OtterPill is a 3$ STM32F072 devboard featuring USB 2.0 full-speed, a DFU Bootloader, a USB-PD Phy and Arduino nano alike pinout and size.
Changelog V1.2: BOM cost reduction by ~40%, PCB can be fully populated by JLCSMT, more efficient buck converter (PCB gets less warm at 20V), GND-hook for probing, Reset-Pin exposed as pad, power pads for 20V/5A
More documentation and firmware examples will be aviable soon.
How do I get an OtterPill? I have made a small production run, OtterPills will be available soon! More details will be announced via Twitter :3
Building and Flashing
Via Makefile and DFU
Or you can generate a basic firmware, with HAL init and Makefile, with CubeMX. The binary can then be build with make and flashed with dfu-utils. To enter DFU mode, press and hold the Button while plugging in power.
$ make $ dfu-util -a 0 -s 0x08000000:leave -D build/firmware.bin
Blink example firmware
USB-PD example firmware
This is a working USB-PD example using ChibiOS, a new voltage can be requested by pressing the Button.
Shields and addons
Most Arduino shields should be compatible.