[Nix-dev] Cross development for STM32

[Tim Barbour]

Thank you Philip and Alexey.

I have tried gcc-arm-embedded as you suggested, and had no trouble building
the ChibiOS UART demo for a Maple Mini board (I did have to change GPIOC_LED
to GPIOB_LED; presumably the demo was written for a board with more LEDs).

$ file build/ch.elf 
build/ch.elf: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, not stripped

$ arm-none-eabi-size build/ch.elf 
   text    data     bss     dec     hex filename
   6880     416   20448   27744    6c60 build/ch.elf

I have yet to figure out how to get the code onto the board. Something like
connecting to UART1 and starting the boot loader. I also have an stlink
device, so openocd should work too, if necessary.

Tim