alex9ufo 聰明人求知心切: ESP32 MQTT – Publish and Subscribe with Arduino IDE

ESP32 MQTT – Publish and Subscribe with Arduino IDE

Installing the PubSubClient Library

The PubSubClient library provides a client for doing simple publish/subscribe messaging with a server that supports MQTT (basically allows your ESP32 to talk with Node-RED).

Click here to download the PubSubClient library. You should have a .zip folder in your Downloads folder
Unzip the .zip folder and you should get pubsubclient-master folder
Rename your folder from ~~pubsubclient-master~~ to pubsubclient
Move the pubsubclient folder to your Arduino IDE installation libraries folder
Then, re-open your Arduino IDE

The library comes with a number of example sketches. See File >Examples > PubSubClient within the Arduino IDE software.

Important: PubSubClient is not fully compatible with the ESP32, but the example provided in this tutorial is working very reliably during our tests.

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

// GPIO 2 D1
#define LED 2

#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>

#define DHTPIN 27     // Digital pin connected to the DHT sensor 
// Feather HUZZAH ESP8266 note: use pins 3, 4, 5, 12, 13 or 14 --
// Pin 15 can work but DHT must be disconnected during program upload.

// Uncomment the type of sensor in use:
//#define DHTTYPE    DHT11     // DHT 11
#define DHTTYPE    DHT22     // DHT 22 (AM2302)
//#define DHTTYPE    DHT21     // DHT 21 (AM2301)
DHT_Unified dht(DHTPIN, DHTTYPE);
uint32_t delayMS;

// WiFi
const char *ssid = "alex9ufo"; // Enter your Wi-Fi name
const char *password = "alex9981";  // Enter Wi-Fi password

// MQTT Broker
const char *mqtt_broker = "broker.mqtt-dashboard.com";
const char *topic1 = "alex9ufo/esp32/led";
const char *topic2 = "alex9ufo/esp32/temperature";
const char *topic3 = "alex9ufo/esp32/humidity";

const char *mqtt_username = "alex9ufo";
const char *mqtt_password = "public";
const int mqtt_port = 1883;

bool ledState = false;

WiFiClient espClient;
PubSubClient client(espClient);

long lastMsg = 0;
char msg[50];
String json = "";    
char jsonChar1[100];  //client.publish("alex9ufo/Esp32/temperature"
char jsonChar2[100];  //client.publish("alex9ufo/Esp32/humidity"

//===========================================================
void setup() {
    // Set software serial baud to 115200;
    Serial.begin(115200);
    delay(1000); // Delay for stability
    //======================================================
    dht.begin();
    Serial.println(F("DHTxx Unified Sensor Example"));
    // Print temperature sensor details.
    sensor_t sensor;
    dht.temperature().getSensor(&sensor);
    Serial.println(F("------------------------------------"));
    Serial.println(F("Temperature Sensor"));
    Serial.print  (F("Sensor Type: ")); Serial.println(sensor.name);
    Serial.print  (F("Driver Ver:  ")); Serial.println(sensor.version);
    Serial.print  (F("Unique ID:   ")); Serial.println(sensor.sensor_id);
    Serial.print  (F("Max Value:   ")); Serial.print(sensor.max_value); Serial.println(F("°C"));
    Serial.print  (F("Min Value:   ")); Serial.print(sensor.min_value); Serial.println(F("°C"));
    Serial.print  (F("Resolution:  ")); Serial.print(sensor.resolution); Serial.println(F("°C"));
    Serial.println(F("------------------------------------"));
    // Print humidity sensor details.
    dht.humidity().getSensor(&sensor);
    Serial.println(F("Humidity Sensor"));
    Serial.print  (F("Sensor Type: ")); Serial.println(sensor.name);
    Serial.print  (F("Driver Ver:  ")); Serial.println(sensor.version);
    Serial.print  (F("Unique ID:   ")); Serial.println(sensor.sensor_id);
    Serial.print  (F("Max Value:   ")); Serial.print(sensor.max_value); Serial.println(F("%"));
    Serial.print  (F("Min Value:   ")); Serial.print(sensor.min_value); Serial.println(F("%"));
    Serial.print  (F("Resolution:  ")); Serial.print(sensor.resolution); Serial.println(F("%"));
    Serial.println(F("------------------------------------"));
    // Set delay between sensor readings based on sensor details.
    delayMS = sensor.min_delay / 1000;
  //======================================================
    // 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");

    // Setting LED pin as output
    pinMode(LED, OUTPUT);
    digitalWrite(LED, LOW);  // Turn off the LED initially

    // Connecting to an MQTT broker
    client.setServer(mqtt_broker, mqtt_port);
    client.setCallback(callback);
    while (!client.connected()) {
        String client_id = "esp8266-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 HiveMQ MQTT broker connected");
        } else {
            Serial.print("Failed with state ");
            Serial.print(client.state());
            delay(2000);
        }
    }

    // Publish and subscribe
    client.publish(topic1, "hello HiveMQ MQTT broker");
    client.subscribe(topic1);
    client.subscribe(topic2);
    client.subscribe(topic3);
}
//===========================================================
void callback(char *topic, byte *payload, unsigned int length) {
    Serial.print("Message arrived in topic: ");
    Serial.println(topic);
    Serial.print("Message: ");
    String message;
    for (int i = 0; i < length; i++) {
        message += (char) payload[i];  // Convert *byte to string
    }
    Serial.print(message);
    if (message == "on" && !ledState) {
        digitalWrite(LED, HIGH);  // Turn on the LED
        ledState = true;
    }
    if (message == "off" && ledState) {
        digitalWrite(LED, LOW); // Turn off the LED
        ledState = false;
    }
    Serial.println();
    Serial.println("-----------------------");
}
//===========================================================
void loop() {
    client.loop();
    delay(100); // Delay for a short period in each loop iteration
    long now = millis();
    if (now - lastMsg > 15000) {
    lastMsg = now;
    dht.begin();
    // Delay between measurements.
    delay(delayMS);
    // Get temperature event and print its value.
    sensors_event_t event;
    // Temperature in Celsius
    dht.temperature().getEvent(&event);
    if (isnan(event.temperature)) {
      Serial.println(F("Error reading temperature!"));
    }
    else {
      Serial.print(F("Temperature: "));
      Serial.print(event.temperature);
      Serial.println(F("°C"));
          
      String json1 =String(event.temperature);
      // Convert JSON string to character array
      json1.toCharArray(jsonChar1, json1.length()+1);
      client.publish(topic2, jsonChar1);
    }
 
      // Get humidity event and print its value.
    dht.humidity().getEvent(&event);
    if (isnan(event.relative_humidity)) {
      Serial.println(F("Error reading humidity!"));
    }
    else {
      Serial.print(F("Humidity: "));
      Serial.print(event.relative_humidity);
      Serial.println(F("%"));

      String json2=String(event.relative_humidity);  
      // Convert the value to a char array
      json2.toCharArray(jsonChar2, json2.length()+1);
      client.publish(topic3, jsonChar2);
    }  
  }



}
//===========================================================

alex9ufo 聰明人求知心切

2023年7月9日星期日

ESP32 MQTT – Publish and Subscribe with Arduino IDE

Installing the PubSubClient Library

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張貼留言

2024_09 作業3 以Node-Red 為主

2023年7月9日 星期日

ESP32 MQTT – Publish and Subscribe with Arduino IDE

Installing the PubSubClient Library

沒有留言:

張貼留言

2024_09 作業3 以Node-Red 為主

2023年7月9日星期日