[Arduino demo source code for KC868-A4]-14 MQTT demo

Code:
// MQTT demo source code for KC868-A4

// Remote control relay ON/OFF by any MQTT broker

// Digital input use by switch button for ON/OFF and demo show state feedback

// You can use by MQTTBOX for test or KinCony KBOX android phone app



#define Relay1  2 

#define Relay2  15 

#define Relay3  5 

#define Relay4  4 



#define Key1  36 

#define Key2  39 

#define Key3  27 

#define Key4  14

 

 

int KEY_NUM1 = 0;    //key_1 value

int KEY_NUM2 = 0;    //key_2 value 

int KEY_NUM3 = 0;    //key_3 value 

int KEY_NUM4 = 0;    //key_4 value 



#include <string.h>

#include <WiFi.h>

#include <PubSubClient.h>





// WiFi

const char *ssid = "KinCony"; // Enter your WiFi name

const char *password = "a12345678";  // Enter WiFi password



// MQTT Broker

const char *mqtt_broker = "iot.kincony.com";  // or your MQTT broker IP/Domain

const char *topic_command = "relay4/123456/set";  // if use by KBOX android phone app, use relay4/xxxxxx/set      for command

const char *topic_state = "relay4/123456/state";  // if use by KBOX android phone app, use relay4/xxxxxx/state    for feedback state

const char *mqtt_username = "mqtt"; 

const char *mqtt_password = "123";

const int mqtt_port = 1883;



WiFiClient espClient;

PubSubClient client(espClient);



void setup() {



  pinMode(Relay1,OUTPUT);   //Relay1 IO2

  pinMode(Relay2,OUTPUT);   //Relay2 IO15

  pinMode(Relay3,OUTPUT);   //Relay3 IO2

  pinMode(Relay4,OUTPUT);   //Relay4 IO2



  pinMode(Key1,INPUT);  //Digital input1 IO36

  pinMode(Key2,INPUT);  //Digital input2 IO39

  pinMode(Key3,INPUT);  //Digital input3 IO27

  pinMode(Key4,INPUT);  //Digital input4 IO14



  pinMode(2, OUTPUT);   //relay1

  pinMode(15, OUTPUT);  //relay2

  pinMode(4, OUTPUT);   //relay3

  pinMode(5, OUTPUT);   //relay4



  digitalWrite(2, LOW);   // turn the LED OFF (HIGH is the voltage level)

  digitalWrite(15,LOW);

  digitalWrite(4, LOW);

  digitalWrite(5, LOW);



  

 // Set software serial baud to 115200;

 Serial.begin(115200);

 // connecting to a WiFi network

 WiFi.begin(ssid, password);

 while (WiFi.status() != WL_CONNECTED) {

     delay(500);

     Serial.println("Connecting to WiFi..");

 }

 Serial.println("Connected to the WiFi network");

 //connecting to a mqtt broker

 client.setServer(mqtt_broker, mqtt_port);

 client.setCallback(callback);

 while (!client.connected()) {

     String client_id = "esp32-client-";

     client_id += String(WiFi.macAddress());

     Serial.printf("The client %s connects to the public mqtt broker\n", client_id.c_str());

     if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {

         Serial.println("Public emqx mqtt broker connected");

     } else {

         Serial.print("failed with state ");

         Serial.print(client.state());

         delay(2000);

     }

 }

 // publish and subscribe

 client.publish(topic_state, "Hi I am KC868-A4");

 client.subscribe(topic_command);

}



void callback(char *topic_command, byte *payload, unsigned int length) {

 Serial.print("Message arrived in topic: ");

 Serial.println(topic_command);

 Serial.print("Message:");

 for (int i = 0; i < length; i++) {

     Serial.print((char) payload[i]);

 }

 Serial.println();

 Serial.println("-----------------------");



 if (!strncmp((char *)payload, "{\"relay1\":{\"on\":1}}", length)) digitalWrite(Relay1, HIGH);

 else if (!strncmp((char *)payload, "{\"relay1\":{\"on\":0}}", length)) digitalWrite(Relay1, LOW);



 if (!strncmp((char *)payload, "{\"relay2\":{\"on\":1}}", length)) digitalWrite(Relay2, HIGH);

 else if (!strncmp((char *)payload, "{\"relay2\":{\"on\":0}}", length)) digitalWrite(Relay2, LOW);



 if (!strncmp((char *)payload, "{\"relay3\":{\"on\":1}}", length)) digitalWrite(Relay3, HIGH);

 else if (!strncmp((char *)payload, "{\"relay3\":{\"on\":0}}", length)) digitalWrite(Relay3, LOW);



 if (!strncmp((char *)payload, "{\"relay4\":{\"on\":1}}", length)) digitalWrite(Relay4, HIGH);

 else if (!strncmp((char *)payload, "{\"relay4\":{\"on\":0}}", length)) digitalWrite(Relay4, LOW);



 



 if (!strncmp((char *)payload, "{\"relay4\":{\"read\":1}}", length)) {   //for app read all state, replace with your read relay and input code

      client.publish(topic_state, "{\"relay1\":{\"on\":0},\"relay2\":{\"on\":0},\"relay3\":{\"on\":0},\"relay4\":{\"on\":0},\"input1\":{\"on\":0},\"input2\":{\"on\":0},\"input3\":{\"on\":0},\"input4\":{\"on\":0}}");

    }



 

}



void loop() {

  ScanKey1();            //scan key1

  ScanKey2();            //scan key2

  ScanKey3();            //scan key3

  ScanKey4();            //scan key4

 client.loop();

}



void ScanKey1()            

{

  String temp="{\"relay1\":{\"on\":";



  KEY_NUM1 = 0;                      

  if(digitalRead(Key1) == LOW)         //key1 pressed

  {

    delay(20);                        //anti-interference

    if(digitalRead(Key1) == LOW)       //key1 pressed again

    {

      KEY_NUM1 = 1;                   

      while(digitalRead(Key1) == LOW); //wait remove hand

    }

  }

  if(KEY_NUM1 == 1)              //if key1 pressed

  {   

    digitalWrite(Relay1,!digitalRead(Relay1));    // toggle relay1 state

    if(digitalRead(Relay1) == LOW) temp=temp+"0}}"; 

    if(digitalRead(Relay1) == HIGH) temp=temp+"1}}"; 



    client.publish(topic_state, temp.c_str());

  }  

}



void ScanKey2()            

{

  String temp="{\"relay2\":{\"on\":";

  KEY_NUM2 = 0;                      

  if(digitalRead(Key2) == LOW)         //key2 pressed

  {

    delay(20);                        //anti-interference

    if(digitalRead(Key2) == LOW)       //key2 pressed again

    {

      KEY_NUM2 = 1;                   

      while(digitalRead(Key2) == LOW); //wait remove hand

    }

  }

  if(KEY_NUM2 == 1)              //if key2 pressed

  {   

    digitalWrite(Relay2,!digitalRead(Relay2));    // toggle relay2 state

    if(digitalRead(Relay2) == LOW) temp=temp+"0}}"; 

    if(digitalRead(Relay2) == HIGH) temp=temp+"1}}"; 

    client.publish(topic_state, temp.c_str());

  } 

}



void ScanKey3()            

{

  String temp="{\"relay3\":{\"on\":";

  KEY_NUM3 = 0;                      

  if(digitalRead(Key3) == LOW)         //key3 pressed

  {

    delay(20);                        //anti-interference

    if(digitalRead(Key3) == LOW)       //key3 pressed again

    {

      KEY_NUM3 = 1;                   

      while(digitalRead(Key3) == LOW); //wait remove hand

    }

  }

  if(KEY_NUM3 == 1)              //if key3 pressed

  {   

    digitalWrite(Relay3,!digitalRead(Relay3));    // toggle relay3 state

    if(digitalRead(Relay3) == LOW) temp=temp+"0}}"; 

    if(digitalRead(Relay3) == HIGH) temp=temp+"1}}"; 

    client.publish(topic_state, temp.c_str());

  } 

}



void ScanKey4()            

{

  String temp="{\"relay4\":{\"on\":";

  KEY_NUM4 = 0;                      

  if(digitalRead(Key4) == LOW)         //key4 pressed

  {

    delay(20);                        //anti-interference

    if(digitalRead(Key4) == LOW)       //key4 pressed again

    {

      KEY_NUM4 = 1;                   

      while(digitalRead(Key4) == LOW); //wait remove hand

    }

  }

  if(KEY_NUM4 == 1)              //if key4 pressed

  {   

    digitalWrite(Relay4,!digitalRead(Relay4));    // toggle relay4 state

    if(digitalRead(Relay4) == LOW) temp=temp+"0}}"; 

    if(digitalRead(Relay4) == HIGH) temp=temp+"1}}"; 

    client.publish(topic_state, temp.c_str());

  } 

}