NVIDIA Jetson Xavier - Using the serial console

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The NVIDIA Jetson carrier provides a USB connector for debugging using the serial console. The debug port location can be found on one of the sides of the board. The exact location can be seen at the Front view of NVIDIA Jetson Xavier developer kit.

Connecting this port to a PC running Ubuntu using a micro-USB cable will register four serial ports in the PC. They will be assigned devices /dev/ttyUSB0, /dev/ttyUSB1, /dev/ttyUSB2 and /dev/ttyUSB3, assuming no other /dev/ttyUSBn existed before the connection. This will only work if the board is connected to the power supply but will work even if it is not powered up.

The debug port will be the one in the last position, usually /dev/ttyUSB3.

To connect to the debug port on the Developer Kit, any serial console interface can be used.

Using minicom

To use minicom for accessing the debug port, make sure you have installed minicom on your PC:

apt install minicom

and then open minicom on your PC with the corresponding parameters:

minicom -D /dev/ttyUSB3 -8 -b 115200

If you have trouble accesing the /dev/ttyUSB3 device, it may be related to the ownership of the serial port device. It is usually owned by root, but available to the dialout group:

$ ls -al /dev/ttyUSB*
crw-rw---- 1 root dialout 188, 0 Oct 31 15:56 /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 1 Oct 31 15:56 /dev/ttyUSB1
crw-rw---- 1 root dialout 188, 2 Oct 31 15:56 /dev/ttyUSB2
crw-rw---- 1 root dialout 188, 3 Oct 31 15:57 /dev/ttyUSB3

You can either run the minicom command as the super-user (not recommended for long-term use), or add your user to the dialout group:

sudo addgrp $USER dialout

You may need to log-out and log back in for the group change to be applied.

How to set up and use minicom

When you have the setup ready and you have connected to the corresponding serial port, you'll be able to watch the full output of the startup process from the early stages, including the bootloader debug:

[0000.086] I> MB1 (prd-version: 1.0.0.0-t194-41334769-a3872862)
[0000.091] I> Boot-mode: L0 coldboot
[0000.094] I> chip revision : A02 
[0000.097] I> Bootrom patch version : 7 (correctly patched)
[0000.102] I> ATE fuse revision : 0x200
[0000.106] I> Ram repair fuse : 0x0
[0000.109] I> Ram Code : 0x0
[0000.111] I> rst_source : 0x0
[0000.114] I> rst_level : 0x0
[0000.118] I> Boot-device: eMMC
...


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