Orin Nano UART0

[matt.read]

The Jetson I am using:
Jetson Orin NX Engineering Reference Developer Kit - Jetpack 6.0 [L4T 36.3.0]
699-level Part Number: 699-13767-0005-300 M.1

• P-Number: p3767-0005
• Module: NVIDIA Jetson Orin Nano (Developer kit)
• SoC: tegra234

I am trying to write to UART0 (UARTB – M2 key WI-FI slot) but I think its disabled by default. Here are the UART devices I can see after bootup:

As I have already flashed I wanted to try enabling UART0 in the dts file that the extlinux.conf points to:
/boot/dtb/tegra234-p3768-0000+p3767-0005-nv.dts

I converted my dtb to a dts and it was disabled so I changed it to:

I then compiled it back to dtb and rebooted but I still cant se a new /dev/THS device, I still only see:

No new device at MMIO 0x3110000

Does anyone know what I am doing wrong?

[KevinFFF]

Hi matt.read,

@matt.read

Module: NVIDIA Jetson Orin Nano (Developer kit)

Are you using the Orin Nano devkit board or the custom carrier board from ConnectTech?

Please check if there’s FDT entry in /boot/extlinux/extlinux.conf.
If not, it would load DTB from partition rather than rootfs.

[matt.read]

Hi @KevinFFF, I am on the Orin Nano devkit board (p3768-0000).

I have now tried to do this pre-flash and have edited the dtb file in Linux_for_Tegra/kernel/dtb/tegra234-p3768-0000+p3767-0005-nv.dtb

I converted my dtb to a dts and it was disabled so I changed it to:

I then compiled it back to dtb and flashed my devkit with:

sudo ./tools/kernel_flash/l4t_initrd_flash.sh --external-device nvme0n1p1 --erase-all -c tools/kernel_flash/flash_l4t_external.xml -p "-c bootloader/generic/cfg/flash_t234_qspi.xml" --showlogs --network usb0 jetson-orin-nano-devkit internal

After the Orin Nano booted up I checked my extlinux.conf file and it was missing the FDT entry so it will be using the DTB from partition like you mentioned in your previous post. I then added the FDT entry line manually and rebooted:

After reboot I still didn’t see a new TEGRA_UART@0x3110000

Maybe Im missing something from my dtb?
Do I need to add a serial3 = “/bus@0/serial@3110000”;

And a uartb = “/bus@0/serial@3110000”;

[matt.read]

just an update I have changed serial@3110000 to:

And also included:
serial3 = “/bus@0/serial@3110000”;
uartb = "/bus@0/serial@3110000";

and after a reboot I now see a THS3:

It all works now