Power BBB from cape


I was under the impression that the BBB could be powered through the SYS_5V pin. I designed a prototype cape and tried this method, but it doesn’t power up so I assume that I presumed wrong. Is there a way to power the BBB through the P8/P9 headers? If there is already a discussion on this, I’m sorry. Could you link me to it if there is? I Googled for a couple hours and couldn’t find the answer.


Did you look at the System Reference Manual? It is covered there.

You can use either the VDD_5V or the SYS_5V to power a cape. But you need to make sure the power sequencing is all taken care of on driving the pins of the processor.


Hi Jeremy,
VDD_5V is what you want to power the Beagle. It is the same net that is connected to the +5v barrel connector. SYS_5V is an output from the PMIC chip.


Oh, OK mark! Thanks for that! That is where I went wrong. I appreciate the help.


BUT, male sure you don’t have things powered on the cape before the board powers on. Otherwise, you can damage the board. So make sure you fully understand what you need to do before just grabbing that rail and using it.

If you don’t want to check the SRM, at least read this. http://circuitco.com/support/index.php?title=BeagleBoneBlack#Expansion_Header_Usage


Thanks Gerald, I will definitely look into that. Not sure how you can use that rail without powering everything at once… So far it has worked fine, I shall see after more testing.