MQTT Basic2 (WOKWI ESP32 + MQTT Box )

 MQTT Basic2  (WOKWI  ESP32 + MQTT Box )

使用 <ArduinoMqttClient.h> library

主題有修正如下

const char broker[] = "test.mosquitto.org";

int        port     = 1883;

const char Pubtopic1[]  = "alex9ufo/hello";

const char Subtopic2[]  = "alex9ufo/led";

message == "on" 亮 message == "off" 熄

WOKWI程式

#include <ArduinoMqttClient.h>

#include <WiFi.h>

///////please enter your sensitive data in the Secret tab/arduino_secrets.h

char ssid[] =  "Wokwi-GUEST"; // your network SSID (name)

char pass[] =  "" ;           // your network password (use for WPA, or use as key for WEP)

WiFiClient wifiClient;

MqttClient mqttClient(wifiClient);

const char broker[] = "test.mosquitto.org";

int        port     = 1883;

const char Pubtopic1[]  = "alex9ufo/hello";

const char Subtopic2[]  = "alex9ufo/led";

const char willTopic[] = "alex9ufo/Starting";

//set interval for sending messages (milliseconds)

const long interval = 8000;

unsigned long previousMillis = 0;

int count = 0;

const int LED = 2;

char msg[50];

int value = 0;

//=======================================================================

void onMqttMessage(int messageSize) {

  // we received a message, print out the topic and contents

  Serial.println("Received a message with topic '");

  Serial.print(mqttClient.messageTopic());

  Serial.print("', length ");

  Serial.print(messageSize);

  Serial.println(" bytes:");

  String Topic= mqttClient.messageTopic();

  String message="";

  // use the Stream interface to print the contents

  while (mqttClient.available()) {

    //Serial.print((char)mqttClient.read());

    message += (char)mqttClient.read();

  }

  Serial.println(message);

  message.trim();

  Topic.trim();

  if (Topic=="alex9ufo/led") {

    if (message == "on") {

      digitalWrite(LED, LOW);  // Turn on the LED

      Serial.print("LED = on ");

    }

    if (message == "off" ) {

      digitalWrite(LED, HIGH); // Turn off the LED

      Serial.print("LED = off ");

    }

  }

  Serial.println();

  Serial.println();

}

//=======================================================================

//副程式  setup wifi

void setup_wifi() {

  delay(10);

  // We start by connecting to a WiFi network

  Serial.println();

  Serial.print("Connecting to ");

  Serial.println(ssid);     //print ssid

  WiFi.begin(ssid, pass);  //初始化WiFi 函式庫並回傳目前的網路狀態

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

    delay(500);

    Serial.print(".");

  }   //假設 wifi 未連接 show ………

  Serial.println("");

  Serial.println("WiFi connected");

  Serial.println("IP address: ");

  Serial.println(WiFi.localIP());

}  

//=======================================================================

void setup() {

  //Initialize serial and wait for port to open:

  Serial.begin(115200);

  pinMode(LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output

  Serial.begin(115200);   // Initialize serial communications with the PC

  while (!Serial);    // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)

 

  setup_wifi();

  Serial.println("You're connected to the network");

  Serial.println();

 

  String willPayload = "ESP32 Start working....!";

  bool willRetain = true;

  int willQos = 1;

  mqttClient.beginWill(willTopic, willPayload.length(), willRetain, willQos);

  mqttClient.print(willPayload);

  mqttClient.endWill();

  Serial.print("Attempting to connect to the MQTT broker: ");

  Serial.println(broker);

  if (!mqttClient.connect(broker, port)) {

    Serial.print("MQTT connection failed! Error code = ");

    Serial.println(mqttClient.connectError());

    while (1);

  }

  Serial.println("You're connected to the MQTT broker!");

  Serial.println();

  // set the message receive callback

  mqttClient.onMessage(onMqttMessage);

  Serial.print("Subscribing to topic: ");

  Serial.println(Subtopic2);

  // subscribe to a topic

  // the second parameter sets the QoS of the subscription,

  // the the library supports subscribing at QoS 0, 1, or 2

  int subscribeQos = 1;

  mqttClient.subscribe(Subtopic2, subscribeQos);

}

//=======================================================================

void loop() {

  // call poll() regularly to allow the library to send MQTT keep alive which

  // avoids being disconnected by the broker

  mqttClient.poll();

  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {

    // save the last time a message was sent

    previousMillis = currentMillis;

    //record random value from A0, A1 and A2

    ++value;

    snprintf (msg, 75, "hello world #%ld", value);

    Serial.print("Publish message: ");

    Serial.println(msg);

    Serial.print("Sending message to topic: ");

    Serial.println(Pubtopic1);

    Serial.println(msg);

    // send message, the Print interface can be used to set the message contents

    mqttClient.beginMessage(Pubtopic1);

    mqttClient.print(msg);

    mqttClient.endMessage();

    Serial.println();

  }

}