help-with-hw-design

[unreal flax]

If nothing else, generally you can extract a footprint from an Eagle board file, as the library object gets embedded in it.

[rustic linden]

Adafruit don't make it, and it doesn't seem to have anything but the datasheet so I feel like I'm just gonna have to figure out a way to add like... dimension constraints and such, idk

welp there goes my afternoon

[unreal flax]

Ah, I see. If it's chip or standard part you could check sites like UltraLibrarian to see if there is a footprint package available for it.

[rustic linden]

It's an RGB LCD 😢

[rustic linden]

I managed to nicely do it up though!

[supple pollen]

Nice! Making your own custom parts is a useful skill.

[rustic linden]

I made a board that slips on the back of the LCD, and it mounts using the pinheader and the screw locations in the LCD (not all of them, though)

[supple pollen]

So it fits on the LCD like a backpack?

[rustic linden]

yeah

I considered calling it a backpack at one point actually

it's very much a specific use case though, so it's not like anyone but me would need it

[carmine scarab]

Until someone sees you using it and asks "Where did you get that??!!?!"

[rustic linden]

i mean, i plan on bringing it to PAX in October

[supple pollen]

Sounds like a nice design

[silk lark]

another samd21 board

pin-compatible with Arduino Pro Micro, so I can upgrade some old projects

[fast tundra]

@silk lark you're really all about using the bare minimum caps 😂

[silk lark]

@fast tundra it's a scam of the capacitor manufacturers to get us to buy more

I mean, what do I care if the power is filtered before the regulator?

[fast tundra]

😅

[distant raven]

Haha 😂

[pearl tapir]

Possibly the regulation loop will be unstable. It needs to be verified on the data sheet but it might oscillate. I've seen it happen.

[south gazelle]

In fact if you look at the schematics of the Adafruit M0 Express, it really has a minimal set of caps. In fact there is not a single 0.1uF decoupling cap on there.

[distant raven]

Yup, M0 usually just uses 1uF caps

[rustic linden]

I'm very proud of the last PCB I designed to be fabbed

[vocal abyss]

Hi there, I am wondering if anybody can help me understand making a ground and voltage plane in my 2 layer PCB. Currently in my layout, I have tracks going from my component pads to where I want them to connect to their respective plane with vias. In KiCAD, am I able to trust that the whole plane is electrically connected when I do this and regenerate the plane (the rats nest connection indicators disappeared). Thanks

[distant raven]

Ordered some E-Ink displays off Aliexpress

Hopefully they work LOL

[compact lotus]

Hello <@&741361254035095602>

Is it possible to auto-generate using a KiCAD add-on or a different tool a pinout refrence ( similar to the one in the picture ) ?

[distant raven]

Hey there @compact lotus there isn't a straight forward way to make graphics like this

I think a lot of people who make these use either Inkscape or Adobe Illustrator

[tough matrix]

I saw this video: https://www.youtube.com/watch?v=ndVs1UvK6AE

[compact lotus]

Yes I already found the same video

I was hoping to find a python script or an app that can automate the task

I posted the same question on KiCAD forum

[rustic linden]

I don't know if anyone has made it yet but... it seems like an interesting project I'd totally see myself doing, at least just in a basic sense at some point

[compact lotus]

https://forum.kicad.info/t/generate-pinout-refrence-from-kicad-design/29069

Here is the link to rhe post on KiCAD forum

One of the users found an article on hackday

That is interesting

https://hackaday.io/project/162131-graphical-pinout-generator

I will check it later

[tough matrix]

nice
would be interesting to see how it works in real life

[unreal pollen]

https://media.digikey.com/pdf/Data Sheets/Rohm PDFs/RPR-220.pdf

Anybody know how a sensor like this could be mounted to a pcb or better yet, use something like a ribbon cable to connect it?

Do I need to be looking at this instead?

https://fscdn.rohm.com/en/products/databook/datasheet/opto/optical_sensor/photosensor/rpr-220pc30n.pdf

[silk lark]

it's a through-hole part, you just make holes in your pcb, put those legs through them, and solder them

[unreal pollen]

Is there a way to 90 degree mount stuff like this?

As in perpendicular to the board itself

[distant raven]

If you make a carrier PCB and solder it into a plated slot on your main PCB

[unreal pollen]

Is that in any way a common thing for fab/assembly shops to put together?

[distant raven]

Depends on the contract manufacturer

But special things like that usually cost extra

[inland jungle]

solder it in normal, and then just bend it

[plush root]

Hi, I have experience with electronics from undergrad classes. I want to learn a new skill now that the semester is over. I am planning on building a PCB this weekend and would like a mentor I could ask a few questions/get on a call with. I am going to be working on Eagle so if you have experience please add me!

[distant raven]

@plush root it’s better to ask your questions here so other people can learn too 🙂

Just post them and most everyone here can help you in some manor or another

[feral mulch]

I want to use a part that's (seemingly?) only available in an LGA package

https://www.mouser.com/ProductDetail/403-SCD40-D-R2

does this seem possible to hand solder?

I've done ones where the pins are on the bottom and on the edges

but these are only on the bottom :(

[long wraith]

You should be able to do it with solder paste and a reflow station

[silk lark]

or a hot plate

I finally finished converting the Chocolad keyboard to CircuitPython. Had to make Pro Micro-compatible SAMD21 boards.

[vapid grove]

Heyyyy

@silk lark

What firmware are you using?

ZMK?

[silk lark]

wrote something simple myself

ZMK is C++

[vapid grove]

Oh, cool!

[silk lark]

I'm using CircuitPython code here

[vapid grove]

Ok

[rustic linden]

Anyone have any suggestions for a PCB design software for the Raspberry Pi? My regular PC is playing up and I have a Raspberry Pi laying around to use

[heavy jasper]

I think kicad may be your only option for something that natively runs on arm64 linux.

or a web-based tool

[rustic linden]

thank you! luckily im actually familiar with KiCAD

[vapid lark]

anyone in here who works in easyEDA who can help me look over my new revision board? apparently i screwed up the first revision for some reason when power the LED strips (all 8 strips x 32 LED per) the ESP32 just "dies" as in i lose connection to it and wifi wont turn on again!!! so i made some changes to the board going from 2 layer to 4 and fixed some footprint errors i made (they were way to small 😅 ) and also changed the polarity of the DC jack 😛 i was following a british guy on PCB making and he put center negative and without thinking so did i! 😛 but i've changed it now!

i would love some help so that there is no mistake on batch 2 when i order now! :/ (all 5 boards i have now are useless because of that power mistake)

[heavy jasper]

@vapid lark I'm willing to take a look if you can post the link to it here and are willing to have the design and feedback be public.

(I prefer to do these sorts of things in an open forum so that others can learn as well)

[tough matrix]

@compact lotus (and everyone else interested) did you see latest LadyAda show - she talks about automatically generating pinout diagrams and board definition files from the same source:
https://www.youtube.com/watch?v=tAKLygjfO_U

[long wraith]

She be magic!

[long wraith]

OwO what's this

[distant raven]

An FPGA feather that I don’t have the parts to build

[long wraith]

Uhoh... Well, at least you have the board!

[distant raven]

Yeah, need to just back order the parts

[long wraith]

Completion soonTM

[distant raven]

Coming Soon™️

[long wraith]

Hehe

[gaunt cedar]

hi - I'm designing a board that will usually be powered from an SAO or coincell. I'll manage which with a simple slide switch. I'd also like the option to throw a USB on the board for easier code hacking and I'm not sure how to handle that third source of power. the usb will go through a 3.3 voltage regulator but I'm stuck on how to handle this. looking for any suggestions

my electrical circuit ignorance is going to show here. could I feed a 3.3v bus from both a coincell and the output from the usb voltage regulator or do I need to isolate those two voltage sources from each other?

[distant raven]

Usually you want to block voltage from usb going to the battery, but if the battery is on the 3.3V side, you could just disable the regulator when a coin battery is present

Many regulators have enable pins

[gaunt cedar]

thank you @distant raven I'll look into this

[heavy jasper]

Make sure that your regulator also has a reverse-blocking feature when enable is off, or put in your own reverse-blocking circuit. many regulators are not designed to prevent back-powering from their outputs to inputs, and you could end up back-under powering your USB.

[distant raven]

Most USB applications recommend Schottky diodes anyway, yeah? I know I use them everywhere

[heavy jasper]

If you can stand the overhead, works great.

I actually tend to also put diodes at the inputs of all my LDOs unless they're specifically back-power rated

When you remove power from a board, if the input rail discharges first before the output rails do, then the LDO can possibly get damaged with uncontrolled reverse current flow to keep the rest of the circuit up.

[unkempt remnant]

Testing some ideas for Itty bitty teeny tiny battery contacts for zinc air batteries partially potted in silicone. All I can say about my first try was that An Attempt Was Made. Hopefully these work better

Size tests in silicone. Eventually the battery flex board will be cast into this mold

[unkempt remnant]

Fingers crossed that I can make the zinc air batteries work. That power density 👌 and you can source like an order of magnitude more current than lithium coin cells (where by "an order of magnitude" I mean 10-20mA... it's not so much that zn batteries are high power as that you just cannot get any significant amount of juice out of a typical coin cell, they're not designed for it)

even if I could fit a miniscule pouch battery into the space I have available, I would really rather go with something that I can buy at the grocery store in an emergency

[supple pollen]

I had no idea you could get that much current from a zinc-air cell.

[unkempt remnant]

I was pretty surprised too. Not sure how it will do with a continuous load, but we'll see.

[elder peak]

I didn't zinc so either, but I guess you can.

[distant raven]

I suppose you could use it if it metal the requirements

[rocky quest]

is the ms5611 better than the mpl3115a2 or is it the other way around

[silk lark]

better for what

[rocky quest]

like the overall better barometer

[silk lark]

if one of them were just better, why would they still be selling the other one?

[unkempt remnant]

speaking of zinc-air batteries, here's a power supply dilemma. so zinc air batteries can start out sourcing like 40 mA (!) but as it runs out of air, the current decreases fairly significantly over several seconds until you give it some time to rest.

wonder if there's a simple way to switch between batteries every few seconds?

[unreal flax]

If you have multiple batteries, it's probably more efficient to run them all at a lower current at the same time.

[unkempt remnant]

true, but zn-air batteries have some particular quirks

I'll need to see what max current they can sustain. they can definitely source much more current when they've had a chance to refresh their air supply, thoug

so depending on how that works out, I might be able to get significantly more current by switching between batteries every second or something

https://d2ei442zrkqy2u.cloudfront.net/wp-content/uploads/2016/03/Zinc-Air-Tech-Bulletin.pdf
see section 5.5/5.6

thte nice thing is that the batteries are small enough that I could fit, like, four into the teeny tiny space available

the graph in section 5.4 also shows drain rate, which even for bitty 312 cells can go up to 13mA or so

[gaunt cedar]

follow-up from yesterdays question regarding multiple possible inputs. using this schottky diode on the inputs and landing on the same vbus I believe this will accomplish what I need. any examples I've seen are only 2 inputs and not a third. does this look like a workable solution? I've got a really rough route as well to see if I'm doing it correct.

[plush root]

I am looking for a dc power connector for my pcb, does anyone have a specific part (both female & male) they suggest? I am unsure about diameter sizes (do they even matter?) . I also prefer something that is made in US that is readily available

[gaunt cedar]

are you familiar with looking up items on digikey? @plush root

[plush root]

I have never used digikey but I have looked at Newark Electronics, do you think digikey has better selection? @gaunt cedar

[gaunt cedar]

looking at newark, i think the selection at either is good. I was more checking to see if you're familiar with way to look up items to narrow down your scope. im more familiar with digikey but they both show in stock items, quantities available for immediate ship etc.

to answer your question better - if you can define your requirements a bit more that should get you closer to what you want. through hole, surface mount, etc etc

searching for barrel plug on either site and then applying filters to narrow down what you are after would be my suggestion. I dont have an answer to a catchall favorite dc connector tho sorry

[plush root]

oh I see. I am pretty new at it but I am getting better at filtering through as there are aloooot of parts. I got worried about choosing something that won't fit as it seems to be a common issue with barrel connectors. And I was mainly wondering if someone had some go-to parts that fit and work well. I appreciate your suggestion thou @gaunt cedar

[distant raven]

My only issue with Newark is there are a number of things that they carry that are just a lot more expensive than mouser and Digi-Key

[inland jungle]

I prefer the filtering on Digikey, especially since you can sort on more columns (like in-stock qty) compared to Mouser.

[heavy jasper]

Specifically sorting for "made in US" on connectors is going to be difficult, and if you're not careful you'll fall into the trap of military/aerospace connectors. They're very very nice admittedly, but also $$$. You might have luck with these folks: https://www.switchcraft.com/

Not sure what voltage of DC you're looking for, but if you can find a matching wall wart power supply, usually best to match that.

[vapid grove]

Do I get it right that SAO is a “standardized” badge expansion connector or it is something else?

[supple pollen]

@plush root The AdaFruit PartFinder is useful for finding common components like that. Here's the power connector page, which gives Digikey and Mouser part numbers too. http://www.ladyada.net/wiki/partfinder/powerconn

[gaunt cedar]

https://hackaday.io/project/52950-shitty-add-ons/log/159806-introducing-the-shitty-add-on-v169bis-standard

[tough matrix]

haven't seen that site before. Cool idea, but it looks like it hasn't been updated in a while - e.g. there si no mention of JST SH 4-pin, aka Stemma QT, connector
Maybe we coudl clone it and have a community- maintained database of "our favorite parts"?

[supple pollen]

It does show a modified date of 2016. It would be cool to have a crowdsourced version that was reflected into nice neat web pages like that.

[tough matrix]

Making wiki page on github is easy. But maybe there is already a DB like that? anyone knows?

[plush root]

@supple pollen this site was very useful, thanks for sharing! @tough matrix we should definitely have this! I feel so much more comfortable buying a recommended/reviewed product

[distant raven]

Prototypes and some production panels

[tough matrix]

we need enough people willing to contribute to that - othrwise the project will slowly die...

[supple pollen]

You'd have to have a way to deal with different peoples' preferences too: some like Samtron, some like Berg, some like AMP, some like Molex, some like 4UCON.

[tough matrix]

yeah...
On a positive note, I just ordered some SAMD21G18 - the order was accepted and chips are scheduled to arrive on my doorstep in a couple of weeks.
As opposed to "some time in late August" you see on Digikey 🙂

[distant raven]

Oh good! 🙂

Did you order through Microchip Direct?

[tough matrix]

yes
it was easy, thanks to Stargirl for the tip

[distant raven]

I’m surprised they had any available that soon

[tough matrix]

maybe I got lucky
They had no samd21g18a-au in stock, but kindly suggested samd21g18a-af as drop-in replacment (the only difference is range of temperatures it can work in)

[distant raven]

Yeah, slightly more expensive but the same for most applications

[elder peak]

Thanks to Stargirl, now we can be well ARMed.

[supple pollen]

But ... why?

[distant raven]

More for the lolz

It’s a Cursed Board ™️

[silk lark]

some people like to see the world burn

[distant raven]

some people like BGA

[elder peak]

I dono, man, it makes me want to take my ball and go home

[long wraith]

https://tenor.com/view/love-it-horsehead-i-love-it-gif-6012326

[distant raven]

Maybe I’ll turn it into a curse SMT soldering challenge with associated mounting board

The mounting board will have all the IO broken out with USB, SPI flash and other necessities

All you have to do is successfully solder all the bits on the BGA board and then solder the BGA board to the carrier/mounting board

[elder peak]

Why do you hate people, @distant raven ?

[long wraith]

It's just the Advanced Insanity Challenge

If the shenanigans of that board bother you... you failed :D

[distant raven]

I was told y’all love BGA

[rustic linden]

what even is BGA

[heavy jasper]

Ball Grid Array. Where all the little dots are on the PCB, some solder would get deposited and melted into small very-similarly-sized balls. Then that's a finished part, and can be soldered again onto another board with some new solder for flux/gap-filling.

For an application like this, it's kind of just a fun exercise, but they're pretty much the only way to go when you have very high pin count soldered parts, on the extreme end think things like laptop processors:

[rustic linden]

huh!

[heavy jasper]

(for a sense of scale, that's 1377 balls, on a 0.43mm pitch).

[long wraith]

Much more dense pinning than QFP!

[haughty wolf]

bga is necessary and nothing more lmao

[supple pollen]

SparkFun realized they'd need an expensive fine pitch multilayer board for their Artemis BGA MPU, but instead of making their entire board that way, they made a little carrier board that they then attached to a larger, lower cost board.

They do sell the little carrier board separately, for those who want to use it with their own designs https://www.sparkfun.com/products/15484

Their writeup on the thinking behind it is informative on BGA issues in general. https://www.sparkfun.com/news/3122

[tough matrix]

never tried soldering a BGA... and hope to avoid it in my future life, too

[distant raven]

The RP Baller has a super wide pitch that’s friendly towards makers

1.6mm pitch and 0.5mm ball size

[haughty wolf]

i would squeeze solder paste on the pads and reflow with a hot air gun
you could get a stencil for not too much money though. they can be a pain to use sometimes though

[heavy jasper]

At certain volumes, even the cost of adding a hot air gun may not be well amortized; you’ll want to have an iron anyway for touch-ups. The cheapest answer I can think of is “design only with parts you can solder with an iron, then do so.”

[distant raven]

I use a combination of hot plate and hot air gun

I’ve not soldered a BGA part yet but I will be soon

Good hot plates transfer decently

But it’s the accuracy of temperature that is the biggest issue

Metal top, no ceramic or glass

Nothing

The heat plate I have has a metal top

The only issue with mine is the PID isn’t very well tuned

So to get the 140°C I need for my solder paste, it has to be around 165-170°C

Which is better than similar hot plates

Yes I use low temp lead free

The hot plate has a heating cycle

Yeah

I paid like $10 for a 15g syringe of NC191LT15

It’s T4 ball size

It’s from ChipQuik

Yeah, you need to be careful about it

nah, it's usually pretty well priced for syringes

it's like $60 for 250g of it

[distant raven]

If you got on Digi-Key you can get 35g for $26 in a syringe

I’m not sure

I use Autodesk Eagle

Eagle comes off as fusion360

And they do have a startup program

You can apply as long as you don’t design for other companies

I didn’t apply because I do work for other people

[fathom lotus]

hi guys, reverse engineering a pcb solenoid driver, i've got the circuit down correct but can someone check if my understanding of how it works/what it's doing is correct? the only part i'm confused about is why r2 is pulling pin 2 of q1 high

the only thing that may be wrong here is the pinout of q1, as i was unable to find a datasheet for it so i went off what i know to be the standard/most common pinout

[unkempt remnant]

Interesting. I've finally managed to make the thermocouples on my reflow oven swappable, and run some profiles using thermocouples firmly attached to PCBs... turns out that my oven has a tendency to overshoot by 10-20 degrees or so. Or more likely, the copper cladding on the board has too much inertia.

(Celsius)

But with low temp solder it probably doesn't matter

[supple pollen]

The diode doesn't look right and you'll want a series resistor for the base

[unkempt remnant]

controleo 3 kit

I'll re-run its learning thingy and see if it does better after that

[south gazelle]

I suspect that pins 1 and 3 from Q1 should be flipped around here, with the emitter (pin 3) connected to GND. I also think that R2 should probably be between pin 8 of U1 and pin 2 of Q1, instead of pulling the gate of Q1 high. As an other alternative, perhaps Q1 is a PNP transistor instead of the NPN showed here. The the circuit would then probably work in an inverted logic (Solenoid turns on when pin 8 of U1 is low). I think this is unlikely however.

[silk lark]

trying a PCB battery holder

[rustic linden]

how do i design a lipoly battery charging circuit like the ones the feathers have?

I've never made a battery charging circuit, but I have a project that will need it and I can't just use a board someone else has made, cause it needs to be integrated into the board

[heavy jasper]

Straightforward starting point: clone the one on the feather if it works for you; the schematics are available.

[rustic linden]

Duh ofc they have it available

[distant raven]

Yeah, the mcp73831 can be tricky to get your hands on right now though

[cerulean crest]

Seems to be lots of stock on mouser

[distant raven]

I haven’t looked in a few days

Depends on the variation you’re looking at

[cerulean crest]

All variants in stock from what I see, some have lower stock around 200 quantity

[distant raven]

Oh cool

I’ve got 150 on hand currently

[cerulean crest]

Oh didnt go to the next page, there are 4 variants out of stock

[distant raven]

Just have to get more 3.3V ldo

I use the 2 at variant

[cerulean crest]

MCP73832T-2ACI/MC, MCP73832T-2DCI/MC, MCP73832T-2ACI/OT, MCP73832T-4ADI/MC best of luck 😆 chip shortage is pretty bad

[distant raven]

Yeah

I ordered the tps22917 load switch. Probably won’t see it until October

[cerulean crest]

Im not sure what Im gonna do at work, we cannot get parts for the "legacy" product and they are selling like absolute hotcakes, I only have enough stock to get me to fall

[distant raven]

Dang

[cerulean crest]

I had to source almost every IC in the last two pcb orders from weird niche places

[distant raven]

That’s scary

[cerulean crest]

I am currently one of the largest holders of isl28635 amps in north america from what Ive seen 😆

[distant raven]

Off channel part sources leave a lot to be desired

[cerulean crest]

Indeed, making a few friends along the way however. Some places I never heard of did great work

[distant raven]

That’s good to hear

I successfully found a good reel of sk6812mini on Aliexpress

[cerulean crest]

When I saw the airtags tho... "ahhh thats where all my bga nrf52832s went" 😭 . And nice, that can be a challenge

[distant raven]

It was a bit nerve racking wondering if I was getting legitimate ones or not

Oh dang, yeah a lot of nRF chips are gone

And a lot of STM stuff too

I’m just waiting to get my hands on the rp2040 chip but I won’t have them until mid July

[cerulean crest]

I was kinda surprised by the stm stuff at first, I would have thought st was gonna be right on top of it.

[distant raven]

I’ve got samples I working with but lead times are 8 weeks so.. a 500 pc reel won’t arrive until July so that kind of hampers things

[cerulean crest]

Its fine, just buy 500 picos

[distant raven]

This is because a ton of resellers hoarded them and are selling them marked up like crazy

[cerulean crest]

And a nice desoldering setup 😆 😆 😭

[cerulean crest]

Ah makes sense

[distant raven]

Oh, I couldn’t buy 500 Pico for the price I’m paying lol

[cerulean crest]

I know 😆 Was a joke since Im finding myself desoldering from dev boards to make new pcb designs

[distant raven]

If I bought the Pico boards directly from RPi, I think I could get them for like $1.75 a piece

I only asked for a quote on the chips though not the actual Pico boards

Maybe I should ask

Become a reseller

[distant raven]

I have also done this lol

But anyway

What I do know is I have 190 Samd21 chips left

[cerulean crest]

Is that good or bad compared to usual stock? I havnt checked SAMD21/51 availability recently

[distant raven]

They are back ordered most places until July or later

I think microchip direct has some same51

But by and large, a lot are sold out

[cerulean crest]

Indeed. I hope not too many smaller players are dying out waiting for parts

[distant raven]

I can see to about.. Julyish

I don’t know how things look after that

Hard to really tell

[cerulean crest]

Just imagine starting your own small thing right before the pandemic, you put a lot of time and money in, now you cant get parts to sell product to pay for the things you need then you're back working at walmart. Id just cry myself to sleep 😆

[distant raven]

I’m glad I have a nice software engineering role but I like my maker business and I’m trying hard to grow it. But semiconductor shortage was not on my pandemic bingo card

I can float my business to keep it going while things recover

It’s not ideal but it’s something o can do anyway

[long wraith]

Random question -- I've only ever done basic PCB design on paper or in MS Paint... Any recommendations on an easy software to start with, preferably free, that can export appropriate files to send off for production?

[tough matrix]

I ordered some ATSAMD21G recently directly from Microchip

[tough matrix]

Commonly used is Eagle (free for very limited use) and KiCad (free, open source)

But I think the easiest one to start is online one, easyEDA

[long wraith]

Cool. I've heard of Eagle, thought it was expensive XD what would classify as "very limited use"?

[tough matrix]

EAGLE free download is a limited version for hobbyists including 2 schematic sheets, 2 signal layers, and an 80cm2 (12.4in2) board area.

But check easyEDA

[long wraith]

Ah... I'd like to get into multi-layer design, and easyEDA shows that in the front page, so I think I'll start there. Thanks!

[rustic linden]

gosh this is confusing

I'm trying to figure out how to add a battery charging circuit to something, I'm starting with what a feather has but I'm not 100% sure on everything and the diagrams are a little confusing

[cerulean crest]

Do you have a more specific question around the schematic for the feather? Im familiar like many others here and happy to help

[rustic linden]

How would I go about adding a battery circuit to a rapsberry pi pico?

(assuming a battery charging circuit similar to the feather boards is even possible with a pico)

[cerulean crest]

Im not too too familiar with the pico, but looking at its schematic, you need a battery charger, battery input, then protection between the battery and the VSYS

Lmao, right after I sent that, there is a section in the pico datasheet "Adding a charger"

[rustic linden]

Wait what

Am I just blind

I have the Pico datasheet here

[cerulean crest]

Section 4.6, Using a battery charger sorry, but its adding a charge circuit to the board

[rustic linden]

I am blind

That's exactly what I needed

Well that makes thinking about all of this incredibly simple

[cerulean crest]

Lmao, happens to all of us, really make sure to add that mosfet (as pictured in the diagram) otherwise youll have a bad time

[rustic linden]

Yeah, I'm just trying to find a suitable mosfet rn

it talks about a voltage out, what would that be on the MCP73831?

[cerulean crest]

The battery output

Some chargers have integrated power paths

[rustic linden]

But it also has the battery separately as a listed pin

I don't know what that means

[cerulean crest]

If you look at the feather schematics, you will see that exact layout with the MCP73831 and the mosfet. Some chargers have a separate out also known as a power path, so it may be regulated, have extra protections, or other features

[rustic linden]

ah okay thank you

OH

they put the mosfet over in power and filtering so i missed that that was basically how it was set up

I'm really sorry

[cerulean crest]

Oh dont be, nothing to be sorry for

[rustic linden]

What charge led does adafruit use? just for funsies, i'm probably going to pick my own, but just curious

i know it's a 0603 package

[distant raven]

10k for 100mA I believe

[cerulean crest]

Good question on the part number, would just use any highly available orange LED

[distant raven]

Oh color lol

I read resistor 😂

Look for low test current LEDs

[rustic linden]

okie

[cerulean crest]

Will be under indication leds in supplier websites

[distant raven]

Something with a test current of like 1 to 5 mA

Then you can use a 4.7k to 10k resistor on the charge LED

Reduce overall power consumption due to the charge LED

[cerulean crest]

Eh, plugged in anyways, Id rather blind myself, 10 ohms and pray 😉 (Joke plz dont do this)

[rustic linden]

How to burn out an LED

[distant raven]

I decided one time I wanted to blow up an LED. I put 5V on it without a resistor. It just fizzled. 🙁

No spectacular explosion like I was promised

[cerulean crest]

Backward cap next time 😉

[long wraith]

One time I stuck an LED into a wall outlet

[rustic linden]

I'm having trouble finding the right JST connector on the site I'm looking at

good LORD

[long wraith]

It exploded :D

[elder peak]

I think the only thing I've ever really smoked was like a potentiometer.

[rustic linden]

gosh why is finding a ph connector so difficult sometimes

[elder peak]

I've zapped some parts including a 6502.

But never in a fun way.

I've even connected a capacitor backwards and it didn't asplode.

[long wraith]

The only thing I remember burning unintentionally was an LCD HDMI controller for a laptop screen when I accidentally fed it 12VAC instead of 12VDC

[elder peak]

Like, other folks talk about EE classes and the smell of burnt opamps and I feel like I've not inhaled enough magic smoke to count myself as actually qualified.

[long wraith]

lol

If you've been doing EE for a while and haven't smelled a lot of magic smoke... you might be overqualified!

[rustic linden]

the only parts i can find are throughhole :(

[elder peak]

Oh, I've never done EE, just make random weird stuff.

[proud harness]

Hi all, sorry to interupt, but had a quick question. I'm designing a carrier board for 2 SPI devices that will connect to a Metro M4 Express. Should I wire the SPI lines as a "Y" or in series with each other? Does it matter? I'm still a newb at PCB design.

[unreal flax]

It shouldn't really matter, as long as the wires make an electrical connection, as the inactive SPI device should essentially disconnect itself from the bus.

Note that you'll need separate chip-select lines for each device, as those are not shared like the other SPI signals.

[proud harness]

Thanks. That's what I thought. I know about CS. Well adept at dealing with these, but I have not made a carrier board before myself. Other simpler boards.

I have this all working on breadboard. Porting to something cleaner.

[rustic linden]

are the jst connectors that adafruit sells decently easy to hand solder?

https://www.adafruit.com/product/1769 these

[cerulean crest]

Yeah itll be okay, the two mechanically supporting tabs are the "hard" part, just put a little solder on each pad, put the connector on, touch the iron to the corner of one pad until flush, then the other. Then the actual pins can be soldered down

[rustic linden]

thank you! just panicking a little because i've been finding them a little difficult to find on the service I'm going to be using to actually assemble the SMD parts (as I cannot do that very easily right now myself)

also, why are there so many 0.1uF capacitors in parallel on the Feather RP2040?

[distant raven]

welllll

because that's the recommendation of the hardware reference design

but the EE reasoning is filtering

[silk lark]

noise filtering, basically

they had to pass the CE tests for resistance to harmful interference

[rustic linden]

ah

[distant raven]

unintentional radiators

[tough matrix]

someone wrote that 0.1uF capacitors are like fairy dust of electronics

you should sprinkle it on everything, any circuit

[silk lark]

yeah, you need them everywhere, but they are too big to include on the chip itself

[tough matrix]

I wonder if the optimal value of 0.1 uF was computed or found experimentally.. why not 0.01uF or 10F 🙂

[rustic linden]

I think 10F is a little high

[silk lark]

10F would let it run without a battery for three days

[tough matrix]

well, 10F is certainly somewhat too high, that much I guessed. But I would still like to know how they came up with the value of 0.1uF

[distant raven]

It’s based on differential equations

[silk lark]

and experimenting

[distant raven]

Yup

[silk lark]

this is why it's such a nice round value of 100nF

you could probably use 47nF or 220nF without much difference

[tough matrix]

sure

[distant raven]

Basically you have the characteristics of how fast capacitors charge which relates to frequencies up to a certain point or down to a certain point depending on where the series resistance is measured and calculated

There’s also line inductance which is a consideration too

[tough matrix]

but you need to know the amplitude and frequencies of noise you are trying to filter

[distant raven]

Yeah

[silk lark]

it's all specified in the CE requirements

[distant raven]

If you know that, and other parameters you can deduce back filtering requirements

[tough matrix]

i thought there is a document somewhere that specifies that... thanks!

[silk lark]

well for US it's FCC

for Europe it's CE

other countries have their own, but it's similar

it tells you exactly what kinds of interference the device needs to be resistant to

[rustic linden]

why is the header layout so confusing on the schematic for the 32u4

it had the 14 pins on the left of the 16 pins

[tough matrix]

which 32u4? Feather?

[rustic linden]

yeah

[tough matrix]

all feathers have 12 pin header on one side, 16 pin on the other

[rustic linden]

i meant 12

[tough matrix]

I guess having different pin counts was intentional
it guarantees that you won't be able to plug the board in the wrong way

[rustic linden]

nono

I mean on the schematic

it was all weird and backwards

[tough matrix]

I see what you mean.. comparing the schematics to actual physical board, the long header is upside down in the schematics

of course, you can place it any way you like, it doesn't matter, but it does look weird

[silk lark]

making understandable schematics is a bit of an art too

and sometimes you just can't be bothered

[tough matrix]

My first attempt at importing 3d model of a PCB generated in Kicad into Fusion 360.

somewhat disappointed that 3d model created by KiCad doesn't show traces ....

[silk lark]

but it does show tracks!

[tough matrix]

not designed in KiCad, though 🙂

[silk lark]

I wonder if you need to enable something, because I definitely remember seeing kicad renders with traces

maybe the traces are there, but you can't see them because they are set to the same material?

[tough matrix]

KiCad has built-in 3d viewer that shows traces and all
But if I export the file as STEP to use in another 3D modeling program, the exported file doesn't have traces information
Maybe if I export in another format, it would help..

[cerulean crest]

VRML output does

or VMRL or whatever. The thing that exports a .wrl file XD

[distant raven]

Just cooking up some creativity

I wish JLCPCB would have put a little space between the boards

[cerulean crest]

Cant you ask for tabs instead of vscore?

[distant raven]

Probably could

The vscore is nice though

[cerulean crest]

https://tenor.com/view/what-do-you-want-argue-gif-4857255

[long wraith]

Gotta go tighter!

[rustic linden]

You can panelise the boards yourself, if you need

I'm curious though, what boards are they?

[distant raven]

CP Sapling Rev B

Samd21 dev board

[tough matrix]

So this is where all the SAMD21 went...

[distant raven]

Lol

[elder peak]

You could ask for tabs but who's keeping sore?

[tough matrix]

I know it had been discussed before but can't find it now.
What is the usual stackup for 4-layer boards?
I was thinking:

signal1
ground
vcc
signal2

The board is pretty simple, no RF frequencies to worry about, the most sensitive is USB D+/D- which I will keep on top layer. Some number of analog signal lines going into ADC, which again I intend to keep on top layer.

[cerulean crest]

That is the usual stack-up, in that order unless your RF/hs differential signals are on your signal2 layer (If you did happen to have it)

[vapid grove]

Btw LTC4056 seems to be a drop-in replacement for the charger adafruit uses

But it costs 3$ per unit

Maybe resistors should be changed, but anyway

Holy shield, atmega32u4s cost up to 13$

[distant raven]

It isn’t if you’re talking about the MCp73831, one is 6 pin and the other is 8. It appears the LTC also uses a transistor.

It might if you’re talking about the TP4056 or whatever the part number is

But even the tp4056 doesn’t have the same recommended schematic

[vapid grove]

Oh ok

[distant raven]

Wait there is supposedly a 6 pin variant according to one thing I found

But I’d have to find the data sheet to verify

https://www.analog.com/media/en/technical-documentation/data-sheets/405442xf.pdf

There’s this, but it’s not the same pin wise

Same footprint but I’m not sure same pinout

I’ll be had

Looks like you could basically drop the LTC4054 in for the MCP73831 with minor changes to the values

This is good to know

Only downside is it’s $3 more per unit lol, that’s my whole margin on LiPo power packs lol…

[tough matrix]

what???

[sour coyote]

Total PCB design noob here - building my first board in Eagle CAD - is there an equivalent SMD version of the ATTINY85V-10-PU? It's easy enough finding the 0805-styles of resistors and capacitors, but this one's got my part picker stumped. ... Or maybe a better question is: How could I find an equivalent SMD chip to whatever THT chip I'm used to using? (Also, if someone's responding to this, could you @ me?)

[unreal flax]

@sour coyote The closest equivalent would be the ATTINY85V-10-SU, which is in an 8-pin SOIC package. The datasheet lists all the ordering variations available.

[sour coyote]

Sweet, thanks so much!

[left python]

Hello people! I am trying to build a PCB using an ESP32 Pico D4(first attempt at my own board) in KiCAD. I want to run it on LIPO 3.3V and program it using an external device like the USB-UART modules. Also need to connect it to MLX90614 and MQ135(not the modules but the individual sensors). Any suggestions how to go about doing this and what I need to be careful about here?

[tough matrix]

Just great.

Anyone knows where I could look?
Or should I just buy a lot of breakout boards and desolder chips?

[distant raven]

What’s the lead time?

Wow November

[primal schooner]

Yup, it's everywhere. I had to do a respin on a board because of this. Going TI was what I did and using octopart as a way to source parts. Arrow was good, once you get over the interface issues. BTW, this what I had to do for a simple LDO power management ic. I'm eyeing my pile of failed development boards for my ongoing development (in house) boards......

[distant raven]

I’m going to be back ordering 500 of the LDO I use that will hopefully be in by the end of the year

[elder peak]

It's kinda a good thing that I just started a new job so I've got a lot less time to design new things because I can't get parts for them.

[distant raven]

Lol…

[elder peak]

But, yah, I do feel bad for everybody whose new businesses are going to have to try and squeeze by without any stock.

[distant raven]

It’s an interesting position to be in

[tough matrix]

fortunately for me it is not a real business, but yes, it is annoying

[rustic linden]

I'm just lucky that right now the parts I need to get for a product aren't out of stock

Also, unrelated: how do I add fiducials to a board in EasyEDA?

[pearl tapir]

I don't specifically know about EasyCAD but in Pads PCB, I have fiducials as a component and just put it on the schematic,

[hallow pelican]

With a Teensy 4.1, whats the best way to get contact with the pins on the bottom of the board?
I really need the USB data lines and some of the memory bank pins (to use as an extra SPI bus)

I was thinking soldering pogo pins on my board to reach to the teensy pads, but curious to know if there is another way

[vapid grove]

If you want to solder your teensy permanently, you can place some solder pads under back pins of the teensy, so you can solder those pins to your board

[hallow pelican]

yes but these are pads on the bottom with smd components on that side

[vapid grove]

You can make holes on a pcb under those components

[hallow pelican]

yeah so pogo pins in PTH

[silk lark]

I usually just use wires

[drowsy talon]

Anyone wanna make some money for a small circuit/pcb design? I don't have the time to sit down and learn a brand new skill right now but I really want my idea to be real.

[unreal flax]

If you don't get any takers on Discord, there's a job board on the Adafruit forum as well. And platforms like Upwork or Fiverr can also be useful to find freelancers for one-off jobs like that.

[drowsy talon]

Yeah Fiverr was a bust. Gave a dude 150 bucks for him to copy the diagram from the datasheet.

multiple components not wired together. Just kinda laid out on a sheet individually.

[unreal flax]

That's not necessarily wrong, depending on the tool. If a wire has the same signal name, it's usualy considered connected to every other wire of that name even if there isn't a drawn line between them.

[drowsy talon]

True but it's also wrong components and a battery that's way under spec. I'll just consider it lost and look for someone else. I think the problem might be my explanation of the project. It's a weird one but I didn't think it was so unique it would cause issues

[unreal flax]

(But, yeah, I've had bad luck with Fiverr too. Some really horrible logo designs. Upwork has been much better for me.)

[drowsy talon]

I'll check it out. Never heard of it before. I wish I had more than a day and a half in town or I'd just learn to do it myself.

[unreal flax]

You might consider dropping a hint or two about the project here if it's somewhat weird, heh heh. Many casual people will be more motivated by whether it's interesting or not rather than just the promise of getting paid.

[drowsy talon]

I wanna make a mechanical key adding machine but instead of just doing math it's a dice roller. The part that seems to confuse people is using mechanical keyboard keys but not connecting it to a pc

like this but with way less buttons

[unreal flax]

Cool. Yeah, I expect folks would understand that right away. A number of projects have involved keys and microcontrollers in various combinations. Type in "2d8" and get a dice roll back?

[drowsy talon]

actually you can type in 2d8 +8-3 and get the individual rolls and the totals with modifiers printed out

and I'll have two special modes for advantage/disadvantage as well as reroll 1's.

[unreal flax]

Neat!

[drowsy talon]

right?

There's all kinds of hacky ways I could do it but I wanted to get a PCB and have a more finished product so I could make some as gifts for friends.

[silk lark]

mechanical keyboard switches are on the expensive side

what do you want for display, a 7-seg?

[drowsy talon]

I'm open to suggestions but I was thinking https://www.adafruit.com/product/198

[silk lark]

I would go for something like https://www.adafruit.com/product/880 — brighter, bigger and cheaper

as long as you only need to display digits and maybe some simple letters

[drowsy talon]

It would need a lot more digits

[silk lark]

how are you with soldering?

[drowsy talon]

I'm fine with soldering.

[silk lark]

smd?

[drowsy talon]

I have only a couple times. I don't have the tools at home. Gotta go to a local makerspace for it.

[silk lark]

sounds good

how many digits do you need? do you have a mockup of what you would like the display to look like?

[drowsy talon]

I do not. To be honest I know so little about circuit design I wasn't even sure if my choices would work.

[silk lark]

I don't mean the circuit, I mean the user interface you want to display

[drowsy talon]

Like a calculator. expands from the right as you type. I might need a character or two to display the mode but ultimately it'll just be a place to make sure you typed the right stuff before you print it.

[silk lark]

but you said you wanted the individual rolls to be displayed?

[drowsy talon]

not displayed. Printed.

https://www.adafruit.com/product/2753

like an adding machine

[silk lark]

oh

[drowsy talon]

I would probably just show total on the screen and print out the individual data.

[silk lark]

you would need a proper case, you can't mount that printer on a PCB easily

[drowsy talon]

in terms of rolling it should be under 20 characters for a big roll. "##d### + ## - ##"

yeah. I need to finalize the components before I start designing a case for it though. That part I can handle no sweat.

[silk lark]

do you know the keyboard layout?

[silk lark]

there are ready macro pads like that

[drowsy talon]

that need to be plugged into a computer.

[silk lark]

they have an atmega 32u4 on them which you can reprogram

90% of them use the same 32u4 chip

[drowsy talon]

wouldn't I still need a PCB made since I don't need to connect it to a PC and I need to connect a printer?

and does a 32u4 support 5v on rx?

[silk lark]

Operating Voltage Range (V)
2.7 to 5.5

https://www.microchip.com/wwwproducts/en/ATmega32U4

it's the same chip as Arduino Leonardo and Arduino Pro Micro use

in fact, some of those macropads simply have a socket for a pro micro

[drowsy talon]

okay but connecting the printer. I'd still need a pcb.

[silk lark]

and you will need a battery

that printer takes too much current to be powered by usb

[drowsy talon]

I'm okay with the idea of either a battery or plugging into the wall.

[silk lark]

how do you imagine connecting that printer with a pcb?

[drowsy talon]

I assumed a header somewhere

[silk lark]

so basically you would need to take some design like https://github.com/imchipwood/dumbpad and add some headers for the display, printer and power to it?

[drowsy talon]

I guess? Is it that easy?

We're outside of things I know here. This is all a learning experience for me

[silk lark]

perhaps you should start by wiring it by hand after all, and get back to the pcb once you know how everything is going to be connected

you will need a case anyways, so you can make the keyboard switches sit in the case

[drowsy talon]

that's why I was offering to pay someone. I'm a truck driver. I'm home for 2 days on the weekends and have other stuff that needs to be doing during that time. I just don't have the time to sit down and learn it. I want to but I'd rather have the idea become reality in a reasonable amount of time rather than spend a few days a month learning how to not break things.

[silk lark]

I hear you

it doesn't help that the hardware is just the beginning, someone has to write the software too

[drowsy talon]

That I can do out on the road. I've got my laptop so when I stop for an evening I can mess around til I get it working. I have some experience programming.

[silk lark]

can you bring a bunch of electronic modules and a breadboard with you?

[drowsy talon]

technically I could but I don't really have a safe space to store components. I dunno if you've ever been out on the roads but they're not all smooth. Sometimes things just go flying.

[silk lark]

well, it would go into a box when on the way, of course

the thing is, sometimes it's not obvious how to best connect things before you start writing the program, the mechanical, electric and software parts kinda inform each other

if you just pay someone, and don't tell them exactly how to connect things, they will just come up with some way they think best, which doesn't have to be best for you use case

that's why people often build a prototype on a breadboard, write the program, and then build the final version

[drowsy talon]

okay. I'm still lookin to pay someone. You interested?

[silk lark]

I can do it, but I wouldn't take money for it

[long wraith]

Work for the low, low price of $free.99

[drowsy talon]

that sounds kinda ominous. what kinda weird things you want me to do in recompense?

[silk lark]

I don't want people to be angry at me if what I did doesn't meet their expectations. I will cobble something together tomorrow, and you will see if you like it or not, and if you do you can order the pcb.

if you don't mind, I'm going to use Kailh choc switches, because I already have the footprint for them

oh, and I will make all keys 1U, because I hate dealing with stabilizers

[drowsy talon]

are choc switches clicky?

[silk lark]

there are 13 kinds, more or less clicky, linear, tactile, etc.

I use whites, which are the standard clicky kind

and some light blues, which are low-force linear

[drowsy talon]

as long as there's options for people. it'll probably be easier to figure out how to change the switches than anything else if someone wants to use something different. I like cherry red linear but since it's a dice roller I'm sure some people are gonna want clicky

[silk lark]

the main problem is that there are only a few sets of keycaps available for those switches -- they have a different stem than the standard cherry "+"

but changing the footprint for the switches later on shouldn't be that much work

I will put a feather socket on it, so you can use any feather board, and I think I will use a tft screen module, so you have plenty of space for display, and can easily see circuitpython errors

then headers for the printer and for power

the feathers also include battery charging on them, so that's solved

[drowsy talon]

awesome. Thanks for the help.

[gaunt cedar]

I've got a question related to kicad and inkscape

for my front copper layer. it's imported into pcbnew as a footprint and the copper layer looks good. I'm running into an issue trying to assign GND to that copper layer. is there a way to do this?

[gaunt cedar]

I think the issue I need to resolve is to pass design rules. I have a VIA that lands on the front copper pour but it doesnt register that its grounded.

[rustic linden]

how do i choose a connector for an expansion port?

[rustic linden]

eh I'll leave it to later

[silk lark]

@drowsy talon got a simple design for you

[supple pollen]

I'm fond of card edge connectors, and ordinary two-row Berg style connectors for expansion ports (sometimes with a ribbon cable that plugs in and goes to a chassis mounted chAMP or other suitable IDC connector)

[long wraith]

Edge connectors are fun :D

It's satisfying to plonk a board into a socket that way

[drowsy talon]

Message me

[ivory jasper]

Someone mentioned my analog hall effect rotary encoder on one of Adafruit's broadcasts yesterday so I thought I'd share what I've put together so far: https://youtu.be/OOdjR3yBLNo

Now that I've made a slider thumbstick mechanism to go with it I'm going to change that layout a bit... The top right hall effect sensors are going to be moved further out.

It takes up about 30mm of space which is 10mm more than the compact resistive slider thumbsticks that are on the market but it has an RGB LED, is contactless, and also works as a rotary encoder! So with the right hardware configuration it could be quite a powerful input device! 👍

If you just want it to be a rotary encoder it should only take up ~13mm of space. Though, without the LED I can probably make it smaller: I had an earlier prototype that only took up about 9mm 👍

Then again, if I switched to smaller magnets I bet I could get it down to 5-7mm! 😄

[elder peak]

If you were to present this at a conference, clearly you'd be presenting it in the hallway track.

[rustic linden]

lord that joke

[rustic linden]

Gosh I wish I knew how to optimally place components

[elder peak]

I take no position on this issue.

[rustic linden]

it's just annoying trying to figure things out, especially when space isn't a huge issue

[gaunt cedar]

that's part of the fun. the journey. I just routed my first pcb and it was a bit overwhelming at first.

[vapid lark]

is this ok? it's a SRD-05VDC-SL-C Relaya

[opal tusk]

I know some components are very specific but with a pretty heft lead time, i'm looking for an alternate to, is this a part that is safe to assume is swappable with something that has similar specs and package?

[distant raven]

All I can say is good luck

Trying to source PMICs has been a certifiable pain in the butt

[opal tusk]

thanks 🙂 i just want to make a sweet portable scratch instrument so i can make some sweet portable hip hop

[tough matrix]

Looks ok.
Minor suggestion: it is common convention that GND is always pointing down, and VCC/+5V is always up

[vapid lark]

does it look ok (the relay part)?

[tough matrix]

Looks one of the pins of transistor Q1 is not connected?

[vapid lark]

that is GND

[tough matrix]

Oh, right, connected to copper fill

[vapid lark]

yea 🙂

[tough matrix]

Did you run DRC? Looks like the clearance between lower row of pins of ESP32 and traces is very small

BTW, what width traces do you use?

[vapid lark]

1.5mm

on every trace

[tough matrix]

Wow
Usual width is 8-10 mils on signal traces, i.e 0.2-0.25 mm

1.5mm is 60 mils... I'd use it for 4A current

[vapid lark]

btw DRC is fine

[tough matrix]

Ok

But it is still a massive overkill for signal traces

[distant raven]

Large signal traces can sometimes be prohibitive and have extra inductance

I wouldn’t do bigger than 12, maybe 16mil tops

[vapid lark]

in mm please 😛

0.4mm 😛

[distant raven]

Sorry most fabs work in mil so that’s what I use lol

Like smallest trace/spacing you’ll find is listed 3/3 which is 3mil trace 3 mil spacing lol

For reference 50mil is 0.394mm I believe is the conversation

[tough matrix]

No.
1mm is about 40 mil

To be precise, 1000 mils=1in=25.4mm

So 1mm=1000/25.4 mil

[supple pollen]

That's backwards: wide traces have lower inductance

I like wide traces, where they'll fit (like here), and they're easy to manufacture.

[elder peak]

I like my circuit boards with a smol outline and wiiiiiiiiide traces.

[distant raven]

Ah right yeah had that back

Increased line resistance

[carmine scarab]

That one just takes the Cake now, don't it

[distant raven]

I like big traces and I can not lie

[vapid lark]

so im trying to follow this breadboarding i did
https://cdn.discordapp.com/attachments/622118305930674192/847228512972570644/unknown.png

https://cdn.discordapp.com/attachments/622118305930674192/847551258700939284/unknown.png

https://cdn.discordapp.com/attachments/622118305930674192/847551313684463636/unknown.png

but it is crying because it want 5v connected -.-
how to fix that?

[distant raven]

Add a 5V line to the collector of the transistor

If you turn on that transistor as is, I’m fairly sure you will have a Vce of < 0.7V

https://www.google.com/amp/s/www.instructables.com/Driving-a-Relay-With-an-Arduino/%3Famp_page=true

[vapid lark]

there is still no +5V on the collector side

[distant raven]

Do you have more than one of the relay to test against?

[vapid lark]

i only have 1 relay

[lavish herald]

When designing, EasyEDA says "There are some unfinished nets" What are nets?

[gaunt cedar]

nets are the connections. you'll have a GND net, 3.3v net etc. that error means you don't have something connected

[gaunt cedar]

Regarding USB D+/D-

The spec calls for 90ohm impedance on the differential trace. Does anyone have experience finding the limits to this? I'm working on a samd21 board and unless I place the usb really close to the samd pins, I'd have to run 1mm (!) traces to meet the specifications on a normal 1.6mm FR4 board.

If I've got .45mm traces on top of a ground plane, will usb be happy? traces are about 40mm long

[supple pollen]

It may not be happy, but it will likely still work.

You could play with co-planar waveguides, but I don't think it's necessary.

This person built an ATX form factor Arduino and stretched out the USB signals in the process, and it worked okay. https://www.sparkfun.com/news/2561

[tough matrix]

I had a board where the IC (SAMD21) was about 5cm away from USB connector connected by 10 mil traces on regular 2-layer 1.6mm pcb. It worked - had no problems.

[gaunt cedar]

@supple pollen thanks for the article. funny read too.

[gaunt cedar]

thank you! I'm accepting both of these as confirmation bias that I'll be fine and I don't need to change to a 4 layer board to meet spec. I'm just using data for loading code.

it's ok if you are aware of the requirements, decide that aesthetics are more important and to not be surprised if it goes sideways. right?

[supple pollen]

That's my usual approach, and I usually get away with it

[tough matrix]

When I designed my board, I was not aware of the requirement🤪

[gaunt cedar]

ignorance is bliss!

[supple pollen]

æsthetics matter

[tough matrix]

How about this? https://cdn.tindiemedia.com/images/resize/K7OI-B0ZwRiWgx-YaH5b97ku-rw=/p/full-fit-in/1378x1034/i/90179/products/2021-02-11T02%3A29%3A44.935Z-PSIHateYouBottom.jpg?1612984468

[gaunt cedar]

mixed message but I like it!

[tough matrix]

Not mine - but you can buy it on Tindie

[gaunt cedar]

someone was sneezing non stop when they routed the traces. glad it worked out

[vapid lark]

so im following this
https://cdn.discordapp.com/attachments/637812536158453780/847773007451258890/unknown.png

why does the ratline popup here -.- saying to connect the transistor to +5V -.-
https://cdn.discordapp.com/attachments/637812536158453780/847773141120057354/unknown.png

https://cdn.discordapp.com/attachments/637812536158453780/847773207490199582/unknown.png
what am i doing wrong here?

[heavy jasper]

It looks like there's a very thin blue line running from the middle pin of Q1 down

It may be just that that net is still there and 5V even if you don't want it to be.

I'd zoom in at Q1 and see if there's an extra trace that needs deleting.

[vapid lark]

@heavy jasperthere we go

i moved the transistor and behind it was the 5V "pad"?

i removed it and now it is fine

[heavy jasper]

Also, if you relay is on the bottom of the board, I think you have your NC/NO labels reversed on the header

Unfortunately the datasheet doesn't specify whether the pinout view is from the top or the bottom, so I actually couldn't tell you which of the slightly different schematic/layout drawings and labels are correct.

[tough matrix]

designing a robot...
powered by: 4*1.5V=6V
obviously, I need 3.3 LDO for the MCU
but I also need in ICM-20948 IMU, which requires 1.8V, so add also 1.8V LDO

but I also need VL53l0X laser ToF idstance sensor, which needs 2.8V , so add 2.8V LDO
and looks like I might need 5V LDO for neopixels

did I miss any other common voltages? bring it on, the more the merrier

I might get a bulk discount for LDOs

[unreal flax]

You might be able to consolidate a few of those, such as running your MCU at 1.8V. It also looks like the 2.8V of the ToF sensor can go up to 3.5V, so you could probably run that on 3.3V, or compromise on 3.0V or something.

[elder peak]

Sometimes the real dropout was the low dropout regulators you Muntzed along the way.

[distant raven]

Yeah, I had my head mixed up, 1mm is 39.37mil.

[rustic pewter]

Tutorial I wrote last week, using keepout shapes and copper pours in HV design.

https://www.pcbway.com/blog/PCB_Design_Tutorial/Increasing_PCB_clearance_in_HV_circuits__Low_Inductance_Capacitor_Bank.html

[distant raven]

https://tenor.com/view/satisfaction-uhh-kevin-owens-reassured-relaxed-gif-15742160

When that paste goes on perfectly

Solder pasting with a stencil really is an art

[gaunt cedar]

did you plot the gerbers first? File -> Plot

open GerbView, then go to file -> open plot files. then you just need to find the folder you plotted all the .grb files and select them all

[rustic linden]

ooh

[distant raven]

Andddd I recovered two boards that didn’t initially flashhhhh

Wooo

Looking at 100% success on the two panels I’ve done today 🙂

[rustic linden]

ayyy

[tough matrix]

RP 2040 chip now available for purchase for $1!
Time to decide if I am ready to switch from SAMD21 to it...

[crude ocean]

<jacknicholsen>and thats not bad!</>

[tough matrix]

Just when I managed to get 20 SAMD21G18 directly from Microchip and hide them in high security vault in my basement

[distant raven]

I ordered a reel of 500 😅

I ordered a few weeks ago

Should be here in July

[tough matrix]

For me the biggest problem with RP2040 is that they only have 4 ADC pins

[distant raven]

Just use an external ADC

You get better precision anyway 🙂

[crude ocean]

4 more than a classic pi has

at that price you can just add more 2040s :-)

[distant raven]

Volume pricing on the RP2040 is ridiculous

I don’t know how they are making them so cheap

[crude ocean]

necromancy probably

[light ermine]

Maybe everyone else makes their chips that cheaply too, but add higher margins.

[distant raven]

You’re probably right

RPi doesn’t have much need to make a profit since they are mostly an educational foundation

[crude ocean]

others certainly are doing higher margins, the pi foundation has goals beyond profit

[distant raven]

Or make a huge profit I should say

[crude ocean]

they also made a new thing, so for the next little bit they just lead the tech

the industry was happy where it was :-)

not that I ever wanted to pay $25 for a mere arduino

[tough matrix]

Have they published the volume pricing on RP2040?

[distant raven]

The crazy thing here: the flash chip on the Qt Py rp2040 cost more than the RP2040 chip itself

[distant raven]

No, I just happened to order a reel a few weeks ago directly from RPi

[tough matrix]

Secret early developer program?

[crude ocean]

it will be hard to make me stray from the pi foundation 2040 board

[distant raven]

Let’s just say I spent $580+ on 200 samd21… I spent $280 on 500 rp2040..

[crude ocean]

even with terrible availablility

[light ermine]

That flash chip costs more for you but not for them, probably.

[distant raven]

Should have them by July with current lead times

The 3000 pc reel is even cheaper per unit

I just couldn’t justify buying 3000 pieces

Lol

[crude ocean]

wait, 56 cents/unit?

[distant raven]

Flash chips at volume are still $0.60+ a piece for 16Mbit

Especially if you want qspi

[distant raven]

$0.50 a unit and $30 for shipping

[crude ocean]

I ponder how many chips can be on a sanely designed board :-)

[distant raven]

With a good usb hub controller.. probably 4 🙂

[tough matrix]

But why?

[distant raven]

Well, for practical reasons a hub controller and 4 microcontrollers in one board would be practical from a multi system monitor stand point

Big applications in the industrial world

Obviously it doesn’t make sense for the average user

[rustic linden]

wait the chip is available for purchase now?

only place I can see it is sadly limited to 3

also id probably have difficulty adding one myself to a circuit, like, soldering

[unreal flax]

I think that's used as part of the USB power-negotiation process, to set how much current the port supplies.

[slim sandal]

How can I make my own developer pc with eagle

[unreal flax]

Eagle is a tool for making circuit boards, drawing out every wire between every chip. It would be a BIG job to design a full desktop computer at that level of detail.

[tough matrix]

Eben Upton (from Raspberry Pi foundation) wrote on twitter that they are currently talking to JLCPCB to add RP2040 to the list of components available for assembly - so you woudl be able to order a board with RP2040 on it assembled from JLCPCB

[slim sandal]

I’m thinking a little bigger than a jetson nano

[rustic linden]

That's news I'm glad to hear! I use them for my boards, so that's good to hear

[primal schooner]

It's time to make the FTDI jump........for JTAG!

[slim sandal]

What arm processors can i run Ubuntu on

[haughty wolf]

if you need to ask how to design a computer, then you are nowhere near able to make one. this happens all the time. people jump in with a incredibly ambitious and then give up and never touch electronics again. not trying to discourage you, just trying to realise your expectations

[slim sandal]

Oh ya I completely understand that and I know what to do I just mean to get the ram slots in to eagle and such

[haughty wolf]

well you're asking very broad questions for someone who knows what theyre doing

[slim sandal]

Ya I know

[long wraith]

How does one order them from RPi Foundation?

[ivory jasper]

What do you guys think of my analog hall effect rotary encoder PCB? It's 19x19mm so it can fit in the space of a normal keyboard key (which FYI, is 19.05mm spacing). I'm going to add a pushbutton to it I think.

Back side has the pin reference

The plan for the push button is to just send a sensor pin (or maybe both) to GND. That will make it super easy to detect button presses in firmware.

(and no need for extra pins)

Was thinking about adding 4 pushbuttons (somehow--space is pretty tight) so the encoder knob could be used like a 4-way had switch or d-pad

They are, I used kicad's "Move exactly" feature to move them a precise amount away from each other. I did the same with the edge cuts lines. I went back and triple-checked everything and have absolutely no explanation as to why one of the corners doesn't have a complete GND plane connecting around it 🤷‍♂️

I'm tempted to move that one corner's hole by 0.001mm down/right to see if that fixes it

Hall effect rotary encoders exist but they're all proprietary, ultra expensive thingies ($200+)

Well the hall effect ones have a configurable resolution whereas the optical ones have a fixed resolution

Just like with analog hall effect switches you can configure the point at which some amount of rotation is considered a, "movement"

With a normal rotary encoder you've got two square waves that are offset slightly from each other. With an analog rotary encoder you've got two sine waves that are slightly offset from each other. With the square waves you don't have a choice: You get the next "bump" in the wave when the encoder switches the signal internally. With the sine waves you can just pick a certain amount of up/down movement in the wave and say, "I want to divide the wave into this many parts"

The only limitation is the resolution/stability of your analog signals

Unshielded analog hall effect sensors coming down a wire can have a lot of voltage wobble (think: ±80mA; I know because that's how much I get on my breadboard here haha)

If you use a nice voltage regulator and some caps you can cut that to about 1/3rd the wobble (±26mA)

However, if you go the extra mile and shield everything and use an ultra high quality (super low tolerance) LDO you can get voltage wobble down to like ±1mA and then you can reliably detect like sub-millimeter movements

It's more like: Each wire acts as an antenna and nearby digital signals (don't we all have those? hehe) can cause minor spikes in the analog signal. You can filter them out with careful choices in caps and resistors and whatnot but I find it's easier to just implement such filters in software 😄

Like, voltage wobble doesn't matter at all if the wobble is stable! If the wobble is ±50mA but it's consistently ±50mA then I know the user rotated the encoder by a little bit if a mA reading of like 2500 changes to 2501 because I'll see that the average across multiple readings went up by a little bit. The problem is that even after averaging you still get ±80mA without doing things right hehe

Well it depends on how many magnets yo used and their strength and tolerances and how well you designed your PCB, laid out your traces, put filters in place, etc. My Riskeyboard 70 uses 12 magnets in its rotary encoder but that's really unnecessary. It'd be just as good with 6 👍

Even with the mistakes I made in the PCB design (oh I made a lot of them! haha) I can still get like 50-60 "steps" per 360° rotation

I haven't done much to filter things in the code though (yet) so with some optimization I bet I could get more like 100-120

Commercial hall effect rotary encoders claim to be able to do 256 steps per 360° rotation

...but they have all-aluminum casings and expensive voltage regulators and run off 24-48V (with really great/expensive sensors too)

It lasts forever. Not theoretically forever. Literally forever. Your knob and maybe the bearings will wear out before the magnets/sensors do. Five hundred bazillion years of operation and rotations 🙂

The optical ones wear out due to UV exposure and the LEDs inside wearing out which they do regardless of whether or not someone has been turning them 🙂

I've had several optical encoders wear out/stop working in my time and it had nothing to do with electrical signals. They all either had the LEDs stop working or the little spinning disk thing broke

(spinning disk can also break due to UV exposure)

The hall effect kind can also be made waterproof and is completely immune to dust and grime 👍

...which is why the main place you see them is on things like forklifts and factory equipment

There's UV all around us all the time. Even reflected UV from nearby lights and sunlight can damage components slowly over time

Ever see an old computer that "yellowed"? That happened because of UV exposure. You can't avoid it. You can see some stuff yellowed that had been sitting in boxes for decades because some light snuck in through the cracks in the sides of the box and the plastic part was kept in a transparent bag.

The spinning disk broke in my case because it was super old (it was inside a car) and had become brittle. Just the force of me turning it really fast resulted in it detaching itself from the base. So I would spin the knob but the disk would only spin a little bit because it wasn't attached to the shaft anymore

There's another benefit to the hall effect rotary encoders: You can take the whole knob (with magnets inside) right TF off it for cleaning or swap it out for a different one 🙂

Hall effect rotary encoders can also be 100% SMD components

No through-hole soldering means cheaper PCBs 👍

Because the industries where they're used demand high quality/unbreakability (i.e. forklifts)

Lab equipment sometimes has hall effect rotary encoders too. Though that's probably more due to the fact that if you're going to pay $200,000 for a piece of lab equipment it'd better have super reliable knobs and not generate any light at all (even if invisible IR hehe)

I like them for ease of use and the adjustable resolution 👍

There's resistive ones like pots that don't stop when you turn them enough

Those wear out fast though (like all resistive pots, haha)

Yeah

I've had nothing but trouble with pots when it comes to reliability. The brushes wear down the metal coating on the inside of them over time. Especially in humid environments (I live in Florida)

Oooh, a capacitive rotary encoder sounds neat!

Pro tip: Capacitive touch pins work with analog multiplexers 👍

Well if you have the capacitive sensing over say, a 20° area of your overall encoder diameter you can just gradually add more metal wires/tracks as the encoder turns.

Stack em 👍

Well, the way the capacitive sense pins work on MCUs means that if you put a thin wire over it it'll probably pick up the rest of the wire too. So you'd need to have longer/shorter tracks pass over it

Can't just make it get wider as you go around

If you did it with a different sort of capacitive sensing that might work though

To a capsense pin your finger is representative of your entire body. You can measure this effect with a small dog's paw VS your own finger. The small dog may not even get detected! Medium size dogs work fine though. Ask me how I know this 😄

I tried it with a wet small dog too and that definitely upped the capacitance but not by enough 🤷‍♂️

I had this plan to make a capacitive touch... pad made out of aluminum sheet that would open the automated door opener when the dogs stepped on it with their bare paws.

It worked great for the medium-sized dog but the little one didn't have enough capacitance!

Well ideally you'd want it contactless

Contactless all the sensing!

Another thing I always wanted to try was a short-distance time-of-flight sensor: Print out a knob with ever-increasing heights of steps around the perimeter and bounce that little micro laser off of them to detect what position you're at in the rotation.

That's kinda how gesture sensors work too 🙂

[fervent lance]

Nix! -nis

[pearl tapir]

Note that digital micrometers use capacitive sensors.

[distant raven]

You need a company + lots of patience and knowing who to first get in contact with. Mileage varies

[rustic pewter]

https://www.raspberrypi.org/blog/raspberry-pi-rp2040-on-sale/

they'll let you order as little as one now

[gleaming thistle]

I'm adding a Flash chip to a SAMD21E, can any 4 pins work for this?

[distant raven]

They have to be capable of SPI communication

Which variant are you using?

[gleaming thistle]

So anything with SERCOM or SERCOM-ALT?

[gaunt cedar]

do they also need to be on the same sercom interface?

[gleaming thistle]

the non-L one

[gleaming thistle]

that was going to be my follow-up question 🙂

[haughty wolf]

Did you really have to capitalise sercom twice lol

[gleaming thistle]

Just trying to stick with the documentation 😅

[haughty wolf]

i dont know why it just annoys me a bit lol

[gaunt cedar]

@gleaming thistle which samd21 board?

[gleaming thistle]

I'm working with the SAMD21E chip, working on a custom board

[gaunt cedar]

https://learn.adafruit.com/using-atsamd21-sercom-to-add-more-spi-i2c-serial-ports

the multiplex section will be helpful. your board has 4 SERCOM vs 6 just be aware

[fast tundra]

Also keep an eye on which of the SERCOM pads you use, since only certain ones can be clock

[gleaming thistle]

that's a good point, i'd forgotten about that

[fast tundra]

if you tell me your exact part number I can tell you which pin combinations will work

[gleaming thistle]

right now I have everything on SERCOM0 (ALT) but i want to see if I can optimize my layout

[gleaming thistle]

Aren't all D21ExxA/B/D devices the same? (last batch: ATSAMD21E18A-AU)

[fast tundra]

Pin assignments are different

A & B have 32 pins, C has 35.

[gleaming thistle]

ah, gotcha

[fast tundra]

I didn't think you'd be using the C but it never hurts to check

[gleaming thistle]

had me worried for a second there 😅

[distant raven]

I use 17/18/19/22 for SPI and three other I can’t think of off the top of my head

[gleaming thistle]

i'm on 4/5/6/7 but i'd like those analog pins back 😄

[gleaming thistle]

22 for chip select?

[gleaming thistle]

it does appear based on the example that they need to be on the same SERCOM (Chip Select shouldn't matter)

[distant raven]

Yes

[fast tundra]

Yes, you have to use pads from the same SERCOM instance

Here's the valid configurations for SERCOM SPI for the E:

You can use any pad for DI (see CTRLA's DIPO in section 27.8.1 of the datasheet

& you can use any GPIO pin for SS, but if you do the hardware SS it'll handle pulling it low during a transaction.

If you don't the hardware SS you just need to set it low before sending / receiving and set it high when you're done.

I really need to get around to writing a nice interface for figuring out the SERCOM pins, especially for the SAMD51

[gleaming thistle]

@fast tundra thank you for this, I was going through it manually, I agree a script or interface would be great for this.

[elder peak]

I swear, Microchip ought to write you some checks for making their hardware more explained, @fast tundra. Or at least some nice pieces of schwag.

[gleaming thistle]

So I can mix and match between SERCOM and SERCOM-ALT as long as they're on the same channel (0/1/2/3)?

[fast tundra]

Yes, as long as it's the same sercom instance it doesn't matter.

[fast tundra]

I'd settle for them sending me the MCP4728s that I need 😭😭😭

[gleaming thistle]

On the QT Py M0 guide it states:

A0 / D0 - Digital/analog GPIO pin 0. Can act as a true analog output with 10 bit precision, but does not have PWM.

But in the pin descriptions it has a PWM attribute:
{ PORTA, 2, PIO_ANALOG, (PIN_ATTR_DIGITAL|PIN_ATTR_ANALOG|PIN_ATTR_PWM|PIN_ATTR_TIMER), ADC_Channel0, PWM2_CH0, TCC2_CH0, EXTERNAL_INT_2 }, // A0 / D0 / DAC

Is this for maintaining backward compatibility with other devices that have this limitation on A0 or is this an error?

[gleaming thistle]

I'm pretty sure the variant.cpp is at fault here, based on looking through the datasheet and other variants that use this chip.

[heavy jasper]

For a fixed spacing of signal-to-signal, generally yes.

For an article based on some simulations: http://iconnect007.uberflip.com/i/1014812-design007-aug2018/57?

I'm assuming here you're talking about board thickness when you say "closer to each other"

where you have signals on one side and plane on an adjacent layer.

[rustic linden]

When designing a breakout for a chip, it has some requirements like a pin tied to ground here, and a pin tied to VCC through a resistor there, and I'm wondering what I should add to the board? Should I just connect the chips directly up to pins or should I add some of the circuitry needed to get it up and running?

[supple pollen]

I like to add support circuitry as a convenience, unless it's expensive or specific to a mode I'm likely to not need. I'll also tend to leave a way to disable it, if it seems possible I would want more control, another version, or somesuch.

[haughty wolf]

pull up resistors for reset pins are a must for breakout boards. if youre going through the effort to buy boards you might as well add more than just a chip

[unreal flax]

If you didn't want to use two separate layers, you could put them both on the same layer, routing horizontally at different offsets.

I presume it's to support reversing the cable plug.

[supple pollen]

Could a coplanar structure work?

[primal schooner]

Rotate chip.

Rotate chip if 1) speeds below 10MHz. 2) Impedances that differ are calcualted and are within an acepatble Q value.

Or flip the chip on the other side

[supple pollen]

Could you do something like this?

[tough matrix]

quick question.
I finally decided to move to KiCad 5.99 (after several years of using Eagle).
Now, I tried uploading my gerbers to JLCPCB (following instructions from https://support.jlcpcb.com/article/149-how-to-generate-gerber-and-drill-files-in-kicad)

the board previews OK on JLCPCB quote page, but when I click on "Gerber viewer", this is what I get:

and "analysis" shows

any ideas what it could be? DRC finds no errors (other than some issues with silkscreen overlaps which I told it to ignore), and KiCad 3d viewer previews th board just fine

[distant raven]

Hmmm interesting

I wish I was more familiar with KiCAD

[tough matrix]

just in case, the gerber is here

[tough matrix]

pcbway online gerber viewer shows the board fine, too: https://www.pcbway.com/project/OnlineGerberViewer.html

so it is probably a bug in jlcpcb viewer... but yet, anyone knows if there is a way around this?

[tough matrix]

Sorry - what do you mean by that? If you upload the Gerber file I posted before to JLCPCB, it shows correctly in their Gerber viewer?

Is it JLCPCB?

Did you try clicking on "Gerber viewer" link underneath?

[heavy jasper]

@thick willow This is pretty much just the way for type-C, nearly everyone I know just routes the crossover and it works, or routes on an inner layer to loop around and that also works. The stub length ends up being not that huge of a deal for USB2. IF you really really care, there are various input protection/mux chips that accept both ports and the CC pins to detect orientation and mux the appropriate lines. More so you generally use those chips if you need their other features (PD support, or muxing of the high-speed signals as well for alternate modes)

[rustic linden]

What is the width of a DIP chip?

[heavy jasper]

0.1" pitch, with varying width depending on the chip; most commonly 0.3"

[rustic linden]

what's the minimum size I can make a hole/pad for a set of headers?

[silk lark]

your fab specifies what holes they can make

so it depends where you want to send it

[rustic linden]

yeah, but if i make tiny holes, the headers I have probably won't fit

[silk lark]

well, then it depends on what headers you have

I usually use 0.9mm holes and 0.4mm ring around them

for the standard goldpin headers

at 2.54mm spacing this leaves enough room between them for an additional trace

[tough matrix]

The usual 0.1" spacing male headers are square with side 25mil=0.64mm, so diagonal is 0.9mm

But of course there are many different kinds of less usual headers

[distant raven]

Yeah

[tough matrix]

@thick willow for me the problem was exactly with the gerber viewer. the quote page which you get after uploading gerbers looked OK, but gerber viewer had difficulties. Can't explain why.
But I had fixed the issue by making minor modifications to the design, so now it works OK.

[supple pollen]

The "(null)" errors imply a problem with file upload or naming.

[fierce apex]

so is kicad the program to use for board designing ? if given a choice

[silk lark]

YMMV

[unreal flax]

Yep, if you're starting from zero, that's a good one to pick. A lot of Adafruit designs are done in Eagle CAD as well, for instance.

[fierce apex]

well eagle has a board size limit?

[silk lark]

Eagle is subscription now, no?

[unreal flax]

Yes, and yes. Kicad I would say is the best free alternative to paid CAD apps. Personally I pay for Eagle, but that's just because I learned it a long time ago, so it's worth it to my productivity versus switching tools.

[fierce apex]

well i dont know any packages yet

i cant escape , SMD , parts

[vapid grove]

That feeling when tsot-48 atmega32u4 footprintalmost fits into arduino pro micro footprint so you need to pay almost twice the price for qfn version

[fierce apex]

i did make a tiny adaptor board so a FTD232 SMD can fit on a DIP chip style for a breadboard , but the 100 + pin chips are a nightmare

[silk lark]

get a hot air gun or a hot plate

they make qfn easier than tht

[fierce apex]

old toaster oven?

[silk lark]

that's good for reflowing them initially, but not for reworking

[fierce apex]

mmm ok , is that using that paste stuff ? its lower than normal temp solder

i have been avoiding SMD -- but looking at if fondly from a distance

[silk lark]

I'm using both hot air gun and hot plate with regular solder -- I tin the pads first with soldering iron, and then heat them and place the components

there are many ways of doing this

[distant raven]

I stencil paste on my boards

And I use a hot plate to reflow

[silk lark]

I'm too stingy for stencils

[distant raven]

And then adjust position and take care of bridges if they happen

[tough matrix]

Same here

[tough matrix]

Stencils from JLCPCB are $7, so it is much cheaper than it used to be

[silk lark]

considering the PCB is $2...

[tough matrix]

:)

[distant raven]

I paid $40 for 10x 20 board panels

Lol so $7 for a stencil was worth it

[silk lark]

and then you need a new one for each new revision

[distant raven]

Well, no planned revisions for a while on those panels

Only downside is I won’t be able to get the samd21 I use on it for a while

Looks like September if I order now

[rustic linden]

Personally use EasyEDA, it's the one I'm the most familiar with, I also use JLCPCB, there's only 2 services I can use (JLCPCB and PCBWay) and I find JLCPCB much easier and better to use (but ymmv)

[tough matrix]

didn't you order like a full reel of SAMD21?

which one is it that you are using on these boards?

[distant raven]

I ordered 200 back in April. I have 20 left

[tough matrix]

wow, you do make a lot of boards

Microchip expects new batch of ATSAMD21G18 to arrive in late August

(this is for TQFP)

[distant raven]

I’m looking at getting 50-100 more. But I need more LDO first

[rustic linden]

I'm very curious to get my hands on the RP2040, I luckily have no designs that need a chip that's been out of stock

[distant raven]

I think it is probably safe to say that most accessory boards will use 150-200mA

[tough matrix]

Good luck

(this is for AP2112K-1.8)

[distant raven]

I found some from Richtek

$0.37 a piece though but exact drop in without any changes to capacitors

1uF supply side, 0.47uF output side

[tough matrix]

replacement for AP2112?

[distant raven]

Nah, I use the TLV75533

It’s a low quiescent 3.3V 500mA LDO

Like <30uA without load

The Richtek one is 39uA quiescent

But it’s a common LDO in automotive applications as are most Texas Instruments LDO and power products

So if you could imagine there are none of these LDO available anywhere. I’ve got about 140 left

[tough matrix]

"low-IQ" chip :)))

that's what it says on product page in Mouser

Actually this one is in stock (ony 300mA): https://www.mouser.com/ProductDetail/Texas-Instruments/TLV73333PQDBVRQ1?qs=9r4v7xj2LnnYANXVL3PB4Q%3D%3D

[distant raven]

I may have to keep that one in mind for some of my breakout boards

[untold seal]

What is the cheapest PCB design maker for small quantities?

I mean to buy a design that I made from a PCB manufacturer...

[distant raven]

Depends what on the size and where you live

Generally JLCPCB is good for larger boards which are greater than a few square inches

Or PCBWay

I use OSH Park because I’m in the US and most of my boards are small. I can prototype for less than $5 and get free shipping with a similar turn as JLCPCB when considering shipping

[silk lark]

I use elecrow because different colors and thicknesses are the same price

and I'm sick of 0.6mm green

[supple pollen]

I normally use PCBGogo, OSH Park, or JLCPCB. Another friend of mine is fond of Seeedstudio (10 boards for $4.90 + shipping). Pictured is a board I designed for a local hackerspace that I had made by PCBGoGo.

[silk lark]

oh, and for special needs, when I need multiple projects on one board, I use DirtyPCBs

[elder peak]

Oh, yeah, I have a giant blob of PCB bits almost ready to DirtyPCBs.

[tough matrix]

Have any of you used stickvise: https://www.adafruit.com/product/3197 ?
is it worth the money?

[elder peak]

I LOVE MY STICKVISE.

It's the only grippy-ish thingie on my electronics bench that I don't actively loathe.

[untold seal]

All of these companies put the components in the PCB? All ready?

[distant raven]

No, only a handful will do PCBA service

I assemble all my boards myself

[untold seal]

These have PCBA service?

[distant raven]

JLCPCB does

[unreal flax]

JLCPCB does, pretty cheap, but they do it by having a fixed catalog of available parts they will assemble, so you kind of have to design your board for that.

[distant raven]

PCBWay

[untold seal]

I think I desined yeara ago on EasyEDA

And they had a direct connection to PCBWay so you could buy it directly.

But I really don't remember if it was PCBWay...

I think I heard years ago that Adafruit produces their own products.

I tought it was really cool.

[distant raven]

EasyEDA connects directly to JLCPCB

[untold seal]

Cool.

Study break is over.

Time to go.

Bye.

[ivory jasper]

So if I put an electromagnetic coil underneath this what is the likelihood that it'll fry the ws28128b-b LED or the (SOT-23) hall effect sensor (or the tiny caps) when I use it to provide haptic feedback on a keypress? 😄

My guess: It'll disrupt the signal going to the LED so it'll flicker for a moment while the coil is active. The signal coming off the hall effect sensor will basically go nuts as well. The real question is: Will this permanently damage them? I honestly don't know!

Another question: Would it increase the voltage on the signal trace coming off the hall effect sensor that I'd need to have some protection at the IC reading that signal? Assume it's 5V

[pearl tapir]

It's not clear what the purpose of the coil is. Does the key have a magnet that you are trying to vibrate?
LEDs are current operated and, assuming a reasonable limiting resistor, it is doubtful that you could see the tiny induced voltage. Also note that your eyes are logarithmic in their perceived intensity.
It's not clear how a strong magnetic field would cause the Hall effect sensor output to exceed it's supply voltage but you can always add a clamp diode and not populate it if it isn't required.

[twilit aurora]

well first of all: How big is the size of the coil (in Henry)?

[worldly schooner]

So I have access to a surplus of 800x480 capacitive touch screens, and I'm trying to design a custom dev board for tinkering with it. My idea is to stick some headers on a carrier board for a Pi Pico and CircuitPython it, but I'm wondering if I can source a driver chip like an RA8875 to free up some GPIO for other tinkering. I looked around, but all the chips for this seem to be reserved for large escrow orders directly from HK/TW, as they seem to be nonexistant outside of dedicated prototype boards like Adafruit or Sparkfun. Does anyone have any ideas?

[silk lark]

there is a global chip shortage right now, it might get better later

[scarlet chasm]

Anybody know of an Eagle .lbr that has a QT Py footprint? I see the XAIO footprint from Seeed, but it doesn't have the header holes (and there's no cutout for the back for the extra memory or the RP2040 components). Hoping to avoid duplicating some work! 🙂

[distant raven]

I have a footprint that I could probably modify for cutout

[scarlet chasm]

Even just the one w/headers would do for now (my current project won't use the castellated pads & will have headers so the cutout's not critical

In the long-run I'd like one that had "all of the above"

[distant raven]

I think mine is castellated pass with headers

[scarlet chasm]

That would be great

Is it shared anywhere?

[distant raven]

I’m not 100% sure. I may have at one point but it was a while ago

I try to share things but sometimes forget

[scarlet chasm]

Well, point me at a link if you find one - thanks!

[ivory jasper]

Yeah, I'm trying to add a bit of force feedback indicating when the switch actuates (because it's an analog key switch the end user can choose the point of actuation).

[supple pollen]

I doubt the magnetic field would induce enough voltage/current to interfere with the operation of the LED

[silk lark]

so the experiment is inconclusive

it's too tight right now, but I think I can make it work with longer thingies