 2 x 10^6 ohms PASS

As an unrelated question, https://www.adafruit.com/product/4405 states "If you want to test the coating, you will not be able to use a multimeter in resistance mode, they're not sensitive enough!" But my cheapo meter claims it can do 2M ohms and 20M ohms and both scales measure ~ 2M ohms RTG. I did not do the microamp - inline test (for a different mat I already had). Should I not trust this 2 x 10^6 ohms reading RTG nor 2 x 10^4 ohms reading RTT?

Anti-Static ESD Rework Mat with Grounding Clip - A4 Size

This anti-static work mat is great for electronic work and repair, especially delicate or ESD sensitive work. It's 2mm thick and has a very high-resistance covering, like 10's of ...

pure gorge
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Im wondering if theres any obvious mistakes I made with this

board.png
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I'm not too confident with the PCM1860 setup

woven bluff
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just found out the day after the production is finished...

vast flume
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Ouch

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I think I found a solution out of pure luck

woven bluff
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I could just turn it around during soldering, but the mechanical pins wont fit

vast flume
woven bluff
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it was incorrect to begin with.

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turning it makes it correct

vast flume
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Lucky

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🤣

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Mine has the correct pin order when installed backwards

woven bluff
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now JLC is charging 20% more for tax in UK

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does PCBway do the same?

vast flume
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I don't know, I used jlc

void sentinel
# pure gorge Im wondering if theres any obvious mistakes I made with this

What are the D+ and D- for? There does not seem to be any need to break those out. Are you powering the pi from that usb port? I am not really sure why you even need the USB in this setup. This is a mic input adapter for the pi? dual mics though? I see 10uF coupling caps they seem high not sure what your low end cutoff frequency is. I saw the example breakout in the datasheet and they use 10uF also. They also use 100k pull down resistors on the input. also you tied pi pins 2 and 4 and 1 and 17 together. Why?

vast flume
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Do I need to flash the firmware on my custom esp12 board before programming it?

vast flume
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Never mind, looks like I got it to work without that

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Also for anyone interested, I was able to find a hacky solution to the usb problem

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I desoldered it, and then resoldered it so it was standing up vertically

pale umbra
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"I need to plug my USB on my PCB hanging down from the ceiling but it works" 🤣

vast flume
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Only problem is all of the shield pads cant be connected, so you cant really unplug the cable once its plugged in without ripping the entire port off lol

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Good enough for testing tho, was able to verify my cp2102n config

woven bluff
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you can reinforce it with epoxy

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if you have copper pour around the usb, you can solder the shield to the ground plane

vast flume
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Yeah I soldered a wire from the shield to ground, but good idea with the epoxy reinforcement

pale umbra
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id like to stand this off to about an inch or 1.5 inch above 6-32 to3 standoff dont fit barely. any ideas?

IMG_20220905_154225.jpg
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apparently the screws that fit normally are #2-56 machine screw with a nut under the board, but I don't know what 2-56 and 6-32 mean

knotty tiger
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2-56 probably means drill size #2, 56 threads per inch, etc.

pale umbra
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I want to raise and put a cardboard box 1 inch above that robot so I can put a pi or pico in there with a lithium battery or a 4-cell nimh

knotty tiger
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are you sure the hole isn't sized for metric screws? what particular board is it?

pale umbra
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seems they are slightly too big by like maybe 0.2mm 😦

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I have a standoff kit and this would have allowed me to screw standoffs on each other and raise the cardboard box 1 feet if I wanted...

knotty tiger
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numbered drill sizes go smaller with increasing number, so it's puzzling that 6-32 didn't work

pale umbra
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mine vs original in the nut

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whoops wrong one

woven bluff
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imperial thread, you heretic ;p

pale umbra
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I'm going to look at sumo competition designs I guess. Polulu don't seem to sell an expansion kit (they do for the arduino version but this is a u32 version)

woven bluff
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that thing looks like a Goliath bomb

void sentinel
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I am confused. they never use that hole in the directions

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Other options: smaller bolt, bigger hole, new location or different mounting technique...

pale umbra
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I'm not I'm using the ones on the side

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and new location, well after it's assembled I don't have many left, I basically have 6 holes left in pairs of 3 along the board on each side

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and the battery limit how deep inside the battery box the other side can go (that's why the nuts)

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just need to find the standoffs, hardware store don't sell them or screws of that size for some reason (M2.2 might work too)

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I also don't have "rules" this isn't for a competition 😄

woven bluff
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does m2.5 work?

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once I drilled RPi mounting holes to 3.2mm so they can fit both m2.5 and m3

vast flume
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Hey guys, so I am using a 2020 sized neopixel, but when I try to run strandtest it just turns white https://www.amazon.com/DIYmall-WS2812B-Built-Programmable-Arduino/dp/B0B1MC997K?pd_rd_w=JhLGe&content-id=amzn1.sym.deffa092-2e99-4e9f-b814-0d71c40b24af&pf_rd_p=deffa092-2e99-4e9f-b814-0d71c40b24af&pf_rd_r=VEQZNWCJS44ZZ9E1RQ38&pd_rd_wg=JisIl&pd_rd_r=5829d92d-86df-4c71-9410-342c3ac11d0b&pd_rd_i=B0B1MC997K&psc=1&ref_=pd_bap_d_rp_1_t

DIYmall 20pcs 2020 RGB WS2812B LEDs, Built-in IC Programmable 0805 ...

DIYmall 20pcs 2020 RGB WS2812B LEDs, Built-in IC Programmable 0805 RGB Light Beads for Arduino SMD PCB

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Any ideas on what could cause this?

void sentinel
vast flume
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Ah thx 🤣

void sentinel
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😉

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is it rgb vs. rgbw? or rgb vs. rbg or bgr whatever the dumb one is that is not rgb? lol

vast flume
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On amazon it says rgb so I tried both rgb and grb

void sentinel
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just a single pixel?

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yeah grb so silly

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what processor board?

vast flume
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Yeah

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ESP-12f

void sentinel
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running c or python?

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maybe strip is only for > 1 pixel?

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there is a simple one that seems to have been made for the rings, but it uses a pixels function

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method/object whatever...

vast flume
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C

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And no I've done this with a single neopixel before

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Just never with a "nano" 2020 sized one. Trying to figure out if I made a mistake with my pcb design

knotty tiger
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do you have a known-good NeoPixel or strand to test against?

void sentinel
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#include <Adafruit_NeoPixel.h>
#define PIN 6
#define NUMPIXELS 1
Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
pixels.begin();
pixels.clear();
}
void loop() {
pixels.setPixelColor(1, pixels.Color(0, 150, 0));
pixels.show();
}

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well i copy pastaed it already so...

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oh you made a board with those?

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I could have skipped 2 copies with just changing the variables in the init line

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"if they all work the same and you've done this before and there are no software errors then it must be a hardware error" - captain obvious

vast flume
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This bad boy 😎

IMG_1524.jpg IMG_1525.jpg
void sentinel
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in and out are the only thing I don't get about them. (im kidding) The power part is easy

vast flume
vast flume
void sentinel
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I saw this board before we were in the usb department

vast flume
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Yeah

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Its been a rough few days 🤣

void sentinel
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i guess

vast flume
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The accelerometer is also showing up under an i2c address that shouldn't even exist lol

void sentinel
#

I sent a board to the builders without having the rest of the parts first if that makes you feel better

vast flume
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Oof

void sentinel
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it only cost me 30 to learn to make sure you can still get samd21...

vast flume
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Jeez 🤣

void sentinel
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I could still get 3. the boards wont be here for days maybe a week still

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the price of these don't matter "too" much

vast flume
#

Yeah

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The rough part is when you have them assemble for you

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It takes like an extra week

void sentinel
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they cant assemble what they dont have

vast flume
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Especially if you do a special colored solder mask

vast flume
void sentinel
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of course they could be the ones hording all the M0s

vast flume
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Strangely they do have some parts that you cant get elsewhere

vast flume
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And the MPU6050s

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1 year + backorder

void sentinel
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yeah

vast flume
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But they have them in stock by the thousands 🤣

void sentinel
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that's why I just quickly made a rp2040 board

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not quickly to print though just the design

vast flume
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Ah yeah

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This was my first pcb so I guess its working better than I thought it would

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Even though it has all its issues

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At least I can program it 🤣

void sentinel
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I am waiting to figure out if I want to figure something else out. And for Friday when I get paid. I can only afford errors every 2 weeks.

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This is my first professionally made board

vast flume
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Yeah luckily the dev shop I run is getting some good business now so I have funds to make many mistakes with my other hobbies 🤣

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(except skydiving, still no mistakes there) 🤣

void sentinel
#

These are over 30 years old. I guess the solder doesn't go away just sitting there...

PXL_20220906_011909495.jpg PXL_20220906_011926492.jpg
vast flume
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Wow that is something!

knotty tiger
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nice! hand-drawn traces?

void sentinel
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I would say it's something embarrasing, but it was in high school so it doesn't count

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ferric chloride

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not soaked enough lol

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resistive ink pen

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i had rub on transfer pad things too

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555 74193 or 74192 some kind of decade counter. And a big fat 74154 thats the bcd to 1 of whatever

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Maybe 15

vast flume
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Back when the pins on an ic were visible

void sentinel
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my 7400 series ttl and the 4000 series cmos

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the 7470 was my chip really

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the just kidding flip flop

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also my initials are: jk

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Is D1 where the pixel goes?

vast flume
vast flume
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I took those pictures before assembling the components they didn't have in stock

void sentinel
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what code are you using to turn it on?

vast flume
#

I was just using the adafruit neopixel strandtest code

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Looks like its too long for me to send through discord

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But yeah I think its probably a hardware issue

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Just to confirm though, do I refer to GPIO2 on the ESP-12F as pin 17 in arduino?

void sentinel
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that driver chip is the same one in adafruit's 5050s

vast flume
#

Oh

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Does that mean I have to change something?

void sentinel
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I think those are just the board pin numbers not sure I check...

vast flume
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Hmmm

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If thats the case then how should I figure out what the actual pin number is?

knotty tiger
#

i would look up the definitions in the appropriate header file in the Arduino Espressif BSP

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yeah i agree with @void sentinel those might just be module pin numbers, not Arduino API pin numbers

pale umbra
#

sorry but what's the name of the stemma qt expander (plug 1, get 1) and the plug 1 get 3 ones(4 ports on it) ?

knotty tiger
vast flume
#

Thats so strange lol

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I'll try that I guess 🤣

knotty tiger
#

what board name are you using in Arduino?

vast flume
void sentinel
#

I would think in Arduino it would be called D2

vast flume
#

2 or D2?

void sentinel
#

I was looking at a guide on microcontrollers site and they mentioned 11 grio pins and not gpio2 on pin 17 and there was a comment on it that said hey you said 11 and there should be 12 and what about... And I thought... How ironic

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2

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I mean normally thats how they are referred to

vast flume
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Ok I'll try that

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It works!

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Thanks so much

void sentinel
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sweet

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no problem.

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I enjoy learning in order to help others.

vast flume
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I'm the same way

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This one was just so confusing to me for some reason hahaha

void sentinel
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Oh funny you gave that link. I actually was at the one for your board lol

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I was thinking that I was overthinking

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that's why I started asking what may have been redundant

vast flume
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All good

void sentinel
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My ESP collection

PXL_20220906_020612934.jpg
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My first one didn't even have the shielded case

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ESP-EYE

vast flume
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Oh wow 🤣

void sentinel
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Then I got the ESP-CAM

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Actually that should say ESP32-S2-TFT

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I think I bought the rover from Adafruit as soon as I saw how cool it was in the Titano. even though that is a wroom.

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And you are mostly really dealing with the samd51 in that. The esp is mostly just used for wifi

vast flume
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Yeah

knotty tiger
vast flume
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Yeah GPIO2 is D4, which is "2" to the arduino ide

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Very confusing lol

knotty tiger
#

yeah, usually digital pins are labeled on Arduino boards with simple integers that are inputs to the Arduino API. dunno why the NodeMCU pins are labeled as Dn and why the BSP uses the GPIO numbering for the Arduino API

vast flume
#

@void sentinel @knotty tiger Thanks again for the help! 🙂

void sentinel
#

Ok I think I am done. Again. I also really find it hard to not just have this sent to the printer...

v3.0b.png
hushed smelt
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ha, i like all the acorns scattered around, that's cute.

woven bluff
#

I have the opposite problem. I have a hard time sending my design to fab because I can not be sure if I got everything right.

hushed smelt
#

oh i have plenty of shiny pcb paperweights from not getting designs right. got uart and spi lines mixed up once. that was disappointing. to be fair i designed that one when i didn't even know what spi was. i really need to remember to design them big enough to make drink coasters out of at least.

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now i think of spi and i2c as magic busses ferrying data to and from components. it's whimsical and helps me remember never to make that mistake again. 😛

knotty tiger
#

have them shipped as panels? sure, you have to cut/separate them yourself, but it's easier to make coasters out the busted ones 😁

woven bluff
#

I dumped all flawed pcb recently. I don't need to be reminded of my failures every time I look at them.

void sentinel
#

Lessons, not mistakes.

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If you are not failing, you are not innovating enough. Elon said that

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Simone said she likes failing because it takes the pressure off...

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My failed print drawer:

PXL_20220906_182503583.jpg
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Not the same as the failed prints that go into the garbage.

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Actually a lot of these weren't failures, just different iterations.

vast flume
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Made the mistake of not asking last time and ended up with a connector that didn't fit

limpid nest
#

On some adafruit I2C boards, there are selectable pads to set the address. These pads make use of a pulldown resistor. If I have an I2C device and I just want it to have one fixed address, can I just pull its pads to GND/VCC as appropriate?

hollow flame
#

anybody haver a favorite MOSFET IC wiht maybe 4 internal fets that you can drive with 5v logic signals?

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need to turn on four sets of LED strips, draw low enough power that usb power works, but can't pump that much out of arduino digital pins

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did some searching on digikey but im not having a lot of luck

twilit mango
limpid nest
#

physically on the board

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can I just tie the pins of the device high or low

twilit mango
#

Yes, you can. Then don't break anything out to the user, and the address will be what you set it to on the board.

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Typically on the Adafruit boards, even when you can change the address, the first address pin pad is always bridged to create the initial address.

limpid nest
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oh sorry, to be super clear, I meant when making my own board

twilit mango
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Do that, except not on a broken out pad.

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I know what you meant.

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I'm saying in your board design, if you want it to remain fixed, don't break the address pin out to the user. Then folks can't mess with it.

limpid nest
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oh yeah no I wouldn't do that

#

Pesky users!

#

thc

#

thx

twilit mango
#

😄 You're welcome!

pale umbra
#

how does that even work anyway?

#

how does it know it's been soldered ?

twilit mango
#

Because it ties the pin to GND or VCC, which changes the pin state. The device then sees that and alters the address it's broadcasting when scanned.

pale umbra
#

bit puzzled why this keep the adress static doesnt seem to be soldered to anything else

IMG_20220906_195736.jpg
knotty tiger
limpid nest
#

What's the point of pulling say an OE pin down rather than just tying it, when there's no other interaction with that pin?

knotty tiger
limpid nest
#

Using a resistor vs direct connection

knotty tiger
#

if you use a resistor, you can inject a high logic level later to override it. otherwise, if it's connected directly to ground, you'll have to break the connection to do so. also the resistor can be for safety reasons, sometimes

pale umbra
#

I feel like a I made a mistake getting a Pimironi PIM357- BME680 Breakout - Air Quality, Temperature, Pressure, Humidity Sensor

#

Like I was checking for a sensirion temp/humidity sensor and saw those Bosch 4-in-1

#

but since sensirio are 20$ and BME is 29$ I guess the accuracy is going to be really bad

limpid nest
knotty tiger
# limpid nest That was my understanding but this particular circuit, the pin doesn't connect a...

to some extent, it might be a holdover from TTL logic families, because the inputs go directly to the base terminals of bipolar transistors, and can source/sink measurable current under static conditions. for those cases, it's good practice to use a resistor instead of directly wiring an input to GND or VCC. this can limit the idle current consumption, and also prevent damage to the rest of the circuit if there's a chip failure that ends up sourcing/sinking excess current from an input

#

also, even with CMOS, if the pin is an I/O pin, using a resistor can mitigate the damage if the pin is accidentally set to output mode to a conflicting voltage level

pale umbra
#

Do you guys mean the common technique of "Connect unused input pins to pull-up or pull-down resistors" ?

limpid nest
#

This is more properly biasing a pin

knotty tiger
pale umbra
#

man 8 ma per pin on an atmel 32u, seems a very useless chip...

knotty tiger
limpid nest
#

Usually you don't want to drive much of consequence from an MCU directly

#

Consequence meaning high current reqs specifically

#

Because you just can't

#

That 8mA per pin gets eaten up pretty quickly into the max current output of a chip like that.

pale umbra
#

yeah which is even worse since it's driving 4 motors and the whole thing goes at around 12-14mph

#

could be directly plugged to battery too, not sure don't really have a schematic

#

but the board uses an atmel 32U4

knotty tiger
pale umbra
#

in polulu spec I think they put more pins out than the chip

#

like there is 3 pairs of i2c

rustic fulcrum
#

Pretty sure you'd only use the pins from a MCU to control something else which actually does the heavy power switching/current supply

knotty tiger
surreal summit
supple pollen
#

Yes, pin 5 is tip (left channel, the pin on the right in this view) and pin 2 is ring (right channel, the pin on the left in this view)

screenshot_1401.png
surreal summit
#

@supple pollen Thanks for confirming it. The other jacks usually use pin 2 for tip so it almost confused me!

hushed smelt
#

most I2C addresses jumpers simply go straight to ground. the I2C chip itself does continuity/voltage checks on the I2C address pin, if it's grounded it sets the address internally. i actually just figured that one out a couple days ago doing the 16 step sequencer board with I2C expander bare chips.

#

the unsoldered pads for the I2C addresses are in a float state, when you solder bridge them they get grounded and the chip itself sees that and sets the address appropriately.

#

generally speaking, i'm not going to say it's like that for every I2C chip out there

unreal flax
void sentinel
#

Also I want to start studying for my test. are there more preferable brands of solder paste?

hushed smelt
#

@unreal flax ohh that's interesting. will have to watch out for those. tricky buggers.

knotty tiger
distant raven
knotty tiger
distant raven
#

Yeah, pretty neat way to approach the “I need lots of these” problem

woven bluff
#

use 2 ADC just for addr sel?

knotty tiger
woven bluff
#

and 2-bit resolution?

knotty tiger
#

i assume it has more resolution, but they're only looking at the high bits for address selection

woven bluff
#

what about 256 addresses? something like FUSE?

knotty tiger
woven bluff
#

EPROM

knotty tiger
#

i'm still not sure what you're asking about

woven bluff
#

digitally programmable memory

#

with 8 bits to access all addresses

#

most chips only give you 2 or 3 options

#

I wonder how often do they collide

knotty tiger
#

if you mean I2C EEPROM devices, they're usually used to store configuration or calibration information, and there's usually no design reason to use more than one on a bus. and the I2C bus address space is only 7 bits (or 10, but that's rarely implemented), with some reserved

inland jungle
#

mcp23018, cousin to the 23017 I2C I/O expander, also uses voltage division to set the address

distant raven
supple pollen
inland jungle
distant raven
#

Darn

distant raven
#

Weird.. it keeps saying there is a new message here but the there isn’t.. hmm

void sentinel
wicked root
supple pollen
spice zenith
#

Is the following possible using a Feather board with an attached Li-Po? I'm thinking it could be prototyped on a Proto-Featherwing.

So I have a Feather that's normally powered by USB, what I want to do is detect loss of USB power and when that happens, gracefully shut down.

The Li-Po should easily keep the Feather going long enough for that, I'm expecting a graceful shutdown to take no more than a second or two: basically close and sync files that have been written to an attached sd card.

Then stay powered off as long as USB power is not available, but when it returns, power on the Feather again, and continue operation.

I'm thinking of an SR latch with the output attached to the "en" pin on the Feather. To turn off, pulse one side, so "en" is disabled and stays disabled. To turn on, pulse the other side directly from the USB bus power line.

IANAE, but I think that ought to work. Any thoughts? Does it have a chance, or am I completely out in left field here?

woven bluff
#

How do you properly solder QFP without stencil? last time I used solder paste and got shorting everywhere

#

I only have iron and heat gun

supple pollen
limpid nest
#

Does anyone know what kind of crystal adafruit uses on the RP2040 QT py?

pale umbra
limpid nest
#

the particular model

distant raven
pale umbra
#

does it matter as long as you provide one for the specs just like resistors and caps ?

#

I don't know what to say/how to find that out because to me the brand doesn't seem like a factor

distant raven
#

I use this one with 27pF caps and a 953ohm series resistor

limpid nest
distant raven
#

Reduce drive strength, lengthening the life of the crystal

#

The RP2040 HW design guide heavily suggests adding a 1K with the 50ohms ESR crystal they picked. The one I use is 100ohm ESR so I adjusted the drive resistor down by ~50ohms

pale umbra
#

If it help someone to answer the question this is the crystal in the schematic

schematic123.jpg
knotty tiger
knotty tiger
pale umbra
#

I wonder that too, just need any 22pf/12mhz crystal

#

but not in the sense that I am questioning the reason, more like I'm surprised and would like to know if it matters because I assumed its like caps and resistors

knotty tiger
#

the RP2040 datasheet should have detailed requirements for the crystal and supporting parts to achieve the recommended operating conditions. if you need better performance than that, it would be good to know more about what you're trying to do @limpid nest

limpid nest
#

I was specifically looking to know about the crystal that adafruit uses, it's not urgent though

distant raven
#

From my understanding Adafruit has used a few different 12MHz crystals on the feather rp2040 so it just depends on what they are using now

knotty tiger
limpid nest
#

only tangentially, I'm mostly interested in how the crystal will affect that goal

knotty tiger
#

one millisecond per 7 hours is in the neighborhood of 20 parts per billion. edit: oops was off by order of 1000, so it's actually close. i'm reading that 32kHz watch crystals are usually in the range of 20 parts per million if not temperature-compensated. multi-MHz crystals like used with MCUs seem to be in the 100s of ppm, though

pale umbra
limpid nest
#

Which I'm pretty sure the qt can handle with ease

pale umbra
#

otherwise you are just betting on a low-probabiliy of kattni/etc seeing the question

limpid nest
#

But now I'm just curious what the error bars are

knotty tiger
#

the main contributor to rate error in crystal oscillators seems to be temperature, and maybe to a lesser degree, aging. temperature compensation, or oven control, are ways to get orders of magnitude improvement for frequency stability. neither is commonplace on MCU boards (though you can kind of hack temperature compensation if there's an onboard thermometer)

pale umbra
#

I keep seeing this topic and it seem easier to make a 60 khz receiver and synchronize a timer with no drift on it than to even find the right crystal to start a timer with no drift project 😦

limpid nest
#

it's not necessarily easier if you're working in a language without interrupts

knotty tiger
#

precision timekeeping is hard. that's why the people who do it get the big bucks

pale umbra
#

yeah but receiving 60 khz is much easier no ?

#

and reading the bits that keep being broadcaster over and over ?

limpid nest
#

I'm prototpying so I can always try that if it doesn't work

pale umbra
#

an atomic clock probably don't drift much ?

knotty tiger
#

you don't even need to read the bits, if you don't care about the exact time. just phase-lock to the carrier

pale umbra
#

I'm kinda disappointed in atomic clock projects when they just receive 60khz and not measure an atom themselves 😦

knotty tiger
# pale umbra an atomic clock probably don't drift much ?

the specified atomic oscillation of the cesium atom is the definition of the second. granted, it's been refined to specify in free fall, at absolute zero, so practical atomic clocks have to apply corrections for operating on a gravitating body at a temperature above 0K

limpid nest
#

What's the utility of a series resistor and a pull down here? I've always just seen RX/TX connected directly

unknown.png
inland jungle
#

that's likely a voltage divider to convert 5V TX to 3.3V RX

limpid nest
#

ah that makes sense

pale umbra
#

that's what I thought too but why not on TX ?

#

and both chips seems to be 5V

#

my only hypothesis is that since the RX pin is used as output instead of as input normally you have to protect it

spice zenith
#

A little late to the party, but @limpid nest do you have network connectivity on the RP 2040 you're using? If so, have you considered pinging the public NTP servers, like pool.ntp.org. Your worst error there will be approx half of the round trip time, which for most people means either single digits or low double digits of milliseconds.

I've built a couple of clocks here, one used an ESP8266, so it's very possible using Arduino, and I'm working on a project now in CircuitPython that's successfuly doing the same thing.

#

That does depend on what's an acceptable error for your project, of course.

limpid nest
inland jungle
#

Also, the MCU on the right is almost certainly 3.3V

woven bluff
#

USB seems to give a lot more than 5V1

#

my 5V1 zener is burning hot

unreal flax
woven bluff
bitter flare
signal topaz
#
  1. I think you are missing decoupling capacitors
  2. switch (?) in lower left has no unmasking on pads
bitter flare
bitter flare
signal topaz
#

At each IC. Use ceramic capacitor at your smallest used size, I think you are using 0402. Something like 100n or 1uF

#

close to supply pin, and add local via to GND plane, near capacitor pad

bitter flare
#

Good catch on the switch 🙂

signal topaz
#

also for U1, use some thicker connections for the GND pins in center of the package. I think it should act a little bit as a heat sink

#

in datasheet they also suggest adding some GND pour on top layer, going north and south of the package for heat dissipation

#

but capacitors is a must to have. On 6V you have completely no capacitors. You might want to add something bigger there as well

bitter flare
#

@signal topaz Nice thanks 🙂

wicked root
supple pollen
#

I think you'd want an N-channel MOSFET there, or just drive the enable input directly from the Q output.

wicked root
#

You're right I reversed S and R while I was diagramming.

wicked root
warm bluff
#

Hey guys

#

I have a flex sensor

#

Now I just needed to know what resistor I need yo use for the flex divider

#

Do I use 220 ohms? 20 ohms?

#

Wdid

unreal flax
warm bluff
#

okay, that makes sense

#

thanks a lot

warm bluff
#

this is the flex sensor and im not able to find the amount of resistance needed

unreal flax
warm bluff
#

okay got it

#

thank you

#

does it matter if a flex sensor is torn?

unreal flax
#

Possibly, yes. It might have broken the electrical path.

knotty tiger
#

even if it doesn't break the electrical path completely, it might change the characteristics enough to make it less accurate or repeatable

umbral sphinx
#

Does the Monochrome 0.91" 128x32 I2C OLED (product ID: 4440) need pull-up resistors on the I2C lines if my microcontroller doesn't have them on-board?

#

Looking to drive it with a Pico

supple pollen
#

No, it includes both pull-up resistors and a level shifter, so you don't need additional ones.

umbral sphinx
#

noice. that'll be perfect, then

#

Does Adafruit sell a pack of screws and nuts that will fit the holes on that display board as well, or should I source those elsewhere?

dry pelican
#

This is my Tesla Coil Power driver board that I'm designing. Will the copper fills on the power side (right side) cause any problems with the MOSFETS being driven? (ringing, too much capacitance, capacitive coupling, unwanted inductance). The PGND (power ground) is the fill on the bottom (connected to the source of the bottom MOSFET). The PVCC (Power V+) is connected to the drain of the top MOSFET through the top copper fill. The Primary connection is connected to both MOSFETS through a bottom plane. It's a half bridge arrangement.

unknown.png unknown.png unknown.png
#

It's a half bridge, but you can combine 2 and reverse the phase on one for full bridge operation

#

The coils that I have built resonate at around 1.2MHz

#

PCB details: 1.6mm, all 2mm traces on right side, 0.254mm clearance

supple pollen
#

I suspect the MOSFET gate capacitance will be more than the capacitance caused by the ground fills, so I don't anticipate any problems from that. Inductance shouldn't be an issue, as ground fills are low inductance.

dry pelican
#

That's what I would think, but my last design had an issue where I just couldn't get it to oscillate, which I suspect was caused by having a ground plane after the mosfet driver, and not using it according to how it was recommended in the datasheet. It was a single mosfet coil driver, though.

#

This is the old one

#

Although it did oscillate a few times, but it won't anymore

#

It might be because I haven't tried something like getting some fresh driver ICs or feeding the circuit higher current (but the circuit does have tendency to get stuck (as the small capacitance of the input of the hex inverter IC holds some charge and turns the rest of the circuit on), meaning that I'm afraid to bump up the current limit to 8A because I may fry the MOSFET, the board, or both)

supple pollen
#

The first thing I try on boards like that when they won't oscillate is swap the leads on the driver transformer

#

You even seem to have a phase jumper for that very purpose

dry pelican
#

The old board (V1) had no drive transformer

#

Maybe that had something to do with it

#

I also did not have much protection on the driver

#

except for a 1.5ke12CA

supple pollen
#

The single MOSFET ones sometimes need something to kick them into operation, as they can sometimes find a stable steady state where they're sort of half-on

#

My single MOSFET boards all use a separate oscillator, which will reliably oscillate but won't self-tune

dry pelican
#

What I would do is touch the antenna, which would cause the 60hz line noise to turn the hex inverter on and off and cause it to start oscillating

#

A breadboarded version actually worked very well with a very similar circuit

supple pollen
#

Yeah, that's the "something to kick it into operation"

dry pelican
#

So that's part of the reason why I suspect it's the ground plane

supple pollen
#

I rather doubt it's the ground plane

#

I only left a ground plane off my little flyback driver because I have the HV on the board and wanted to avoid corona

flyback-board-early.jpg
dry pelican
#

it is 1.2MHz though, so there's a possibility that the ground plane acts as a low pass filter. But I think that's unlikely since higher frequency things have ground planes

supple pollen
#

Right. The ground plane will add a few dozen picofarads of capacitance, but the MOSFET gate is going to be much more, so it's not likely to have much of an effect.

dry pelican
#

The UCC37322 datasheet says "If a ground
plane is used, it may be connected to AGND; do not extend the plane beneath the output side of the package
(pins 5 – 8). Connect the load to both OUT pins (pins 7 and 6) with a single trace on the adjacent layer to the
component layer; route the return current path for the output on the component side, directly over the output
path."

#

I did not read the datasheet until later, and just connected AGND and PGND together

#

and used a ground plane

supple pollen
#

Assuming 10Ω of resistance (since that's what you have on the board) and 50pF of capacitance, it would be about 10dB down at 100MHz. That "low pass filter" isn't going to affect much of anything at 1.2MHz.

dry pelican
#

there's also 2000pF on the MOSFET gate

supple pollen
#

Right: that's going to determine the cutoff frequency, not your ground plane

dry pelican
#

7.76

#

MHz

#

cutoff

#

so that shouldn't affect much of anything (it might even be beneficial because it could filter any high freq harmonics)

supple pollen
#

Note that "cutoff" doesn't mean "no signal gets through above this", just "3dB down at this point, and you'll be getting phase shift"

dry pelican
#

yes

#

But why does the datasheet say to have no ground plane near the output

#

The UCC47425 has nothing telling you to not use a ground plane

supple pollen
#

I can't find that verbiage, but it does say "Use a ground plane to provide noise shielding."

#

It does say "The ground plane must not be a conduction path for any current loop." which is slightly odd but possibly intended to keep ground bounce out of the ground plane.

#

It does say "The gate driver should be placed as close as possible to the MOSFETs." which you're not really doing in your design, and offers this layout example, showing the (short) drive and return paths overlaid so they enclose the minimum area.

screenshot_1405.png
#

That gate drive transformer looks pretty chonky, I'm used to a little toroid with flying leads

woven bluff
#

also you can filter out DC by adding large series cap at terminal 1 and 3 of the transformer

signal topaz
dry pelican
dry pelican
# signal topaz what is PVCC voltage? in relation to PGND

It'll be very variable. Lowest will probably be 12v, but I might want to run it lower just to see how low it can go. Highest will likely be 30v, or maybe even 60, but I'm never going to run it off 120V AC because I don't want to have to deal with death capacitors.

dry pelican
supple pollen
dry pelican
#

That could work. That transformer is pretty inexpensive and would have more predictable characteristics (which would work better when I go full bridge) than a hand-wound one. It's also smaller, so that might reduce unwanted inductance. I would still stick with tht for the resistors, capacitors, and phase jumper. A tht hand-wound gdt would be more customizable, swappable, and testable, though. I might make another revision of the power board with lower inductance and smaller loop area in mind. (Probably with my own gdt footprint). I assume that the current design is "pretty good", but could be made better. Another thing I could do to minimize inductance after I find the resonant frequency of the coil is to use a capacitor that resonates with the inductance of the transformer and the traces to drop that impedance to almost 0 (like a drsstc). (Although I would need a very precise and accurate inductance meter.)

hushed smelt
# signal topaz what is PVCC voltage? in relation to PGND

Pvcc is likely the constant current to the associated ground. You’ll see avcc and agnd sometimes too. Technically it stands for analog gnd but naming is less important than its intended function. Just means it wants a different gnd plane than the normal net gnd… from what I understand, I could be wrong, do some research on it.

signal topaz
dry pelican
signal topaz
#

So I am not an expert in those high-voltage systems, but I do not think we can expect some high voltage (>1kV) between those nets on that PCB, correct?

#

I would increase the clearance just to avoid some problems with dirt, debris, humidity, flux residues, or something like that. I would just expect bigger clearances in systems >48VDC.

worn sinew
#

I'm trying to create a UPS of sorts with my keyboard and a Feather 32u4 BLE, but I'm not sure what I need to make this work (I'm new to this). I made this diagram to show what I mean. Ideally, the usb pin should power the keyboard when the usb is connected to the feather

diagram.png
#

I was thinking the blue line would be a transistor, but that wouldn't really work because to my understanding, this diagram looks more like an 'OR' gate than a transistor

supple pollen
#

The easiest way is with steering diodes, which lets the highest voltage flow through. Another approach uses a diode for the 5V line and a MOSFET for the battery line, to avoid the voltage drop of a diode on the lower voltage line.

woven bluff
#

@supple pollen how's your divergence meter going?

supple pollen
#

Version 2 is kinda stalled, I should pick that up again

woven bluff
#

just got version 3, came back with 3 design flaws...

dry pelican
# signal topaz So I am not an expert in those high-voltage systems, but I do not think we can e...

Neither am I an expert in HV stuff. There shouldn't be any 1kV+ spikes because I will add TVS diodes and/or BEMF diodes. (If there are any, it would be in the moment before the MOSFETs die). I do agree with increasing the clearance. It won't hurt (and it will probably more desirable because it decreases capacitance). I'll have to add all that in version 3 of the power board. (Version 3 because the one I posted is actually Version 2)

dry pelican
dry pelican
glacial gale
#

dumb question: are cpu registers usually shift registers? like parallel in parallel out?

unreal flax
glacial gale
unreal flax
knotty tiger
#

yeah, CPU registers are usually parallel load/store for speed. some CPUs have barrel shifters in their ALUs (or similar components) that allow single-clock shift or roll of arbitrary amounts, but they're usually not part of the register file design

woven bluff
#

I don't know why but somehow the blanking pin of a shift register has internal 100Ohm connected to VCC.

#

I checked 3 chips, and got 20MOhm, 400Ohm, 100Ohm

#

all chips are working, but I don't have enough logic current to drive the 100Ohm chip

knotty tiger
#

how are you testing them? if you're using a multimeter, have you tested with the probes reversed as well? resistance readings on chips can be misleading because of diodes and other semiconductors

knotty tiger
woven bluff
#

that's too many defective parts, I added 1KOhm pull down, the blanking line has 1 V when driven down

knotty tiger
woven bluff
#

3 in series

knotty tiger
#

breadboard? custom PCB?

woven bluff
#

all share blanking, SCK, Latch

unknown.png
knotty tiger
#

was the 1V from pulling down all 3 blanking lines together? or did you test that chip individually?

#

(still out of spec though)

woven bluff
#

yes, 1V with three

#

only one chip is in spec

#

the other two draw way too much from the blanking

#

I have 6 chips, 1x20MOhm(in spec), 2x 400Ohm, 3x100Ohm

#

my driving capacity is only 20mA

knotty tiger
#

again, how did you measure the resistance?

woven bluff
#

multimeter, both direction has the same resistance

knotty tiger
#

when not installed?

woven bluff
#

yes, when installed the total resistance is the harmonic mean of each one

#

those dam_n chip costs £8 a piece

knotty tiger
#

it's orders of magnitude out of spec. i'd suggest taking it up with the supplier. is it a reputable supplier?

woven bluff
#

digi-key, came in cut-tape

knotty tiger
#

and when you tested the pull-down on the blanking input, were all other inputs at defined voltages?

woven bluff
#

yes, all other digital pin has >1MOhm resistance, and all behaves at 5V

knotty tiger
#

otherwise, it's possible that your board has a wiring error, or stray conductive paths from solder. (unless you've tested each chip in isolation?)

woven bluff
#

the board is fine, tested

#

maybe a bad batch, I'll order 3 more from Mouser

#

otherwise, this is the ideal chip to drive Divergence meter

#

the strange part is that those chips even work at this defected condition

knotty tiger
#

they work apart from the excessive input current on the blanking input?

woven bluff
#

yes

knotty tiger
#

that does make me wonder if it's an assembly issue

woven bluff
#

I drag-soldered them, PQFP

knotty tiger
#

VDD is adjacent to /LE on the QFP pinout, so i'm a bit suspicious because of that

#

maybe try reflowing and a thorough defluxing?

woven bluff
#

the fact that individual chips have different resistance is suspicious

#

after I noticed the problem(not blanking) I hot air them off to examine individually

knotty tiger
#

oh, you actually probed them individually when uninstalled? could still have conductive residues

woven bluff
#

when using MOSFET as diode, is it better to use N channel or P channel?

dry pelican
# woven bluff when using MOSFET as diode, is it better to use N channel or P channel?

I don't think it matters. I've seen power switching and reverse polarity protection circuits that use mosfets as diodes (power switching (power preference) circuits use n-channels, and reverse polarity protection circuits use p-channels). N-channel is more common and has lower on resistance, but I don't think it affects the diode. But why do you want to use a mosfet as a diode?

woven bluff
#

I dont want forward drop

#

for 2A diode, Vf is at least 0.3V

dry pelican
supple pollen
distant raven
woven bluff
#

Now all of my HV5530 chips are dead

#

I'll transplant the components to a new board when I go to lab tomorrow

#

I also ordered some new HV5530

#

@supple pollen What's your solution for your divergence meter?

supple pollen
#

You may not like the old inefficient 74141 chips, but I'll say this for them: they're robust.

woven bluff
#

this time I'll test the new chip off the reel for resistance

#

I gave away my old divergence meter, which is 3xHV5530 driven directly by Arduino nano

supple pollen
#

Another approach is David Forbes' nixie watch, which uses TD68023 chips as cathode drivers (along with an interesting 60V "pull mid" clamping arrangement to avoid overloading them with too-high voltage)

woven bluff
#

the new version is isolated, 3xHV5530 driven by MAX14930

supple pollen
#

I think the ArduNIX board uses discrete transistors, similar to the old four letter word kit.

woven bluff
#

I know the Darlington transistor approach, but the HV series chip just too nice and convenient

supple pollen
#

Nope, I'm wrong, the ArduNIX uses the same 74141 chips as my divergence meter

woven bluff
#

if you want your divergence meter compact as the one in Anime, you'd better off with HV series chip

supple pollen
#

Yeah, the combination of shift register and high voltage driver and a bunch of channels in a single chip is attractive (aside from the 12V signalling a bunch of those chips use)

woven bluff
supple pollen
#

The one in the manga and anime was fairly bulky, plenty of room for DIP packaged chips

woven bluff
#

you forgot the battery

supple pollen
#

The battery is going to be similar for most designs

woven bluff
#

I put an Adafruit ChargeBoost 1000C on my design

supple pollen
#

My version 1 was pretty chonky as I threw it together out of parts I had lying around in a few days for cosplay. Version 2 is intended to be somewhat more compact.

woven bluff
supple pollen
#

I ended up using a chonky 3S1P lithium pack because I have a bunch of them available for drones, props, R/C cars, ham radio gear, etc.

woven bluff
#

input power typeC->load switch->ChargeBoost 1000C+UVLO supervisor

#

I want to order a custom li-po from aliexpress

supple pollen
#

Ugly but it works

diverge-connectors.jpg
#

I really oughta put v2 together

woven bluff
#

My old V2, gave to my friend today.

#

this one is 3xHV5530 driven by Arduino Nano 33 IoT

supple pollen
#

The original breadboard version

nixie-breadboard.jpg
woven bluff
#

is that IN-8-2?

supple pollen
#

Heh, yup

#

A handy tube for prototyping with

artomatic1.jpeg
woven bluff
#

what value is your drop resistor?

supple pollen
#

I think it's 15kΩ, but that's from memory and could be wrong

woven bluff
#

I use 47K and additional 470k on the dots

supple pollen
#

Amusingly, the CPU in that last pic is a genuine AdaFruit Boarduino. I built those into all sorts of projects.

knotty tiger
woven bluff
#

at some point I shoved all AVR boards to a dark corner of the lab and never be found

supple pollen
#

I finally started buying the blank boards and getting the components separately

boarduino-build.jpg
knotty tiger
#

i still have a soft spot for the 328P and 32U4

#

also i have a small tube of 328P chips that i never got around to building into stuff

woven bluff
#

now I have no working clock I cannot even sleep.... time for pills

#

hopefully Mouser will deliver the parts before I explode

void sentinel
void sentinel
#

I don't know much about ferrite but when I went to order some, apparently that is a variable. lol

pale harness
#

Hey there!

Here i lock the power going to the dashboard of an escooter. When you press the button, you only turn on the microcontroller which then waits for custom unlock requirements and then let's it through to the dashboard. If not unlocked for X minutes i want to simulate a long button press, in order to turn the scooter and the MC off. However i am quite unsure how to do that here. Any help would be appreciated ❤️

Can i do another P channel setup, connecting Drain to Ground with a resistor in between & Green to Source?

Greetings from Vienna

unknown.png
pale harness
#

would that work?

unknown.png
supple pollen
# pale harness would that work?

I suspect that would work, but it's probably overkill. The transistors depicted are TO-220 power types, I don't know if the actual ones are, but you probably don't need something that powerful just to emulate a microswitch. I'm also unsure why a pair of transistors is used instead of just one. It could be acting as an inverter, but that seems easier to do in software. It could be acting as a driver, which would probably only be necessary when switching a large amount of power.

pale harness
limpid nest
#

what would folks call an H Bridge driver that has gate driver outputs instead of built in FETs?

inland jungle
#

aren't most of them like that?

limpid nest
#

most of them have internal fets, to my knowledge

#

I'm looking to drive a motor with a high stall current

knotty tiger
#

i think they're simply called "H-bridge gate drivers"

limpid nest
#

ok I'll google that, thanks

knotty tiger
limpid nest
#

hard to find any in stock

#

of this or other drivers

limpid nest
#

I'm making a library part for this device (an RP2040 stamp) in KiCad. How would folks label pins 1-30? I was thinking just GPIO0-29 but I'm not certain

unknown.png
supple pollen
distant raven
supple pollen
# limpid nest hard to find any in stock

If I do a search for "gate drivers" on Digikey, select parts in stock, and exclude marketplace items, there are still over 1000 different options, including common ones like ICL7667, MAX4427, and TC4427

distant raven
pale harness
limpid nest
#

Oh maybe it is

distant raven
#

🙂

limpid nest
#

Yeah just noticed that

distant raven
#

Arturo makes some really cool stuff, hopefully those footprints help 🙂

#

Or saves some time anyway

rustic linden
dry pelican
dry pelican
#

I'm hoping this is a really easy question: I'm trying to make PartSim work, but it refuses to make any sort of graph. When I press run, and all it does is generate a "report". How do I simulate something in PartSim version 2.2.7?

distant raven
#

I have some comparators I bought for a VLC project I left and part of me wants to make a coax sniffer

#

Take a coax connector, feed it into the comparator and then fill a 16 bit buffer on an fpga and push that out to a bank of LEDs

#

Just to get a crude visualization of the data

supple pollen
#

That would be fun to watch, especially if it could do things like pick up details of baseband video, QAM, etc.

distant raven
#

Yeah, I’d need to learn qam demodulation, but definitely a cool idea

dry pelican
distant raven
#

FPGA for speed

dry pelican
#

FPGAs are fast but they can be expensive

distant raven
#

I’ve got that covered

IMG_8759.jpg
dry pelican
#

and using one just to fill a buffer seems like underutilization (although I'm also the type of person that puts unnecessarily powerful hardware in stuff that really doesn't need it)

distant raven
#

The FPGA wouldn’t need to be crazy complex. Mostly looking for fast acquisition and output. Plus some internal logic

dry pelican
#

yes I guess you would need that to figure out a clock signal from just a pulse train

#

to put in a shift register

distant raven
#

TTL logic would be too slow to sniff coax lines in my house

#

Propagation delay and whatnot between chips

dry pelican
#

it doesn't have to be a ttl shift register

#

yes and capacitance and inductance and whatnot

#

if you were to build it out of discrete logic chips

#

but maybe you could use the propagation delay?

distant raven
#

A shift register implemented on an fpga would be fast since I’d have to shift 16 bits at a time, load them to an output buffer that would shoot it out

#

I’d have to derive timing like you said which would be interesting

woven bluff
#

the only thing I don't like about FPGA is that there's no opensource IDE

#

I remember some project trying to crack bit streams but in the end not production-ready.

unreal flax
#

I haven't used them myself, but I think the Lattice open-source tools are at least mature enough to use in real projects.

woven bluff
#

FPGA development bring back nightmares like Keil

supple pollen
#

I tried for years to get the vendor tools to work but never managed.

distant raven
#

I’ve used IceCube2 on windows pretty painlessly

oblique flint
#

Anyone here happen to have a glowforge? I'm curious to see how the black hinges are installed on it

supple pollen
#

The last time I used windoze was before FPGAs or even CPLDs were a thing, back in the 1900s when 22V10 was a nice device and PALASM.EXE was the way to build the fuse map (although you could do it manually, the data sheet showed the entire fuse map for the device).

#

Or WINCUPL.EXE. However for me, "painlessly" and "windoze" do not go together.

woven bluff
#

sadly I need windows for DirectX

supple pollen
#

Well I'll be, you can still buy 5V CPLDs these days...

woven bluff
#

is it possible to remove a TCXO RTC chip from a breakout board without damaging it?

#

cannot find any TCXO RTC chip in stock, but I have some DS3231 and DS3234 breakouts

distant raven
woven bluff
#

I'm concerned that hot air gun would damage it

distant raven
#

Most chips can handle 2-3 times of being reflowed without damage

woven bluff
#

and why would you need solder wick if you have hot air gun?

distant raven
#

Solder wick for if you don’t have a hot air gun

woven bluff
#

I have removed SOIC with solder wick and razor blade before, pin by pin

#

for hot air, I usually use 500C 20%

distant raven
#

500C 😶

woven bluff
#

too hot?

distant raven
#

I’m not a thermodynamics experts

#

But I believe my station is in F in which I use 500F for hot air

woven bluff
#

I also bought lowest melting point chipquick paste

distant raven
#

Though I try lower temps when I can, 450F.

#

That stuff will wet at 150C so great to work with if you do a lot of rework

#

I use it as well

woven bluff
#

still, I don't think I can squeeze a DS3231 in there

unknown.png
#

not,with a battery holder

distant raven
#

Hmm

dry pelican
woven bluff
#

OK, the blanking pin resistance of HV5530 is 600K for the 4 pieces I bought from Mouser

#

humm, one became 12M after soldering

gusty aspen
#

Hi folks - I'm having a real brain fart moment. Hoping someone can help me untangle this from my brain.

I have the 2.13" tri-color e-ink display I am hooking up to a Node MCU ESP 8266 board. Here's my Fritzing. Everything is working great, and I'm ready to move it into a permanent case to mount on the wall. My plan was to solder in some female headers to a perma-proto board, put the Node MCU board in there, then I got some 7-wire JST cables to use to connect the E-ink display, since I'm only using 7 of the pins.

What's tripping me up is that the female end of the JST is just the pins, and the male end has the wires. I can't put the female end on the perma-proto, because they're in the wrong order. I wanted to make sure that if either the board or the e-ink display has to be replaced, I can remove just that component, so that's why I'm using the JST connector (especially given the cost of the e-ink display!) On another project I soldered one of my Node MCU boards directly to the perma-proto to save on space, then a few weeks later had to change something and it was a huge pain 🙂

What am I missing? How would you build this as a finished project?

#

These are the JST cables I got

unknown.png
fervent lance
#

Why not cut and strip the conductors of a double-ended cable so that there are wires on both male and female connector ends?

gusty aspen
#

Hmm, I'm following... I actually couldn't find any pre-wired 7-pin JSTs that had connectors on both ends, or both sides with wires, all I could find was this kind of set. Do you mean like the connected dupont type cables?

#

It doesn't have to be JST I just wanted to make sure nothing would come lose when we mount it on the wall or anything, so I figured a good connector would be smart.

#

That was supposed to be I'm not following. Wow having trouble typing today

fervent lance
#

I'm guessing 'miniaturization' is a design goal - wires that stick out axially from the pins they are connecting (at a moulded plug housing) tend to eat more stacking space than two or three flat boards they are meant to interconnect. ;)

gusty aspen
#

I would like to keep it fairly thin because it is going on the wall. There's a 9V battery going in so that's about as "thick" as I want it. I also did try to find the right angle / side entry kind but couldn't find a 7-pin one either!

#

I'm open to whatever suggestion, I'm a newb, just figuring most of this out on my own 🙂

fervent lance
#

Probably my best observation of the multi-wire connection is that if several DuPont style connector are 'ganged' they hold better. ;)
I've also used those stacking headers at times; they provide stiffness and the pins are really quite long.
I'd rather trade a bit more horizontal expansion than stacking vertical expansion.

gusty aspen
#

Oh I could put them side by side no problem - what I'm stuck on is that the 7 pins I want to wire into the female end are in the wrong order

#

The 7 pins on the board go D4, 3V3, GND, D5, D6, D7, D8 - and the e-ink needs VIN, GND, then D5-8, THEN D4

fervent lance
gusty aspen
#

this brown wire is the one I'm flummoxed about

unknown.png
fervent lance
#

I usually use those housings by removing the housing of a singleton (or just buying jumpers without housing. Jumper insulation is very stiff and doesn't bend hardly at all and will spring back into shape if you try to put a crimp bend in them. ;)

gusty aspen
#

if I put the female JST where these are plugged in right now, the e-ink wires have to be crossed, just like these ones are. I'm trying to figure out if there's a better solution so that the "crossing" of the wire happens at this end, and the wires go in the "right" order

#

does that make sense?

#

the height isn't what is bothering me, it's the order of the pins/wires 😄

fervent lance
#

Yes it makes sense. ;) I often ask myself what's really going to happen after thinking it out, and (again, often) decide that it's a fixed thing that can't be changed at that level. That I didn't buy the right thing for the job, after all. ;)

#

You can very easily imagine what the right part 'should' be.

gusty aspen
#

Okay so I think I follow your suggestion, to use that housing instead

fervent lance
#

Yeah I like the jumper/housing idea. Very long pins (if you can find them) can allow change of geometry (migrating to a plane 90 degrees from the 'current' plane).

#

Stacking headers accomplish some of that; haven't used them all that much for this, but somtimes they're helpful to have on hand, to try out an idea. Same with the extra long header pins:
http://adafru.it/400

gusty aspen
#

Oh I have a bunch of stacking headers handy

#

How would long pins allow that change?

#

To go 90 degrees?

fervent lance
#

Long pins give you more options and there's more length to play with for bends.

#

If it's too short then it won't hold well - connectors will separate.

gusty aspen
#

Gotcha

#

Thanks for the help, I'm gonna see what I have on hand I can play with

fervent lance
#

I've never had luck crimping them to get them to hold better, but I didn't pursue it enough, either.

supple pollen
gusty aspen
#

I was asking for advice on making it a permanent installation

#

I want to be able to replace the e-ink screen or the board, if something goes wrong with either. So I want to install them with connectors that have a male/female part, like JST, so the entire project is permanent but individual components which are more expensive can be easily swapped out. Like was shown here: https://learn.adafruit.com/permaproto-feather-case

Adafruit Learning System
PermaProto Feather Case

Make a snap fit enclosure for your project!

woven bluff
#

is this right to prevent current flow out of VIN?

distant raven
#

Why not use a Schottky diode?

#

The body diode in the mosfet won’t be as effective as a Schottky diode

woven bluff
#

forward drop

#

I'm using the channel as diode, not the body diode

distant raven
#

I still don’t think it’s a smart move. Diodes are much better suited for this than mosfets

woven bluff
distant raven
#

That’s not a huge deal as most devices have tolerances of usually +/-0.3V

#

Some even more

knotty tiger
#

i think it might be backwards if you want to use the P-MOSFET as a reverse current blocker

distant raven
woven bluff
#

I think P channel conduct current from source to drain

dry pelican
#

Here's an example of reverse polarity protection with a mosfet

Screenshot_20220916-135854_WordPress.jpg
woven bluff
#

so drain to source is blocked

knotty tiger
#

no, there's a source-body short (that makes the body diode) and that will be forward-biased if VIN is greater than the +5V input

dry pelican
#

Although, if it's a low power application, just use a schottkey

distant raven
#

Usually anything 12V or less Schottky diodes work much better and are cheaper. Mosfets have their place for this, but usually you’re using something with lower breakdown voltages.

dry pelican
#

With that mppt charger, a diode drop could become a significant power loss, so the designers of that mppt board decided to use a mosfet. The other reason you would use a mosfet is if a diode drop would produce too much drop (like with a lipo battery going into a 3.3v ldo)

#

Because the mppt is rated to charge a battery at up to 5a

distant raven
#

Right

woven bluff
#

I cannot afford to lose 0.3V

knotty tiger
#

you also should make sure your MOSFET has a low enough RDS(on) for your use case, then

dry pelican
#

Some schotkeys have super low voltage drop like 0.18v

distant raven
#

The Schottky diodes I use drop ~0.2V worst case

woven bluff
dry pelican
#

Looks like good mosfet

knotty tiger
#

that's 300mV to get that 30mOhms? or is it a 300mV VGS(th)?

woven bluff
#

VGS(th)

dry pelican
#

How much current will your thing use?

knotty tiger
#

you need to check the VGS for the desired RDS(on); it might be quite different than VGS(th)

dry pelican
#

There are graphs in the mosfet datasheet

distant raven
#

Also what chip are you feeding 5V to?

woven bluff
#

2.5V to get 30mΩ, the MOSFET is rated 4.3A at 2.5VGS

woven bluff
dry pelican
#

That will do fine with schottkey

distant raven
#

Curious what part needs 5V on that?

#

The micros on that are 3.3V logic

#

So losing 0.3V on input isn’t going to drop the on board regulator 0.3V

#

Unless you’re also powering 5V devices?

woven bluff
#

I also have 5V device

knotty tiger
#

what are the current requirements of the 5V device? and its input voltage range?

woven bluff
#

humm, I could just put a diode at the input of micro, instead the output of power source

distant raven
#

there's the schematic for it, it's going to a 3.3V regulator so a schottky diode would work great in this case

#

if you put 5V right to the VUSB pin you could avoid using an external schottky diode all together

#

as long as you don't power with a USB cable at the same time

#

😛

woven bluff
#

divergence meter

supple pollen
woven bluff
#

PM4 is isolated 5-to-12 convertor

#

PM1 is 12-to-170 boost

#

PM3 is 12-to-5 buck

#

the HV area is isolated

dry pelican
#

Actually, you might be able to disregard the scottkey entirely because boost converters and flyback converters already have diodes.

#

But that hack would not work with a buck

#

I'm not an EE though so I'm not 100% sure about things

spice zenith
#

Is i2c generally open-collector ish with pullups to get things somewhere near VCC?

limpid nest
#

it's my understanding that it always is

distant raven
#

Huge link my lanta

#

There we go

dry pelican
#

The reason is because otherwise one device could go high, and another could go low, causing a short.

hushed smelt
#

Bad pull up resistor design. Don't do this. Yes I already have my boards in and discovered this mistake. 😦

SCL_SDA.PNG
#

Can fix it with by running wire from 3v3 to resistor. Here's a fixed pull up design to the I2C expander chip. Learn from my mistake.

SCL_SDA2.PNG
dry pelican
#

I'm in the process of making a PCB. I've gotten all the small traces laid out (although the traces to the MOSFETS are not very clean and are very thin (I don't know if this would be a problem though)). I still need to get the power traces done. I'm going to do those by using copper fills as extra thick traces to handle the 9A continuous current that can flow through the FETS. I'll put the A, B, C connections in the top layer, and I'll put PVCC and GND (LSS) on the bottom. Since the components are SMD, and I need high current traces on the bottom, how can I do that? I've seen a lot of PCBs use a lot of vias in one area, but I'm not sure what the best way to do this is.

#

Basically, how do I "via stuff"?

#

stuff vias

unreal flax
#

You will probably run into DRC-check problems with closely-packed vias like that, since the drill holes can't be that close to each other.

#

(The term you might be looking for is "via stitching"?)

dry pelican
#

yes

#

I just looked it up

#

yes the closely packed vias do produce drc errors

#

would be cool if adafruit could manufacture the board 🙂

unreal flax
#

I think they outsource PCBs themselves these days. It's a messy fabrication process.

dry pelican
#

What is the best way to do via stitching? Place them in the pad? Put a whole bunch of vias around the pad(s)?

#

Those ICs are dual mosfets that are hooked up as half bridges. Each chip is one half bridge.

#

Also, how would I account for thermals and be able to put a heat sink on it?

unreal flax
#

I'm not an expert in high-current design myself, but my instinct would be to route the pad out to a fat trace or a small polygon where you could place a bunch of vias down to the bottom.

hushed smelt
#

When people use via's for heat transfer they still have to space them out. I realize you want a lot in a small space but you can't overlap them like that. If you want more open air surface area then look into a castellated cut out.

#

via's are also used to help negate some types of RF reflectivity on power and gnd planes. you'll see that a lot with wifi module boards.

#

If easyeda has a way to do real via stitching which is basically castellation, then i don't know how. that's a question you should ask easyeda.

ember laurel
#

Don't place any vias between the pads on those SOICs. Also never place vias in pads, unless you have some very special situation.

#

If you need to move to bottom layer for the power, just pull the signal out to a larger polygon and make the vias there.

#

there will be enough solder and pad on that SOIC to handle the current - but better make the trace wider just when you leave the pad.

#

@dry pelican

#

also - what kind of mosfets are those? they have a strange S/G config.

#

@dry pelican for tweakability of your source/sink currents, I'd also add resistors to the gate lines.

#

to tweak source/sink separately, add one resistor in parallel with another resistor and diode.

#

and just put 0 ohm resistors there to start with

ember laurel
#

What are your MOSFET RdsOn values, your switching frequency, and your slew rate?

#

this will determine the losses generated in the MOSFET - most likely you may not need a heat sink.

#

You also lack some capacitors in your design - you should put some bulk capacitance for the mosfet drains.

#

... and do 4 layer board. You'll get in trouble otherwise 🙂

dry pelican
#

They're really sq... made by vishay

dry pelican
ember laurel
#

nice mosfet

#

but is it available?

dry pelican
#

Yes

#

Wait no

ember laurel
#

how much current do you need?

dry pelican
#

Probably 8-9A. Although I'll probably be driving motors that use much lower current.

ember laurel
#

what kind of motor?

dry pelican
#

3 phase bldc. I just want to use bldcs without the expensive escs.

ember laurel
#

I hope you'll be ok with the allegro chip

#

I used the A4964 once

#

it was quite tricky to tune it

#

what's the use ase for your BLDC though?

dry pelican
#

No real use case, but I thought it would be cool and I might be able to sell it on tindie

worn sinew
#

sorry, noob here, am I right to assume that the current flows like this in a schottky diode?

unknown.png
dry pelican
#

Conventional, yes

#

Electrons flow the other way

#

But most people use conventional current, which flows from positive to negative

#

I don't think there are any diodes that are labeled with the anode being the one with the stripe.

worn sinew
#

ohhh right right cuz electrons technically have a negative charge so technically they would flow from negative to positive
I was looking for the conventional so thank you in that regard

ember laurel
#

@dry pelican just so you know, BLDC motors are quite finicky - and you'll really have to tune the whole system to a specific motor

#

you cannot just attach any motor and go

supple pollen
void sentinel
#

I will just drop this here even though the end result for me is 3d printing, this is about a "hardware adapter"
I have an Ender3 and I don't use serial comms to print as it is less reliable for me. Every time I want to print something, I have to take the microSD card out of the printer and put it in my card reader and transfer files and then take it back out and put it back there...
Is there a thing already that I can use or do I have to build something so that i can put the sd card in a holder and leave it there and just flip a switch or something between the 2 devices that read or write to the card?

distant raven
#

I have an Ender 3 Pro

#

There is supposed to be a wireless board upgrade that you can get that has onboard storage but I have no experience using it

void sentinel
#

I was thinking if it didn't exist:

uSD_r-w_adapter.png
#

lol

#

I have an extra pi. I also liked the camera thing and I want to say I remember a plugin that scanned for nesting. (I don't generally have a problem with adhesion though)
Wasn't the octpi a device that just connected to the printer via usb? ie: serial printing?

distant raven
#

It plugs into octopi

#

And yea, it is still technically usb serial, it’s more reliable in my opinion than straight serial from a standard computer

void sentinel
#

Also this was acquired.

PXL_20220917_051843949.jpg
fair crown
#

I'm trying to decipher which cable I need to connect https://www.adafruit.com/product/4566 to https://www.adafruit.com/product/4116. I've found this page https://www.adafruit.com/product/4399 but Adafruit seems to randomly mix the terms STEMMA, STEMMAQ QT, Qwiic, Grove, JST PH, and JST SH making it extremely confusing.

Does anyone have any insight into what cable I need and how I can provide feedback to Adafruit about the term confusion?

Adafruit AHT20 - Temperature & Humidity Sensor Breakout Board

The AHT20 is a nice but inexpensive temperature and humidity sensor from the same folks that brought us the DHT22. You can take sensor readings as often as you like, and it uses standard I2C ...

STEMMA QT / Qwiic JST SH 4-Pin Cable - 50mm Long

This 4-wire cable is 50mm / 1.9" long and fitted with JST SH female 4-pin connectors on both ends. Compared with the chunkier JST PH these are 1mm pitch instead of 2mm, but still ...

limpid nest
#

The cables you're looking for are the STEMMA QT/Qwiic/JST SH. They are all names for the same thing.

#

Strictly speaking stemma qt and qwiic are brands of JST SH

#

Rebrands*

fair crown
#

I figured that was the case but it seems sloppy of Adafruit to spend effort on branding the connectors but then not being consistent when using the terms.

limpid nest
#

I'm not sure what the strategy is but you're not the first to be confused

#

Let me look at your devices again

#

Yes that seems to be correct, I misspoke earlier

fair crown
#

Excellent, thanks for the help

limpid nest
#

Any time

limpid nest
#

I'm looking at the rp2040 stamp/2040 in general. Under uart the stamp has multiple callouts for rx0, tx0, cts0, and rts0 (1 as well). What does this mean?

rocky pelican
#

Hello, sorry maybe it's a wrong thread, is there something like a pi camera that can do 1080p 60fps?

unreal flax
limpid nest
#

Ok but it doesn't mean that all those pins will twiddle when I send uart commands right?

unreal flax
#

Correct, just one that you configure for it.

limpid nest
#

Ok thx

void sentinel
#

So the plug is a JST but there are 2 sizes. the PH is bigger and you see it on a lot of lipo and it happens to be on the Titano. The smaller size is SH. Sparkfun calls their version Qwiic. Adafruit calls their version Stemma. The i2c bus on most of these single chip breakout boards is the smaller JST SH.

Also for fun there is a thing:
https://learn.adafruit.com/introducing-adafruit-stemma-qt

Adafruit Learning System
Adafruit STEMMA & STEMMA QT

Plug & play connectivity

hushed smelt
#

Hehe @distant raven bodge life

IMG_0133.jpg
dry pelican
#

No. Even though cameras like Arducam’s 64mp autofocus camera exist (which would be able to push 8k video) the pi cannot encode video above 1080p30fps.

dry pelican
dry pelican
# supple pollen In my experience, cheap ESCs are generally fine for my uses

I just looked up “cheap esc” on Amazon, and they’re really cheap for the 20A that they can provide. However, my version has foc and i2c support (if it works). I guess now I have some experience in high current design, even though my version cannot match the price per amp of a cheap esc from China.

supple pollen
woven bluff
#

@supple pollen do you think driving nixie tube with reduced current will increase its lifetime?

#

I'm driving IN-14 with only 1mA, some places are still a bit dark

supple pollen
inland jungle
woven bluff
#

is there a single IC that can generate complimentary PWM with variable duty?

supple pollen
woven bluff
#

complimentary PWM = phase shift exactly 50%

supple pollen
#

Oh, like quadrature signals?

woven bluff
#

PCA9685 is too big, I have restricted space, I only need two channels

woven bluff
supple pollen
#

An inverter would give you that, or if you're actually using a bridge chip, many are available with one inverted channel (that also offer built-in shoot-through protection)

woven bluff
#

inverter only works at 50% duty

supple pollen
#

I disagree there, but it's possible I'm missing some detail.

woven bluff
#

try draw it on paper, inverted signal has 1-d duty

supple pollen
#

Exactly what you want for a bridge driver

spice turtle
woven bluff
spice turtle
woven bluff
knotty tiger
#

one of the main reasons to use MCUs with a specialized complementary PWM peripheral is to have dead time control

#

i guess you could build dead time control into the analog side of the gate driver, but if you have a MCU peripheral that will do it for you, that could be more versatile

spice turtle
dry pelican
spice turtle
woven bluff
#

For this project I'm working with duty <<50%, so dead time is not a issue.

#

I worked with applications that require precise DT, after trying SG3525 and TL494 I finally landed on Arduino due.

#

After that I absolutely hate external RC timing, and been avoiding them ever since.

spice turtle
#

I do know that for pics you can use the same io and set it to whatever I want. So just choose arbitrary pins and you're OK. Others might have the same pin selection as well but you would have to check

woven bluff
knotty tiger
woven bluff
#

I could always cut the trace and jump wire...

knotty tiger
#

what kind of production quantities are you considering here?

woven bluff
#

one or two

spice turtle
#

So if anything, future micros will be even easier to put in

woven bluff
#

hopefully future MCU will have full xbar

knotty tiger
spice turtle
#

I understand the want to design around different mcus due to the chip shortage, but if you are doing this for yourself, you usually have an ecosystem that you use.

Even makers either use arduino, stm or pic.

inland jungle
woven bluff
#

I always use Arduino nano, now I'm also considering adafruit boards.

#

this board is too small for Arduino nano form factor to fit in

gilded lodge
#

A wise decision

vast flume
#

Hey guys, I am planning to make an stm32 based pcb

#

I was wondering if anyone knows of any documentation showing what the configuration should be for programming mode & normal operations?

#

I've never used this micro before

bitter flare
vast flume
#

I asked in the general chat but I guess I'll also ask here, Are there any good guides out there for an intro to the ATmega328?
Looking to use it as the microcontroller in my next project but I'm having some trouble with finding a tutorial that just explains everything

distant raven
supple pollen
# vast flume I asked in the general chat but I guess I'll also ask here, Are there any good g...

That's a member of the AVR family, there's a nice writeup here: https://www.engineersgarage.com/avr-microcontroller-all-you-need-to-know-part-1-46/

Engineers Garage
Akshay Daga
AVR Microcontroller : All You Need To Know- (Part 1/46)

There are number of popular families of microcontrollers which are used in different applications as per their capability and feasibility to perform the desired task, most common of these are 8051, AVR and PIC microcontrollers. This article introduces the AVR family of microcontrollers.AVR was developed in the year 1996 by Atmel Corporation. AVR...

vast flume
#

Thx

knotty tiger
#

@vast flume it's one of the original Arduino MCUs (the 328P is used in the Uno), so lots of guides for the Arduino ecosystem will talk about it

woven bluff
#

is this a good plasma speaker design?

#

I'm using a CRT flyback transformer

vast flume
#

I'm planning on using the ATMEGA328P-MMHR for my PCB, and in the datasheet it says that it has an internal calibrated oscillator

unknown.png
#

Does this mean that I don't need to add an external one? I am going to be communicating with a device over I2C, idk if that makes a difference

knotty tiger
vast flume
#

Ok, I guess I'll still use an external one to be safe then