A free/libre/open-source firmware library for various ARM Cortex-M3 microcontrollers.
Here is a list of all modules:
[detail level 12]
 User interrupt service routines (ISR) prototypes for Atmel SAM3A series
 DebuggingMacros and functions to aid in debugging
 NVIC Defineslibopencm3 Cortex Nested Vectored Interrupt Controller
 User interrupts for Atmel SAM3A series
 Cortex M0/M3/M4 System InterruptsIRQ numbers -3 and -6 to -9 are reserved
 SysTick Defineslibopencm3 Defined Constants and Types for the Cortex SysTick
 Clock source selection
 User interrupt service routines (ISR) defaults for Atmel SAM3A series
 NVIClibopencm3 Cortex Nested Vectored Interrupt Controller
 SysTicklibopencm3 Cortex System Tick Timer
 Gpio_definesAccess functions for the SAM3A/U/X I/O ControllerLGPL License Terms libopencm3 License