When customizing and debugging a boot loader including u-boot, it is necessary to connect to the UART and check the output. This article explains how to connect to the Jetson Nano’s UART.
How to connect UART
- Carrier board A02
- Connect UART receive to RXD, UART transmit to TXD, and UART ground to GND on J44.

- Carrier board B01
- Connect UART receive to RXD, UART transmit to TXD, and UART ground to GND on J50.

Refer to this article for the types of Carrier board above.
A cheap USB serial converter is available at https://amzn.asia/d/dYlzl4M. USB extension cables can be purchased at 1$ stores.
On Linux host PC, use gtkterm and connect to /dev/ttyUSB0 with Baud Rate 115200, Parity None, Bits 8, Stopbits 1, Flow control none.

That’s all.