mqtt 예제 > 아두이노

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#include <ESP8266WiFi.h>
#include <MQTTPubSubClient.h>

WiFiClient client;
MQTTPubSubClient mqtt;

char* ssid     = "무선 SSID";
char* password = "비밀번호";

void setup() {
  Serial.begin(115200);
 
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {    
    Serial.print(".");
    delay(500);
  }
  Serial.println("WIFI connect OK");

  Serial.println("mqtt connecting ");
  while (!client.connect("mqtt 서버주소", 1883)) {
    Serial.print(".");
    delay(500);
  }
  Serial.println("mqtt connect OK");

  mqtt.begin(client);
  Serial.println("mqtt broker connecting");
  //while (!mqtt.connect()) {
  while (!mqtt.connect("클라이언트 이름", "mqtt ID", "mqtt PW")) {
    Serial.print(".");
    delay(500);
  }
  Serial.println("mqtt broker connect OK");

    // 모든 패킷이 올 때 호출되는 subscribe 콜백
    mqtt.subscribe([](const String& topic, const String& payload, const size_t size) {
        Serial.println("mqtt received: " + topic + " - " + payload);
    });

    // /hello가 왔을 때 호출되는 주제 및 콜백 구독
    mqtt.subscribe("/hello", [](const String& payload, const size_t size) {
        Serial.print("/hello ");
        Serial.println(payload);
    }); 
 
}

void loop() {
  mqtt.update();  // should be called
 
  // publish message
  static uint32_t prev_ms = millis();
  if (millis() > prev_ms + 1000) {
      prev_ms = millis();

      String msg = "arduino - " + String(prev_ms);
      Serial.println(msg);
      mqtt.publish("/intertech/arduino", msg);
  }
}