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

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

Raspberry Pi

Raspberry Pi 4 Model B 4GB (Japan authorized distributor)

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CO2-mini (CUSTOM CO2 Monitor)

CUSTOM CO2 Monitor CO2-mini

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Power Supply and microSD Card

Smraza Raspberry Pi 4 USB-C Power Supply 5V 3A with On/Off Switch

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SanDisk Ultra microSD 128GB UHS-I Class10

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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

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']))

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.

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

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.

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

Summary

The complete scripts are available on GitHub:

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