Libopencm3

''The libopencm3 project (previously known as libopenstm32) aims to create a free/libre/open-source (LGPL v3, or later) firmware library for various ARM Cortex-M0(+)/M3/M4 microcontrollers, including ST STM32, Ti Tiva and Stellaris, NXP LPC 11xx, 13xx, 15xx, 17xx parts, Atmel SAM3, Energy Micro EFM32 and others. ''

http://libopencm3.org/wiki/Main_Page

=Premiers pas= Suivre https://balau82.wordpress.com/2015/04/19/libopencm3-on-stm32-nucleo-board/