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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
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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
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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> -
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 -
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; -
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.."); } -
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); } } -
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); -
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("-----------------------"); } -
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
- 请应用 Arduino IDE 将残缺代码上传 ESP8266，并关上串口监视器
- 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
