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FAQ

System Issues​

System Fails to Boot​

We provide two types of system images:

  • Standard System Image: Includes a partition table and can be directly installed to the boot media.

  • Phoenix System Image: Does not include a partition table and requires the Phoenix tool for flashing.

First, verify that the correct system image is being used. If the system image is correct, you can check the system boot logs via serial debugging for further troubleshooting.

Remote Access Issues​

SSH Connection Failure​

The factory system image has SSH service enabled by default. Generally, you only need to ensure that both the Cubie A7Z and your PC are on the same local network to establish an SSH connection.

Troubleshooting steps:

  1. Check if the Cubie A7Z is connected to the network and has a valid IP address by running ip a to view network connection details.
  2. Verify that both the Cubie A7Z and your PC are on the same local network by pinging each other's IP addresses.
  3. Check if the SSH service is running by executing sudo systemctl status ssh.

VNC Connection Issues​

VNC remote access requires manual configuration of the VNC server. If configured according to the tutorial, the VNC server will automatically shut down after each reboot or shutdown.

Troubleshooting steps:

  1. Complete the VNC remote configuration as per the tutorial.
  2. Ensure that SSH remote access is working properly.
  3. Check if the VNC server is running by using the command vncserver -list.
  4. Connect via VNC using ip:5901, where ip is the IP address of your Cubie A7Z.

Serial Port Issues​

Failed to Open Serial Port​

If you encounter the error Error: Permission denied, cannot open /dev/ttyUSB0 when trying to access the serial port, follow these troubleshooting steps:

  1. Check if the serial device is properly connected.

  2. Verify serial device permissions:

For Linux systems, if the serial device has insufficient permissions, run the following command to grant all users access to the serial device:

Linux@host$
sudo chmod 777 /dev/ttyUSB0
  1. Check if the serial device is being used by another program.

Network Bandwidth Testing​

Port in Use​

If you see the error iperf3: error - unable to start listener for connections: Address already in use, it means that port 5201 is already in use by another iperf3 process.

Solution:

  1. Check for running iperf3 processes:
Linux@host$
ps -ef | grep iperf3
  1. Terminate the iperf3 process by replacing <PID> with the actual process ID:
Linux@host$
sudo kill <PID>