/STeMCell

STM32F4 breakout board in pro micro pinout. Designed mainly for ergo split keyboards.

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STeMCell

STM32 breakout in promicro footprint

Features:

  • Pro micro footprint
  • STM32F4x1 series MCU
  • Support half duplex USART communication in any of D0, D1, D2, D3 using jumpers
  • Onboard switch to enable/disable USB DFU bootloader
  • Inbuilt TX pullup for UART half duplex communication
  • User LED on PA8
  • Extra 5 pinout on bottom like Elite C
  • Supports QMK and ZMK
  • JLCPCB assembly supported

WARNING: This design does not have any fuse, esd protection or reverse voltage protection.

v1.0.0

Front         Back

In Real Life

irl1         irl2

Order it here:

v0.0.2 https://oshpark.com/shared_projects/LJiMLzWF

Working:

  • Voltage regulator
  • User LED
  • All pinouts
  • I2C - with OLED
  • UART - Split communication
  • UART Half duplex on D0, D1, D2, D3
  • VUSB sense

UnTested:

  • With RGB lights

Changelog:

v1.0.0

  • Change all components to 0402 for easier routing and jlcpcb manu
  • Added Boot0 switch for easier USB bootloader access
  • Assembled in JLCPCB

v0.1.0

  • Silk screen update to v0.1.0
  • Use 4.7k/10k for VBUS sense resistor bridge. Changed after testing

v0.0.2

  • Added VBUS Sense
  • Removed SWD breakout
  • Added extra pinout at bottom like elite C

v0.0.1

  • Initial revision
  • 0602 SMD components
  • SWD breakout at bottom

Previous versions:

v0.1.0

Front         Back

v0.0.2

Front         Back

In Real Life

irl1         irl2

v0.0.1

Front         Back

** Warning:** Current version might be not tested yet

Pictures are generated using pcbdraw:

pcbdraw --dpi 1024 -s set-blue-enig -l lib\pcbdraw_footprints\,default stemcell.kicad_pcb images\v1.0.0_front.png
pcbdraw --dpi 1024 -s set-blue-enig -l lib\pcbdraw_footprints\,default -b stemcell.kicad_pcb images\v1.0.0_back.png