Jetson Xavier NX UART can't send

I want to use the serial port (J12 pin8 pin10) of NX development kit for data transmission. The hardware connection uses TTL to USB, but in the process of using it, I found that the serial port receives data normally (PC → NX), but when it sends (NX → PC), the PC can’t receive data.
But I can detect the waveform sent by the serial port by using the oscilloscope, and I have also detected the hardware tool of TTL to USB, which is good. What is the reason? Do I need to set the device tree? I have never changed the device tree before, and I think this serial port can be used directly.

hello xiaopang059,

you’re using port J12, 40-pin expansion header, pins 8 and 10, which are UART TX and RX.
the default uart baudrate is 115200/8n1, please check $ ls -la /dev/ttyUSB* on your host Ubuntu machine, and please using serial port utility (such as, picocom or minicom utility) to setup the communication.

It’s /dev/ttyTHS0. The operating system of PC is win10. Nx’s serial port software uses cutecom, so there should be no problem in setting it, because I can receive the correct data from / dev / ttyths0。

hello xiaopang059,

so am I understand correctly there’s no further issues?

But I send data from / dev / ttyths0, and the PC can’t receive it

hello xiaopang059,

may I know what’s your steps to send data for testing?
could you please use the serial port utility to setup communication.

Thank you for your patience. I connect the ttyths0 of NX development kit directly to the STM32 development board, and it can communicate normally. It should be that there is something wrong with my TTL to USB tool.

My TTL to USB tool can communicate with STM32 development board directly, but when I connect with NX development board suite, I can only receive, not send. What a strange phenomenon.

@xiaopang059 you may also try J14 UART rx/tx pins
also there is a third UART on m.2 header somewhere

What are the permissions found via “ls -l /dev/ttyTHS0”? Btw, “/dev/ttyTHS0” is the same hardware as “/dev/ttyS0”, but with different drivers. If the “group” of this device is tty instead of dialout, then you are probably getting some interference due to serial console already owning this port. The group “tty” gives away whether this port is bound to serial console, versus if available for general use (group “dialout” is general use).

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.