How to use UART3 on beagleboard-xm which runs Android?

I want to use the DB9 connector on the Board for communicating with a serial port.
how can I do that?

Accoarding to the schematics, the Pin is GPIO166 and 165, I set the mode to UART using

echo 2 > uart3_rx_irrx
echo 2 > uart3_tx_irtx

and then I tried to use microcom to check if it works:

busybox microcom -s9600 /dev/ttyO2
root@android:/sys/kernel/debug/omap_mux # busybox microcom -s9600 /dev/ttyO3
busybox microcom -s9600 /dev/ttyO3


I didn’t receive any char on the other side,

If there is any sample script which shows how to do that on the BeagleBoard-xm, I would love to see it!
thank you very much!