px4io boot: kinda works, but not quite
px4io boot: kinda works, but not quite

*  was not able to stumble upon correct timing...
*  usually boots two or three motors, maybe takes a reboot to get the
   third and fourth..
*  need to benchmark timing of hwf4 a bit better to reproduce it.

GaloisInc/ivory-tower-stm32,GaloisInc/ivory-tower-stm32,GaloisInc/ivory-tower-stm32