Jetson Orin Nano (DevKIT) /dev/ttyTHS0 buffer debugging

Robotics & Edge Computing Jetson & Embedded Systems Jetson Orin Nano
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Hello fellow humans,

I am currently working on debugging a serial connection between a Jetson Orin Nano, and some custom microchip.

To make it very simple - I am doing this:
1.)

stty -F /dev/ttyTHS0 115200 -parity cs8 -cstopb

while true; do
  echo -e "#something#something/r/n" >> /dev/ttyTHS0
  sleep 1
done

2.) echoing what is coming in on ser.µC.RX to ser.µC.TX.
3. ) Trying to read the answer with cat < /dev/ttyTHS0 - not getting anything.

So I did a little bit of research - finding, that the ttyTHS0 seems to have DMA.
→ [A] so I am wondering - does the good old way of echo and cat work on DMA-UARTs?

[B] Is there a way, to just use ttyS0 (any interaction of mine with it causes an Input/output error so far)?

Thanks and have a great day.

3

Hi m.j.kurz,

What do you mean about custom microchip?
Do you mean that you setup the serial communication from Orin Nano devkit with other microchip?

It seems you are verifying with loopback test.
Do you connect the TX/RX of UART1?

Could you also share the dmesg as file here for further check?

5

What do you mean about custom microchip?
Do you mean that you setup the serial communication from Orin Nano devkit with other microchip?

Yes:
[[Jetson Orin Nano Module] Devkit]<{UART0-RTxD}>[µController]

It seems you are verifying with loopback test.

Basically - yes. The µC reads and responds with the same packages.

Do you connect the TX/RX of UART1?

No - UART0. Pin 22 and Pin 32 on the DevKIT.

We figured out, that we had a problem with our ground-connection between the devices, and therefore my question [A] is solved (yes, echo and cat work for debugging basic functionality).
Regarding question [B]:
Looking for /dev/ttyS0 in the forum gave some answers - simplest one for me was this:

6

If you are talking about /dev/ttyTHS0, it should be UART1.
The UART0 is from the M.2 Key E.
You could refer to the following thread about the mapping for UART interface for Orin Nano devkit.
OrinNX : How to check UART is working? - #3 by KevinFFF
Could you help to confirm which UART do you want to use?

/dev/ttyS0 would use 8250 driver.

May I know what’s your use case?
make the debug message output from UART1 (uarta@3100000)?

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