libopencm3_dfu

Modified DFU bootloader example from libopencm3-examples repository.
Modified DFU bootloader example from libopencm3-examples repository.

Controlled by GPIO B12 - tied to ground it boots user app,
tied to 3v3 it jumps to dfu bootloader. Debug led on GPIO C13
should blink few times when entering dfu bootloader.

Make sure you're flashing your application to 0x80002000
or adjut APP_ADDRESS in usbdfu.c