Embedded boot loader

The embedded boot loader is located in the System memory, programmed by ST during production. It is used to reprogram the Flash memory using one of the following serial interfaces:

• USART on pins PA14/PA15 or PA9/PA10

• I2C on pins PB6/PB7 (STM32F04xxx, STM32F07xxx and STM32F09xxx devices only): This is what we're using!

• USB DFU interface (STM32F04xxx and STM32F07xxx devices only)

What are we using? NEITHER! We use gdb to flash.