derf / co2-monitor-mhz19-ssd1306

ESP8266 and MH-Z19 based CO₂ monitor with SSD1306 OLED and HomeAssistant integration

CO₂ Monitor

This repository contains NodeMCU Lua source code for an MH-Z19 based CO₂ monitor. It shows the current CO₂ concentration and MH-Z19 temperature on a 128×32 SSD1306 OLED and makes them available to Home Assistant via MQTT. It can also publish readings to InfluxDB.

Features

• Display for CO₂ and temperature
• Home Assistant integration via MQTT
• Optional logging to InfluxDB
• Powered via USB

Components

• Processor: ESP8266
• CO₂ sensor: MH-Z19
• Display: 128×32 OLED via SSD1306 (128×64 also supported with some changes)

Flashing

This repository contains a NodeMCU build that provides the required modules. You can flash it using e.g. esptool:

esptool write_flash 0x00000 firmware/nodemcu-release-13-modules-2022-04-17-19-03-07-integer.bin

After flashing, the firmware will need a few seconds to initialize the filesystem. You can use that time to create config.lua (see below) and then flash the Python code, e.g. using nodemcu-uploader:

ext/nodemcu-uploader/nodemcu-uploader.py upload *.lua

Afterwards, you can check whether everything works using the serial connection, e.g.

pyserial-miniterm --dtr 0 --rts 0 /dev/ttyUSB0 115200

You may need to adjust the /dev/tty device name.

Configuration

WiFi, Home Assistant, and InfluxDB configuration is read from src/config.lua. You will need the following entries.

WiFi

Assuming ESSID "foo" and PSK "bar". WPA2 Enterprise is not supported. Leave out the psk for open WiFi.

station_cfg = {ssid = "foo", pwd = "bar"}

MQTT

The only configurable entity is the hostname of the MQTT broker. The ESP8266 will register itself as homeassistant/sensor/esp8266_XXXXXX with the last six digits representing its WiFi MAC address.

mqtt_host = "mqtt.example.org"

InfluxDB

These settings are optional. Specify a URL and attributes in order to enable InfluxDB publishing. For instance, if measurements should be stored as mh_z19,location=lounge in the sensors database on https://influxdb.example.org, the configuration is as follows.

influx_url = 'https://influxdb.example.org/write?db=sensors'
influx_attr = ',location=lounge'

You can also use the esp8266_XXXXXX device id here, like so:

influx_url = 'https://influxdb.example.org/write?db=sensors'
influx_attr = ',location=' .. device_id

Optionally, you can set influx_header to an HTTP header that is passed as part of the POST request to InfluxDB.

Images

Resources

Mirrors of this repository are maintained at the following locations:

• Chaosdorf
• git.finalrewind.org
• GitHub