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这篇文章主要讲解了“ESP8266+MQTT怎么实现LED灯的远程控制”,文中的讲解内容简单清晰,易于学习与理解,下面请大家跟着小编的思路慢慢深入,一起来研究和学习“ESP8266+MQTT怎么实现LED灯的远程控制”吧!
MQTT 是轻量级的、灵活的物联网消息交换和数据传递协议,致力于为 IoT 开发人员实现灵活性与硬件/网络资源的平衡。
NodeMCU 是一个开源的物联网平台。它使用 Lua 语言编程。该平台基于eLua开源项目,底层使用ESP8266 sdk 0.9.5版本。
在此项目中我们将实现 NodeMCU(ESP8266) 与 EMQ X Cloud 运营和维护的免费公共 MQTT 服务器远程控制 LED 灯,并使用 Arduino IDE 来对 NodeMCU ESP8266 进行编程。 EMQ X Cloud 是由 EMQ 推出的安全的 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。
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
免费的公共 MQTT 服务器
Broker: broker.emqx.io
TCP Port: 1883
Websocket Port: 8083
首先我们将导入 ESP8266WiFi 和 PubSubClient 库,ESP8266WiFi 库能够将 ESP8266 连接到 WiFi 网络,PubSubClient 库,使我们能够连接到 MQTT 代理并发布/订阅主题消息。
#include <ESP8266WiFi.h> #include <PubSubClient.h>
我们将使用 NodeMCU ESP8266 的 D1 引脚来连接到 LED,实际上该引脚内部连接到 ESP8266 模块的 GPIO5。
// GPIO 5 D1 #define LED 5
设置 WIFI 名称和密码,以及 MQTT Broker 连接地址和端口
// 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;
我们打开了一个串行连接,以便于输出程序的结果并且连接到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.."); }
我们将设置 MQTT Broker,同时将连接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 连接成功后,ESP8266 将向 MQTT Broker 发布和订阅消息
// 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控制 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("-----------------------"); }
完整代码
#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(); }
请使用 Arduino IDE 将完整代码上传 ESP8266,并打开串口监视器
建立 MQTTX 客户端 与 MQTT Broker 连接, 并向 ESP8266 发送指令
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