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.

• Downloads
• Status
• Release Status
• API Documentation
• Showcase
• Datasheets
• GIT Library Code Browser
• GIT Examples Code Browser
• Licensing
• Development project discussions

• Mailing lists: libopencm3-devel (archive gmane archive), libopencm3-commits (archive)
• Gitter Chat: libopencm3 discuss
• IRC: #libopencm3 on libera.chat
• Sourcecode: GitHub
• Issue Tracker: GitHub Issues
• Sites: SF, Fm, ohloh, del.icio.us

• 2015/10/xx: Initial STM32L4 and STM32F7 support
• 2015/09/xx: USB layer overhauls
• 2014/10/15: Initial VF6xx support
• 2014/10/15: Initial STM32L0 support
• 2013/07/08: Initial STM32F0 support
• 2013/06/26: Initial STM32F3 support
• 2013/04/29: Initial SAM3 support
• 2012/10/29: Initial EFM32 support
• 2012/10/04: Using github as source code repository and bugtracker
• 2012/03/02: License changed to LGPL v3 (or later)
• 2011/11/01: Project renamed to libopencm3
• 2011/10/31: Initial STM32F4 support
• 2011/10/29: Initial STM32F2 support
• 2011/04/02: Initial LuminaryMicro LM3S support
• 2010/12/30: Initial NXP LPC13xx support
• 2010/10/02: STM32 USB device stack support
• 2009/07/20: First working STM32F1 example
• 2009/07/15: Project started