Continuous CO2 Monitoring with Raspberry Pi, CO2-mini, and Zabbix: A Complete Setup Guide

Tue, 19 Jul 2022 00:00:00 +0000

During the COVID-19 pandemic, I bought a CO2 monitor — the CUSTOM CO2-mini. It runs on USB power, and as it turns out, it can also communicate over USB. I connected it to a Raspberry Pi and set up Zabbix to continuously monitor indoor CO2 levels. Here is the full setup guide.

Hardware

Reading Data from the CO2-mini (Python)

When you connect the CO2-mini to a Raspberry Pi via USB, it is recognized without any special drivers. Data retrieval uses the heinemml/CO2Meter Python library.

Installing the Library

On Raspberry Pi OS Bookworm (2023 and later), installing packages directly into the system Python with pip is restricted. Use a virtual environment instead:

python3 -m venv /root/co2env
/root/co2env/bin/pip install git+https://github.com/heinemml/CO2Meter

On Raspberry Pi OS Bookworm and later, sudo pip3 install ... may fail with an “externally managed environment” error. Using a virtual environment as shown above is the safe approach.

Script: Writing CO2 and Temperature to Shared Memory

To make values accessible to the Zabbix agent, the script continuously writes them to files under /dev/shm/.

from CO2Meter import *
import time

sensor = CO2Meter("/dev/hidraw0") # may be hidraw1 or similar on your system

while True:
 time.sleep(1)
 data = sensor.get_data()
 if 'temperature' in data and 'co2' in data:
 with open('/dev/shm/co2', 'w') as f:
 f.write(str(data['co2']))
 with open('/dev/shm/temperature', 'w') as f:
 f.write(str(data['temperature']))

The device path /dev/hidraw0 may differ on your system. Run ls /dev/hidraw* to find the correct path after plugging in the CO2-mini.

Auto-start at Boot (crontab)

The device requires root access, so create a shell script that runs as root:

/root/co2.sh

#!/bin/bash
sleep 5
/root/co2env/bin/python3 /root/co2.py

Add to root’s crontab to run at boot:

@reboot /root/co2.sh

Zabbix Configuration

The approach is:

The Python script continuously writes CO2 and temperature values to /dev/shm/
The Zabbix agent reads those files via cat and returns the values

Zabbix Server: Creating the Host and Items

Install the zabbix-agent on the Raspberry Pi and add it as a host in Zabbix server.

Adding the Raspberry Pi as a Zabbix host

Create two items — one for CO2 concentration and one for temperature.

Creating CO2 and temperature items in Zabbix

Configuring item keys to match UserParameter names

Use the following item keys:

co2.co2 (CO2 concentration)
co2.temp (Temperature)

Zabbix Agent: Configuration File

Edit /etc/zabbix/zabbix_agentd.conf to set the server address:

Server=<zabbix-server address>
ServerActive=<zabbix-server address>
Include=/etc/zabbix/zabbix_agentd.conf.d/*.conf

UserParameter Configuration

Create /etc/zabbix/zabbix_agentd.conf.d/userparameter_co2.conf. It simply cats the shared memory files:

UserParameter=co2.co2,cat /dev/shm/co2
UserParameter=co2.temp,cat /dev/shm/temperature

Restart the agent:

sudo systemctl restart zabbix-agent

Results

CO2 concentration and temperature are now graphed in Zabbix.

CO2 concentration graph in Zabbix. Values drop at ventilation events

Long-term trend. In winter, windows tend to stay closed, allowing CO2 to build up

Since setting up the monitor, I ventilate much more frequently. Seeing the numbers makes it obvious exactly when ventilation is needed.

Summary

Component	Role
CO2-mini	Measures CO2 concentration and temperature via USB
Raspberry Pi	Reads sensor data and writes it to shared memory
Python (CO2Meter library)	Communicates with CO2-mini and parses data
Zabbix (agent + server)	Collects data, graphs it, and stores long-term history

The complete scripts are available on GitHub:

GitHub - yukishita/co2-mini: Program to log CUSTOM CO2-mini data with Zabbix

Zabbix | Tomokatsu Yukishita | yre.jp