LPG Cylinder Leakage Sensor using MQ6 Sensor and ESP8266

mqtt_lpg_gas.ino

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "Ermenegildo Zegna";
const char* password = "hhjw-ofvq-pafm";

//const char* mqtt_server = "test.mosquitto.org";
const char* mqtt_server = "192.168.100.113";

unsigned long lastUpdate;
int GAS_DO = 10; 
int STATE = 0; 
int lastState = 0;     // previous state of the sensor
#define BUZZER_PIN  D1

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
    delay(60000);    // allow the MQ-6 to warm up
  pinMode(BUILTIN_LED,OUTPUT);
  digitalWrite(BUILTIN_LED,HIGH);
  pinMode(GAS_DO,INPUT);
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
  reconnect();
}

void setup_wifi(){

  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }

  Serial.println();
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP8266Client")) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish("ESP8266/status", "Connected!");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void loop() {
 //Serial.println("Before reconnect");
  if (!client.connected()) {
    reconnect();
  }
//  Serial.println("After reconnect");
  client.loop();
    STATE = digitalRead(GAS_DO); 
    // compare the sensor State to its previous state
  if ((STATE != lastState)&&((millis() - lastUpdate) > 10000)) {
    // if the state has changed, increment the counter
    lastUpdate = millis();
    if (STATE == HIGH) {
      // if the current state is HIGH then the sensor is not detecting leakage:
   Serial.println("NO LPG LEAKAGE");
   digitalWrite(BUILTIN_LED,HIGH);
   client.publish("ESP8266/LPGStatus", "OFF");   
    } else{
      // if the current state is LOW then the sensor detected gas leakage:
      digitalWrite(BUILTIN_LED, LOW);     
     Serial.println("GAS IS LEAKED");
     client.publish("ESP8266/LPGStatus", "ON");
    }
    // Delay a little bit to avoid bouncing
    delay(50);
    lastState = STATE;
  }
   if(STATE == LOW) {  
     playTone(BUZZER_PIN, 2000, 200);
  }
  
}

void playTone(int _pin, int _frequency, int _length){
  analogWriteFreq(_frequency);
  analogWrite(_pin, 512);
  delay(_length);
  analogWrite(_pin, 0);
}

Thanks for the code. I am trying to add another MQ2 sensor with few LED's as I sensor is not enough for me.. I tried modifying your code but for some reason I can't get it working. Can you help?

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "MYSSID";
const char* password = "MYWEPKEY";

//const char* mqtt_server = "test.mosquitto.org";
const char* mqtt_server = "192.168.1.48";

unsigned long lastUpdate;
int GAS_DO = D2;
int GAS_D1 = D6;
int REDLED = D5;
int GREENLED = D3;
int BLUELED = D8;
int STATE = 0;
int STATE1 = 0;
int lastState = 0; // previous state of the sensor
#define BUZZER_PIN D1

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
delay(6000); // allow the MQ-6 to warm up
pinMode(BUILTIN_LED,OUTPUT);
pinMode(REDLED,OUTPUT);
pinMode(GREENLED,OUTPUT);
digitalWrite(BUILTIN_LED,HIGH);
pinMode(GAS_DO,INPUT);
pinMode(GAS_D1,INPUT);
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
reconnect();
}

void setup_wifi(){

delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}

Serial.println();
}

void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("ESP8266Client")) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("ESP8266/status", "Connected!");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}

void loop() {
//Serial.println("Before reconnect");
if (!client.connected()) {
reconnect();
}
// Serial.println("After reconnect");
client.loop();
STATE = digitalRead(GAS_DO);
STATE1 = digitalRead(GAS_D1);
// compare the sensor State to its previous state
if ((STATE != lastState)&&((millis() - lastUpdate) > 10000)) {
// if the state has changed, increment the counter
lastUpdate = millis();
if (STATE == HIGH) {
// if the current state is HIGH then the sensor is not detecting leakage:
Serial.println("NO LPG LEAKAGE on SENSOR 1");
digitalWrite(BUILTIN_LED,HIGH);
digitalWrite(GREENLED,HIGH);
client.publish("ESP8266/LPGStatus", "OFF");
} else{
// if the current state is LOW then the sensor detected gas leakage:
digitalWrite(BUILTIN_LED, LOW);
digitalWrite(GREENLED,LOW);
Serial.println("GAS IS LEAKED on SENSOR 1");
client.publish("ESP8266/LPGStatus", "ON");
}
// Delay a little bit to avoid bouncing
delay(50);
lastState = STATE;
}
if(STATE == LOW) {
playTone(BUZZER_PIN, 2000, 200);
if(STATE == LOW) {
digitalWrite(REDLED,HIGH);
delay(100);
digitalWrite(REDLED,LOW);
delay(100);
digitalWrite (GREENLED, LOW);
}
}

if ((STATE1 != lastState)&&((millis() - lastUpdate) > 10000)) {
// if the state has changed, increment the counter
lastUpdate = millis();
if (STATE1 == HIGH) {
// if the current state is HIGH then the sensor is not detecting leakage:
Serial.println("NO LPG LEAKAGE on SENSOR 2");
digitalWrite(BUILTIN_LED,HIGH);
digitalWrite(GREENLED,HIGH);
client.publish("ESP8266/LPGStatus1", "OFF");
} else{
// if the current state is LOW then the sensor detected gas leakage:
digitalWrite(BUILTIN_LED, LOW);
digitalWrite(GREENLED,LOW);
Serial.println("GAS IS LEAKED on SENSOR 2");
client.publish("ESP8266/LPGStatus1", "ON");
}
// Delay a little bit to avoid bouncing
delay(50);
lastState = STATE1;
}
if(STATE1 == LOW) {
playTone(BUZZER_PIN, 2000, 200);
if(STATE1 == LOW) {
digitalWrite(BLUELED,HIGH);
delay(100);
digitalWrite(BLUELED,LOW);
delay(100);
digitalWrite (GREENLED, LOW);

 }

}
}

void playTone(int _pin, int _frequency, int _length){
analogWriteFreq(_frequency);
analogWrite(_pin, 512);
delay(_length);
analogWrite(_pin, 0);
}
#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "MYSSID";
const char* password = "MYWEPKEY";

//const char* mqtt_server = "test.mosquitto.org";
const char* mqtt_server = "192.168.1.48";

unsigned long lastUpdate;
int GAS_DO = D2;
int GAS_D1 = D6;
int REDLED = D5;
int GREENLED = D3;
int BLUELED = D8;
int STATE = 0;
int STATE1 = 0;
int lastState = 0; // previous state of the sensor
#define BUZZER_PIN D1

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
delay(6000); // allow the MQ-6 to warm up
pinMode(BUILTIN_LED,OUTPUT);
pinMode(REDLED,OUTPUT);
pinMode(GREENLED,OUTPUT);
digitalWrite(BUILTIN_LED,HIGH);
pinMode(GAS_DO,INPUT);
pinMode(GAS_D1,INPUT);
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
reconnect();
}

void setup_wifi(){

delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}

Serial.println();
}

void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("ESP8266Client")) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("ESP8266/status", "Connected!");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}

void loop() {
//Serial.println("Before reconnect");
if (!client.connected()) {
reconnect();
}
// Serial.println("After reconnect");
client.loop();
STATE = digitalRead(GAS_DO);
STATE1 = digitalRead(GAS_D1);
// compare the sensor State to its previous state
if ((STATE != lastState)&&((millis() - lastUpdate) > 10000)) {
// if the state has changed, increment the counter
lastUpdate = millis();
if (STATE == HIGH) {
// if the current state is HIGH then the sensor is not detecting leakage:
Serial.println("NO LPG LEAKAGE on SENSOR 1");
digitalWrite(BUILTIN_LED,HIGH);
digitalWrite(GREENLED,HIGH);
client.publish("ESP8266/LPGStatus", "OFF");
} else{
// if the current state is LOW then the sensor detected gas leakage:
digitalWrite(BUILTIN_LED, LOW);
digitalWrite(GREENLED,LOW);
Serial.println("GAS IS LEAKED on SENSOR 1");
client.publish("ESP8266/LPGStatus", "ON");
}
// Delay a little bit to avoid bouncing
delay(50);
lastState = STATE;
}
if(STATE == LOW) {
playTone(BUZZER_PIN, 2000, 200);
if(STATE == LOW) {
digitalWrite(REDLED,HIGH);
delay(100);
digitalWrite(REDLED,LOW);
delay(100);
digitalWrite (GREENLED, LOW);
}
}

if ((STATE1 != lastState)&&((millis() - lastUpdate) > 10000)) {
// if the state has changed, increment the counter
lastUpdate = millis();
if (STATE1 == HIGH) {
// if the current state is HIGH then the sensor is not detecting leakage:
Serial.println("NO LPG LEAKAGE on SENSOR 2");
digitalWrite(BUILTIN_LED,HIGH);
digitalWrite(GREENLED,HIGH);
client.publish("ESP8266/LPGStatus1", "OFF");
} else{
// if the current state is LOW then the sensor detected gas leakage:
digitalWrite(BUILTIN_LED, LOW);
digitalWrite(GREENLED,LOW);
Serial.println("GAS IS LEAKED on SENSOR 2");
client.publish("ESP8266/LPGStatus1", "ON");
}
// Delay a little bit to avoid bouncing
delay(50);
lastState = STATE1;
}
if(STATE1 == LOW) {
playTone(BUZZER_PIN, 2000, 200);
if(STATE1 == LOW) {
digitalWrite(BLUELED,HIGH);
delay(100);
digitalWrite(BLUELED,LOW);
delay(100);
digitalWrite (GREENLED, LOW);

 }

}
}

void playTone(int _pin, int _frequency, int _length){
analogWriteFreq(_frequency);
analogWrite(_pin, 512);
delay(_length);
analogWrite(_pin, 0);
}

Just like you have added parameters for both sensors, there should be 2 parameters for lastupdate and laststate.

I have made the changes.... but the Builtin LED is not on... Also REDLED is not flashing and buzzer is also not playing tone ... I guess these function are not exactly in loop... can't figure out whats the problem: Here's the code:

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "Digoo";
const char* password = "C!$c0#B@z1ng@@";

//const char* mqtt_server = "test.mosquitto.org";
const char* mqtt_server = "10.12.47.48";

unsigned long lastUpdate;
unsigned long lastUpdate1;
int GAS_DO = D2;
int GAS_D1 = D6;
int REDLED = D5;
int GREENLED = D3;
int BLUELED = D0;
int STATE = 0;
int STATE1 = 0;
int lastState = 0; // previous state of the sensor
int lastState1 = 0; // previous state of the sensor 2
#define BUZZER_PIN D1

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
delay(6000); // allow the MQ-6 to warm up
pinMode(BUILTIN_LED, OUTPUT);
pinMode(REDLED, OUTPUT);
pinMode(GREENLED, OUTPUT);
digitalWrite(BUILTIN_LED, HIGH);
pinMode(GAS_DO, INPUT);
pinMode(GAS_D1, INPUT);
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
reconnect();
}

void setup_wifi() {

delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}

Serial.println();
}

void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("ESP8266Client")) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("ESP8266/status", "Connected!");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}

void loop() {
//Serial.println("Before reconnect");
if (!client.connected()) {
reconnect();
}
// Serial.println("After reconnect");
client.loop();
STATE = digitalRead(GAS_DO);
STATE1 = digitalRead(GAS_D1);
// compare the sensor State to its previous state
if ((STATE != lastState) && ((millis() - lastUpdate) > 10000)) {
// if the state has changed, increment the counter
lastUpdate = millis();
if (STATE == HIGH) {
// if the current state is HIGH then the sensor is not detecting leakage:
Serial.println("NO LPG LEAKAGE on SENSOR 1");
digitalWrite(BUILTIN_LED, HIGH);
digitalWrite(GREENLED, HIGH);
client.publish("ESP8266/LPGStatus", "OFF");
} else {
// if the current state is LOW then the sensor detected gas leakage:
digitalWrite(BUILTIN_LED, LOW);
digitalWrite(GREENLED, LOW);
Serial.println("GAS IS LEAKED on SENSOR 1");
client.publish("ESP8266/LPGStatus", "ON");
}
// Delay a little bit to avoid bouncing
delay(50);
lastState = STATE;

if (STATE == LOW) {
  playTone(BUZZER_PIN, 2000, 200);
  if (STATE == LOW) {
    digitalWrite(REDLED, HIGH);
    delay(100);
    digitalWrite(REDLED, LOW);
    delay(100);
    }
}

}

if ((STATE1 != lastState1) && ((millis() - lastUpdate1) > 10000)) {
  // if the state has changed, increment the counter
  lastUpdate1 = millis();
  lastState1 = STATE1;
  if (STATE1 == HIGH) {
    // if the current state is HIGH then the sensor is not detecting leakage:
    Serial.println("NO LPG LEAKAGE on SENSOR 2");
    digitalWrite(BUILTIN_LED, HIGH);
    digitalWrite(GREENLED, HIGH);
    client.publish("ESP8266/LPGStatus1", "OFF");
  } else {
    // if the current state is LOW then the sensor detected gas leakage:
    digitalWrite(BUILTIN_LED, LOW);
    digitalWrite(GREENLED, LOW);
    Serial.println("GAS IS LEAKED on SENSOR 2");
    client.publish("ESP8266/LPGStatus1", "ON");
  }
  // Delay a little bit to avoid bouncing
  delay(50);
  

  if (STATE1 == LOW) {
    playTone(BUZZER_PIN, 2000, 200);
    if (STATE1 == LOW) {
      digitalWrite(BLUELED, HIGH);
      delay(100);
      digitalWrite(BLUELED, LOW);
      delay(100);
      

    }
  }
}

}

void playTone(int _pin, int _frequency, int _length) {
analogWriteFreq(_frequency);
analogWrite(_pin, 512);
delay(_length);
analogWrite(_pin, 0);
}

Hi, The code seems proper. Please check individual components with standard code on serial monitor to check they are working or not. Regards, Samir

…

________________________________ From: abhishekakt1 <[email protected]> Sent: Sunday, June 23, 2019 10:56 PM To: samirsogay Cc: samirsogay; Author Subject: Re: samirsogay/mqtt_lpg_gas.ino Thanks for the code. I am trying to add another MQ2 sensor with few LED's as I sensor is not enough for me.. I tried modifying your code but for some reason I can't get it working. Can you help? #include <ESP8266WiFi.h> #include <PubSubClient.h> const char* ssid = "MYSSID"; const char* password = "MYWEPKEY"; //const char* mqtt_server = "test.mosquitto.org"; const char* mqtt_server = "192.168.1.48"; unsigned long lastUpdate; int GAS_DO = D2; int GAS_D1 = D6; int REDLED = D5; int GREENLED = D3; int BLUELED = D8; int STATE = 0; int STATE1 = 0; int lastState = 0; // previous state of the sensor #define BUZZER_PIN D1 WiFiClient espClient; PubSubClient client(espClient); void setup() { delay(6000); // allow the MQ-6 to warm up pinMode(BUILTIN_LED,OUTPUT); pinMode(REDLED,OUTPUT); pinMode(GREENLED,OUTPUT); digitalWrite(BUILTIN_LED,HIGH); pinMode(GAS_DO,INPUT); pinMode(GAS_D1,INPUT); Serial.begin(115200); setup_wifi(); client.setServer(mqtt_server, 1883); client.setCallback(callback); reconnect(); } void setup_wifi(){ delay(10); // We start by connecting to a WiFi network Serial.println(); Serial.print("Connecting to "); Serial.println(ssid); WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); Serial.println("IP address: "); Serial.println(WiFi.localIP()); } void callback(char* topic, byte* payload, unsigned int length) { Serial.print("Message arrived ["); Serial.print(topic); Serial.print("] "); for (int i = 0; i < length; i++) { Serial.print((char)payload[i]); } Serial.println(); } void reconnect() { // Loop until we're reconnected while (!client.connected()) { Serial.print("Attempting MQTT connection..."); // Attempt to connect if (client.connect("ESP8266Client")) { Serial.println("connected"); // Once connected, publish an announcement... client.publish("ESP8266/status", "Connected!"); } else { Serial.print("failed, rc="); Serial.print(client.state()); Serial.println(" try again in 5 seconds"); // Wait 5 seconds before retrying delay(5000); } } } void loop() { //Serial.println("Before reconnect"); if (!client.connected()) { reconnect(); } // Serial.println("After reconnect"); client.loop(); STATE = digitalRead(GAS_DO); STATE1 = digitalRead(GAS_D1); // compare the sensor State to its previous state if ((STATE != lastState)&&((millis() - lastUpdate) > 10000)) { // if the state has changed, increment the counter lastUpdate = millis(); if (STATE == HIGH) { // if the current state is HIGH then the sensor is not detecting leakage: Serial.println("NO LPG LEAKAGE on SENSOR 1"); digitalWrite(BUILTIN_LED,HIGH); digitalWrite(GREENLED,HIGH); client.publish("ESP8266/LPGStatus", "OFF"); } else{ // if the current state is LOW then the sensor detected gas leakage: digitalWrite(BUILTIN_LED, LOW); digitalWrite(GREENLED,LOW); Serial.println("GAS IS LEAKED on SENSOR 1"); client.publish("ESP8266/LPGStatus", "ON"); } // Delay a little bit to avoid bouncing delay(50); lastState = STATE; } if(STATE == LOW) { playTone(BUZZER_PIN, 2000, 200); if(STATE == LOW) { digitalWrite(REDLED,HIGH); delay(100); digitalWrite(REDLED,LOW); delay(100); digitalWrite (GREENLED, LOW); } } if ((STATE1 != lastState)&&((millis() - lastUpdate) > 10000)) { // if the state has changed, increment the counter lastUpdate = millis(); if (STATE1 == HIGH) { // if the current state is HIGH then the sensor is not detecting leakage: Serial.println("NO LPG LEAKAGE on SENSOR 2"); digitalWrite(BUILTIN_LED,HIGH); digitalWrite(GREENLED,HIGH); client.publish("ESP8266/LPGStatus1", "OFF"); } else{ // if the current state is LOW then the sensor detected gas leakage: digitalWrite(BUILTIN_LED, LOW); digitalWrite(GREENLED,LOW); Serial.println("GAS IS LEAKED on SENSOR 2"); client.publish("ESP8266/LPGStatus1", "ON"); } // Delay a little bit to avoid bouncing delay(50); lastState = STATE1; } if(STATE1 == LOW) { playTone(BUZZER_PIN, 2000, 200); if(STATE1 == LOW) { digitalWrite(BLUELED,HIGH); delay(100); digitalWrite(BLUELED,LOW); delay(100); digitalWrite (GREENLED, LOW); } } } void playTone(int _pin, int _frequency, int _length){ analogWriteFreq(_frequency); analogWrite(_pin, 512); delay(_length); analogWrite(_pin, 0); } #include <ESP8266WiFi.h> #include <PubSubClient.h> const char* ssid = "MYSSID"; const char* password = "MYWEPKEY"; //const char* mqtt_server = "test.mosquitto.org"; const char* mqtt_server = "192.168.1.48"; unsigned long lastUpdate; int GAS_DO = D2; int GAS_D1 = D6; int REDLED = D5; int GREENLED = D3; int BLUELED = D8; int STATE = 0; int STATE1 = 0; int lastState = 0; // previous state of the sensor #define BUZZER_PIN D1 WiFiClient espClient; PubSubClient client(espClient); void setup() { delay(6000); // allow the MQ-6 to warm up pinMode(BUILTIN_LED,OUTPUT); pinMode(REDLED,OUTPUT); pinMode(GREENLED,OUTPUT); digitalWrite(BUILTIN_LED,HIGH); pinMode(GAS_DO,INPUT); pinMode(GAS_D1,INPUT); Serial.begin(115200); setup_wifi(); client.setServer(mqtt_server, 1883); client.setCallback(callback); reconnect(); } void setup_wifi(){ delay(10); // We start by connecting to a WiFi network Serial.println(); Serial.print("Connecting to "); Serial.println(ssid); WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); Serial.println("IP address: "); Serial.println(WiFi.localIP()); } void callback(char* topic, byte* payload, unsigned int length) { Serial.print("Message arrived ["); Serial.print(topic); Serial.print("] "); for (int i = 0; i < length; i++) { Serial.print((char)payload[i]); } Serial.println(); } void reconnect() { // Loop until we're reconnected while (!client.connected()) { Serial.print("Attempting MQTT connection..."); // Attempt to connect if (client.connect("ESP8266Client")) { Serial.println("connected"); // Once connected, publish an announcement... client.publish("ESP8266/status", "Connected!"); } else { Serial.print("failed, rc="); Serial.print(client.state()); Serial.println(" try again in 5 seconds"); // Wait 5 seconds before retrying delay(5000); } } } void loop() { //Serial.println("Before reconnect"); if (!client.connected()) { reconnect(); } // Serial.println("After reconnect"); client.loop(); STATE = digitalRead(GAS_DO); STATE1 = digitalRead(GAS_D1); // compare the sensor State to its previous state if ((STATE != lastState)&&((millis() - lastUpdate) > 10000)) { // if the state has changed, increment the counter lastUpdate = millis(); if (STATE == HIGH) { // if the current state is HIGH then the sensor is not detecting leakage: Serial.println("NO LPG LEAKAGE on SENSOR 1"); digitalWrite(BUILTIN_LED,HIGH); digitalWrite(GREENLED,HIGH); client.publish("ESP8266/LPGStatus", "OFF"); } else{ // if the current state is LOW then the sensor detected gas leakage: digitalWrite(BUILTIN_LED, LOW); digitalWrite(GREENLED,LOW); Serial.println("GAS IS LEAKED on SENSOR 1"); client.publish("ESP8266/LPGStatus", "ON"); } // Delay a little bit to avoid bouncing delay(50); lastState = STATE; } if(STATE == LOW) { playTone(BUZZER_PIN, 2000, 200); if(STATE == LOW) { digitalWrite(REDLED,HIGH); delay(100); digitalWrite(REDLED,LOW); delay(100); digitalWrite (GREENLED, LOW); } } if ((STATE1 != lastState)&&((millis() - lastUpdate) > 10000)) { // if the state has changed, increment the counter lastUpdate = millis(); if (STATE1 == HIGH) { // if the current state is HIGH then the sensor is not detecting leakage: Serial.println("NO LPG LEAKAGE on SENSOR 2"); digitalWrite(BUILTIN_LED,HIGH); digitalWrite(GREENLED,HIGH); client.publish("ESP8266/LPGStatus1", "OFF"); } else{ // if the current state is LOW then the sensor detected gas leakage: digitalWrite(BUILTIN_LED, LOW); digitalWrite(GREENLED,LOW); Serial.println("GAS IS LEAKED on SENSOR 2"); client.publish("ESP8266/LPGStatus1", "ON"); } // Delay a little bit to avoid bouncing delay(50); lastState = STATE1; } if(STATE1 == LOW) { playTone(BUZZER_PIN, 2000, 200); if(STATE1 == LOW) { digitalWrite(BLUELED,HIGH); delay(100); digitalWrite(BLUELED,LOW); delay(100); digitalWrite (GREENLED, LOW); } } } void playTone(int _pin, int _frequency, int _length){ analogWriteFreq(_frequency); analogWrite(_pin, 512); delay(_length); analogWrite(_pin, 0); } — You are receiving this because you authored the thread. 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can i use MQ2 sensor and ESP8266 CH340 version for this project?