I’ve had to just stop accepting LinkedIn requests for PCB/PCBA sales persons from China
#help-with-hw-design
pearl tapir
Probably a bigger cost driver in the States is disposing of the hazardous materials used in PCB fab We can't just flush them.
distant raven
True
Environmental rules are costly measures
But necessary to protect our environment
misty escarp
Lead lined fish are resistant to radiation though
Fo real though, where I grew up, the main lake used to be so polluted that you would get rashes from swimming in it
now that it's clean, it's a huge part of the local economy
distant raven
Good for the economy
inland quest
so due to manufacturing costs, i'm going to try to cram the entire 4-bit CPU on a 2 layer board
here's a better image of the decoder and control unit
the 10 ICs on the bottom are the control unit
misty escarp
do they make these in SMD? or are you going for easy to solder for your kit?
inland quest
i'm doing THT because it's all i have in storage right now lol
misty escarp
lol
inland quest
Plus i don't have an SMD air gun at home
misty escarp
makes sense
inland quest
the goal with this system is to hit at least 5 megahertz without crashing
misty escarp
cool!
inland quest
that's why i have so many decoupling caps
misty escarp
No power planes?
inland quest
i don't know how to do that, and it's probably going to drive overall price up 😦
misty escarp
I don't think fab shops charge that way? I've been wrong a bunch tho
distant raven
Power planes are good and don’t increase costs
misty escarp
Oh I might have been englishing poorly, maybe they meant that not knowing how will drive costs up?
inland quest
yeah... i should do a 5v and ground plane
i don't know how to do it in eagle. i'll look into it
distant raven
Polygon pours
misty escarp
It's super straight forward
inland quest
aye thanks! the pcb now has a ground plane
elder peak
Pour one out for better grounding
misty escarp
just waiting on parts now 🙂
cerulean crest
Huh, really? Up to how much?
cerulean crest
Is that really DDR memory though?
Oh it is
I guess I never understood the term DDR
So... what does the standard x86 computer actually use? Not the DIM form factor, but rather the interface?
distant raven
I’m going to use a 64MB psram on my ESP32-s2 board
DDR is just double data rate, just allows you to access more memory at have the clock speed
cerulean crest
Fun, it is also a standard
amazing work by all engineers who contributed to this naming, I thought USB was getting bad
distant raven
Haha yeah, just keep adding the number to it or a new letter
GDDR memory is even more original
cerulean crest
But it actually means nothing, its a standard of the flash memory itself it seems, not interface, form factor, etc. It just happens to use DDR for transfer
distant raven
Yeah
That’s why PSRAM is so interesting to me
Mostly because they explicitly state that it is “pseudo” SRAM
But PSRAM will likely cause me to make my first BGA board
cerulean crest
Nice, Im likin' BGA, easier than QFN
distant raven
I found this part with the Digi-Key mobile app. https://www.digikey.com/product-detail/en/S27KS0641DPBHB020/S27KS0641DPBHB020-ND/6596281
misty escarp
They are so cute
distant raven
This is what I’m thinking
It may not work though as I’m not seeing what the minimal clock rate for it
Only Max clock so maybe 40MHz should be okay since it’s below the max rate
heavy jasper
@cerulean crest standard X86 memory is also dual-data-rate (clocked on both edges).
distant raven
@heavy jasper if minimum clock rate isn’t specified, should the memory work at 40MHz rate specified by the ESP32-s2?
heavy jasper
This doesn't seem to be a SPI device
so if that's what you're expecting, it won't work.
(not sure if esp32 has a true external memory controller, ala. STM32F4)
heavy jasper
DDR just means you get a data bit on rising and falling edge of a clock
It doesn't necessarily say anything else
distant raven
cerulean crest
That was my whole thing about the DDR naming 🤪
Doesnt mean much other than dual-data-rate which is... not important compared to type of memory, interface, etc, so its weird in PCs we use the term DDR as a standard
heavy jasper
e.g. this is the part they specifically make and guarantee works along with it: https://www.espressif.com/sites/default/files/documentation/esp-psram64_esp-psram64h_datasheet_en.pdf
which specifically says SPI and QSPI mode
vs. the one you linked is specifically parallel
which means that it needs things like read/write strobes
which may be this "SPI 8-line mode" but I need to do some more digging
Re: PC naming, it is indeed unfortunate that we use DDR as a shorthand, but to be more direct, each of e.g. DDR2, DDR3, DDR4, LPDDR3, LPDDR4, etc. are named standards.
(from JEDEC)
distant raven
Yeah
Hardest part is sourcing that part they specifically guarantee support for
As far as I can tell, Adafruit is the most reputable supplier of that part
And it’s out of stock basically everywhere
Except AliExpress which would be okay if I wasn’t making this to sell
heavy jasper
It is possible that this one can be made to work: https://www.digikey.com/en/products/detail/cypress-semiconductor-corp/S27KS0643GABHV020/11611408
But it's larger than can actually be addressed by the ESP32
(so you'll either be throwing away bits, or it just expects extra bits that the ESP32 can't give it)
and may have e.g. different command opcodes than the one that's normally supported, and I'm not sure how espressif handles that.
And also is expensive
distant raven
Yeah
Whoops guess the president is a banned word or phrase
Lol
The trade disputes and COVID have complicated board development
cerulean crest
Whoops guess the president is a banned word or phrase
That is hilarious
misty escarp
I've seen people get caught in that
cerulean crest
I think I can take a guess why
distant raven
😂
tough matrix
indeed, looks like one needs to write president T***p
misty escarp
how do you say X T___ps Y?
silk lark
I think generally speaking politics is out of bounds in the Adafruit channels
misty escarp
which is a great rule
tough matrix
makes sense
tough matrix
Just got this from fab house. Boards are done, components are sourced, they are ready to begin assembly - so hoepfully within two weeks I will have my boards.
misty escarp
woot!
tough matrix
then it will be just flashing firmware onto 55 boards and testing each of them
tough matrix
my co-creator actaully made a pogo pins testing jig, will see how well it works
distant raven
Nice nice
elder peak
I can see you spent some time railing against the troubles of panelization.
misty escarp
Just got this from fab house. Boards are done, components are sourced, they are ...
Anyone else see TIE fighters?
elder peak
I just see opportunities for snappy puns.
distant raven
Lol
elder peak
Yah, lost opportunity to put a tie-fighter silkscreen on the back, lol.
misty escarp
George Lucas' lawyers have entered the chat
distant raven
Maybe his hands were... tied..
elder peak
So I think I'm at the point where 0.65 pitch is now as effortless as 1.27 pitch.
misty escarp
*Disney's lawyers now
tough matrix
I should try and use this board in a tie fighter...
misty escarp
Do they make TIE RCs?
tough matrix
if you have the force, you do not need radio cotnrol
distant raven
Speaking of the force
misty escarp
If you have the force space is also not a vacuum, per canon
distant raven
Did any of you watch the latest Mandalorian episode
distant raven
I about cried when the thing was destroyed
misty escarp
I made a bad word
tough matrix
haven't seen any episodes...
distant raven
Hehe
misty escarp
It's OK though, our landfills Sarlaac pits greedily accept all the baby yoda merch
Does anyone have a favorite tweezer for placing parts? I have some fine tipped ones that work OK but wondering what folks use
cerulean crest
Yes, let me find them
tough matrix
Nothing special for me - some set bought on amazon
cerulean crest
Oh the ones I like are technically not ESD safe... whoops
misty escarp
I found ones that claim to be esd safe but they are also cheap from china so idk if that's real
Oh iFixit sells a set, they are pretty reputable
misty escarp
I trust them well enough
elder peak
The big thing is that if you are doing SMT parts, you need something that's ridiculously and dangerously pointy.
misty escarp
Yeah the iFixit one was advertised as such
I'm looking for the kind of thing you use to take out those hair thin cactus spines
First time in the American SW I thought to myself "Hey that cactus has no spines" and patted it to see
It did have spines
distant raven
Hehe...
misty escarp
Cool!
misty escarp
You don't have to worry about it, "airwires" are part of the new wireless technology that fab houses have, they handle it all for you
inland quest
heh
the only issue i see right now is the size. it's a huge PCB, and i'm not sure where i can get such a thing made
misty escarp
how huge?
inland quest
honestly i'm not sure. i can't seem to get the mark tool to work right
misty escarp
mm go to Manufacturing on the RHS
then click board
it will give you your dimensions
the dimension tool doesn't work super hot
misty escarp
sorry my fingers are cold so I went with abbreviation of Right Hand Side. I've yet to learn that unnecessary abbreviations lead to more typing
inland quest
ok right now it's 12x17 in
misty escarp
that's a big boi
inland quest
i know that's going to get smaller when i work on routing stuff
BUT the school is funding the manufacturing so i don't really need to worry all that much
misty escarp
JLCPCB can do that
inland quest
YES
misty escarp
their max is 400x500mm
inland quest
thank god
misty escarp
but it'll cost you especially for lead free
inland quest
eh i might pass on that
misty escarp
I guess you can expect college kids not to lick the boards 😉
inland quest
i'm not in college
misty escarp
it's for college folks right tho?
misty escarp
I saw school and made what seems to be a bad assumption
inland quest
nah don't worry, i get that a lot
inland quest
yeah i go to a tech school and major in industrial robotics and electrical engineering. It's a lot of work
but it's going to look great when I go to college
inland quest
Yeah. i really hate talking about myself like this cause it feels like bragging
misty escarp
tons of people enter engineering school with no background in engineering
It's OK to be lucky and be glad about it
*and to be a hard worker
inland quest
i'm really happy with this. the reason i know a lof of this stuff and not evev be in college is because of my relatives and my girlfriends dad.
Uncle one: used to work at Sun microsystems, now works at oracle
Uncle two: worked at Microsoft in the 80's up to the early 2000's
Girlfriends dad: Worked with the people who designed the intel 8080
misty escarp
you should apply for tons of internships your first summer too. or even co-ops. Lots of people don't when you def can get them that early
even if you're putting toner in a printer and getting coffee it's something
inland quest
yeah i applied for a few. one of them is at a silicon wafer laser diode fab!
misty escarp
that's awesome!
inland quest
yeah it's super cool
i also got my dad's C64 when i was around 10-ish, and got into programming because of that
that might of helped too
misty escarp
could be 😉
You could probably get hired as a tutor for your classmates pretty easily too, once you've taken the classes. It's good money for college and you can set your schedule.
inland quest
totally
last year i got to teach the digital logic class when the teacher was out from knee surgery. most fun i've ever had in school
misty escarp
Cool!
inland quest
yeah! it was great
it was pretty simple stuff (gates, flip-flops, counters) but it was so fun teaching people
inland quest
the thing was i didn't have to do any grading lol
i'm not a certified teacher. i'm just a student who was taking a digital class for a year. i know the teacher out of school, and he asked me to teach the class. the class also had a sub because i was a student, not an adult
so the sub did all the grading and i did the teaching
tough matrix
nice:)
inland quest
yeah it was great
tough matrix
did they pay you?
inland quest
nope, i was enjoying it too much to ask for pay
plus i'm not sure how legal that would be
tough matrix
yeah, might be a problem... for a school to hire someone to teach, there are a lot of hoops to jump through
inland quest
yeah, it was still really fun
once the world stops ending, i'm going to see if i can host a workshop at a makerspace i go to
it's going to be on digital logic
tough matrix
i am actually working on a demonsteation kit for that
inland quest
oh cool! have any pictures? also i think we should move to #general-chat
clever nacelle
Anyone know how to export a PCB from Fusion360 to F3D?
Every time I attempt this Fusion crashes
distant raven
@plush phoenix question for you about the ESP32-S2
so I'm seeing that CHIP_PU is used for reset.. should I have a button on it? Or should I just be concerned about having GPIO00 and GPIO46 connected to the buttons?
okay so CHIP_PU needs a pullup resistor and a capacitor to ground.
Can I leave GPIO45 unconnected?
timid portal
Hey can please someone tell me what is that symbol ??
distant raven
usually an input or supply symbol
distant raven
yeah
a lot of people like the up arrow because it points to "higher voltage potential"
distant raven
you should be able to
timid portal
ok thank you!
plush phoenix
Can I leave GPIO45 unconnected?
yes...
plush phoenix
okay so CHIP_PU needs a pullup resistor and a capacitor to ground.
do check TinyUF2... for resistor and capacitor values if you want to enter UF2 bootloader on double press of reset button.
its 100K and 1uF
distant raven
so instead of 10K that adafruit lists on theirs?
plush phoenix
have you checked soala schematic? I think 100K value in documentation is from there
distant raven
also, the series resistor and capacitor for the DM/DP lines?
I see Limor didn't use them on her design
so maybe just a "would be better if you did" but not necessary
distant raven
interestint
they use the DP/DM lines for debugging and use a USB-Serial converter as well
elder peak
Would you say that people who use the arrow instead of a circle in their schematics are the designers who really show potential?
distant raven
@plush phoenix one other question
is it necessary to break out the JTAG debugging headers for programming?
distant raven
bottom view
top side
Hmm, I could actually move the USB off a little bit
much better
misty escarp
Easier to assemble I bet
distant raven
probably lol
This was one heck of an undertaking
I started around 10am EST
it's 4:42PM
lol
almost completely straight
misty escarp
That's p fast in my experience
distant raven
I'm a verty determined person lol
I start finals this week and I needed a little motivation for the week haha
distant raven
thanks lol
distant raven
This probably won’t be the smallest ESP32-S2 dev board
But it will likely be in the running
tough matrix
how much flash?
distant raven
But that’s mainly due to it being so hard to source
Should support up to 64MiB
Which I think is the largest SPI flash you can buy in 8-soic
I’ll probably sell it with a 32MiB SPI flash
tough matrix
nice
misty escarp
That's mibibytes right?
distant raven
Yeah
misty escarp
I have to look that up every time
distant raven
Which is basically a MegaByte
distant raven
I don’t remember the exact correlation
But it’s pretty close
One is closer to 2^20
distant raven
I probably need the overall design verified by someone with more expertise than me with RF design
marble gazelle
chip not module, so RAM is 320KB (48K available to CircuitPython)?
distant raven
Yeah, just the chip
marble gazelle
Kind of like a QT Py with wi-fi
distant raven
Basically 😃
distant raven
Actually, TMS/D42 for neopixel
marble gazelle
oh I see, you have both DACs on pins 😄
distant raven
Yeah 😄
marble gazelle
and three GPIOs from ADC1, that's about the best config possible
distant raven
I took a page from ladyada
Nice thing with the ESP32-s2 is any of the GPIO can be configured for i2c/SPI
But I think for circuitpython you define which are which
marble gazelle
yeah, doesn't matter
as long as they are otherwise unconstrained pins
there are a lot of "special" pins
distant raven
Overall, about 6 hours total designing and routing
Had a buddy of mine who is doing his masters in microwave RF design help with the matching network selection
So the thing should be pretty well tuned for 2.4GHz
marble gazelle
with two more pins, you could reroute and make it compatible with your QT Py power board 😉
distant raven
If I chose smaller buttons, I might be able to get things even smaller
True lol
I’m sitting here wondering if I could get away with reducing the number of filtering caps
Right now it’s following the design manual cap for cap
distant raven
Shoot, I forgot a series resistor for the crystal
distant raven
32.7**kHz
distant raven
I’d rather the 32kHz crystal rather than trying to use a 40MHz oscillator 😅
misty escarp
*an SMD one I could easily solder
misty escarp
I’d rather the 32kHz crystal rather than trying to use a 40MHz oscillator 😅
that makes sense
distant raven
Yeah
misty escarp
How did you decide on 32.7**? Is it from the datasheet?
For my chip it specified a 32.678 kHz if you want to avoid using an oscillator
distant raven
ah wait
looks like it say it only supports a 40MHz crystal for the internal clock
37.768kHz for the RTC sleep clock
misty escarp
Oh gosh it's 768
misty escarp
I could only find parts that I can't solder and thru hole can ones. So I went with the thru hole can
distant raven
I have a hot air gun so all SMD here lol
misty escarp
nice, that's next on my list of tools
distant raven
Definitely worth the investment
distant raven
round 2
top
everything on the top is mostly the same
though.. I need to move that resistor in the button footprint
misty escarp
what size traces?
distant raven
6mil with 5mil clearance
misty escarp
Dang that's smol
distant raven
yeah
I also changed the antenna trace going from the matching network to the esp
chose to use a fatter trace before making it small to reach the pin
board file view
I think I have enough space for a stemma connector
on the bottom that is
misty escarp
Is the power plane cutout an RF decision?
distant raven
yeah
antenna like the one I'm using (a chip antenna) require a keepout area
it's sized as best I can get for the manufacture recommendation
Alrighty, I squeeze a Stemma connector
how about it @misty escarp ?
lol
misty escarp
My enthusiasm can't be STEMMA'd
distant raven
makes me want to put stemma on everything
misty escarp
they are pretty great
distant raven
the Rev B of the Mega Sapling board I have in the works has Stemma lol
misty escarp
I'm a big fan of the stemmafication of all the I2C board from adafruit
misty escarp
You said any port can be I2C right?
distant raven
yeah
misty escarp
Are you saying that there are headers with i2c and the stemma and they are separate pins?
*sets of pins
distant raven
not exactly
it's more or less to be a guide
more advanced users would have no issues swapping pin definitions for their project
misty escarp
Hm I'm not groking
distant raven
my board will use these pins
these ones
and these
all but two of those are broken out to headers.
the two that are not broken to headers go to the Stemma/Qwiic connector
that would be GPIO 10/GPIO11
so realistically, 5 channels of the ADC. 3 channels of the capacitive touch, both DAC pins
pretty nice all things considered 🙂
distant raven
I'm kind of impressed by the ESP32-s2
what do ya think @marble gazelle ?
I added a Stemma connector for more connections
marble gazelle
I've never designed a board, so...
but no ADC1 pins? they are unencumbered by any wi-fi entanglements
GPIO 1-10 are prime real estate
marble gazelle
and not only that, you also get the free bamboo steamer
elder peak
I have totally started putting STEMMA QT connectors on all the things.
distant raven
lol
distant raven
GPIO 1-10 are prime real estate
honestly, it was about ease of routing
reef flicker
I have assembled my breakout board for my sensor with the pads underneath. To check that everything is OK I visually inspected and it looks like none of the connections are shorted, but my multimeter reports a short between GND and a lot of other pins, same with Vin. Any clue if that could be due to how the sensor works or if it's guaranteed to be a short?
distant raven
reef flicker
Or maybe I killed it during the process
distant raven
not sure @reef flicker can you share a good picture or two?
maybe a view of the board in your cad program?
reef flicker
Sure, give me 2 seconds
My first attempt looked like this, definitely shorting all three of these pins
This attempt now i see a clear space between all of them
reef flicker
Now it looks okay tho
After quite a few tries lol
Mind that this is extremely tiny so taking a decent pic is very hard, but the actual pads don't look shorted
As for the cad, I have this
distant raven
yeah, hard to say. It's too bad you don't have a microscope camera to inspect with
reef flicker
GND seems to be continuous with pins nowhere physically close
So I'm thinking maybe that's just a normal thing?
distant raven
might be
have you attempted to interface the board with a microcontroller or apply power at all?
reef flicker
Not yet, I'm scared something will blow up due to these "shorts"
I do have the adafruit breakout I could compare results with, but that one has pullup resistors, capacitors, a diode
So I'm unsure if that will impact the comparison
distant raven
well, if you haven't smoked a device, are ya really learning? 😄
i understand not wanting it to "blow up" but honestly, the worse it'll do is heat up and maybe smoke a little
reef flicker
I'm observing similar shorts on the adafruit board, so that's promising
reef flicker
this looks like it could've been a big error 🙃
misty escarp
Hm
reef flicker
I could give a shot at throwing a tiny bit of solder to meld them together
Btw, my testing so far shows that it's functional!
misty escarp
that's great!
reef flicker
I am getting some odd behaviors, but tracing that is going to be hard
Blowing continuously on the sensor has these weird "cuts"
Using my finger directly on the pressure sensor and pressing/releasing renders these expected gradual curves
The only difference is that I use my finger. Could it be that my finger acts as some sort of ground?
plush phoenix
is it necessary to break out the JTAG debugging headers for programming?
nope...
vapid grove
Ok guys, so life-size print, a lego tile for size comparison
Also seems like my PCBs arrived, so now I need to get to the post office 😉
Also @distant raven jtag headers are used for debugging
vapid grove
Yay! Look what I received today
What a beauty!
Although, back side didn’t turn out as well
distant raven
Very nice
vapid grove
That exact moment when you realize that your first ever and soldering includes 0404 resistor array
reef flicker
Why are the pads silver? Did they come pre-coated in solder from the fab?
distant raven
tin coating was probably cheaper that ENIG
supple pollen
Or simple HASL
tough matrix
for JLCPCB, ENIG coating is much more expensive than the default HASL
@vapid grove did they charge you extra for panelized board?
vapid grove
No
tough matrix
I had mixed experience there - twice I used JLCPCB for panelized boards (panelized myself, copies of same design, separated by V-Cut)
vapid grove
Mine are stamp holes
tough matrix
once it went through without a problem, the other time, they added $4.50 extra charge for panelized
elder peak
Given how many designs I have squeezed into my snap-apart boards, I've never risked sending one to JLCPCB because if they added an extra charge, it would be huge.
tough matrix
so where did you send it?
elder peak
DirtyPCBs.
Basically, I keep a file open that's got a 10cm x 10cm square in it and I just throw random bits on it until it gets full and then send it away.
There's a significant price bump if you go over 10cm x 10cm
reef flicker
Turns out yesterday's misreadings were caused by a glitch between the board and the chair I was sitting in 😂
Forgot to tie the address pin, so the address was floating and meant the sensor got disconnected randomly
pearl tapir
Connect the chair to 240VAC. Problem cured.
misty escarp
I would have thought that canada banned the electric chair
pearl tapir
Not for home use.
misty escarp
Personal consumption is decriminalized?
pearl tapir
Just in the prison system
misty escarp
Oh haha I meant closer to the bottom edge
But that's Also a good spot
Depends on your enclosure design.
pearl tapir
@inland quest Are those ICs through hole?
inland quest
yes
pearl tapir
You may not agree with this, so make your own decisions.
I'm kind of a nut about eliminating anything that in any way might reduce reliability. That means eliminating vias wherever possible. A via is just less reliable than a straight trace that has no vias. There are several places on you board where a trace leaves a pin, flips to the opposite side, runs for a distance, flips back to the first side and then connects to a pin. All that could be done on one side with no vias.
I also prefer to have the traces on the bottom side for through hole boards because it is easier to inspect.
The way I do this in my CAD system is force the board to be single sided, bottom only and turn the autorouter loose to get as much done on the bottom. Then turn off rip up and re-route. Then allow double sided and turn on the autorouter again. I then hand route what is left with rip up and re-route turned on along with the interactive router which will plow. Very old school but very effective. Probably not worth while unless you intend to produce high volume.
inland quest
yeah there's a lot of things that could be improved
i'm only planning on producing 10 at most
plus i'm on a tight-ish deadline, so i wanted to get it done quick
distant raven
It’s such a sweet feeling seeing your commits to Adafruit repos get merged in
Especially for boards you designed
misty escarp
Waiting for mine! Can't wait
distant raven
😄
ivory jasper
EXPERTS! I need an expert opinion: Should the QWIIC connector on my hall effect keyboard have its own LDO?
ivory jasper
Well, an LDO is only $0.16 and on a keyboard I have plenty of room so I'm thinking, "why not?"
ivory jasper
In fact, I'm taking ideas for anything else you think a hardware hacker-friendly keeb should have. I have loads of room and little components and connectors cost basically nothing. This isn't a for-profit enterprise so let's make something awesome!
distant raven
temperature sensor?
maybe some RGB LEDs (if you're not already using them)
set it so people can enable temperature variant keyboard color
silk lark
@ivory jasper one thing I did with my last keyboard is a connector for extra modules, so that I can add things to it, such as an encoder or a joystick
ivory jasper
@distant raven Already got per-key RGB LEDs 👍
silk lark
even a gesture sensor
ivory jasper
@silk lark Yeah I've got loads of 2.54 header holes on the back of the keeb for stuff like that. Any and all unused GPIOs are present (except one I think... Because I couldn't get a good route for it... it would cross my analog signals)
"Gesture sensor"? When I think, "sensing gestures" I think, "cameras" or "multitouch surface".
Oooh! JLCPCB has an "attitude sensor" as a basic part! I can make the keeb react when you're angry, sad, or just plain hungry!
distant raven
hehe
ivory jasper
I've actually only got one free non-basic part slot in my BOM
...and it looks like they don't have a temperature sensor as a basic part which is frankly surprising
ivory jasper
@distant raven Yeah I'm thinking that. Add some through-holes for a DHT11
The chip (stm32f401ceu6) has a built-in temperature sensor but I'm pushing it pretty hard with the ADC so it'll probably be hotter than ambient
distant raven
yeah, good idea to use off chip.
the internal temp sensors on MCUs are pretty fun to work with
ivory jasper
I also added a port on the back that connects to the tail end of the WS2812b-b chain so you can hook up more LEDs if you want
(the ws2812b-b is the newest version of that line of chips and uses much less current and doesn't need resistors or capacitors! It's kinda awesome)
distant raven
I wrote a small tutorial on my company page about using the temperature sensor and displaying the temp based on the LED color
ivory jasper
I'd use the mini version but JLCPCB is all out
tough matrix
the 1515 neopixel are tiny
do you plan to solder it yourself? that would be impressive
distant raven
Yeah, hot air reflow
reef flicker
What's the most common screw sizes to use for fastening PCBs?
I think I see a few M2s and M2.5s
misty escarp
I think it depends on a lot of factors
I'd go with what fits in your enclosure well
Just don't do what I did, which is look at a tap and drill chart and accidentally pick the tap hole size instead of the clearance hole size
misty escarp
Those look like loose fit clearance holes
which should be what you want
"loose" meaning .2mm on either side as opposed to .1mm for the M2, for example
reef flicker
Hmm. Am I misusing the hole tool in Eagle perhaps? The hole dimention presets are all smaller than M2 screws
misty escarp
you can change it
reef flicker
I can make them bigger yeah, but why have holes this small?
misty escarp
one use case is for panelization, you can make little mouse bite cutouts so it's easy to cut/snap off the boards
misty escarp
but yeah I'm not sure of any other reasons for such a small hole
strain reasons or something maybe?
although that would make the board weaker
reef flicker
Gotta figure out how all of these board shaping tools work now
reef flicker
There a way to move the lines defining the edges of the board while keeping their angles? For some reason the move tool doesn't behave the same as traces
misty escarp
what I usually do is Right click on the edges and define their coordinates in order to resize my board
but be careful if you have rounded corners, I usually remove the rounds first
if I only need to write a little bit of data (just a time_struct) to an FRAM, is there any reason not to use I2C (100kHz) over SPI?
Main reason to use SPI is to get experience with it but I'm using CP so the SPI of it all should Just Work(TM)
unreal flax
No particular reason if your FRAM accepts the interface... I2C is perfect for modest amounts of data.
reef flicker
Is this too close to the edges of the board?
DRC isn't flagging it, so I assume it's fine
reef flicker
Yeah sorry
misty escarp
It's not too close for fab, I don't think, but it might be close enough that it isn't very strong
Can I get away with a 10 uF decoupling cap where a 1 is specified?
tough matrix
yes
in general, for decoupling, bigger is better - except that you also want to keep ESR low
but difference in ESR between 10uF and 1uF shouldn't be too serious
tough matrix
this doesn't apply to feedback capacitors in buck voltage regulators - there you do want to use specified values. But this is different from decoupling
misty escarp
Yeah it's just on power input for an IC
I ended up going with an LDO reg for my design in the end
Less empty space now!
Just gotta clean it up heh
Is this zigzag in a diff signal a problem? The trace distance for D- is just under 0.25"
unreal flax
No, it should be negligible. The speed of light is about 1 foot per nanosecond.
misty escarp
Thanks
Now I just need to find another peripheral to add so I can fill up the upper right hand corner
distant raven
What do you currently have?
misty escarp
for peripherals?
I2C FRAM, an RTC, an I2C Level Shifter IC, SPI Storage, and a Darlington array
Everything is I2C for this board. Next project I'm gonna pick something that's all or mostly SPI
I think I'm gonna just redo this with a true display instead of 14 segment LEDs
misty escarp
well it's gonna just sit in a box
I do want temp/humidity in the chambers of the box at some point but I need to figure out how to organize that first
distant raven
use the IMU to detect if it's fallen? lol
misty escarp
I'm gonna go with a biological auditory sensor for that 😉 The box is 2x1x1 ft and wood
distant raven
working on finishing a design from my first semester of senior design
misty escarp
Maybe an over current sense of some kind would be good
Nice! That looks simpler than what you're used to!
distant raven
does it have battery power?
distant raven
maybe add the option for battery power
misty escarp
I was thinking of a backup coin cell
distant raven
maybe do LiPo and the MCP73831
the MCP73831 is what I use on the LiPo power pack
Adafruit also uses it
misty escarp
I'm honestly afraid of lipos
misty escarp
This is meant to be plugged in for months at a time, do I need to worry about the lipo overcharging?
tough matrix
I'm gonna go with a biological auditory sensor for that 😉 The box is 2x1x1 ft a...
wow.... this is some serious PCB enclosure
misty escarp
I wanted to make sure it had plenty of room to feel comfortable
The enclosure itself is about 1/4 of that volume but still real big
tough matrix
I am almost afraid to ask what size is your PCB
misty escarp
Well there are 5
tough matrix
"Soviet microelectronic devices are the largest in the world!"
misty escarp
3 of them are 4x1.5, 1 is 1.5x1.5 and the brains is ~2.2x2.2
tough matrix
inches, I hope?
misty escarp
the 4 x 1.5 are honestly bigger than they need to be but I did them in JLC so it wasn't super expensive for 10 of them. The others are going to be done via OSH so I'm making them as small as I can
Inches yeah
tough matrix
this is not too large, in fact - but why do you need 2x1x1 ft box then?
misty escarp
To fit stuff in ha
TBH the hardest part is gonna be making the box, I am a sub par woodworker
tough matrix
but 2 ft??? even for 5 PCBs this is an overkill
misty escarp
Ah I'm not explaining, the 2' constraint is because of hte size of things I need to put in the box that aren't PCBs.
tough matrix
🤣
misty escarp
TBH it's a bit bigger than it needs to be but there was a special on plywood one day so I have plenty
cerulean crest
I'm gonna go with a biological auditory sensor for that 😉 The box is 2x1x1 ft a...
If you make more of these, telecom has solved this enclosure issue of yours 😉
misty escarp
The "enclosure" really has a completely different function and only incidentally has a little space leftover for (most of) the electronics
cerulean crest
Oh I see, are you amplifying the sound mechanically?
misty escarp
I'm relying on nature for the bonk sounds
cerulean crest
Is that the right term? mechanically doesnt seem right, there must be a word for what Im talking about
misty escarp
physically?
I am pretty sure I'm on the page you're on
I would use the term mechanically
misty escarp
if you get down to it, all sound amplification is mechanical
cerulean crest
Not electrical amplification
misty escarp
but a speaker is an electromechanical device
misty escarp
but what is sound if not the projection? That's more of a philosophical tree-in-a-forest question though
I see what you mean though
cerulean crest
Yeah, I was exaplining my thought process but now while I still disagree, I see what you mean as well
misty escarp
I've had hour long discussions about this exact problem with friends before. we agreed to disagree
cerulean crest
We agreed to disagree
A rare find
cerulean crest
curious what enclosure you were referring to?
Oh just telecom boxes are the best, you can fit PCBs, radios, cabling, sensors, elements, they have holes for conduit to be ran, or for accessories used with conduit, they usually have a mechanism for locking, bugs dont get in them, its waterproof, and will age well in the UV light
You can get metal or plastic variants, they are also cheap
When I did a squirrel tracking thing, thats what I used
misty escarp
I think I know what you're referring to. those are p useful, I just don't need it for this project. Maybe for my next one
elder peak
With telecom boxes, whatever you want to do, you conduit.
cerulean crest
With telecom boxes, whatever you want to do, you conduit.
You really need a ToS, I never agreed to these puns 😆
misty escarp
EULA never know when one will pop up
cerulean crest
sigh
distant raven
also, it's final exam season for the college/university folks on the server
including me 😛
so how do I study? by doing the exact opposite of what you would consider "studying"
lol
elder peak
You don't give a ToS about my puns?
cerulean crest
Very nice, you know, having the designators under ICs looks nice, but I hope no other poor soul needs to know which chip is which
elder peak
One time in college, we declared one of the guys on the floor dead and "sold" all of his stuff, during exam week
cerulean crest
You don't give a ToS about my puns?
Lmao, I want to be mad
elder peak
The odds might be stacked against you
misty escarp
Just pin down the problem, work hard and you'll make some headway
distant raven
nice catch
also weighing putting this BMS chip on the LiPo power pack
battery management isn't really all that big of a value add, except that it can extend the life of a battery over time
it's crazy that if you use a LDO on a same41 you can get away with not using a ferrite bead
which is nice.
Drop some 10uF ceramics for those caps and it should be good
honestly, could probably get away with 4.7uF ceramics
cerulean crest
it's crazy that if you use a LDO on a same41 you can get away with not using a f...
Yeah, but higher power draw
Worth a few BOM items to me most of the time
distant raven
I mean, what's really the different in power draw? a few uA?
maybe a few mA
also curious, can you leave the external crystal off the same/d51 boards?
it says it has an internal 32.768kHz internal oscillator
but I don't know if that means you can opt out of using an external crystal
cerulean crest
maybe a few mA
Makes a huge difference
Even a few uA in sleep mode is huge
Difference between 1 and 10 year battery life
Even a voltage divider for a battery, with two 200K resistors cant really be used
Every uA counts
distant raven
4uA vs 8uA, not nearly as significant as say 4uA vs 80uA. I'm just curious what the actual difference is on average
cerulean crest
If you are using low powered parts, and are making a low power product, 4uA means you can or cannot have other features if you have a battery life constraint
Take for instance my environment monitor, it would not be able to also monitor sound constantly if I used the LDO in my MCU, and that feature is something customers looking at other products want
An extra 4uA constantly also means a considerable decrease in battery life ignoring that
distant raven
I wasn't intending on primarily using the internal LDO
but maybe I misunderstood what you meant
cerulean crest
but maybe I misunderstood what you meant
Probably, and you are probably quite correct in using the LDO, I was just pointing out, there are two options for a reason, and in many cases might really effect your design if you default to it
distant raven
right, and I'm not quite sure what people would use the board I'm making for
misty escarp
should probably go with the lowest power option right? leaves your customers the most room
distant raven
right now, tentatively just making a dev board, 24 broken out pins and a few i2c sensors
battery charging, and whatnot.
cerulean crest
Nice, have fun, gotta love SAMD based boards, they are always a pleasure to work with. Though nrf52 is trying to take my love
distant raven
the esp32-s2 is pretty new so I'm trying to make a sapling with that
cerulean crest
Indeed, S2 is going into a wall mounted display for a customer
distant raven
the board is mostly done, though Ladyada on sunday showed off the new ones with SPI Flash integrated
which as far as the datasheet goes it's a pin for pin drop in for non-integrated versions.
which removes the need for SPI flash on my board
and removes 7 components.
cerulean crest
Integrated on a SoM or a SoC?
cerulean crest
Interesting...
distant raven
just with 2MB or 4MB depending on your needs
cerulean crest
I will need to look more into that, but if external does it support a larger flash?
distant raven
I imagine it supports up to 64MiB external like the regular variant
but I imagine it's a "use one or the other"
cerulean crest
Alright, I might need to go with integrated flash and find another solution for my issue
distant raven
it was a pleasant surprise and good for my design and my hands
they were already cramping at the though of placing all the caps and resistors on the bottom side of the board.
elder peak
Hm, if Nordic Semiconductor started restricting more heavily who could use features of the chips, would that mean they nRFed the boards?
distant raven
the process of making a footprint perfect
so many measures
pins labeld. Almost done with the footprint
distant raven
symbol created and connected. now for a 3d package
distant raven
SAME51J20A
vapid grove
Ok
distant raven
decided I wanted to make a board with an M4 with a bunch of capabilities
tough matrix
@distant raven for the qt py charging board - most of the header pins are not connected, right?
distant raven
correct
tough matrix
thought so
distant raven
only 5V GND 3V are connected
tough matrix
btw, why did you need to make a footprint for the SAME51?
isn't it a standard 48TQFP?
distant raven
64TQFP
tough matrix
oh
but still, that footprint must be in plenty of libraries
tough matrix
🙂
tough matrix
isn't adafruit releasing their CANBUS feather now?
so you are in direct competition with them?
distant raven
the CP Sapling is technically a competitor for the Qt Py
plus there are plenty of CAN Bus boards that use the SAME51
this is the 1MB version though so it's 2x the FLASH
elder peak
So it's a real CAN-do sort of processor.
distant raven
I haven't worked out the name yet but preemptively is the CAN Tree
elder peak
I want to make some sort of gantry pun given industrial control but probably nobody would get it.
distant raven
lol
tough matrix
and have an 18+ logo
elder peak
Or just a 2can
tough matrix
choosing between this https://animals.sandiegozoo.org/sites/default/files/2016-11/animals_hero_toucan.jpg
misty escarp
I pick the second one for..reasons
I'm using some 5V PC fans controlled with PWM, any reason to sense their current draw?
At this point I'm just looking at any useful features I could add
vapid grove
vapid grove
@distant raven which tact switch do you use for reset button
distant raven
vapid grove
Thanks
tough matrix
it is pricey...
carmine flint
@elder peak the ones on the pygamer are soooooo good
the little bit of rubber squish makes all the difference
elder peak
Yah, like, the 6x6 tact buttons are pretty nice in general, but I'm always like "Well, if I just had something smaller than that and maybe SMT, I could use it for reset buttons and stuff"
and I've got an assortment of attempts
carmine flint
don't we all!
distant raven
Also, those buttons I linked too are much cheaper on DigiKey
tough matrix
I am using these ones: https://lcsc.com/product-detail/Tactile-Switches_BRIGHT-TSA453G38-250_C294494.html
distant raven
I found this part with the Digi-Key mobile app. https://www.digikey.com/product-detail/en/KSR223GLFG/401-1704-1-ND/958078
Like $0.20 cheaper
Still pricy at $0.76 a piece but they are nice
tough matrix
the ones I linked are quite cheap, but are quite nice. Maybe a tad too stiff for my taste, but they are large enough so that they are easy to press and give you a very satisfying click
misty escarp
is there a footprint for the qt py anywhere? Or would I need to make my own?
misty escarp
I'd need a cutout for the flash chip so I guess making my own is the better choice?
haven't done anything with internal corners before, should be a fun challenge
distant raven
well, if you just use header holes it would need it because the headers provide the clearance necessary
misty escarp
Yeah I was thinkin of taking advantage of the castellated pads
distant raven
it only adds like... 2-3mm to your total height compared to using the castellated pads
distant raven
I was saying just solder the headers
misty escarp
Ah yeah i gotcha now
distant raven
but removable is a great option too
misty escarp
If the DS3231 lib worked with the D21 I could scrap about half of my existing board design for one project
But in true me fashion I am starting another before the first is finished
do people prefer english screws for their PCB designs or Metric?
Or rather how would you prefer to mount a PCB in a 3d printed enclosure
I usually go for screws but if there's a better option I'm all about improvement
vivid roost
oh definitely Imperial, I love the fact my car gets 14 rods to the hogshead (sarcasm intended lol)
misty escarp
So metric?
vivid roost
sry for bursting in, i just wish the world would go metric and be done with it...
misty escarp
How would you mount into 3d printed material? I haven't 3d printed much but my intuition says heat press inserts
I do too
vivid roost
press in inserts or just self tapping screws
misty escarp
I think I'll go with inserts so it can be removed repeatedly
vivid roost
i guess that is the criteria, cost or long term serviceability
vivid roost
thru hole flat heads from the bottom creating a stud?
misty escarp
creating a stud?
elder peak
You can do a captive nut.
vivid roost
the ends of the screws protruding into the case, put bd on and add nuts
misty escarp
this is where I wish inventor was tied in with eagle
vivid roost
captive nut is prolly better, nobody likes loose nuts inside their electronics
waiting for it....
elder peak
Like, pretty much, you can just model a hexagonal nut with a bit of clearance on the blind side and leave it be or you can add a bit of glue to keep it in place.
Oh, that's close to where the community moderators would want to step in so I didn't insta-pun on you.
You might say that it's a tough nut to crack.
vivid roost
lol
vivid roost
like aircraft sytle with the plastic insert?
elder peak
The other trick I generally do is make sure that all of my screwholes are on a 5mm x 5mm spacing so that I can make a chassis that holds any multitude of my project boards.
That's not aircraft style. 😛
misty escarp
yeah they have those at my local hardware store. They don't have captive nuts tho
vivid roost
ok, very small "aircraft style"
elder peak
I usually think "safety wire through the cotter pin hole" when you say aircraft style, although yeah nylock nuts are also a thing.
misty escarp
I'll probably order online though, since my local hardware store seems to be the gathering place for my town's chin-maskers
elder peak
So, problem is that you have a single blind side, inevitably.
vivid roost
yeah the safety wire is likely overkill
elder peak
Nylock does have a reduced chance of unscrewing, but doesn't help the blind side.
elder peak
So, easiest way to handle the blind side is to make a 3D printed projection that the sides of the nut can be affixed against, which will work with nylock or plain old hex nuts or square nuts.
Square nuts have the added advantage of also working within laser printed chassis designs.
misty escarp
I'm having a hard time visualizing what you mean, do you mind expounding?
misty escarp
Hm I think i'll be able to get away with printing the whole thing and then inserting
@distant raven any chance you know where to find that footprint? the official XIAO fpt doesn't have holes for the headers
elder peak
Carriage bolts on the blind side and then a nut on the other side is another option, but they don't make tiny carraige bolts, like the smallest is M6.
misty escarp
I was thinking of being gross and using machine screws with nuts
distant raven
I could make one for ya
elder peak
I mean, here's my intentionally-exposed thing that hangs on my wall: https://www.wirewd.com/make/blog/esphome_geekroom_node
misty escarp
ah I can handle making it, I was just being lazy
distant raven
Just give me like.. 20 minutes or so
I like helping and I already have Eagle open lol
distant raven
Sounds good
misty escarp
idk how accurate the usb length is but pretty sure the outline is correct
Should probably make these fit the castellated aspect somehow
hm vias are probably too small as well
ack another mistake
distant raven
Not bad
misty escarp
I realized the pads are in the wrong spot
distant raven
I got wrangled into bath time so I’m delayed in makinng lol
misty escarp
how dare your children come before strangers
distant raven
😂
misty escarp
also weird is that the drill for the official pads is in mm instead of in
but I guess 40mil is close enough to 39.37008
mixed units never caused any problems
bettah
distant raven
pure SMD castellated
unless you want through-hole
pads could probably be rounded
misty escarp
I was wondering if thru holes could be added on top of SMD but that would be via in pad hm
distant raven
castellated is usually for soldering without pins
misty escarp
yeah
but I think with the haxpress addition, having thru hole pads to either add female headers or a permanent header installation makes sense
misty escarp
just do a cutout?
distant raven
Yeah
misty escarp
sorry I meant what do you mean by that
distant raven
Oh, just add a polygon in the spot where the SPI flash would be
misty escarp
ohh duh
misty escarp
Just realized I set up my SAMD51 in switching mode but I'm using an LDO. Do I need to redesign?
fast tundra
@misty escarp the switching/linear mode for the SAMD51 is for its internal LDO, it doesn't matter what the upstream regulator is.
If you do put the SAMD51 into switching mode in the firmware, make sure you have the necessary external components for that.
misty escarp
ah makes sense thanks. I am using an external LDO, is that a bad idea?
fast tundra
no, no, that's fine & normal
Your external LDO is basically what's supplying "IO Supply" in that figure
misty escarp
no, no, that's fine & normal
I'll take things I never hear about my plans for 800, Alex
fast tundra
The internal LDO for the SAMD51 takes VDDIO and regulates it down to 1.2V (which you can monitor from the VDDCORE pin)
fast tundra
yes and no. 🙂
the chip runs at multiple voltages - VDDIO for digital peripherals (and a few analog pins), VDDANA for analog peripherals, and VDDCORE for the cpu, memory, and bus.
fast tundra
Section 7.1 of the datasheet is where you can learn allllll about that
misty escarp
I think I missed that section of the 100s of pages 😛 I'm getting thru it slowly
fast tundra
It takes a while
misty escarp
Part of me misses AVR chips but also circuitpython
fast tundra
There's still large parts of the SAMD21/51 I don't know about because I haven't had to use them yet.
CircuitPython doesn't ever use switching mode for the internal regulator, but most Adafruit boards have the requisite inductor for it.
misty escarp
what's the benefit of switching mode?
fast tundra
lower power consumption
misty escarp
ah ok, I wonder if the boards were built that way so that an eventual version could use sw mode
misty escarp
ah right
fast tundra
That lower power consumption comes in handy for battery powered things
misty escarp
makes sense. It would be nice to have that in CP
fast tundra
I haven't been keeping up with that too much but I know they're working on sleep/deepsleep
(I've been sitting out on all the 6.0 stuff while working on a non-circuitpython product, so I've missed a bit)
misty escarp
Yeah I've been watching that, i'm excited
Eventually interrupt-like stuff is coming
tough matrix
got the photo of the sample assembled board from the fab house
will look at it VERY carefully before confirming.... and then in several short days I will have my 55 boards!
tough matrix
now try to unsee it 🙂
tough matrix
IMU: ICM 42605
misty escarp
This is for RC/Drones right?
tough matrix
more for general (land) robots/smart cars
with closed-loop motor control, IMU, inputs for sonars and GPS, etc
misty escarp
oh very cool
fast tundra
Nice
misty escarp
PID?
tough matrix
yes
there is a video there in crowd supply page, take a look
I am quite proud of how well we made it work
precise turns using IMU
misty escarp
looks like you used the entire chip!
fast tundra
Are you using the fancy motor control features of the SAMD21?
tough matrix
no, we are just using timers for PWM
fast tundra
Cool
tough matrix
to be honest, I didn't know much about fancy motor control features
so we wrote our own PID etc
but we used almost all pins of TQFP48
fast tundra
The TCC peripheral has some wild features for motor control, I haven't ever had a use case for that stuff.
misty escarp
next step, state space!
tough matrix
maybe it is worth looking into for next version... that is, if we can get some funding for it - it was hard enough to get the necessary number of backers
fast tundra
Yeah funding hardware is hard.
I'm lucky with my stuff that I've been able to self-fund, so I haven't had to do crowdfunding.
tough matrix
I just can't really hand solder tqfp48... that is, I can but half the boards will be wasted
and if you want to order assembly, ordering a couple is prohibitively expensive - you need a lot
fast tundra
Yeah. Minimum for our stuff is about 150 units.
Anything lower than that just isn't financially reasonable.
Oh here's the SAMD21 motor control evaluation board, you might find some interesting stuff in there: https://www.microchip.com/developmenttools/ProductDetails/atsamd21bldc24v-stk
tough matrix
thanks - will take a look
I spent a lot of time on Arduino forums looking for help on low-level commands for SAMD21
setting up clocks and timers