J44 serial not working


I’m trying to get the J44 serial working. Right now, the GPIO serial (J41) has no issue working (/dev/ttyTHS1), but /dev/ttyTHS1 is not even passing the “loopback tx to rx” test, and always appears as off in Minicom for example.

Do I need to disable something that is using this serial port? My goal is to exchange messages on this J44 serial port with a flight controller.


There are some posts discussing about J44. Please refer to

Yes, I tried the solutions in there: disabling the different things that output to J44, but without success: running minicom on the jetson nano, with a loop jumper cable between rx and tx, for example, doesn’t give me any output.

Try to also jumper CTS and RTS. If flow control is on, then missing this would block traffic.