Jetson Nano, using UART0

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
1

Hello,
I need to use UART0 ( TX : pin 99, RX pin : 101) from jetson nano Tegra210.
In dev/tty* i don’t see TTYTHS0.
Normally, uart0 is connected on M2 connector for BT/WIFI module of the eval board.
i designed my own board and i use UART0 like a simple UART not for BT / WIFI module on M.2 connector.
Could you tell me how to activate Uart0.

Best regards

3

hello Dawiid71 ,

Jetson Nano brings three UARTs out to the main connector,
please refer to [Jetson Nano UART Pin Description] in Nano Product Design Guide to review the pin connections.
thanks

4

I know Jetson nano has 3 uarts.

But could you give me what’s the tty* for UART0 pin 99 AND 101 ? or how to do to activate uart0 because it doesn’t appear in dev/tty*. I can only see uart 1 : ttyTHS1 and uart2 : ttyTHS2 .

Thanks

5

hello Dawiid71 ,

it’s software mappings to the ttyTHS*.
you should refer to device tree and kernel init messages regarding to serial ports.
check this topic, Topic 153941, it shows the mappings for serial ports of ttyTHS*, and UART*
thanks

6

if i see the device tree and the pinmux_config_file: signal name : uart0 txd/rxd = Ball name uart3 tx/rx are configured as UC3-TXD/RXD and if i see the init messages, we can see the message : “started uart on ttyths0” .
But ttyTHS0 don’t appear in /dev/tty*.

7

hello Dawiid71 ,

it’s serial@70006200 for your uart-3.
for example, $L4T_Sources/r32.5.1/Linux_for_Tegra/source/public/hardware/nvidia/platform/t210/porg/kernel-dts/tegra210-porg-p3448-common.dtsi

        serial@70006200 { /* UART-C : UART3 : M.2 Key E */
                compatible = "nvidia,tegra114-hsuart";
                dma-names = "tx";
                nvidia,adjust-baud-rates = <921600 921600 100>;
                status = "okay";
        };

by checking the kernel logs, it’s actually using ttyTHS2.

[    1.610929] 70006200.serial: ttyTHS2 at MMIO 0x70006200 (irq = 65, base_baud = 0) is a TEGRA_UART
8

hi JerryChang,

so, if i see things correctly, we have 3 UARTS :

the UART0 of the module ( UART3 of the tegra point of view ) on M.2 key
the UART1 of the module ( UART2 of the tegra point of view ) on the 40-pin extension
the UART2 of the module ( UART1 of the tegra point of view ) on the debug serial port

so where can we access it ?

i know I’ve got two ttyTHS1 & ttyTHS2 .

according to what you said , seems to be ttyTHS2 for the M.2 interface, ttyTHS1 for the 40-pin UART.

but where is the debug port interface ?

thks

9

hello bob7421,

you may also refer to Jetson Nano Developer Kit User Guide,
for example, it’s 12-pin button header, J50 for Rev B01 platform.

10

hi JerryChang,

i know that. but how do i communicate with it ? cannot determine the correct tty

11

hello bob7421,

the default baudrate is 115200/8n1, check the port register to your host machine, you may use the utility to communicate with it, such as picocom or minicom if you’re using serial to usb device,
for example, $ picocom -b 115200 /dev/ttyUSB*
thanks

12

Hello,
It’s a mistake ttyTHS2 is good : the UART0 of the module ( UART3 of the tegra point of view ) on M.2 key.
Sorry for the inconvenience.
Best regards

1 Like
14

Hello JerryChang,
It’s OK, this is ttyTHS2 for UART0 (c). Tiredness played on me tricks .
Sorry for the inconvenience.
You can close and erase the issue.
thank you.

15

Hi Dawiid71
So which is debug serial port?
thks

1 Like
17

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