使用MQTTGO.io的服務。範例檔：「5.MQTT_RGB」。
1.新增訂閱主題(Add Subscription)，本範例的Topic為「李小保/ESP32/環境」。
2.Arduino設定推播主題。
1.新增推播主題，本範例的Topic為「李小保/ESP32/Rled」。
2.Arduino設定訂閱主題。
3.在訊息中輸入「on」或「off」，點選「Publish」透過推播來開啟或關閉RGB燈。
#include <WiFi.h>
#include <PubSubClient.h> //請先安裝PubSubClient程式庫
#include <SimpleDHT.h>
#include <ESP32Servo.h> //請先安裝ESP32Servo程式庫
// ------ 以下修改成你自己的WiFi帳號密碼 ------
char* ssid = "test";
char* password = "12345678";
//------ 以下修改成你DHT11腳位 ------
int pinDHT11 = 4;
SimpleDHT11 dht11(pinDHT11);
// ------ 以下修改成你MQTT設定 ------
char* MQTTServer = "mqttgo.io";//免註冊MQTT伺服器
int MQTTPort = 1883;//MQTT Port 除非加密，否則不用更改port
char* MQTTUser = "";//不須帳密
char* MQTTPassword = "";//不須帳密
//推播主題1:推播溫度(記得改Topic)
char* MQTTPubTopic1 = "李小保/ESP32/環境";
//訂閱主題1:改變LED燈號(記得改Topic)
char* MQTTSubTopic1 = "李小保/ESP32/Rled";
char* MQTTSubTopic2 = "李小保/ESP32/Yled";
char* MQTTSubTopic3 = "李小保/ESP32/Gled";
long MQTTLastPublishTime;//此變數用來記錄推播時間
long MQTTPublishInterval = 10000;//每10秒推撥一次
WiFiClient WifiClient;
PubSubClient MQTTClient(WifiClient);
void setup() {
Serial.begin(115200);
pinMode(15, OUTPUT);//rLED燈
pinMode(16, OUTPUT);//yLED燈
pinMode(17, OUTPUT);//gLED燈
//開始WiFi連線
WifiConnecte();
//開始MQTT連線
MQTTConnecte();
}
void loop() {
//如果WiFi連線中斷，則重啟WiFi連線
if (WiFi.status() != WL_CONNECTED) { WifiConnecte(); }
//如果MQTT連線中斷，則重啟MQTT連線
if (!MQTTClient.connected()) { MQTTConnecte(); }
//如果距離上次傳輸已經超過10秒，則Publish溫溼度
if ((millis() - MQTTLastPublishTime) >= MQTTPublishInterval ) {
//讀取溫濕度
byte temperature = 0;
byte humidity = 0;
ReadDHT(&temperature, &humidity);
// ------ 將DHT11溫度送到MQTT主題 ------
String json="{\\"temp\\":"+String(temperature)+",\\"humi\\":"+String(humidity)+"}";
MQTTClient.publish(MQTTPubTopic1, json.c_str());
Serial.println("環境參數已推播到MQTT Broker");
MQTTLastPublishTime = millis(); //更新最後傳輸時間
}
MQTTClient.loop();//更新訂閱狀態
delay(50);
}
//讀取DHT11溫濕度
void ReadDHT(byte *temperature, byte *humidity) {
int err = SimpleDHTErrSuccess;
if ((err = dht11.read(temperature, humidity, NULL)) !=
SimpleDHTErrSuccess) {
Serial.print("讀取失敗,錯誤訊息=");
Serial.print(SimpleDHTErrCode(err));
Serial.print(",");
Serial.println(SimpleDHTErrDuration(err));
delay(1000);
return;
}
Serial.print("DHT讀取成功：");
Serial.print((int)*temperature);
Serial.print(" *C, ");
Serial.print((int)*humidity);
Serial.println(" H");
}
//開始WiFi連線
void WifiConnecte() {
//開始WiFi連線
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("WiFi連線成功");
Serial.print("IP Address:");
Serial.println(WiFi.localIP());
}
//開始MQTT連線
void MQTTConnecte() {
MQTTClient.setServer(MQTTServer, MQTTPort);
MQTTClient.setCallback(MQTTCallback); //收到訂閱資料時，要處理MQTTCALLBACK
while (!MQTTClient.connected()) {
//以亂數為ClietID
String MQTTClientid = "esp32-" + String(random(1000000, 9999999));//建立一個郵差，為了要不一樣，所以使用亂數
if (MQTTClient.connect(MQTTClientid.c_str(), MQTTUser, MQTTPassword)) {
//連結成功，顯示「已連線」。
Serial.println("MQTT已連線");
//訂閱SubTopic1主題
MQTTClient.subscribe(MQTTSubTopic1);
MQTTClient.subscribe(MQTTSubTopic2);
MQTTClient.subscribe(MQTTSubTopic3);
} else {
//若連線不成功，則顯示錯誤訊息，並重新連線
Serial.print("MQTT連線失敗,狀態碼=");
Serial.println(MQTTClient.state());
Serial.println("五秒後重新連線");
delay(5000);
}
}
}
//接收到訂閱時
void MQTTCallback(char* topic, byte* payload, unsigned int length) {
Serial.print(topic); Serial.print("訂閱通知:");
String payloadString;//將接收的payload轉成字串
//顯示訂閱內容
for (int i = 0; i < length; i++) {
payloadString = payloadString + (char)payload[i];
}
Serial.println(payloadString);
//比對主題是否為訂閱主題1
if (strcmp(topic, MQTTSubTopic1) == 0) {
Serial.println("改變燈號r：" + payloadString);
if (payloadString == "on") {
digitalWrite(15, HIGH);
}
if (payloadString == "off") {
digitalWrite(15, LOW);
}
}
if (strcmp(topic, MQTTSubTopic2) == 0) {
Serial.println("改變燈號y：" + payloadString);
if (payloadString == "on") {
digitalWrite(16, HIGH);
}
if (payloadString == "off") {
digitalWrite(16, LOW);
}
}
if (strcmp(topic, MQTTSubTopic3) == 0) {
Serial.println("改變燈號g：" + payloadString);
if (payloadString == "on") {
digitalWrite(17, HIGH);
}
if (payloadString == "off") {
digitalWrite(17, LOW);
}
}
}