Expansion Header P9 pin 41/42 usage

I alread tried to ask this question but it seems my posting got lost, so once again: At http://elinux.org/Beagleboard:Cape_Expansion_Headers#Full_Headers_with_8_Modes the expansion header pinout of BBB is listed. For every pin that corresponds to an output of MPU a single row with up to 8 entries is listed. Every of these up to 8 functionalities can be choosen via pin mux of processor.

But for P9 pin 41 and 42 situation is different, they are named 41# and 42@ and show two rows with different, conflicting functions. So…what does it mean? How can I choose one specific function there?


Look at the schematic. There are two pins from the CPU connected to
each P9.41 and P9.42. It is up to your software and device tree to
insure that these functions do not conflict (ie: do not enable the two
pads tied together as outputs driving different values!).

Typically, you will disable one of the pads (or set it as an input) and
use the other one.