CCCCCCC's Debug serial port output on unsuccessful boot

Working with a BBB that has a custom hardware cape on it.

Sometimes I get an unsuccessful boot out of it where when connected to the serial debug part I see the letter C printed indefinitely.

I’d say 90% of the boot attempts work (serial debug looks normal) and 10% I get the infinite C printout and no successful boot.

Any ideas?

Your cape is screwing up the boot pins. The processor cannot find a valid boot source based on what it reads from those pins.


I have seen this too.
It is as Gerald says. Your cape is loading one or more of the boot pins.
I did a cape - even though all the connections were high impedance inputs,
it was still enough to twitch the boot pins. Anyway, I ended up adjusting a couple
of the pullup resistors to adjust for it on the pins I was using - changed from 100k to
33k. Only had to do this for the pullups - so apparently stealing even a little from the
33uA max source was enough to impact the boot read of the pins.
Hope that helps.


Ok Thanks guys,

Identified and fixed the effected pin and now getting consistent boots.