Use Tegra Combined Uart as regular serial on Orin NX

[EstebanBosse]

Hello,
we are trying to use the serial interface UART2/UC3/ttyTCU0 as multiple posts in this forum.

We base our work on this thread, and we achieve the exactly same results but using an Nvidia Orin Devkit.

We are using the SDK 36.2 and this is the fragment where we disable the combined uart:

	serial {
		compatible = "nvidia,tegra234-tcu\0nvidia,tegra194-tcu";
		status = "disabled";
		phandle = <0x229>;
		mboxes = <0x10b 0x01 0x00 0x12d 0x01 0x80000001>;
		mbox-names = "rx\0tx";
	};

Here is the fragment where we enable the serial port serial@c280000:

aliases {
...
serial3 = "/bus@0/serial@c280000";
...
}
...
                serial@c280000 {
                        clock-names = "serial";
                        resets = <0x03 0x66>;
                        interrupts = <0x00 0x72 0x04>;
                        clocks = <0x03 0x9d>;
                        compatible = "nvidia,tegra20-uart";
                        status = "okay";
                        reg = <0x00 0xc280000 0x00 0x10000>;
                        reset-names = "serial";
                };

We managed to get the serial device present, dmesg:

sudo dmesg | grep 0xc28
[    3.740130] c280000.serial: ttyS3 at MMIO 0xc280000 (irq = 71, base_baud = 114285) is a Tegra

We have tested the serial port with echo, minicom, etc from the PC with a serial to USB device and also sort circuit of tx<->rx on the orin.

tx is currently working as expected, but rx is not working.

We are 100% confident the electrical connections are fine because when flashing the initial jetson image the debuging serial port over /dev/ttyTCU0 is working fine, it is possible login using the serial console as expected.

Some other documentation we used for our testing:

Repurpose Debug UART for 'normal' comms on Xavier NX

Hi, we have been experimenting for a while, with various devicetree and config changes - to make use of the third UART on the Xavier NX. Ideally we want to add an additional serial peripheral (a STM32 microcontroller) on this port, and do reliable bidirectional comms with it. We have LIDAR and other seral This, by default, uses the ‘combined’ or tcu driver - and appears as /dev/ttyTCU0 By default, on startup, there is a lot of logging output sent to this port, as far as we can tell by the BP…

Enabling ttyTCU0 as regular UART on Orin Nano

Thanks Kevin. I’ve lost access to the device for a few days but as soon as I get it back I’ll give this a try.

Orin NANO UART1 (ttyTHS0) functionality not working

It seems the result is expected showed on your logic analyzer. What are you expecting to see in putty? You are connecting this UART from the board to another device. Why you would see the log from the putty of your host PC?

Enabling the correct UARTs on the Orin NX

The default devkit device tree enables the following uart peripherals [ 0.262065] 31d0000.serial: ttyAMA0 at MMIO 0x31d0000 (irq = 63, base_baud = 0) is a SBSA [ 2.440742] usbserial: USB Serial support registered for FTDI USB Serial Device [ 2.453602] usbserial: USB Serial support registered for GSM modem (1-port) [ 5.798301] serial-tegra 3100000.serial: Adding to iommu group 2 [ 5.804654] 3100000.serial: ttyTHS0 at MMIO 0x3100000 (irq = 17, base_baud = 0) is a TEGRA_UART [ 5.…

[Jetson Xavier NX] UART Tune

Dear Sir, Apologize for this question again, this is extend from the this topic below Situation : In our design plan, the UART2 will connect with a micro-processor UART0/1 is design as generic console. According the above topic, I have a doubt/question about to specify the UART0/1 not only act as generic console, but also act with the DEBUG function/feature which could print those whole booting message(Include MB1’s message…etc). About this one, There is the hint about to tune the enable_c…

Disabling combined UART in JetPack 5.1.1 on Xavier NX

So I built our full custom image and disabled the combined UART manually by patching the device tree after flashing. The system boots and the /dev/ttyTCU0 entry is gone. This solves the initial question but unfortunately the serial port is still misbehaving somehow (in terms of communication not being reliable). However, I will mark this request as resolved because the combined UART is successfully disabled. Any suggestions on why the serial port may not be reliable though would be appreciated.

[Jetson Xavier NX] UART Tune

Dear Sir, Apologize for this question again, this is extend from the this topic below Situation : In our design plan, the UART2 will connect with a micro-processor UART0/1 is design as generic console. According the above topic, I have a doubt/question about to specify the UART0/1 not only act as generic console, but also act with the DEBUG function/feature which could print those whole booting message(Include MB1’s message…etc). About this one, There is the hint about to tune the enable_c…

[EstebanBosse]

It is also important to mention that we need to use 3 UARTs for communication with external controllers. For this reason, is mandatory for us to get this working.

[EstebanBosse]

We also tried to disable the TCU uart and use the debuging uart in the same uart.

The debugging UART with the following dtb and extlinux is sending the proper data over tx, but rx is again not working.

Please find attached the involved dts, extlinux and logging output:

no_tcu_dtb.dts.txt (306.0 KB)
extlinux.conf.txt (1.1 KB)
board_booting_output.txt (81.7 KB)

[KevinFFF]

Hi EstebanBosse,

It seems you have referred to several topic for this use case.
You may see that we’ve not verified this officially and we don’t suggest using combined uart as normal uart.
The message output from combined UART is from several firmware and you have to disable each of them. Some firmware can not disable that just using BCT/configuration files.
In JP6.0DP(R36.2), you would also notice that we’ve removed the entry of serial@c280000 so that you tried to add it manually. That’s why we want combined uart working as it is. Without the serial console log, you will be hard to do further debug.
Currently, we don’t support this use case. If you require more UART interfaces, you can use UART expansion modules or just use AGX Orin (which has 4 UART interfaces available).