These are my simple snippets for STM32 (compiled with libopencm3) Be carefull: due to API changes these projects will compile only with opencm3 from archive libopencm3.ori.tgz F0 - for STM32F042 and STM32F030 F1 - for STM32F103 WARNING!!! arm-none-eabi-gcc from gentoo have a bug with division on F0. Use toolchain from https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads instead! CMSIS-headers: https://github.com/modm-io/cmsis-header-stm32