STM32F4XX library for MMDVM project This is the STM32F4XX_Lib directory structure with just the needed code for MMDVM. Copy this STM32F4XX_Lib directory inside the MMDVM source code project. You have to conserve the STM32F4XX_Lib folder name: MMDVM/STM32F4XX_Lib The source of this package can be found here: http://www.st.com/en/embedded-software/stsw-stm32065.html In order to run the MMDVM firmware correctly, there are the following modifications already done in this package: 1) STM32F4XX_Lib/Device/startup/startup_stm32f4xx.c : - Added C++ global constructors support - Changed initial stack pointer 2) STM32F4XX_Lib/Device/system_stm32f4xx.c : - Changed PLL_M definition (support "integer" only crystal frequencies: 8, 12, 16 MHz, etc) 3) STM32F4XX_Lib/Device/stm32f4xx_conf.h : - Peripheral header file inclusions