How do you tell the Offset addresses of all the I/O pins?


I got a BBB.

I’m building a DTO (device tree overlay) in order to set GPIO9_16 (P9-15) to Mode7 (GPIO Mode).

Where can I find the offset address of all the I/O pins? (in P8 and P9 expansion headers)

Is it stored on the BBB itself at some file?

Thank you.

Derek Molloy has published two very nice tables on github, with everything you need. Just do a web search for BeagleboneBlackP9HeaderTable or …P8… and you will find them.

From that table, P9.17 = PIN # 87, addr = 0x44E1095C, offset = 0x15C, in mode7 = gpio[5]

cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pins to see all your current settings

Don’t forget the 4 ma current limit for GPIOs! Too low for even an LED.

Hi Guy,
Thanks a lot again! :slight_smile:

It’s great information!

I wrote to you in another thread that even without compiling the DT Overlay file that should have set the P9.15 to mode 7, I managed to turn on/off and output of P9.15 as if it was GPIO.

Problem solved, thanks to the help of Ralf in that thread

Thank you again Guy.