Monitor CO2 Sensor with MQTT: A Step-by-Step Guide

11.12.2024 - Engine: Gemini

Materials

CO2 sensor (e.g. MH-Z19C)
Microcontroller (e.g. ESP32)
Wi-Fi module (optional, if the microcontroller does not have built-in Wi-Fi)
MQTT client library

Steps

1. Hardware Setup

Wire the CO2 sensor to the microcontroller according to its datasheet.
Connect a Wi-Fi module if your microcontroller does not have built-in Wi-Fi.

2. Firmware Creation

Install the MQTT client library on the microcontroller.
Create firmware that:
- Reads the CO2 concentration from the sensor.
- Connects to an MQTT broker.
- Publishes the CO2 concentration to a specific MQTT topic.

3. MQTT Broker Setup

Set up an MQTT broker (e.g. Mosquitto).
Create a topic for the CO2 concentration (e.g. "co2/livingroom").

4. Data Visualization

Install an MQTT client on a device (e.g. smartphone or laptop).
Connect the client to the MQTT broker.
Subscribe to the CO2 topic.

5. Testing

Upload the firmware to the microcontroller.
Monitor the CO2 concentration in the MQTT client. The data should update in real time.

Example Code (ESP32 with MH-Z19C)

#include <WiFi.h>
#include <PubSubClient.h>
#include <MHZ19.h>

const char* ssid = "Your_Wi-Fi_SSID";
const char* password = "Your_Wi-Fi_Password";
const char* mqtt_server = "Your_MQTT_Broker_Server";
const int mqtt_port = 1883;
const char* mqtt_topic = "co2/livingroom";

MHZ19 myMHZ19;
WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  myMHZ19.begin();
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
  client.setServer(mqtt_server, mqtt_port);
  client.connect("esp32-co2-sensor");
}

void loop() {
  float co2 = myMHZ19.getCO2();
  Serial.println(co2);
  client.publish(mqtt_topic, String(co2).c_str());
  delay(5000);
}