Had a heck of a time trying to get the Jetson Nano UART working, but finally got it to serially communicate with a Teensy 3.5. The Jetson peripherals are not packaged in convenient ready-to-go libraries as they are in Teensy and Arduino. Here's the working UART example:

Jetson Nano UART C++ Example

Here's a photo of the two boards connected via RX1/TX1 on the Teensy, and Jetson pins 6, 8, & 10 ("/dev/ttyTHS1").

Click image for larger version. 

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