XavierNX devKit UART number

Hi all,

I am currently using the Jetson XavierNX devkit, and I have to send and receive data via UART.

I successfully send/receive data through the pin 8 and 10 of the j12 connector, but what about the PIN 3 and 4 of the j14 connector?

I have read some topics, but I am not sure to understand if this UART is available and working the same way as the j12 UART, or if it’s a debug UART or something else.

To be clear, my question is: can I have two independent UART working the same way (THX, RX+GND cable) on the XavierNX dev board? Or is this only possible with the XavierNX module and homemade wiring?

hello matteoluci81,

Jetson Xavier NX brings three UARTs out to the main connector.
please access Jetson Xavier NX Product Design Guide via download center, you may refer to [Table 11-7. Jetson Xavier NX UART Pin Descriptions] for more details.

please also check kernel init messages for registered ports. $ dmesg | grep THS

$ dmesg | grep THS
[    1.461754] 3100000.serial: ttyTHS0 at MMIO 0x3100000 (irq = 47, base_baud = 0) is a TEGRA_UART
[    1.463285] 3110000.serial: ttyTHS1 at MMIO 0x3110000 (irq = 48, base_baud = 0) is a TEGRA_UART
[    1.464602] 3140000.serial: ttyTHS4 at MMIO 0x3140000 (irq = 49, base_baud = 0) is a TEGRA_UART

you may mapping those ttyTHS* with device tree definition for actual UART ports,
for example,

        uarta: serial@3100000 {..}
        uartb: serial@3110000 {..}
        uarte: serial@3140000 {..}

Hello JerryChang

Thank you for your help.

I checked the Jetson Xavier NX Product Design Guide, and if I understand it well, there are two available UART ports and one debug port. Can the debug port be used for something else than debugging (as a usual UART port)?

But those three ports are available with the XavierNX module main connector, as you said. But with the XavierNX DevKit, there is only one UART available on the J12 connector, and one debug UART on the J14 connector no?

Matteo Luci

hello matteoluci81,

there’re 3 UARTs available for Jetson Xavier NX, UART0 to M2; UART1 to 40-PIN; UART2 to debug.

here’re some similar discussion thread for your reference,
please check Topic 160948 for the steps to disable combined uart on Xavier series,
it’s Topic 170116 to talk about use it as normal uart serial port.

I think I have the information I need

Thank you very much.

Matteo Luci