RS232 connection to an Arduino

[dejhost]

Hello!

I cannot find much documentation about how to connect from the Jetson Orin AGX (Ubuntu) to a second board using RS232. In my case, the second board is is a shield, sitting on an Arduino Duo.

Following to the userguide page 19/30, I connected P

• IN31 (Ground)
• PIN 35 (RS232A_TX/) and
• PIN 35 (RS232A_RX/)

of the “40 pin General Purpose 3.3V I/O Connector” to the Arduino shields RS232 interface. Now, I’d like to check if the connection works.

• When I plug in the cables, I cannot see any log entry using dmesg in the jetson.
• I cannot detect a new entry in /dev/ in the jetson.
• Also I do not know which serial-connection properties (baudrate etc.) are supported.

Can you please advise on these three things?

My end-goal is to send and receive data between both boards using Python. Bur for a start, I use minicom.

Thank You in advance.

[carolyuu]

Hi,
Here are some suggestions for the common issues:

1. Performance

Please run the below command before benchmarking deep learning use case:

$ sudo nvpmodel -m 0
$ sudo jetson_clocks

2. Installation

Installation guide of deep learning frameworks on Jetson:

• TensorFlow: Installing TensorFlow for Jetson Platform - NVIDIA Docs
• PyTorch: Installing PyTorch for Jetson Platform - NVIDIA Docs
  We also have containers that have frameworks preinstalled:
  Data Science, Machine Learning, AI, HPC Containers | NVIDIA NGC

3. Tutorial

Startup deep learning tutorial:

• Jetson-inference: Hello AI World guide to deploying deep-learning inference networks and deep vision primitives with TensorRT and NVIDIA Jetson
• TensorRT sample: Jetson/L4T/TRT Customized Example - eLinux.org

4. Report issue

If these suggestions don’t help and you want to report an issue to us, please attach the model, command/step, and the customized app (if any) with us to reproduce locally.

Thanks!

[KevinFFF]

Hi dejhost,

It seems you are using the custom carrier board from Connect Tech.
What’s the Jetpack version in use?

@dejhost

• IN31 (Ground)
• PIN 35 (RS232A_TX/) and
• PIN 35 (RS232A_RX/)

Which UART interface are you using?

Please share the full serial console log for further check.
You should be able to get that log through Micro-USB port.

[dejhost]

Hi!
Thank you for looking into this.

1. Jetpack4. : Version: 5.1.1-b56.
2. UART interface. Not sure what you are asking here. In the user manual, it says “RS232A ttyTHS1 serial@3110000”,
3. full serial console log: I cannot connect using the RS232 connection so far. I have tried logging it using:

• usb-cable between jetson and the usb-port of my arduino due
• Minicom
• The Arduino code below.

But minicoms says Device /dev/ttyTHS1 is locked when I type minicom -D /dev/ttyTHS1 -b 115200
The logfile stays empty.

This is the arduino code I use:

void setup() {
    Serial.begin(115200); // USB Serial for logging
    while (!Serial) {}    // Wait for Serial to be ready

    Serial1.begin(9600);  // RS232 UART Serial for Jetson communication
    Serial.println("Starting RS232 troubleshooting with Jetson...");
}

void loop() {
    // Check for data from Jetson over RS232 and log it over USB Serial
    if (Serial1.available()) {
        char rs232Data = Serial1.read();
        Serial.print("Received from RS232 (Jetson): ");
        Serial.println(rs232Data);
    }

    // Send data from USB serial to RS232 (Jetson) for bidirectional testing
    if (Serial.available()) {
        char usbData = Serial.read();
        Serial1.write(usbData); // Send to Jetson
        Serial.print("Sent to RS232 (Jetson): ");
        Serial.println(usbData);
    }

    delay(10);  // Small delay to prevent overwhelming serial interface
}

[KevinFFF]

@dejhost

Jetpack4. : Version: 5.1.1-b56.

Are you using JP4 or JP5.1.1?

@dejhost

UART interface. Not sure what you are asking here. In the user manual, it says “RS232A ttyTHS1 serial@3110000”,

Okay, it seems UART5 on AGX Orin (uartb).

@dejhost

full serial console log: I cannot connect using the RS232 connection so far. I have tried logging it using:

Do you get /dev/ttyACM0 from your host after connecting the micro-USB port?
If so, please open that port from your host and you should get the serial console log.

[dejhost]

The Jetpack is version:

Package: nvidia-jetpack
Version: 5.1.1-b56

Sorry I - don’t know how the “4” sneaked in there in my previous post.

Yes, /dev/ttyACM0 apears when I connect to the arduino through USB. I also created a udev-rule, so I can address the arduino as /dev/due.

minicom -D /dev/due -b 9600

I wrote a little .ino-skript that sends “Hello” once a second.I can see this text in the minicom log.

But plugging in the RS232 connector doesn’t add any device in /dev/.

[KevinFFF]

@dejhost

But plugging in the RS232 connector doesn’t add any device in /dev/.

Please share how the block diagram of your conenctions.

@dejhost

• PIN 35 (RS232A_TX/) and
• PIN 35 (RS232A_RX/)

Why you said PIN35 for both TX/RX of RS232?

If you want to connect the peripheral device like Arduino through UART interface, you can just connect them from PIN6(GND), PIN8(UART1_TX), PIN10(UART1_RX) of 40-Pin Expansion Header(J30) on AGX Orin.

[dejhost]

I reviewed the cableing and here is the new block-diagram:

I am using the 40 pin General Purpose 3.3V I/O Connector. It seems, that the PIN configuration is different for my custom carrier board from Connect Tech.

[KevinFFF]

@dejhost

40 pin General Purpose 3.3V I/O Connector.

Do you mean PIN31, PIN33, PIN34 of 40-pins expansion header?

Please share the full dmesg and device tree for further check.

[dejhost]

The userguide refers to the connector as “40 pin General Purpose 3.3V I/O Connector”

attached you will find the two requested files: dmesg-log and the device tree

dmesg.txt (84.5 KB)
devicetree.txt (412.0 KB)

[KevinFFF]

It seems they have totally different pin usage for 40-pins expansion header on custom carrier board.
You have to check with your vendor(Connect Tech) about the pinmux configuration and usage for RS232.