What is the name showing up as instead?
#help-with-hw-design
unreal flax
limpid nest
Nothing
unreal flax
Ahem, do you have a >NAME label in the part symbol?
unreal flax
That's curious. I don't think it should permit a blank part name. What does the name show up as when you try to edit it with the NAME tool?
limpid nest
ooh one thing, if I rclick and hit properties, I see the name properly e.g. JP2 JP3
let me see about the above
same thing, of course. Oof I'm sleepy
unreal flax
So it looks like something is weird about the >NAME label. Like it's in white text, or placed off the screen, or behind something else, or marked as non-visible, or the layer is disabled, or...
limpid nest
hmmmm
unreal flax
Or it's been added in the library but the library hasn't been updated into the schematic?
limpid nest
should it show up roughly where I put it in the symbol? I did update the library in the schematic but I did "update all" I'll see what happens if I update just the part
no dice
unreal flax
Yeah, it should show up exactly there.
limpid nest
werid
weird
I may have to go to the official forums
hopefully my handle is available
any idea what they mean by "reposition attributes" and "smash" I don't recall smash from EAGLE but I'm no expert
https://forums.autodesk.com/t5/eagle-forum/gt-name-and-gt-value-does-not-appear/td-p/8747245
unreal flax
The SMASH tool splits apart sub-elements in a part, allowing you to do things like reposition the name label on a part-by-part basis to make the silkscreen tidy.
limpid nest
ahhh ok
Hm, I tried moving the label around, in case that's what they meant by "reposition attributes". No luck though
It's not super duper critical but my schematic looks less professional this way
unreal flax
That's quite weird. You might change the label to just "FOO" or something to make sure it shows up as text in the schematic, independent of the part-name substitution.
unreal flax
Bizarre...
limpid nest
yuuup
@unreal flax I found the right google terms. Seems like this is just plain a bug
using the command reposition opens up a tool and you click the part and it fixes it
unreal flax
🤦♂️
spice turtle
Should I try to pack my board in more? The top half where the FETs are cant really move...I want to try and make provisions for a heatsink if possible (thats the white bar you see on the right), but the board feels empty mostly with all the random stuff on the bottom (like the buttons and speed pot)
Also I realize my RL is in all my file names but idc. I dont have much to hide from my fellow makers
worldly schooner
It does make for a nice space for silkscreen, so you don't have to pack it tight. I would personally rearrange the not-super-heat-generating components to be more organized together, and leave a clearer space for whatever silkscreen I would want to put.
spice turtle
I like how eagle marks QFN packages as having clearance issues when I run DRC. 🤔🤦♂️ 😅
vapid sonnet
OK, I know this may only vaguely qualify as on-topic for this channel, but I've got a mfg side question.
On something like a USB A plug, that has the mechanical through-hole solder tabs.... can that be done in reflow, or is it a selective solder and/or manual only thing?
tough matrix
Didn't try type A, but microUSB connectors with through-hole tabs certainly can be done in reflow
vapid sonnet
Thanks @tough matrix. The connector I'm investigating looks to have similar-ish sized tabs, so we'll go with that assessment until proven oherwise. (No, I don't have the actual thing. I'm investigating a failure by remote 😦 )
limpid nest
anyone willing to review a Fusion360 library I'm making? I'm not done yet but just checking
limpid nest
EAGLE/F360 questions. How can I move the numbers 1-13 to a better position? They don't have anchors in the schematic. Additionally are the extra P$N from the footprint and how can I remove them?
unreal flax
For the second question, I think the pin symbol properties will have a checkbox for showing the pad numbers or not.
For the first question, I'm not sure if pin names can be "smashed" and moved around. One option is to turn off the display of the pin names and place extra labels manually. I'd tend to just suggest leaving the pin numbers where they are and making the connector box bigger to enclose them, though.
limpid nest
Cool thanks a lot I'll try those both
limpid nest
for caps, a voltage rating of 2x my applied voltage is sufficient, correct?
ceramic caps
distant raven
Yup
Honestly, 6.3V are typically enough for 5V or less
But it never hurts to have more overhead
limpid nest
ok I see a bunch of 16V ones available in the capacitance I need
distant raven
If that’s what’s available and 5V is your max, those will work great
supple pollen
It depends somewhat if you're using capacitors with a large voltage coefficient, and if you're depending on the value not changing.
For example if you're using Y5V dielectric 6.3V capacitors at 5V and you need the capacitance to be near the rated value, you may be disappointed.
limpid nest
I'm using 0.1uF 16V X7R caps to decouple 5V inputs to ICs and a 1uF cap of the same specs to do the same to my 5V power input
supple pollen
That will be totally fine.
limpid nest
kool
thx
does the 1 uF cap for my power input count as a decoupling cap or as a filter cap?
supple pollen
It's pretty much both, they're different ways of expressing the same general idea.
frigid seal
Yeah, I agree.
frigid seal
Do you have bulk capacitance on your input?
limpid nest
input to the PSU? Or to the board the PSU powers?
That's what my 1 uF was meant to be
unrelated, but how would folks go about marking a pin on a schematic as NC? I don't see a simple way of doing that in my scenario where I'm using the same IC twice but have several pins NC on only one of the two devices
supple pollen
I just don't hook anything to unused pins (hopefully outputs: leaving inputs floating can cause issues)
unreal flax
I typically drop a little "NC" label on the pin in the schematic to document my design intent.
unreal flax
Not to my knowledge. Other EDA tools like Altium do have a way to explicitly annotate a pin as unconnected, but I don't know of a way to do that in Eagle.
limpid nest
Mk thanks. That's what I gathered from googling
supple pollen
Naming them "NC" would tend to connect them all together to an "NC" net, which is not what you want to do.
limpid nest
Yeah
I have a probably silly question. I'm using one of these (https://www.digikey.com/en/products/detail/bourns-inc/4613X-101-103LF/3741136) and I made a part that looks like the attached image. Any signals I want to pull up need to be routed directly into pins 2-13, correct?
pin one is to my supply voltage
unreal flax
Yes, that's correct. Note that the schematic symbol does not make the function of this part obvious, though. If I were making it myself, I might have put pin 1 on the other side, labeled it "COM" or something, and labeled the remaining pins as "R[n]", etc.
Or, as bonus points, actually drew out the internal connections of the part with little resistor symbols inside the box.
limpid nest
Interesting. I made this one. I can't remember how I changed the pin names from P$N to just N
unreal flax
It would just be the NAME tool in the part schematic editor, I think.
limpid nest
Yes, that's correct. Note that the schematic symbol does not make the function o...
Closer to how you'd do it?
Gotta figure out how to do resistor symbols in here
Iguess I can just use lines 12 times
unreal flax
Yeah. I mean, this is your design, so do what makes sense to you, of course.
limpid nest
I want it to look nice
This looks a little better:
don't like the placement of the numbers but what can you do
unreal flax
Cool, yeah, much more obvious what the part does.
limpid nest
they don't super look like resistors but they don't look like inductors either so that's good
limpid nest
@unreal flax Decided to use 2 6-channel resistor networks for routing reasons. This one had a lib for it. Much more pleasing drawing too
supple pollen
Then there's our nutty resistor network...
limpid nest
You can't tell but my face is doing the thing the bad guy's does at the end of Raiders
supple pollen
If you're curious, here's the physical part...
limpid nest
It reminds me somewhat of the gorgy mosaics you see in mosques.
supple pollen
On the upside, I got two patents out of it.
supple pollen
Heh, yeah, it does kinda look like a spiderweb.
tough matrix
nice
You can see how adafruit does it, e.g.: https://www.adafruit.com/product/2652
basically the outer edge of the mounting pad is aligned with the edge of the board
limpid nest
Why didn't I just think to check adafruit boards.
Any idea if they can be opened in f360? I'm away from my PC for dinner or I'd try it. Buying a 🌯
spice turtle
If you're curious, here's the physical part...
Where is something like this used?
supple pollen
The basic notion is like an analog serial number.
limpid nest
Like you read the resistance and the unique value gives you your code?
supple pollen
Right. With the 8 ports, there are a lot of combinations I can use. I hook 'em up to GPIO pins, so I can ground some pins, connect some others to Vcc, and read the resulting voltage on another. With 8 pins, that's 15456 different combinations that can give useful readings.
limpid nest
Neat
supple pollen
I was originally asked to design a compact ohmmeter for the task, but then came up with the zero extra parts approach that gave many more available readings.
limpid nest
Woooo
distant raven
only goof is I tied the LDO enable to VUSB and not 5V so the battery could turn it on as well
but this is why we do prototypes lol
limpid nest
I don't see the frames or similar library that I got used to using in EAGLE in Fusion360. Does anyone know where that went?
Looking to add a titleblock to my design
I found it. You have to enable it in the library manager.
distant raven
Weird
limpid nest
yeah lots of stuff about Fusion 360 EDA is just odd
elder peak
On the upside, I got two patents out of it.
tl;dr: not only is your resistor network absurd, it's patently absurd.
distant raven
If you're curious, here's the physical part...
What was the application of this network?
supple pollen
I replied above: #help-with-hw-design message
distant raven
Ah okay, very cool
twilit mango
Wheeeee destroying board files to make Fritzing objects work properly. Good thing eagle2fritzing uses a copy of the board file....
limpid nest
I'm very sleepy and tend to second guess myself when so. Does this dimension seem like the distance between the center of the header and the center of a mounting hole?
I'm 99.9% sure it is but wanted to check
spice turtle
I want to say yes but can I have the full drawing view?
warm cradle
it is centred on both hole and header
spice turtle
That is correct then
what an odd way to measure though
usually you would do from the edge to center
ie like the 3.5mm
limpid nest
yup that's my experience as well, which is why I asked
chained dimensions are a thing but I think IIRC that I was taught to avoid them
spice turtle
Its pretty much useless. I mean the IO connector is there, but you would generally give from the left edge, then to the right edge of that connector OR you give the dimension of the connector it self.
🐑
opps
I meant 🤷
limpid nest
My favorite band is The Mountain Goats so I'll take the ram happily
spice turtle
lol
limpid nest
what are folks
oops
what are folks' thoughts on this placement of a barrel jack connector?
Let me get dims
It's ~6mm of overhang
unreal flax
You'll want to check the spec for the copper to board-edge distance for the leftmost hole, but the overhang itself shouldn't be very constrained. It might also be worth checking the connector drawing to see whether it has any bottom-surface features that would benefit from having a board underneath them for mechanical stability.
limpid nest
I've accidentally bought barrel jacks with that little nubbin on them before, let me see if this one has it
It doesn't seem to have any protrusions
Good callout though. I ended up moving it in slightly so less overhangs
limpid nest
lesson I seem to refuse to learn: Laying something out nice and neat in a schematic does not mean that your actual pads will be arranged in a helpful manner
limpid nest
@worldly schooner no rush but a while ago we discussed a pre-AC/DC converter filter. I can't find it in the log. Do you recall which one? I can dig deeper too, just doing several things at once
worldly schooner
Google emc-20, I think?
limpid nest
Ahhh right thanks
limpid nest
I can't find just the ic for the adafruit AW9523 anywhere. anyone know why?
supple pollen
limpid nest
I guess I should have qualified that anywhere wasn't really anywhere. Thanks!
I've never ordered from them but they seem legit
Ah it's an assortment of vendors
supple pollen
I'm not sure the manufacturer has any direct sales (some do), but here's their site: https://www.awinic.com/en/index/pageview/catid/19/id/15.html
limpid nest
So is it sinking current for leds?
supple pollen
Yes, looks that way.
supple pollen
Kinda?
tough matrix
I expect it uses mosfets switching them on/off with high frequency, plus possibly a cap to smooth the current
limpid nest
I was thinks fets too
supple pollen
I'm guessing it's more like running them in the linear region.
limpid nest
But more with varying the gate voltage to vary rds on
supple pollen
That's what "running them in their linear region" means, yes.
limpid nest
Ahhh ok thanks. I'm still learning fets
limpid nest
Is it possible to have a custom board that runs off of a wall adapter (e.g. a barrel jack) but then has USB exposed (e.g. microusb) for programming in such a way power lines don't fight each other?
Would just connecting data and ground from the USB port work?
tough matrix
yes, that would work
of course it means that it won't work without the power supply
limpid nest
Which is what I want
I don't want anyone trying to power it off a limited USB supply
I don't think what I'm thinking of uses more than 500 mA but I don't want a low ceiling like that
limpid nest
Can anyone recommend an off brand crimp tool for criming 2 pin molex connectors?
I want to make cables that can connect to a wire to board housing but don't want to spend hundreds
tough matrix
which ones?
problem is, molex makes hundreds of connectors...
limpid nest
That's true. Let me do more research. Best friend asked me what I want for Christmas and the answer is always a new tool
https://www.molex.com/molex/products/family/minilock?parentKey=wire_to_board_connectors
The 2 conductor version should work fine.
I could do a 12 conductor version I guess.... I do need 12 connections...
tough matrix
engineer is a well respected https://www.adafruit.com/product/350?gclid=CjwKCAiAtdGNBhAmEiwAWxGcUq-4JcNEbhRhMjkwQuvpgNTxtORI-6y6z_3Mu9oPu7L9g3P8kq0ioxoCexwQAvD_BwE
or some crimper from IWISS
limpid nest
That says 1-1.9mm is that referring to the pitch?
Or the actual size of the part you crimp down?
Their site implies that this one can be used for 2.5mm pitch
tough matrix
diameter of contact
limpid nest
Ah ok so I just need to figure out the diameter of the contact I want to use.
tough matrix
Google website of manufacturer, they have a table of all types of connectors and recommended crimpers for each
limpid nest
Engineer Co? Or molex?
limpid nest
Cool I was just on their site, it mentions at least one molex type so I'll just see if I can't use that molex
limpid nest
I've generally heard negative things about JLCPCB's assembly service. Has anyone used them and can give a positive or negative review? I can use another fab house, of course, but I'm familiar with JLC. I want to get assembly because I don't fancy hand soldering any WS2812s
tough matrix
I used them many times and was generally happy with their service
limpid nest
Ok cool. Thanks. I just heard some bad things (can't remember where) and didn't want to let that influence my decision too much
Can they do for example WS2812s on two sides of a board?
limpid nest
Ahh ok so I'll have to do some assembly on my own. Probably will just hand solder them all then.
tough matrix
how many boards do you need?
limpid nest
Undetermined. Probably not more than the minimum of 5
But I need RGB LEDs on both sides of the board
How does 2 sided assembly work? Do they have a heat proof jig that holds the bottom parts in place?
tough matrix
no, afaik, you do two rounds of reflow
limpid nest
Do you just hope that the solder paste doesn't melt and drop bottom components off?
tough matrix
first solder one side, then turn over and populate the other and put it in the oven
and bottom ones are held by surface tension of solder
tough matrix
but I have no first hand experience. Maybe others will comment
in your case, for small quantities, you could just use hot air reflow
limpid nest
It might be worth it to make a test board that's just a few rows of neopixels and try hand soldering them first and see if they light up
Yeah I need a reflow gun
tough matrix
talk to @distant raven
distant raven
yeah, hot air or a hot plate for neopixel
limpid nest
Only issue is I want the board to be bigger than my hotplate. So hot air it is.
limpid nest
Ok that was my first instinct but wasn't sure how valid it was as a technique
So hot plate for one side and hot air for the other?
distant raven
it's pretty valid
limpid nest
So hot plate for one side and hot air for the other?
Yay, nay?
distant raven
if it's two sided design, one side will have to be hot air'd
limpid nest
That's what I thought
distant raven
i would do the neopixel side on the hotplate
limpid nest
Both sides have neopixels
I'm making a Christmas tree
Want the neopixels to look like lights
distant raven
oh i see
yeah, i suppose just do the best you can
if you had a reflow oven, use higher temp paste on one side then low temp on the other
limpid nest
I may have to use hot air for the whole thing.
I'm planning a reflow oven build but it won't be ready in time for this.
limpid nest
They make samd51s with fewer pins, correct? I'm working on a design that doesn't need nearly the number of possible pins.
Well there don't seem to be any in stock anyways.
limpid nest
Are they just not findable right now?
distant raven
But yeah, availability is zero
limpid nest
Yeah that seems tough to solder
Hot plate I guess
Any idea how many neopixels I can drive with 16 MB flash?
Well I got the last two of these https://www.digikey.com/en/products/detail/raspberry-pi/SC0914-7/14306009?s=N4IgTCBcDa4GwBYAcBaAygYQAwE4CMCAFAOwCUGAKigHIAiIAugL5A
unreal flax
Any idea how many neopixels I can drive with 16 MB flash?
That's kind of apples and oranges. Neopixels are usually driven from RAM, not flash, unless you intend to have a completely static pattern.
limpid nest
Ahh ok.
Let me make sure I didn't get the wrong thing, to go along with SC0914(7) there's also a SC0914(13)
Anyone know the difference? They seem identical
unreal flax
I think it's just the reel size. TR7 is 500/reel, and TR13 is 3400/reel.
limpid nest
Ahhh perfect
May as well buy the other two remaining
(Sorry to anyone who wanted one)
unreal flax
All's fair in love, war, and chip shortages...
limpid nest
Yeah I can make at least one of my upcoming work projects work with these and maybe another project
candid maple
Hi!
Noob pcb+assembly ordering question:
Why my pbc component preview looks incorrect - component placement looks like it trying to place stuff on bottom layer where i have nothing but copper pour? The pcb house is jlcpcb.
this is how it detect gerber files:
this is how it detects assembly:
and this is on final page before saving order into cart:
you can see there is no almost no traces here
after closer look i no longer sure this isnt a bottom layer at all - this looks like mix of 2 layers
limpid nest
I think i read that JLC is sometimes wonky but I've never used any assembly services
candid maple
I think i read that JLC is sometimes wonky but I've never used any assembly serv...
how do you look at middle layers of pcb in jlcpcb?
their viewer has only top and bottom layer tab
limpid nest
I'm not sure. It's been a while since I did a 4 layer with them. I think it just showed up but I don't remember specifically
tough matrix
JLCPCB assembly service orders are always checked by a human before putting to production, so many problems will be caught at that stage. On the other hand, they only have a very short time to spend on each board, so they can miss some problems...
candid maple
44$ for two boards - not that high level of risk
(including shipping)
ordered 💸
lets see what they would say
limpid nest
They've reached out to me numerous times about my art projects being super weird PCBs.
Also their visual representations of your CAD are imperfect.
limpid nest
Hoping for some advice on how to route my 2 layer screw terminal (pictured). I have 6 unique signals and 6 power lines (each signal has a power line associated with it). Would folks do all power signals on one level and associated signal on the other level? Or alternate left to right across the top/bottom?
limpid nest
also what's the best way to make a really nice and neat library part like this? I want to make a part that's just a 2x20 with 4 holes in the exact positions I want so that I don't have to position my holes in the actual PCB anymore.
distant raven
Okay so I’m really scratching my head here with this transimpedance op amp design. I’ve used this before in a similar application but with higher supply voltage without issue.
It’s from an OSH VLC transceiver that I’m adapting to another project which I can’t really share details
When I prove the feedback side of C19, I get the expected variation in voltage when the input to my photodiode is changed (more light/less light)
But opposite of C19 where it’s pulled up ~1.65 voltages by the R17 and R15 voltage divider is where I am losing the signal
I wouldn’t think using 3.3V vs 5V would make such a difference but at this point I am a little miffed as to what’s going on
unreal flax
What modulation frequency are you using to test with?
unreal flax
Ah. Well, the capacitor is going to block the DC response, so you really should test with an AC-coupled signal.
distant raven
Sure, but logging the analog input to the Micro I should see more than just 1mV differential when logging at 60Hz+
limpid nest
weird Fusion360 EDA issue. I'm making a library part, but when changing coordinates, it's rejecting my pressing of the - key.
distant raven
I have it logging ever ms
But it only varies 1mV when I should be seeing a 150-300mV change
This photodiode is sensitive enough to pick up the 60Hz noise of household lighting. I don’t even see that
unreal flax
I don't have a good intuition for what the cutoff frequency is for the path out to the ADC, but I'd assume they would have set it fairly high for typical communication applications.
distant raven
If I do this same measurement with my 5V application I can measure the response of 250mV into the ADC
I thought maybe it was the supply voltage being too low but acceptable range is 3.1-5.5V
I’m wondering if I need a weaker voltage divider
I tried to see if I changed the bias resistor for the inverting input would change my outcomes but that was a dead end
Im wondering if I need to just use the 5V design with off chip ADC
Cutoff frequency is 4.24MHz
0.5Msps should be able to handle that but maybe not
limpid nest
Apparently it's a known bug fyi
Won't accept a negative unless there's a number in there already
distant raven
We’re shooting for fairly low data rates but perhaps I need to re-evaluate my design
unreal flax
I'd send you my old 10Mbps design for reference, but alas it's all behind NDA, heh heh.
distant raven
Lol
All good. This op amp can support 4GHz GBW which is super nice considering it’s $13
A few hundred Kbps should be a breeze
4.244MHz cutoff is supposed to support up to 400kbps so some fine tuning (changing feedback resistor) should easily bump to 1Mbps
Anyway, I think maybe I just need to go back to a standalone ADC
supple pollen
Hoping for some advice on how to route my 2 layer screw terminal (pictured). I h...
I'd run the power to one connector/level and the signal to the other: that would likely be the easiest to route. But it's hardly the only way you could do it.
supple pollen
also what's the best way to make a really nice and neat library part like this?...
Best? You can just knock it out manually, or you can write a program to generate the library part automatically, or write a script to do the same. Each is best in different circumstances.
limpid nest
Hmmm thanks. I'm doing it manually for now. I'd like to learn to write scripts to do this.
Maybe when things calm down I can learn that
limpid nest
Is it possible to add holes to a footprint in Fusion360?
just plain holes, not pads
I can do a PTH with drill=diameter I suppose
I got it
cmd line hole
unreal flax
There should be a separate hole tool as well, rather than the via tool.
limpid nest
It doesn't show up in my toolbar, or I'm too sleepy to see it, but running just hole worked great
limpid nest
any idea why my pins on my schematic all have G$1.# on them? I changed all the names to just be #. That is reflected in my pad names correctly.
unreal flax
The G$1 is the placeholder name for the schematic symbol. A library device can have multiple symbols, like a quad op-amp chip where there are 4 individual amplifier symbols.
limpid nest
Ahhhh ok. That makes sense. Thanks
unreal flax
(I think G stands for "gate".)
limpid nest
nice
limpid nest
I'd run the power to one connector/level and the signal to the other: that woul...
That's what I was thinking as well. Thanks for the input
candid maple
Update on pcb - they accepted it without asking me any more info
only corrected some placement - but what they corrected is beyond my comparison skill
limpid nest
How hard is it to solder an SD card slot onto a board? I'm thinking it's easier to just buy the spi breakout from adafruit but that feels a little like cheating
bright thistle
Uh? I cannot use /shrug?
limpid nest
I guess not
distant raven
I’ve been trying to get some of these for months
Found 30 on LCSC and snagged them
distant raven
Nice looks at roughly 70 RP2040 left from 500 piece reel
To be fair, I sold over half the reel to makers in need
limpid nest
Would these marks on the footprint correspond to the dots on the physical device do you think?
worldly schooner
Highly doubt it.
heavy jasper
It’s not rotationally symmetric, is it?
limpid nest
How do you mean? It's def not axi symmetric
heavy jasper
Seems like it’s only possible to put it in one way.
limpid nest
Ah good pt
heavy jasper
e.g. the orientation markings tend to be most useful for parts that you could rotate some angle and it’d still fit
I can’t quite tell based on the drawing - it’s possible this one still is, but then also it doesn’t much matter, except to see which direction the interlocking features face if you want to solder in just one, then interlock and solder another one later (which seems a bit obscure)
limpid nest
ah ok. So any ideas what the two markings on the footprint mean?
I think they mark the "front" of the device. Kinda confusing tbh but from the part drawing it looks like the wider section is in the back
limpid nest
I can't seem to get this stemma QT footprint closer than this to the edge of the board. Anyone have an idea as to why?
The red box is tKeepout, is that hte issue?
unreal flax
It shouldn't be. I suspect it's how close the copper pad is to the edge. You might check your DRC settings to see what that clearance is. Maybe 1mm?
limpid nest
ahh ok.
I'll look at some adafruit boards and see how close their stemma QT connectors go
limpid nest
Theirs are pretty darn close to the edge. Thanks @unreal flax, I'll examine my DRU. Is there any danger in changing the settings?
unreal flax
Theirs are pretty darn close to the edge. Thanks <@!382380426628562955>, I'll ex...
Just depends on what your PCB fabrication house can support.
limpid nest
ah ok
I'll see what JLC can do. What's the relevant metric called? Like i can describe it but it probably has some technical name
unreal flax
Looks like they call it "trace to outline" clearance. Only 0.2mm, so you can scoot things a lot closer if you need to.
They may have an Eagle spec file that you can just download.
limpid nest
I've had a really hard time getting files like that from JLC. 5% of the time it just downloads but 95% of the time it just opens a webpage with a text file in it
also any idea what the metric would be called in Fusion360?
unreal flax
Looks like it's called "Copper/Dimension" in the Distance tab.
limpid nest
ahhhh! I should have realized that's what that diagram meant.
It was confusing because the default board color in the actual CAD program is black, but here it's white!
Thanks!
limpid nest
is 8 mil small enough for traces between low power ICs?
e.g between a GPIO and the gate of a MOSFET?
or even 6 mil?
unreal flax
Yes, that should be fine for low-current signals.
Whatever your PCB house is happy with.
unreal flax
Also should be fine. If you're curious, there are various trace-width calculator tools online which will tell you how much heating you'd expect from different widths with different currents.
limpid nest
Yeah I wasn't sure of the current in my smol traces or I'd have gone to those. I confirmed that 10 mil is enough for 20 mA
limpid nest
I'm considering the CircuitBrains Deluxe board because it's the only way to get a SAMD51 and it simplifies my design work. Since the Deluxe has QSPI Flash on it, does that mean that the SPI bus is busy and I can't use it for an I2S chip?
afaict, the SAMD51 only has one SPI bus. But I'm reading about the I2S functionality
unreal flax
For that chip, they have a dedicated QSPI peripheral, plus up to 8 SERCOM peripherals that can be configured as regular SPI, plus a separate I2S dual-channel peripheral, it looks like.
limpid nest
interesting. Was that in the datasheet and how did you know which table to go to?
unreal flax
Yeah, I was just looking at the initial "features" section of the datasheet.
limpid nest
ahh ok
I see it now. Thanks
seems like this is a good board. I have been pressuring my boss to buy a few. I think I'll point out that if we don't use them, I will buy them from work because I want them lol
unreal flax
Although you'll want to check the particular chip variant against the Configuration table on page 17, as not all D51 variants have I2S, it seems.
limpid nest
let me check then
looks like the J19 does have I2S
good looking out
if I don't want it to be possible to power my device via USB, but I do want some indication that USB is connected, can I just connect the 5V line from the USB port directly to an indicator LED?
unreal flax
Yes, if "directly" also includes a current-limiting resistor in series.
limpid nest
yes of course haha, I just left that off
And then as long as I have common ground between all my DC components, D- and D+ will behave?
unreal flax
Not quite sure what you're asking there, can you clarify "behave"?
limpid nest
Like I can transfer data over USB even if I'm neglecting to use the power from USB for anything but an LED. As long as I provide external power to the chip
unreal flax
Yep, totally. From USB's perspective, it has no idea if that trickle of power for the LED is actually enough to drive your MCU or not.
limpid nest
how can I make covered (not tented) vias in F360? My friend suggested it and I can't find the setting
unreal flax
I'm not sure whether that's something which is done in F360 or done at the fabricator in their setup. The copper in the Gerber file already extends over the via normally, I think, so it's just a matter of telling them that the vias needs to be filled and covered.
unreal flax
"Via in pad" is the usual terminology for that technique.
(Assuming that I'm interpreting your question correctly.)
limpid nest
I think what my friend meant was mask fully covering the via?
I can ask again
Definitely not via in pad
unreal flax
Oh, mask, not copper? I think that would be in the DRC settings. There's one for the via-mask clearance, probably.
unreal flax
Yeah, seems to be in the "masks" tab. You can set a limit such that through-holes smaller than some size don't have a mask clearance at all, while larger ones do.
limpid nest
Yeah, seems to be in the "masks" tab. You can set a limit such that through-hole...
Would I make both of these 0?
No, that didn't seem to do anything
distant raven
No, that didn't seem to do anything
Limit is the field you’re looking for
Just adjust it until the via are tented in manufacturing view
limpid nest
Ahhhhh nice thanks
Pretty proud of this board. Sure it's physically bigger than my last one, but that's just so I can use the mounting holes. But I didn't autoroute a bit of it!
And I used less space on this one than my last one, I think
Or at least used it more effectively
hmm @distant raven I took it all the way down to 5 mil in increments of 5, and it doesn't seem to affect the manufacturing view.
limpid nest
no luck. here's an example of what I see. Doesn't seem different than before.
distant raven
Huh
limpid nest
Holes are .35mm
limpid nest
can you get custom female headers cut? I'm real bad at cutting them myself
unreal flax
can you get custom female headers cut? I'm real bad at cutting them myself
Yes, Digi-Key will do that as a "value-added item" when you order a breakaway header of a particular size.
snow jackal
i'm working on a low power project
and wanted to add battery voltage sensing, and was reminded of that using a voltage divider between vbat and ground puts a steady drain on the battery.
doing some searching, a mosfet disconnecting vbat from the vmon divider would allow the micro to turn sensing on and off.
i then stumbled upon this schematic from the Nordic Thing, and have some questions about whats going on
its using both a p and n channel mosfet to control voltage to the vmon divider
why two and not just one mosfet?
limpid nest
Can this stepper motor driver (https://www.adafruit.com/product/2448) be used with other steppers? And if so how can I determine compatibility?
heavy jasper
@snow jackalYou could technically use one P-FET, and wire the gate of the PFET directly to your microcontroller if you knew these 2 things:
- your inputs were 4.2V tolerant, and didn't leak enough that they'd overwhelm a 1M shunt resistor and pull the line low. (having the second FET means that you can specifically purchase an ultra-low-leakage option)
- you could set the output to open-drain configuration (effectively mimicking the N-FET shown here) - if you only had push-pull available, depending on your high-side output voltage and the VLi-Ion, you could either never turn the battery sensing off when your MCU is powered (say you had a really low voltage MCU - 1.8V - it could only drive 1.8V to the P-FET gate, the source would be up to 4.2V, so the Vgs would be sufficient to turn the FET on).
Also a word to the wise if you're going to do this: check the input impedance of the ADCs you're going to use resistors this huge, and add some cap. This voltage divider has a combined thevenin impedance of 160K - so imagine the "correct ADC voltage" with a 160K resistor in series with it heading into your ADC. If your ADC has, say, a 100K static input impedance, the actual read ADC value would read out as only 38% of what the correct reading would be. Generally the actual input current of the ADCs will be spiky, so a cap can buffer that out to have vagely correct readings. But even more so: if you're adding the FET switching circuitry anyway, you can use way smaller values of resistors (which will make the effective source impedance less) without facing the static leakage penalty.
modest grail
can the 2 circled parts be combined into one?
heavy jasper
Likely yes, though it'd be nice to have the cap near the input of the LDO instead of near the connector. Also FYI -it seems like you've double-named the top net VBUS and +5V by placing two power port indicators.
modest grail
i actually combined a qt py and a powerboost1000c and they have the 5v traces named different things
heavy jasper
find-replace is your friend here
The net can't have 2 names at once in the final design, so best option is your ERC complains loudly at you, worst option is half the things just don't get connected
modest grail
i technically already did in a previous version, but i wanted to trim things up and kinda started over. let me see if i can remember where i placed it
heavy jasper
Not a huge deal - just something to get sorted out before you head into layout (and worth putting a TODO on your schematic as a reminder to yourself if you aren't going to fix it immediately otherwise it's way too easy to forget - ask me how I know)
modest grail
yeah, its right in the original
here are the 2 main components in my original layout, all labeled correctly
i figured that since the usbc and the voltage shifter(not sure if thats the right name) share the same 5v, cap, gnd layout, i could eliminate a capacitor
heavy jasper
This seems like it'd be fine; if anything I'd shift the cap over towards the LDO so it's also not getting in the way of the track currently snaking through.
modest grail
remind me what ldo is please
heavy jasper
Low-dropout regulator (the 5V -> 3.3V linear regulator)
modest grail
ok. so if i remove one capacitor, i should put the remaining one near the ldo
im moving the ldo closer to the connector so it shouldnt be an issue
limpid nest
Might want to double the capacitance of the remaining one, no?
heavy jasper
Meh - just 10uF total is probably fine, especially if you're choosing a good cap.
limpid nest
Something with 2x+ rated voltage?
heavy jasper
That's part of it; I'm spoiled and also don't spec less than X7R dielectric if I can avoid it.
limpid nest
I do the same, with other people's money. But I don't design anything that gets made at scale
heavy jasper
More so in this context - if you need a bulk cap for larger power smoothing on the 5V rail, it's probably worth specifying a separate bulk cap specifically for that purpose
snow jackal
<@!505107768156356657>You could technically use one P-FET, and wire the gate of ...
ah thanks for the writeup!
that answers a bit on the other oddity to the design of the 1M resistors
for my circuit i'm using 3.3v logic and nimh cells, i was trying to figure out the reasoning in their design
heavy jasper
So - I think you meant to use a P-channel MOSFET here, but you used an N-channel MOSFET
so it will never be able to truly turn off (note the body diode going from 3.3 to R3)
snow jackal
whoops
i take it i want to pull the gate up on the p-channel then to have it default to closed?
heavy jasper
Correct - you want the default to be 0V Vgs, so the FET is off.
Then by pulling the gate low, you get -3.3V Vgs, which turns the FET on (as long as you have a logic-level FET)
heavy jasper
Yep! Worth noting - your current through the 10K now completely overwhelms the current in your sense divider when you have it turned on
heavy jasper
Depending on your total duty cycle - this might still be acceptable for your application, but if so I'd advise lowering the resistances of your divider (see above about ADC input impedance)
snow jackal
i hadn't considered either ADC impedance
or the affect that pull up resistors being might be having on the current draw when being driven low by the mcu, and the change in voltage that might have on the divider
thanks!
cedar salmon
whats decent software to plan a pcb free?
nothing super complicated, but not terrible
snow jackal
i've been using KiCad to much success
has a bit of learning curve though
snow jackal
most of the pcb software has some builtin part lists
common "footprints" of standardized part sizes
cedar salmon
perfect
snow jackal
kicad is a multistep process
schematic with symbols -> assign part footprints to symbols -> layout and path circuits on pcb
snow jackal
looks like you can open the kicad pcb editor and just place footprints and draw circuits
but that might not be a good idea depending on the complexity of the design
limpid nest
I dont know any of the symbols
If you decide you want to spend money, EAGLE is what adafruit uses. Autodesk is slowly merging eagle into Fusion360. Fusion360 is great because you can do solid modeling as well. You can make a 3d model of your PCB with components on it and add it to your assembly
The only things I don't really like about F360 is the automatic rat's nest and the cloud of it all. I liked to backup my EAGLE projects with Github
limpid nest
For fab houses, if you want to buy American, OSHPark is a great choice. If you don't care to have the quality of OSH or don't care about buying American, PCBWay and JLCPCB are great. Not an exhaustive list.
cedar salmon
what?
limpid nest
To have the board made
limpid nest
Interesting.
cedar salmon
i needed to buy baby oil or something too
limpid nest
I'm mildly confused.
cedar salmon
bro me too!
limpid nest
Are you gonna etch your own board on copper?
cedar salmon
Im a python programmer
uh
i think im gonna use a flashlight on a piece of copper
and then nail polish off the ink
limpid nest
Interesting. What are you gonna use kicad for then?
cedar salmon
gimme a sec, ill find the video again
apparently I cant swear here
it looked very clean
limpid nest
Ahh. Tbh this sounds like a pretty convoluted and difficult way to get a PCB but I def hope it works and you have fun
cedar salmon
Id love to hear your feedback
limpid nest
I'm no expert, not even close, but if you're just having fun I have no qualms
If you were designing a product for work I'd advise against this method
snow jackal
getting simple 2 layer PCBs printed is pretty cheap, probably less cost than the supplies.
but the DIY approach will be very fun!
limpid nest
It's the way a friend of mine (in his 70s) did it. Except they had to draw the traces. No CAD
If you open up an old enough electronic device you'll see hand drawn traces.
We're spoiled by CAD and library services.
snow jackal
i've seen them! traces drawn that way can be very organic looking
limpid nest
Hope it goes well! It's a cool method
If you don't paint your nails, maybe start so you can get practice with nail polish application lol
cedar salmon
if I only have a single sided pcb.... how do i hop over another line?
drill through it and use a lead?
supple pollen
drill through it and use a lead?
Yes, it's called a "jumper".
worldly schooner
<@!887510739462537236>
If it's worth anything, your ADC doesn't have power or data connections.
bright thistle
For fab houses, if you want to buy American, OSHPark is a great choice. If you d...
AISLER is a good middle ground for what I've seen.
- cheaper on bigger boards (compared to OSHP)
- allows to pubblish boards
- fabs in the US as well, otherwise in DE
- supports Kicad out-of-the-box (allows to donate to them at checkout as well).
- pricing is "open source" as well (https://aisler.net/help/getting-started/pricing)
- their site on github (https://github.com/AislerHQ).
they only offer two or quad layer, ENIG or HAL, with no exotic features like flex PCBs, but I think for prototyping is good enough
(errata: US is the country of origin for their 2-layer ENIG boards, not the fab location 😅 )
cedar salmon
@worldly schooner I couldnt find a device that has the same layout of my lcd driver, it's an 12c line
worldly schooner
What device?
cedar salmon
I was just using something in place to show that yes, those pins are being used
standby
just needed something to emulate the J1 connector
tidal cliff
which of these footprints is better? (same device, found in different libraries)
tough matrix
I expect it is QFN?
I'd go with the second one
tidal cliff
LGA16
left one is copied from adafruit
I tried the one on the right recently and had a poor success rate, wondering if adafruit had a good reason to think the shorter pads are better
limpid nest
Also @cedar salmon I've generally had it recommended to me not to power an LED from a gpio pin. It will work it just isn't the best practice.
Oh looks like you fixed it
cedar salmon
how do i enable it otherwise?
limpid nest
Mosfet
Is this board 3.3V only?
I want to drive my LEDs at 5V, is that possible with this board?
limpid nest
Somehow I thought there wasn't a learn guide. I don't have my glasses on (working nights so this is my morning)
Thank you.
unique patio
what LED's need 5v?
limpid nest
I can level shift the i2c signals.
tough matrix
since it includes constant-current driver, it will provide exactly enough voltage to each LED to maintain required current - so it doesn't really matter if supply voltage is 5v or 3.3v
limpid nest
Ones that are 30+ feet from the board. I just don't want to have to worry about voltage drop in the lines.
I'd hate to spend a bunch of time designing the board and then realize I have too long of cables. I don't think it's an issue but I'd rather avoid it entirely.
Thanks @tough matrix @unique patio
limpid nest
since it includes constant-current driver, it will provide exactly enough voltag...
Does it have boost circuitry in it?
tough matrix
no, as far as I see, so indeed, for long runs of the cable, 3.3v might just not be enough to produce sufficient current
you are right
limpid nest
Thx
unreal flax
I tried the one on the right recently and had a poor success rate, wondering if ...
It may be the difference between a footprint for hand-soldering (where you'd want the extended pads to be able to get an iron on them) versus reflow.
limpid nest
A friend of mine who is consulting for us reviewed my PCB and he's really against my using a giant single signal power plane (+5V). In one instance he's against it because it means there isn't a "direct" connection between my decoupling caps and my ICs. However, electrically it doesn't seem like there's a difference between a short trace and a short travel across a polygon. Am I wrong?
distant raven
Well, is the power plane on the same layer as your components?
I’d argue that it’s okay to have your power planes as inner layers if you have 4+ layers
I would just use traces of its 2 layers. With the exception of powering an array of LEDs since a mostly continuous plane will deliver current better than a trace.
heavy jasper
You still would want to have some of your decoupling capacitors adjacent to your ICs
and then via out from the inner plane to the outer layer and a small trace that runs to your decoupling cap and the component
(at least for the ~0.1uF class decoupling caps - any bulk higher-ESR caps are fine to put further away)
limpid nest
Ah I have only 2 layers
Next revision will be 4 but I have to get this one done soon
I know this has got to be possible, and I'm super over using the group tool and clicking dozens of traces. There has to be a way to globally change all traces under a certain width to a new width, in Fusion360. Anyone have a tip?
supple pollen
A friend of mine who is consulting for us reviewed my PCB and he's really agains...
A plane is a better (lower resistance and inductance) connection than a trace, it also adds useful distributed capacitance.
limpid nest
hmm that's opposite of the advice I've gotten elsewhere. I'm kind of confused as to who to believe. I've already re-worked my board to use traces to nearby planes for my decoupling caps. We'll see who's right if it doesn't work.
supple pollen
A lot of people don't really comprehend the basics. These folks work in industrial lightning protection, for things (like radio transmitter towers) that expect to be struck by lightning while in operation, and are intended to keep operating. They have to get their physics right or equipment and people can be damaged. They have some good explanations on why flat wide conductors are good low impedance routes. Sure, you aren't dealing with lightning, but the same sorts of considerations apply to fast spikes and decoupling capacitors. https://www.polyphaser.com/News/DownloadFile?downloadGuid=3676caa6-581e-40ed-b25a-590bad89ec80
limpid nest
Thanks I'll give that a read.
limpid nest
A lot of people don't really comprehend the basics. These folks work in industr...
Hm, I must be missing it, but I didn't see anything in the white paper that directly relates to the decoupling cap thing.
It was my intuition that a broad connection using a plane is best but I have had a number of EEs tell me that that's incorrect.
distant raven
Hm, I must be missing it, but I didn't see anything in the white paper that dire...
I know plenty of people with EEs that couldn’t design a PCB
limpid nest
These are PCB designers by trade
Here is what was recommended to me. This is a cap connected to ground and the nearby 5V plane.
distant raven
Well, doing something professionally doesn’t always mean you’re following best practices
limpid nest
with 20 mil traces
distant raven
What’s the thing to the right of the cap?
limpid nest
a 5V plane
distant raven
Huh…
limpid nest
I guess the idea is that there should be 1 and only 1 path from the plane to the terminal of the cap and then to the power pin of the IC
distant raven
I would generally agree that would be the case even with a solid plane
limpid nest
that was my intuition as well but I didn't have the extensive electrical education these people had
distant raven
There’s only one entry to the 5V end of the cap
limpid nest
nor practical experience
distant raven
That’s the 5V pad
The more critical thing here is closeness to the IC it’s decoupling
limpid nest
yeah everything is <1mm away. Basically as close as I can get it and still be able to solder
distant raven
Then the plane should be fine
heavy jasper
power distribution network
limpid nest
Thats what I guessed, thx. I get why technical articles are written for a certain audience but the phantom initialisms can be annoying
tacit raptor
What is the best resource to get started with PCB design?
Have experience in CAD
limpid nest
The Art of Electronics is well recommended. I have purchased it but haven't read it yet. It may not cover PCBs but it will help you with components
modest grail
a battery mounting board with hookups for a volt meter (with momentary micro switch,) toggle switch (love clickies,) and a 2.1 barrel port. designed to fit in an altoids tin. with a barrel jack to allegator clip, you can quickly plug it into any 3.7v project
how does it look?
modest grail
so, does anyone have experience with aisler for pcb fab? their boards are cheap, 16usd for 3 budget boards
tough matrix
not me.
But it seems comparable in price to OshPark, which a lot of people - myslef included - have used a lot.
modest grail
same pcb on osh was 33usd
sorry. 37
gerber labs cant even upload the gerber files to tell me how much it is
tough matrix
as for the board design:
- I would use thicker traces for power. You have lots of room to spare - why not make the trace from positive pin of barrel connector 40mils?
- usually the footprint for barrel connector has slots rather than round holes - the "pins" are commonly flat contacts
is there a reason why you use round holes in this case?
modest grail
a, the closest i could find, b im using a breadboard barrel port
tough matrix
in eagle?
modest grail
yes
modest grail
as for the board design:
- I would use thicker traces for power. You have lots...
all the traces or just those to the connector
tough matrix
I am not using Eagle, but I am sure there shoudl be slotted footprints for barrel terminals somewhere there
modest grail
these are the only 2 and only one of them is through hole
tough matrix
all traces that carry main current to/from battery
(but not necessary e.g. for traces to voltmeter)
tough matrix
I'd get footprint eslewhere then. E.g. https://www.snapeda.com/parts/PJ-002A/CUI Devices/view-part/?ref=digikey
modest grail
would a fill work better than a trace on this board?
tough matrix
probably
also: in two places, your traces are too close to another through-hole pad
at the switch SJ1 and SJ2
you have room, move it farther away
modest grail
@tough matrixhows that
apparently the distance between all traces and pads is 6mil
i did not set that up. that is default in eagle
tough matrix
6mil should be ok with most fab houses, but there is still (small) chance of a short. given that you have lots of space, I'd set the separation distance to bet at least 8 mil, better 10 mil.
distant raven
6/6 is usually what I’ll do
I’ve done 5/5 with OshPark successfully many times
And I usually do 10mil holes with 5mil ring
It’s the trick for smöl designs
limpid nest
So I'm looking at frequency vs impedance plots for the decoupling caps I'm considering. I'm working in the 100 kHz range. All the caps I've looked at have really high impedance (relatively at least) in that range. Yet, people are telling me it doesn't matter??
worldly schooner
100kHz noise, or 100kHz signal?
limpid nest
Signal
No idea about noise
But if the noise is lower frequency that's even higher impedance
worldly schooner
The noise frequency is generally the switching frequency of any switching converters that power your device.
That's the range your decoupling caps ideally have lower impedance.
You usually don't put a decoupling cap directly on a signal line, so that shouldn't matter too much?
supple pollen
So I'm looking at frequency vs impedance plots for the decoupling caps I'm consi...
Capacitors generally have lower impedance at higher frequency. At 100kHz, a 1000pF capacitor will have about 1600Ω of impedance. I don't know if that's "really high" to you, or you're looking at even smaller capacitors.
limpid nest
I was wrong about the freq of the signal I'm decoupling. I'm decoupling the frequency of the PSU not the SPI bus
supple pollen
Hmm. If it's an LT1170 based PSU, that frequency would be around 100kHz. 🙂
distant raven
Okay… so I’m looking at the various versions of the MCP73831T in the SOT23-5 package. And I’m trying to figure out why there is none of one variant vs the other
limpid nest
I'm currently trying to figure out how to get an old TV to do what I want but my next step is to figure out the freq of the switching supply
distant raven
For instance, the MCP73831T-ACI/OT has 34k in stock on Digi-Key
But the ATI/OT variant has 0
The difference in them isn’t all that much
Based on this table here you wouldn’t really tell the difference between using one over the other
One might not be as great as power consumption when it’s not charging but that seems to be the biggest difference
supple pollen
7.5 vs 20 is almost a factor of 3, but I don't know what those terms are, offhand
Ah, charge termination current ratio, in percent. Huh.
distant raven
So ideally for the average product this won’t matter that much
Obviously the AT variant has a better ratio but if you need to continue to make a product with the part, the AC variant would be a perfectly acceptable replacement
supple pollen
I wonder if those are basically the same dice, but binned by performance, and they just didn't get many of that bin in the last few runs.
supple pollen
Hence my wonderment
distant raven
I might just snag a bunch
supple pollen
Not a bad idea, all the grades seem like they'd be fairdinkum chips
distant raven
34k in stock at DigiKey vs waiting 2 weeks to get the same but over priced for LCSC of the AT variety
They are charging $0.40 over singleton value
And $0.04 over multiples
I’m also wondering if LCSC ordered all of the TI chips
supple pollen
If they're seeing an ongoing demand for them, it would be a smart move on their part.
distant raven
Because there are some TI regulators I can only get on LCSC but they have 2022/2023 lead times elsewhere
My go to 3.3V 500mA LDO I’ve only been able to get from LCSC
tough matrix
which one is that?
limpid nest
It’s a very nice LDO
Are LDOs hard to get atm?
distant raven
3.3V ones, yes
tough matrix
my favorite LDO, AZ1117, is widely available: https://lcsc.com/product-detail/Linear-Voltage-Regulators-LDO_Diodes-Incorporated-AZ1117H-3-3TRG1_C110474.html
distant raven
I found this part with the Digi-Key mobile app. https://www.digikey.com/product-detail/en/RT9080-33GJ5/1028-1509-1-ND/6161657
tough matrix
it is larger than most, but also provides up to 800mA
limpid nest
I don't design anything to be produced at scale, so I don't mind if something is a little more expensive
limpid nest
I found this part with the Digi-Key mobile app. https://www.digikey.com/product-...
Wow the digikey mobile app actually works for you?
distant raven
Yeah
limpid nest
it simply does not function on my galaxy S21 Ultra
distant raven
The iOS app is pretty stable
limpid nest
Hmm. If it's an LT1170 based PSU, that frequency would be around 100kHz. 🙂
Looked it up, it's 65kHz.... how can I possibly source a suitable bypass cap for this supply with such a low frequency? Don't I want as low of an impedance for my bypass cap as possible?
distant raven
Honestly, 0.1uF is a very good value for filtering in terms of response/impedance.
limpid nest
hmm but the impedance is at or near it's highest in that range..
distant raven
You could use anywhere from 0.1uF to 1uF and be perfectly fine
limpid nest
Maybe I'm giving too much thought to this
I was planning on having 0.1 and 1 uF caps
distant raven
Problem is, the more capacitance, the slower response of the power line
distant raven
With power filtering, you balance speed and impedance which is why filtering ranges between 0.1uF and 1uF.
limpid nest
ah ok
distant raven
Some designs will use 4.7uF and 10uF to decouple lower frequencies and smooth power up
limpid nest
huh it seems like 10 uF is better from an impedance standpoint. I assume it leads to lower rise time in the PSU?
distant raven
Pulled this image from a stack exchange answer
Correct
Which might not be desirable for some microcontrollers and devices
limpid nest
oops I'm in re-routing eternal punishment now
I'll just use 0.1 uFs and do more reading about the issue.
distant raven
Lol
0.1uF is just a very common and good value to use
If you look across lots of designs, it just works really well and is a good balance
limpid nest
what do you think about the issue of, on a two layer board, connecting your decoupling caps using the power pour vs connecting them to the power pin with a trace from the power pour to the cap then to the IC power pin? my friend is insistent that the latter is best practice and demands I find a source saying otherwise. Notably he hasn't provided a source besides him.
I haven't been able to find a source saying either way is best. More copper between the cap terminal and the IC pin seems like it would just lower the impedance of the path.
distant raven
limpid nest
Oh I totally misread the plot. Is the black one both 10 uF tantalum and .1 uF ceramic?
no, I didn't read it wrong
distant raven
In terms of the power plane question, power plane delivery is actually much better
Traces are current limited and offer much less EMI shielding/decoupling than solid pours.
limpid nest
this is my argument but he has a master's degree and I don't
distant raven
On 4+ layer boards especially, power planes are basically vital for power delivery
supple pollen
Looked it up, it's 65kHz.... how can I possibly source a suitable bypass cap for...
That's a pretty high frequency, easy to filter.
supple pollen
this is my argument but he has a master's degree and I don't
I don't have a master's degree either, but you're right and he's wrong.
distant raven
The way I see it, and this is a view from wiring houses. It’s better to have more capacity than you need and never use it, than not have enough and need it.
Madbodger has made a few great points too about impedance and EMI
limpid nest
yeah I'll just do my thing and Live, Laugh, Love.
limpid nest
ah mine is 2 layer, does that matter? I notice adafruit doesn't use big pours super often
I'm looking to put one of these (https://www.cui.com/product/resource/emc-20.pdf) before one of these(https://www.cui.com/product/resource/psk-s25d-t.pdf) but I'm confused about one aspect. What do I do with the ground pin on the PSK?
just leave it floating?
or do I need to loop it back to the ground pin on the EMC-20?
limpid nest
I'm looking to put one of these (<https://www.cui.com/product/resource/emc-20.pd...
Is that in reference to this?
I was hoping to avoid making an AC power PCB.
distant raven
Well, grounds by nature should be connected
limpid nest
Ah I missed this on the first pass thru the datasheet
so I'll have to make a small PCB to bring these together I guess.
distant raven
You want to maintain common ground in your design to ensure you complete the circuit
limpid nest
that makes sense, IDK why I thought it would be otherwise.
Any safety considerations with a small board that just has like a 3 pin terminal block with only grounds connected to it?
I'm thinking ground of the AC/DC converter, Ground of the EMC and ground of the AC power cord all in a 3 position terminal block.
limpid nest
Certainly cheaper
spice turtle
Your stuff is din rail mounted so I assume its going in a metal panel
You can buy them at homedepot, lowes, etc
limpid nest
It's not din rail mounted and it's going in a plastic enclosure so no real chassis ground
spice turtle
Will the enclosure have a sub plate?
spice turtle
It will look neater 😉 lol
limpid nest
It doesn't seem like it has room for that
spice turtle
You mount those things on din rail, mount the ground block to the panel
I mean it could float around as long as your grounds all go to one place
limpid nest
I already have the chassis mount version so I'm a bit locked in there.
limpid nest
Not sure where to ground the block to. I guess it'll go out thru the AC power cable to earth ground.
spice turtle
earth ground
when power comes in, we have ground go direct to that block
then your other grounds connect the same way
limpid nest
interesting. I'd then stick it into the earth right?
I'll need to find a copper rod. Maybe I can weld a wire to the rod
I guess a bit of copper pipe would work.
what about shock potential with that big un-insulated ground bar?
spice turtle
Yes, ground rod is generally earth but you may want to read up on the requirements for that
Its more electrical design
But Ive seen 3ft poles hammered into the ground. Theres usually a screw at the end
https://www.homedepot.com/p/Southwire-5-8-in-Grounding-Rod-or-1-2-in-Rebar-Ground-Rod-Clamp-for-10-SOL-STR-2-STR-Wire-65176440/312648487
https://www.homedepot.com/p/ERICO-5-8-in-x-8-ft-Copper-Ground-Rod-615880UPC/202195738
Oh you probably want this one
https://www.homedepot.com/p/Blackburn-1-2-in-Type-G-Ground-Rod-Clamp-for-10-SOL-to-2-STR-Wire-G5-B1-30/202907599
limpid nest
thx
limpid nest
Its more electrical design
what do you mean by this? More of an electrician thing?
spice turtle
yes
limpid nest
Yes, ground rod is generally earth but you may want to read up on the requiremen...
kool thanks, I'll look into it. Do you mean local code?
spice turtle
kool thanks, I'll look into it. Do you mean local code?
Or general code
limpid nest
local codes are stricter than the state codes, so I'll use those. Thanks again
limpid nest
pg 8 has the selection guide for trimming resistors. I ended up getting an 80k 1/2W resistor but I'm not sure if I should get a higher wattage. Anyone have an opinion? https://www.cui.com/product/resource/psk-s25d-t.pdf
unreal flax
What's your output voltage? You'd need like 200V to hit 0.5W through an 80k resistor.
limpid nest
output is 5V but I don't know what the voltage on the TRIM pin is
unreal flax
I presume it's supposed to be Vref, since that's what it would be in the absence of the trim resistor. You shouldn't have any trouble with resistor wattages... this is a low-power feedback circuit.
limpid nest
that's what I thought just figured I'd check thx
What do I need to google to figure out which pins on this connector are power and ground?
unreal flax
It looks like the pins are just a straight connection to the USB cable wires, so Googling the USB-A standard cable pinout should set you straight. As I recall the middle pair are D+/D- and VBUS/GND are at the ends, but you'll want to verify that and ensure you have the correct orientation.
limpid nest
yeah I don't want to put Power to Ground and vis versa Thx
why might a USB A library part have this big keepout area on it? Is it something I can safely remove? It's very inconvenient.
supple pollen
It may be designed for a connector that is that physical size
limpid nest
Hmm one sec let me get the part
does the mating part not just go inside the receptacle?
supple pollen
It does, but as you can see, USB-A receptacles are chonky
limpid nest
yeah I'm just confused by the huge keepout. I can get around it but it's odd
Like do I need to have the keepout fully on the board or can it be sticking off like it is?
Another thing. I'm making a diode library part but because of the size of the symbol, in the symbol part of the library, the names of the symbols are in the "wrong" place. It's quite misleading. Is there a way to move the name around? There must be but I never learned it.
it appears as if K is A and A is K in this configuration.
Fusion360 though it's probably the same in EAGLE
if it's possible
supple pollen
EAGLE has some weirdness with pin labels, I think there's a way to move them but I don't remember how (and I'm using EAGLE 7.7 which is pretty old)
limpid nest
Hmm, I'll see if I can google my way out of this.
But now that I see the text there I'm going to have to re-listen to the whole Dark Tower series
Looks like it's just a shortcoming of Fusion360. Nobody has answered this question from may https://forums.autodesk.com/t5/fusion-360-electronics/moving-the-name-on-a-pin-in-library-editor/td-p/9448851
the question being the follow up at the bottom
cinder anchor
oh I was about to say, you can totally move them, but, I realized that you're in the library editor
I played around with EAGLE, Fritzing, and KiCad a while back, just trying to understand how they worked. I think I like EAGLE best out of all of them, even though it has quirks.
Then I quickly realized I have no idea how to actually design the circuit board itself, like, with routes and layers and all this other stuff that I have no idea about. Are there any good classes or tutorials you guys can recommend?
tough matrix
which version of KiCad did you use?
cinder anchor
A fairly recent one, it was like 4-5 months ago.
tough matrix
stable version - even now - is 5.x, but they have been working on 6.0 for a long time; it is currently 6.0 RC1
limpid nest
I don't have any tutorial recs but I recommend just picking a simple project you want to do and go from there. Could be as simple as mounting several adafruit breakouts onto one big board with a feather or similar.
tough matrix
as for eagle, sparkfun has a nice series of tutorials
limpid nest
the feather tripler is nice but sometimes you just want to have a bunch of sensors in one place and stringing tons of jumper wires together is not as neat
Is there a way to do simple holes in the board view of F360? I know how to do them in a library part but I don't see the same tool here
I'd prefer true holes over vias
ah there it is
It's under the Place dropdown if anyone was curious
cinder anchor
When I do breakouts and things like that, I usually have QT/Qwiic connectors on those boards, and I tend to just 3D print a base plate with screw bosses. I don't bother with nutserts on these, I usually just use the metric screw features in the BOSL library for OpenSCAD and add threads that way. It's just for little PCB screws anyway...
I've even printed some that were stacked. 😄
You can mount them fairly close to each other, and use the super-short QT cables
cinder anchor
stable version - even now - is 5.x, but they have been working on 6.0 for a long...
You recommend I try KiCad or should I just stick to EAGLE?
tough matrix
i switched to kicad 6, partly because Autodesk is killing standalone Eagle and moving users instead to electronics design component of Fusion 360. Even though that is obviously based on Eagle, somehow I found it much less appealing.
limpid nest
If you want to do 4+layer boards you'll need to pay money for EAGLE/F360
and with how cheap 4 layer boards are, it's worth learning to do them
tough matrix
but everyone has to decide for themselves what you like better. My only advice is,if you are trying kicad, try the 6.0 RC1, not stable
limpid nest
but with F360 for $495 dollars you also get a very good solid modeling program, and can export your PCBs into 3D objects
thats $495/yr
tough matrix
for me it was not a question of price - i have free educational version of F360
limpid nest
ah nice
tough matrix
and i do use F360 a lot for mechanical design
unreal flax
Looks like it's just a shortcoming of Fusion360. Nobody has answered this questi...
I think all you can do is turn off the pin names in its properties, and then place your own labels if you want them. Not really necessary for a diode symbol anyway.
tough matrix
but for EDA, i use KiCad
limpid nest
I think all you can do is turn off the pin names in its properties, and then pla...
That's what I gathered as well. They need to fix this, it's a pretty egregious oversight
cinder anchor
but with F360 for $495 dollars you also get a very good solid modeling program, ...
can you not export 3D objects from KiCad?
limpid nest
I have never used KiCAD.
tough matrix
yes, you can
cinder anchor
Yeah, I just don't have $500 to spend on a software I use as a hobby, like 10-15 times a year. I already don't like F360 for designing 3D models, and I don't really do mechanical stuff, so I have no need for the fancy features of F360 on that side, and like shurik said, the electronics design component in F360 was for some reason kind of like EAGLE, but way more annoying.
@tough matrix how do the auto-tracing (routing?) compare between F360 and KiCad?
limpid nest
makes the evil eye sign at the auto-router
tough matrix
i did a project where i designed board in kicad, exported it as STP and imported in F360 together with other mechanical components.
there is no autprouting in KiCad, and i dont miss it
limpid nest
For a female USB-A thru hole connector, should the SHIELD pins be grounded?
cinder anchor
For a female USB-A thru hole connector, should the `SHIELD` pins be grounded?
they don't need to be (AFAIK)
tough matrix
there is "assisted routing": you drag a trace, and it automatically goes around obstacles
cinder anchor
For a female USB-A thru hole connector, should the `SHIELD` pins be grounded?
wait, which ones are the shield pins? The ones that clamp on the board, the big ones?
limpid nest
yerp
cinder anchor
nah, only reason you solder that down is to improve stability in my knowledge of USB
so you may still want to have ... holes with conductivity ... for those
hahaha, dude, my Swedish/English brain broke
what are those holes called, the ones with copper on 'em?
limpid nest
holes
tough matrix
plated
limpid nest
or vias sometimes
cinder anchor
aaah, plated that's it
limpid nest
I'm getting conflicting answers from StackExchange
supple pollen
Technically the shield pins should be connected, but opinions vary on what they should be connected to. One popular choice is a high value resistor to ground to dissipate static electricity before the contacts begin to mate.
tough matrix
nice, haven't seen that before
limpid nest
interesting. What qualifies as "high value" for this?
this is only transmitting power btw
supple pollen
For instance, Cypress recommends a 1Meg resistor in parallel with a 4.7nF capacitor (to absorb RF interference coming in through the shield).
limpid nest
is the RF interference only an issue for USB ports that will be transmitting data?
supple pollen
Intel recommends grounding it directly.
Kinda-sorta: RF interference can couple into the power leads (which can act as an antenna) then affect anything else connected to the same power net.
limpid nest
man these are all reputable sources, it's hard to pick between them
Hmm
well I guess I'll do the 1MOhm resistor + 4.7 nF cap method. Do you happen to have the source handy?
cinder anchor
bookmarked that, thanks
limpid nest
https://www.infineon.com/dgdl/Infineon-AN15456_Guide_to_a_Successful_EZ-USB_FX2L...
thx
limpid nest
https://www.infineon.com/dgdl/Infineon-AN15456_Guide_to_a_Successful_EZ-USB_FX2L...
What wattage resistor would you use?
limpid nest
oh, duh
I don't see a 4.7 nF cap there, just a 1 MOhm resistor
How about these? I have filtering on my power line already
unreal flax
The ones in the top-right would only be necessary if you need a "USB is plugged in yes/no" logic signal.
limpid nest
iiinteresting. How does that work, electrically? I'm not seeing it.
Can I ignore the .1 uF cap to 3v3? This board doesn't have a 3v3 signal anywhere on it.
unreal flax
Yes, you can ignore it. That's more specific to the chip this app note was written for.
limpid nest
ahh
unreal flax
The 39K/62K is a voltage divider to drop 5V down to 3.3V, and the 0.1uF cap stabilizes the output.
limpid nest
oh my tired brain put the second 0.1 uF cap in series with the 39k resistor. I'm burnt apparently
that makes sense, but hmm, doesn't that drop the USB line voltage to 3v3? Or is this a "specific to the chip in the app note" situation?
supple pollen
Yes, the 3.3V chip would want a 3.3V input, so those resistors provide that from the 5V signal.
unreal flax
VBUS is still available for the raw 5V... the voltage divider just produces a secondary path with a 3.3V signal.
limpid nest
oh, isn't it odd to use a resistor divider as a regulator?
supple pollen
It's not a regulator, just a source of a voltage to be detected.
limpid nest
ohhhhhh
that makes sense
How would folks go about making this symbol in F360 EDA? I know there are convoluted ways to bring art in to F360 but I hate them more than people who have wronged me
supple pollen
Arc tool, line tool.
limpid nest
why do I keep forgetting to expand the dang menus
SMH
This'll have to do
Hm, any idea why the footprint for this part would indicate it's polarized when it isn't? https://www.digikey.com/en/products/detail/kemet/CK06BX105K/2397510?s=N4IgTCBcDaIIwAYFwLRgQZlQOQCIgF0BfIA
unreal flax
Part libraries are made by a lot of different people, so... 🤷♂️
unreal flax
Very likely, yeah. I tend to make a lot of my own library parts, or otherwise carefully check anything I use... 😅
limpid nest
I'm not super careful about checking but the one time I did, it was wrong.
modest grail
6mil should be ok with most fab houses, but there is still (small) chance of a s...
i went with 10m and it looks pretty good
limpid nest
I've gotten away with 6 mil before but it's dicey hand soldering that, esp if you don't have a bunch of soldering experience. Real easy for the heat to lift up traces
modest grail
right now, i am hand soldering, and like was said before, i got plenty of room
modest grail
i just hope the volt meter isnt too big
modest grail
yes. raven
limpid nest
Ahhh ok seemed familiar
limpid nest
i just hope the volt meter isnt too big
Which part is that on the board?
modest grail
the square hole in the upper left
limpid nest
ahh
modest grail
This is what it started as
but it looks like crap an is only insulated with bandage wrappers
so i redesigned it to work with these
limpid nest
Nice work!
modest grail
the toggle cuts power entirely to the barrel and the microswitch turns the volt meter on so its not always on and drawing power
the 6 header holes near the bottom are just to solder wires to keep the battery from moving
if my measurements are right, it will fit in an altoids tin
limpid nest
Getting measurements right is tough. Especially on something so small
modest grail
im currently looking for other barrel plugs so i can use it in many applications
yes it is. luckily, thats part of my formal training
limpid nest
Nice. Can I ask what kind of training?
modest grail
machining, with a furthering in cnc, as well as some draft work
modest grail
anyone know where i can get pink pcbs that wont cost an arm, leg, my soul, and my firstborn?
spice turtle
https://www.pcbbuy.com/online_pcb_quote.html
is the only place coming up. For a 100x100 PCB, x5 its $67+$26 shipping to the US
distant raven
anyone know where i can get pink pcbs that wont cost an arm, leg, my soul, and m...
PCB Buy and PCB Way do pink
worldly schooner
PCBWay technically does purple, not pink, but the preview makes it look more like a magenta than a real royal OSHPark purple...
Oooh, PCBBuy explicitly has a Sakura Pink though
distant raven
Yeah
tough matrix
I heard good things about production quality of PCBBuy. On the other hand, there was also a story when they posted for marketing purposes photo of one of the orders without bothering to ask permission of the client, which made him quite angry.
modest grail
So pcbway is trustworthy?
cinder anchor
So pcbway is trustworthy?
for sure
cinder anchor
I haven't personally tried them yet, but I know people that have used them and been happy
modest grail
a mix of power boost and qtpy rp2040, this little board tells you (I hope) what the power level of your battery is, and shines the appropriate colors on a panel mount rgb switch. it also controls an electromag, with or without a power interrupt switch. its use? to enable switching from a physical pistol to a physical rifle for more in depth immersion into the oculus vr system (no it doesnt act as a controller, you still need the default touches.)
anything that needs to be fixed? i mage the traces as large as i could and added some space between parts. the spacing is about 6mil to10 mill or so.
unreal flax
It's hard to review things in this format, but I am somewhat worried about placing vias directly on some of your pads. It's sometimes a necessary evil for thermal pads under QFNs, but you've also got them on LEDs and capacitors, which could lead to some potential reflow problems.
limpid nest
Also not all fab houses can do that, correct?
I think OSH can but for example JLC cannot
That = via in pad
unreal flax
They can all "do it" if you just want the drill hole to go through the pad, which isn't great for soldering, but is okay for things like thermal pads. Fabricating a board with true "via in pad" support means that they take the extra trouble to fill and cap off the via so the pad on top of it is still smooth like it normally would be.
limpid nest
Ah yes. Thx
spice turtle
anything that needs to be fixed? i mage the traces as large as i could and added...
going with what @unreal flax said, I would also put vias under the thermal pads connected to ground (assuming ground is your 1st and 2nd layer as well) just so they dissipate more heat.
Move that one random via from the largest IC to closer to the pin.
EM+ and D3 look a little close
Remove the values from your PCB. Keep only names (R1,R2,C1,C2, etc etc)
Same with your pin connectors. Just call out the signals (+,-,RX,TX, etc etc). Make the names around 50mils
Normalize all your text for your name designators (I usually use 32 mils)
Im assuming you still have clean up to do, otherwise try to align all the names to one side.
These are only suggestions though 🙂 you may do things differently but this is how i try to do things
modest grail
going with what <@!382380426628562955> said, I would also put vias under the the...
i assume by thermal pads, you are refering to the ones under the 3 main chip (P$21 and P$1). if so, all those large pads do indeed have a via in them. im not sure what one random via you are refering to. em+ and d3 have .5mm between them. should it be more? and yes i still have clean up to do in which most unnecessary values go by by.
as to the via under pad concern, it shouldnt take much to tweek that, just need to spread things out a bit more.
spice turtle
i assume by thermal pads, you are refering to the ones under the 3 main chip (P$...
These are FETS but the idea is the same:
So yes, more pads means more heat transfer
and the 0.5mm looks deceiving is all 🙂 I couldnt tell from my end.
wait, Now I have to go read up on something. Maybe I should have via's under my drain pins.
heavy jasper
This becomes a bit of a trade - yes, it does improve heat connectivity. But also - it improves heat connectivity when you're soldering, so it makes hand-soldering them (even with a hot air gun) a bit of a pain because you have to dump heat into your entire plane in order to get the pad hot enough to melt.