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 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

    // WiFiconst char *ssid = "mousse"; // Enter your WiFi nameconst char *password = "qweqweqwe";  // Enter WiFi password // MQTT Brokerconst 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 networkWiFi.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 brokerclient.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 subscribeclient.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// WiFiconst char *ssid = "mousse"; // Enter your WiFi nameconst char *password = "qweqweqwe";  // Enter WiFi password// MQTT Brokerconst 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