Should we keep the API defined in
./sw/airborne/arch/stm32/mcu_periph/can_arch.c?
Considering that is is not actually used anywhere I would not
feel too bad to scrap it.
The thing is that the libopencm3 API is quite different. And I
would like to take advantage of the hardware filters in the chip
more.
can_hw_init() and can_hw_transmit() would practically be the
same. But I would like to change the rx_callback method so that
every module could register it's own callback.
Which would make the code quite stm32 specific, I admit. More
generic abstractions could be possible though.