MQ-7 Gas Sensor For Carbon Monoxide Detector Module

MQ-7 Gas Sensor For Carbon Monoxide Detector Module Documentation

Overview

The MQ-7 Gas Sensor is a highly sensitive and accurate module designed to detect Carbon Monoxide (CO) gas in the air. This module is widely used in various applications, including industrial, domestic, and automotive settings, to detect and alert users to the presence of CO gas.

Pinout and Connections

| Pin | Description |
| --- | --- |
| VCC | Power supply (5V) |
| GND | Ground |
| AO | Analog Output |
| DO | Digital Output |

Operation

The MQ-7 Gas Sensor module operates by detecting the presence of CO gas in the air and outputting a corresponding analog signal. The sensor contains a heating element, a sensitive layer, and an electrode. When CO gas is present, it reacts with the sensitive layer, causing a change in the electrical resistance of the sensor. This change is then converted into an analog signal at the AO pin.

Programming Examples

### Example 1: Basic Analog Output Reading (Arduino)

In this example, we will connect the MQ-7 Gas Sensor to an Arduino board and read the analog output signal to detect CO gas.

Hardware Connection:

Connect VCC to Arduino's 5V pin
 Connect GND to Arduino's GND pin
 Connect AO to Arduino's Analog Input pin (e.g., A0)

Code:
```c++
const int sensorPin = A0;  // select the input pin for the sensor

void setup() {
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(sensorPin);
  float CO_ppm = sensorValue  (5.0 / 1023.0); // convert analog value to CO concentration (ppm)
  Serial.print("CO Concentration: ");
  Serial.print(CO_ppm);
  Serial.println(" ppm");
  delay(1000);
}
```
### Example 2: Digital Output with Threshold Detection (Raspberry Pi)

In this example, we will connect the MQ-7 Gas Sensor to a Raspberry Pi and use the digital output to detect CO gas above a certain threshold.

Hardware Connection:

Connect VCC to Raspberry Pi's 5V pin
 Connect GND to Raspberry Pi's GND pin
 Connect DO to Raspberry Pi's GPIO pin (e.g., GPIO 17)

Code:
```python
import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)
GPIO.setup(17, GPIO.IN)  # set GPIO 17 as input

while True:
    if GPIO.input(17) == GPIO.HIGH:
        print("CO Gas Detected!")
    else:
        print("No CO Gas Detected.")
    time.sleep(1)
```
Note: In this example, we assume a threshold detection logic is built into the sensor module, where the digital output (DO) pin goes high when the CO concentration exceeds a certain threshold.

### Example 3: IoT-based CO Monitoring System (ESP32)

In this example, we will connect the MQ-7 Gas Sensor to an ESP32 board and create an IoT-based CO monitoring system that sends data to a cloud-based platform.

Hardware Connection:

Connect VCC to ESP32's 5V pin
 Connect GND to ESP32's GND pin
 Connect AO to ESP32's Analog Input pin (e.g., ADC1_0)

Code:
```c++
#include <WiFi.h>
#include <HTTPClient.h>

const char ssid = "your_wifi_ssid";
const char password = "your_wifi_password";
const char serverUrl = "https://your-cloud-platform.com/api/co-monitoring";

WiFiClient client;
HTTPClient http;

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");
  http.begin(client, serverUrl);
}

void loop() {
  int sensorValue = analogRead(ADC1_0);
  float CO_ppm = sensorValue  (5.0 / 1023.0); // convert analog value to CO concentration (ppm)
  String payload = "{""co_ppm"": " + String(CO_ppm) + "}";
  int httpRequestCode = http.POST(payload);
  if (httpRequestCode > 0) {
    Serial.println("Data sent successfully!");
  } else {
    Serial.println("Error sending data:");
    Serial.println(http.getString());
  }
  delay(30000); // send data every 30 seconds
}
```
Note: In this example, we assume you have replaced the placeholders with your own WiFi credentials, cloud platform URL, and API endpoint for sending CO data.