fablabbh_demo_projects/projects/mqtt-nodered/mqtt-nodered.ino

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

// WiFi credentials
const char* ssid                    = "feda";
const char* password                = "66661758";

// MQTT broker details
const char* mqtt_server             = "87.237.194.228";
const int   mqtt_port               = 1883;
// The username and password are not used as per your request.
// const char* mqtt_user            = "mqtt_username";
// const char* mqtt_password        = "mqtt_password";

WiFiClient espClient;
PubSubClient client(espClient);

// Relay pins
const int relay1Pin                 = 0;
const int relay2Pin                 = 1;

// Button pins (connected to GND with internal pull-ups)
const int button1Pin                = 2;
const int button2Pin                = 3;

// MQTT topics
const char* deviceIpTopic           = "home/device/ip";
const char* relay1CommandTopic      = "home/relay1/set";
const char* relay2CommandTopic      = "home/relay2/set";
const char* relay1StateTopic        = "home/relay1/state";
const char* relay2StateTopic        = "home/relay2/state";

// Relay states (use bools for easy toggle)
bool relay1State                    = LOW;
bool relay2State                    = LOW;

unsigned long lastDebounceTime1     = 0;
unsigned long lastDebounceTime2     = 0;
const unsigned long debounceDelay   = 50;

// Function prototypes
void setup_wifi();
void publishRelayState();
void callback(char* topic, byte* payload, unsigned int length);
void reconnect();

void setup_wifi() {
  delay(10);
  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.print("IP address: ");
  Serial.println(WiFi.localIP());
}

void publishRelayState() {
  // Use .c_str() for publishing
  client.publish(relay1StateTopic, !relay1State ? "ON" : "OFF", true);
  client.publish(relay2StateTopic, !relay2State ? "ON" : "OFF", true);
  Serial.print("Relay1 state published: ");
  Serial.println(!relay1State ? "ON" : "OFF");
  Serial.print("Relay2 state published: ");
  Serial.println(!relay2State ? "ON" : "OFF");
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.println(topic);

  String message;
  for (unsigned int i = 0; i < length; i++) {
    message += (char)payload[i];
  }
  message.toUpperCase();
  Serial.print("Payload: ");
  Serial.println(message);

  if (String(topic) == relay1CommandTopic) {
    if (message == "1") {
      relay1State = LOW;
      // digitalWrite(relay1Pin, relay1State);
    } else if (message == "0") {
      relay1State = HIGH;
      // digitalWrite(relay1Pin, relay1State);
    }
    digitalWrite(relay1Pin, relay1State);
    publishRelayState();
  } else if (String(topic) == relay2CommandTopic) {
    if (message == "1") {
      relay2State = LOW;
      // digitalWrite(relay2Pin, LOW);
    } else if (message == "0") {
      relay2State = HIGH;
      // digitalWrite(relay2Pin, HIGH);
    }
    digitalWrite(relay2Pin, relay2State);
    publishRelayState();
  }
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Connect without a username or password
    if (client.connect("ESP32C3Client")) {
      Serial.println("connected");
      client.subscribe(relay1CommandTopic);
      client.subscribe(relay2CommandTopic);

      // Convert IP to String once, then get C-string pointer
      String ipString = WiFi.localIP().toString();
      client.publish(deviceIpTopic, ipString.c_str());
      
      publishRelayState();
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

void setup() {
  Serial.begin(115200);

  pinMode(relay1Pin, OUTPUT);
  pinMode(relay2Pin, OUTPUT);
  pinMode(button1Pin, INPUT_PULLUP);
  pinMode(button2Pin, INPUT_PULLUP);

  // Initialize relays off
  relay1State = LOW;
  relay2State = LOW;
  digitalWrite(relay1Pin, relay1State);
  digitalWrite(relay2Pin, relay2State);

  setup_wifi();

  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(callback);
}

void loop() {
  // Button 1 handling with debounce
  if (digitalRead(button1Pin) == LOW) {
    if ((millis() - lastDebounceTime1) > debounceDelay) {
      relay1State = !relay1State;
      digitalWrite(relay1Pin, relay1State);
      publishRelayState();
      lastDebounceTime1 = millis();
    }
  }

  // Button 2 handling with debounce
  if (digitalRead(button2Pin) == LOW) {
    if ((millis() - lastDebounceTime2) > debounceDelay) {
      relay2State = !relay2State;
      digitalWrite(relay2Pin, relay2State);
      publishRelayState();
      lastDebounceTime2 = millis();
    }
  }

  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}