Triple USB-to-serial adapter firmware for flashing onto an STM32F103C8T6 "blue pill" minimum development board
Run make to build, then flash the src/pill_serial.bin file to a blue pill over the PA9/PA10 serial port with BOOT0=1.
Then plug in the blue pill into your PC using USB, and three virtual (ACM CDC, "/dev/usbmodem") serial ports should appear.
These correspond to the three USART ports available on the board, in order:
| TX pin | RX pin |
|---|---|
| PB10 | PB11 |
| PA2 | PA3 |
| PA9 | PA10 |
This code is heavily based on the Black Magic Debug Probe firmware. Note if you only need one serial port, you may be better off using the Black Magic Probe, since it also provides a JTAG/SWD probe, whereas pill_serial only provides serial ports.
See also associated blog post: Triple USB-to-serial adapter using STM32 blue pill