4. Debugging

4.1. Status

To check the status of the application, connect via SSH and at the command prompt enter:

systemctl status aq

The output will show whether the application is running or has exited, along with recent log messages.

More extensive logs can be found in the /aq/log directory.

4.2. Debug mode

Debug mode can be enabled by setting the following line in the [ESDK] section of the config file:

debug = true

Then restarting. Following which there should be more verbose output in the log files.


Soft reboot (without power cycling) will result in the CO2 sensor going offline.

4.3. Typical problems

The most common problems are likely to be:

  • Missing readings:
    • Sensor chain not properly connected.

    • Faulty/damaged sensor module.

  • Application won’t start:
    • Micro SD card full (delete CSV logs and/or application log files).

    • Configuration file errors (check for typos and correct use of quotes etc.)

  • Crashes, hangs, unreliability:
    • Bad power supply. It is strongly recommended to use the provided official Raspberry Pi PSU!