====== LamaPLC: CJMCU-6814 combined gas sensor module for CO, NO₂, NH₃ ======
{{ :sensor:cjmcu_6814.png?180|CJMCU-6814 combined gas sensor module for CO, NO2, NH3}}
The CJMCU-6814 is a specialized gas sensor module designed for air quality monitoring, primarily built around the MiCS-6814 sensor. It is a "3-in-1" device capable of detecting carbon monoxide (CO), nitrogen dioxide (NO₂), and ammonia (NH₃) simultaneously through three independent analog channels.

**Key Technical Specifications**

  * **Target Gases & Range:** \\
  * **Carbon Monoxide (CO):** 1 – 1000 ppm.
  * **Nitrogen Dioxide (NO₂):** 0.05 – 10 ppm.
  * **Ammonia (NH₃):** 1 – 500 ppm.
  * **Secondary detection:** Detects Ethanol, Hydrogen, Methane, and Propane.
  * **Operating Voltage:** **4.9V – 5.1V**.
  * **Output:** Three analog output pins (Red, Ox, NH3) corresponding to the internal sensing elements.
 
**Important Usage Notes**

  * **Warm-up Period:** The sensor requires a significant warm-up time to reach a stable operating temperature. The datasheet indicates that it can take more than //120 minutes// for the internal heater to stabilize.
  * **Calibration:** It is designed for relative measurement, not absolute precision. You must calibrate it in your specific environment (e.g., "clean air" as a baseline) to convert analog voltage changes into meaningful ppm estimates.
  * **No I²C:** Unlike some other MiCS-6814 breakout boards, the purple CJMCU version typically does not support I²C. You must use the Arduino analog pins (e.g., A0, A1, A2) to read data.
  * **External Resistors:** For optimal results and to prevent sensor damage, it is often recommended to use external pull-up resistors (e.g., 47 kΩ) or a combination with a 10kΩ potentiometer to tune the output range. 

{{page>:tarhal}}
==== Arduino code ====
To interface the CJMCU-6814 with an Arduino, you read the three analog output channels (CO, NH₃, NO₂) using analogRead(). This sensor typically does not use I²C, so you must connect the pins directly to the Arduino's analog inputs.

This sketch reads the raw voltage from each sensor channel every 5 seconds. 

<code c>
// CJMCU-6814 Basic Reading Example
const int pinCO  = A0; // Carbon Monoxide (RED channel)
const int pinNH3 = A1; // Ammonia (NH3 channel)
const int pinNO2 = A2; // Nitrogen Dioxide (OX channel)

void setup() {
  Serial.begin(9600);
  Serial.println("CJMCU-6814 Gas Sensor Initializing...");
  // Sensor requires a long warm-up (up to 30-120 mins) for stability
}

void loop() {
  // Read raw values (0-1023)
  int rawCO  = analogRead(pinCO);
  int rawNH3 = analogRead(pinNH3);
  int rawNO2 = analogRead(pinNO2);

  // Convert to voltage (assuming 5V Arduino)
  float voltCO  = rawCO  * (5.0 / 1023.0);
  float voltNH3 = rawNH3 * (5.0 / 1023.0);
  float voltNO2 = rawNO2 * (5.0 / 1023.0);

  // Print results
  Serial.print("CO: ");  Serial.print(voltCO);  Serial.print("V | ");
  Serial.print("NH3: "); Serial.print(voltNH3); Serial.print("V | ");
  Serial.print("NO2: "); Serial.print(volt8); Serial.println("V");

  delay(5000); 
}
</code>

===== CJMCU topics on lamaPLC =====
{{topic>cjmcu}}

\\
\\

{{tag>analog CJMCU CJMCU-6814 mics6814 MICS-6814 sensor arduino code Carbon_monoxide CO Ammonia NH₃ Nitrogen_dioxide NO₂}}

This page has been accessed for: Today: {{counter|today}}, Until now: {{counter|total}}