Alright, fixed a few traces, moved the ground pour to inner1 and pvcc to the bottom.
Hopefully final design, replaced a few extended parts with basic equivalents, and replaced the voltage regulator due to being out of stock
This newly added trace looks weird. Super close to its neighbor, and vias smaller than the others.
Also, the four traces running along the bottom edge of the board should be spaced out as much as possible, only going close together where pinch points around vias require it. Running side by side for a long distance like that is where crosstalk does become a real concern. Space them away from the traces on the top layer too, since they’re sharing the same ground plane.
EDIT: @Rikky is right, the LDO will burn up. I was off by a factor of 10 in my calculation before. 21.7V*35mA is 760mW, not 76. And most SOT-23 regulators say 200 or 250mW max, so the 500mW from DS8242-33’s datasheet is probably overly optimistic.
But let me ask a so trivial question, why do you need to design a board and still stick with one dev module as bluepill?
alright, ditched the on-board voltage regulation and added a connector instead, fixed the wacky traces on inner 2 and spaced out the bottom edge traces as much as I could.
Edit: added the i2c resistors i seem to always forget, and an spi connector for alternative sensors.
Hi kamilo,
Nice project, could you share a bit about the control and coding side with the C8T6? I want to ask if you plan to do current sensing on this board? If yes, what is your expected control loop frequency? Earlier I tried a similar setup like yours, with the C8T6 bluepill, AS5600, and the DRV8302, but the bluepill couldn’t handle current sensing and that slow AS5600 reading above 4kHz loop. I’m curious to see how your board’s performance would turn out.
Yes, Id be happy to, if I had much of a coding side of this worked out yet. Being designed for a robotic arm, i knew i wouldnt need all that much rpm so i havent really worried about the max loop frequency and am waiting to see that in practice. As for current sensing, yeah im planning to use it.
Ill be happy to share more once i actually find it out.
Yeah, 4KHz is probably about right. IIRC, my Leptons with 64MHz STM32G031 run around 5KHz, but that’s without current sensing. On 170MHz G431, I get around 20KHz without current sense and 16.5KHz with. So if we do 5*(72/64)*(16.5/20) we get 4.6KHz predicted loop rate. Probably fine for a robot arm.
Alright then, ill get ready to order the boards soon-ish.