Enable UART4_TX pin on BeagleBone Blue


I would like to use UART4 interface on BeagleBone Blue. Unfortunately only UART4_RX pin is working.

I already made modification where I soldered cable to put out UART4_TX pin, but I cannot use it as UART pin.

I found out that the pin name is P9_13 here: beaglebone-blue/BeagleBone_Blue_Pin_Table.csv at master · beagleboard/beaglebone-blue · GitHub

I tried to configure it as uart, but config-pin cannot find the appropriate file:
debian@beaglebone:~$ config-pin -l P9.13
ERROR: open() for /sys/firmware/devicetree/base/ocp/P9_13_pinmux/pinctrl-names failed, No such file or directory

I started looking into .dts overlay method:

but I’m not sure if this is right problem solve direction.

Can someone help me to configure pin P9_13 as UART_TX?

Thank you!

I think I found the way. I added line to /boot/uEnv.txt:

and UART_TX pin is working.

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