UART2-TXD-Pin discrepancy on BBone


My BBone has Rev A.5 and I see a discrepancy with the documentation Rev A5.0.0 or Rev A5.0.1 regarding the pin of UART2-TXD.
The docu says Pin P9-21, but I got the signal on P9-23.
The pinmuxing has been set to output and mode 1.

The TXD-pins for the other UARTs fit with my docu.

In case, that for my bone an older docu is relevant, please let me know, where I can fetch it.

Many thanks in advance

I will double check this when I can get to it…


I looked at the schematic, and I see that the transmit data out pin UART2_TXD does indeed go to pin B17 on the processor which goes to
connector P9-21. I also looked at the PCB file and traced the connection from the processor to the P9-21 and it does go to P9-21.

What do you see on P9-21 if it is its the TXD signal?


Hi Gerald,

Many thanks for your quick and professional answer.

In preparation of an answer to you, I doublechecked the signal and to my surprise, the UART-TXD output is on Pin 21!!!

So I must have yesterday a very bad day, not able to count properly, even with checking the pincount twice.

Sorry for your not necessary load.

Best regards

No problem at all! It is hard sometimes to keep the pin numbers straignt especially with no numbers on the board. I wish we had room to put it on there, but we didn’t.