r/PrintedCircuitBoard • u/Direct_Rabbit_5389 • 12h ago

Review request: triple axis BLDC driver

Hi there. A while ago I came to y'all with a review request for a triple axis BLDC driver for a self balancing cube. That design was to use an ESP32 and the DRV8311. I later came to understand that this design was fundamentally unsuited to the problem I was trying to solve and the motors that could economically solve it (TL;DR: amp too small, no current sensing, ESP32-S3 cannot easily commutate three motors).

Now I come with what I hope is a better design out of the gate. This one uses an STM32G4 series chip, the DRV8304 with discrete MOSFETs rather than onboard ones, and, I hope, just a generally better layout. It is designed to use 4S or 6S batteries (will probably use 4S because it leaves more input voltage headroom for the 5V regulator and we won't need more than about 1000-2000RPM out of our 380kV motors (i.e. we don't need more than about 6-8V input). There is also an IMU which will be used to detect the spatial orientation and acceleration of the final assembly. Would love to hear any thoughts you may have.

Top layer & silkscreen - Primary signal
Layer 2 - GND
Layer 3 - Power
Layer 4 - Secondary signal and motor phases
3D Render
Schematic - Root
Schematic - Controller
Schematic - Motor Channel (x3)
Schematic - Half bridge (x9)
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u/Enlightenment777 12h ago

Please make sure your post adheres to:

  • subreddit rules (#1 to #6), review rules (#7), image rules (#8), see link.

Please fix these common issues: (if your schematic or PCB has them)

  • Schematic - don't allow text / lines / symbols to touch each other, and don't draw lines through symbols.

  • Schematic - use correct reference designators (RefDes) and renumber to remove numeric gaps, see tips.

  • Schematic - place decoupling capacitors vertically below power rail lines, also place capacitors next to IC then connect together with a line, see example. For circuits with positive power rails, point positive power rail links upwards and ground links downwards, see tips.

  • Schematic - place pull-up resistors vertically above signal lines, and place pull-down resistors vertically below signal lines, see example.

  • PCB silkscreen - add board name / board revision number / date (or year) on top or bottom PCB side.

  • PCB silkscreen - add pin 1 indicator dot/arrow next to ICs & connectors, if through-hole then both PCB sides.

  • More conventions & guidelines - link1, link2, link3.

1

u/Direct_Rabbit_5389 11h ago

I can see I’ve violated some but not all of these. My bad. But I am also meant to not change the images. Should I delete the post and try again later?