关于物联网:ESP8266-MQTT-如何实现-LED-灯的远程控制

MQTT 是轻量级的、灵便的物联网音讯替换和数据传递协定，致力于为 IoT 开发人员实现灵活性与硬件 / 网络资源的均衡。

NodeMCU 是一个开源的物联网平台。它应用 Lua 语言编程。该平台基于 eLua 开源我的项目，底层应用 ESP8266 sdk 0.9.5 版本。

在此我的项目中咱们将实现 NodeMCU(ESP8266) 与 EMQ X Cloud 经营和保护的收费公共 MQTT 服务器近程管制 LED 灯，并应用 Arduino IDE 来对 NodeMCU ESP8266 进行编程。EMQ X Cloud 是由 EMQ 推出的平安的 MQTT 物联网云服务平台，它提供一站式运维代管、独有隔离环境的 MQTT 5.0 接入服务。

所需组件

• NodeMCU
• Arduino IDE
• LED * 1，330 Ω 电阻
• MQTT X: 优雅的跨平台 MQTT 5.0 客户端工具

• 收费的公共 MQTT 服务器

  • Broker: broker.emqx.io
  • TCP Port: 1883
  • Websocket Port: 8083

NodeMCU ESP8266 和 LED 连贯图

代码编写

1. 首先咱们将导入 ESP8266WiFi 和 PubSubClient 库，ESP8266WiFi 库可能将 ESP8266 连贯到 WiFi 网络，PubSubClient 库，使咱们可能连贯到 MQTT 代理并公布 / 订阅主题音讯。

   #include <ESP8266WiFi.h>
   #include <PubSubClient.h>

2. 咱们将应用 NodeMCU ESP8266 的 D1 引脚来连贯到 LED，实际上该引脚外部连贯到 ESP8266 模块的 GPIO5。

   // GPIO 5 D1
   #define LED 5

3. 设置 WIFI 名称和明码，以及 MQTT Broker 连贯地址和端口

   // WiFi
   const char *ssid = "mousse"; // Enter your WiFi name
   const char *password = "qweqweqwe";  // Enter WiFi password
    
   // MQTT Broker
   const char *mqtt_broker = "broker.emqx.io";
   const char *topic = "esp8266/led";
   const char *mqtt_username = "emqx";
   const char *mqtt_password = "public";
   const int mqtt_port = 1883;

4. 咱们关上了一个串行连贯，以便于输入程序的后果并且连贯到 WiFi 网络

   // Set software serial baud to 115200;
   Serial.begin(115200);
   // connecting to a WiFi network
   WiFi.begin(ssid, password);
   while (WiFi.status() != WL_CONNECTED) {delay(500);
       Serial.println("Connecting to WiFi..");
   }

5. 咱们将设置 MQTT Broker，同时将连贯信息打印到串口监视器上

    //connecting to a 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.println("Connecting to public emqx mqtt broker.....");
       if (client.connect(client_id, mqtt_username, mqtt_password)) {Serial.println("Public emqx mqtt broker connected");
       } else {Serial.print("failed with state");
           Serial.print(client.state());
           delay(2000);
       }
   }

6. MQTT Broker 连贯胜利后，ESP8266 将向 MQTT Broker 公布和订阅音讯

   // publish and subscribe
   client.publish(topic, "hello emqx");
   client.subscribe(topic);

7. 编写回调函数，从串行监视器读取下发指令并且管制 LED 的开和关

   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 = message + (char) payload[i];  // convert *byte to string
       }
       Serial.print(message);
       if (message == "on") {digitalWrite(LED, LOW); }   // LED on
       if (message == "off") {digitalWrite(LED, HIGH); } // LED off
       Serial.println();
       Serial.println("-----------------------");
   }

8. 残缺代码

   #include <ESP8266WiFi.h>
   #include <PubSubClient.h>
   
   // GPIO 5 D1
   #define LED 5
   
   // WiFi
   const char *ssid = "mousse"; // Enter your WiFi name
   const char *password = "qweqweqwe";  // Enter WiFi password
   
   // MQTT Broker
   const char *mqtt_broker = "broker.emqx.io";
   const char *topic = "esp8266/led";
   const char *mqtt_username = "emqx";
   const char *mqtt_password = "public";
   const int mqtt_port = 1883;
   
   WiFiClient espClient;
   PubSubClient client(espClient);
   
   void setup() {
       // Set software serial baud to 115200;
       Serial.begin(115200);
       // 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");
       //connecting to a 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.println("Connecting to public emqx mqtt broker.....");
           if (client.connect(client_id, mqtt_username, mqtt_password)) {Serial.println("Public emqx mqtt broker connected");
           } else {Serial.print("failed with state");
               Serial.print(client.state());
               delay(2000);
           }
       }
       // publish and subscribe
       client.publish(topic, "hello emqx");
       client.subscribe(topic);
   }
   
   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 = message + (char) payload[i];  // convert *byte to string
       }
       Serial.print(message);
       if (message == "on") {digitalWrite(LED, LOW); }   // LED on
       if (message == "off") {digitalWrite(LED, HIGH); } // LED off
       Serial.println();
       Serial.println("-----------------------");
   }
   
   void loop() {client.loop();
   }

连贯和测试

1. 请应用 Arduino IDE 将残缺代码上传 ESP8266，并关上串口监视器

2. 建设 MQTTX 客户端 与 MQTT Broker 连贯, 并向 ESP8266 发送指令

总结

至此，咱们胜利实现 NodeMCU ESP8266 与收费公共 MQTT 服务器近程管制 LED 灯，该例子只是形容了一个简略的场景，在理论的我的项目中，须要更加平安的连贯形式，以及对物联网数据进行长久化等性能。

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版权申明：本文为 EMQ 原创，转载请注明出处。

原文链接：https://www.emqx.cn/blog/esp8266_mqtt_led