Access the Toradex Verdin i.MX95: Serial Console and SSH
To access a Toradex Verdin i.MX95 running a Yocto image, use the serial debug console for U-Boot, kernel boot messages, and recovery when networking is unavailable; use SSH for remote login after Linux is booted and network access is configured. On the Verdin Development Board, connect the host to USB-C debug connector X66. On Linux, compare `/dev/ttyUSB*` before and after connecting the board; usually the highest-numbered port is the Linux console (for example, `/dev/ttyUSB3`). Use 115200 baud, 8 data bits, no parity, 1 stop bit, and no hardware flow control for the serial port configuration.
Choose a board access method
| Method | Use it when | What you need |
|---|---|---|
| Serial debug console (UART) | You need to see U-Boot or kernel output, diagnose a boot failure, or use the board without a network connection. | USB-C cable connected to the Verdin Development Board's X66 debug connector and a serial terminal on the host. |
| SSH | Linux has booted and the board and host can reach each other over a network. | An SSH client, the board's IP address, and valid credentials for the image running on the board. |
The procedures below have been tested by RidgeRun engineers for the Toradex Verdin i.MX95 development board. Continue from Flashing the Board, or see Set up the Yocto environment and Build an image.
Connect to the serial debug console
The debug UART provides access to bootloader and Linux console output. It is useful before the network is configured and when the operating system does not boot far enough to accept SSH connections. Keep UART enabled for diagnostics; disabling or repurposing it can remove an important way to diagnose boot failures.
Serial terminal settings
Configure the serial terminal with these parameters:
- Baud rate: 115200
- Data bits: 8
- Parity: none
- Stop bits: 1
- Hardware flow control: none
Connect the USB cable to X66
Connect a USB-C to USB-A cable between the development host and the USB-C debug connector (X66) on the Verdin Development Board. X66 exposes a USB-to-serial interface as well as JTAG. Toradex identifies X66 as the board's USB-to-serial and USB-to-JTAG interface connector. Verdin Development Board Datasheet
Identify the Linux serial device
On the Linux host, run the following command with the board unplugged, connect the board, and run it again:
ls /dev/ttyUSB*
The newly listed devices may look like this:
/dev/ttyUSB0 /dev/ttyUSB1 /dev/ttyUSB2 /dev/ttyUSB3
For Verdin modules on the Verdin Development Board, the highest-numbered port is the Linux serial console. In this example, use `/dev/ttyUSB3`. Toradex documents the same port-selection rule and explains that other ports are used for control and JTAG. Toradex Serial/UART setup
Optional: allow access through the dialout group
To access the serial port without `sudo`, the original procedure adds the current user to the `dialout` group:
sudo usermod -a -G dialout $(whoami)
Log out and back in for the group membership change to take effect. Note that the group name can vary by host distribution.
Start Minicom and observe boot
Connect Minicom to the example console device:
minicom -D /dev/ttyUSB3
After connecting, power on or reset the board to observe boot messages. Set Minicom's serial parameters to the values above if they are not already configured. For additional Minicom setup guidance, see RidgeRun's Setting up Minicom Client on Ubuntu.
Connect to the board over SSH
SSH provides encrypted remote login and file transfer after the board has booted and has network connectivity. Use the serial connection to configure the network and find the board IP address.
Install an SSH client on a Ubuntu or Debian-based host
The following command installs the OpenSSH client on the host computer:
sudo apt install openssh-client
This installs a client on the host. It does not add an SSH server to the target image. Toradex notes that its demo images can start the SSH server through systemd socket activation, but the exact SSH server, account, and authentication behavior depends on the image configuration. Toradex SSH documentation
On Windows, the supplied page lists PuTTY and Windows Subsystem for Linux (WSL) as possible SSH clients. The detailed commands here use a Linux shell.
Connect using the board's IP address
Once you know the board's address and have valid credentials for the image, run:
ssh root@<board-ip-address>
For example:
ssh root@192.168.10.2
A shell prompt appears after authentication succeeds. Replace the example IP with the address assigned to your board. Do not assume that every Yocto image accepts the `root` account or has the same password or SSH service cBoardonfiguration.
Troubleshooting board access
| Symptom | First checks |
|---|---|
| No serial devices appear | Confirm the USB cable is connected to X66, then unplug and reconnect the board and compare the device list again. Try a known data-capable cable and check host USB device detection. |
| Minicom connects but shows no board output | Confirm the selected device is the highest-numbered Verdin serial port, check the 115200 8N1 settings with hardware flow control disabled, and reset or power-cycle the board. |
| The board does not respond on `/dev/ttyUSB0` | Select the highest-numbered port instead. On this Verdin setup, lower-numbered ports are associated with board control/JTAG functions rather than the Linux console. |
| SSH times out or cannot reach the host | Confirm Linux has booted, the host and board have network connectivity, and the IP address is current. Use the serial console to inspect boot progress or determine the network state. |
| SSH reports authentication failure | Check the username and authentication method configured in the built image. The supplied command uses `root`, but credentials and SSH policy are image-specific. |
| SSH connection is refused | Verify that an SSH server is included and enabled in the target image and that the network path allows TCP port 22. |
FAQ
- Which serial port is the Verdin i.MX95 Linux console?
- On the Verdin Development Board, the highest-numbered serial port exposed by the USB-to-serial interface is the Linux console. For the example `/dev/ttyUSB0` through `/dev/ttyUSB3`, use `/dev/ttyUSB3`.
- What serial settings should I use for the Verdin i.MX95 debug console?
- Use 115200 baud, 8 data bits, no parity, 1 stop bit, and no hardware flow control.
- Can I use SSH before Linux boots?
- No. Use the serial debug console to observe U-Boot and kernel boot output. SSH requires a booted Linux image and network connectivity.
- Does `sudo apt install openssh-client` install SSH on the Verdin board?
- No. It installs the SSH client on the Debian-based host. The target image must separately include and configure an SSH server.
- What username and password should I use over SSH?
- Use the credentials configured for your specific Yocto image.
Related pages
- Flash the Yocto image to the Verdin i.MX95
- Set up the Yocto environment
- Build a Yocto image
- Set up Minicom on Ubuntu
References
For help bringing up or integrating a Yocto-based embedded Linux system, contact RidgeRun Engineering.
