Serial Communication

I am trying to make a serial communication btw Xavier and PC. I made my connections according to this header pinout diagram:
https://www.jetsonhacks.com/nvidia-jetson-agx-xavier-gpio-header-pinout/

BUT when I run “lsusb”, the serial port is not listed.

So, the header pinout just talks about the Jetson TTL UART device.

Which machine do you run “lsusb” on – the Jetson or the PC?
Which serial connection adapter are you using on the PC?

In general, a USB serial device doesn’t care whether it’s actually hooked up to any wires or not – when you plug it in to a PC, and the correct drivers are present, the device will show up as a serial port.
If you try to “talk” to it when no TTL serial wires are hooked up to it, it will simply wiggle the voltage on the pins without anyone listening. (You can verify this with an oscilloscope.)

So, if you run “lsusb” on your PC, and it doesn’t see a USB serial device that you’ve plugged in to that PC, then the problem is with the drivers/compatibility of that PC, and has nothing to do with the Jetson.

If you run “lsusb” on the Jetson, well, the built-in serial ports are not USB serial devices; they are regular serial devices, and thus have non-USB device names.

Addition to what @snarky says: “lsusb” only shows a USB device. This implies the end with a USB cable connected. This end will show with lsusb regardless of whether the serial UART on the USB cable is talking to another device or not. The integrated serial ports, from the Xavier side, will have certain “/dev/ttyS#” or “/dev/ttyTHS#” device special files if the drivers loaded, but there will be no relation to USB (and thus no mention of this in lsusb).

It is the PC side driver for the UART in the USB cable which creates the “/dev/ttyS#” files on the PC side. Even if the driver is not present, then lsusb would show the device via lsusb, but if the actual serial device special files are missing, then you know the driver is missing on the PC.