网站500m空间够用吗,做视频网站软件有哪些,上海网站推广优化,深圳品牌展会一、库介绍 Arduino常用的MQTT库主要有PubSubClient。 PubSubClient库是一个广泛使用的MQTT客户端库#xff0c;它基于MQTT 3.1.1版本#xff0c;并且支持ESP8266和ESP32等Arduino兼容的硬件平台。PubSubClient库允许Arduino设备连接到MQTT服务器#xff0c;发布和订阅MQT…一、库介绍 Arduino常用的MQTT库主要有PubSubClient。 PubSubClient库是一个广泛使用的MQTT客户端库它基于MQTT 3.1.1版本并且支持ESP8266和ESP32等Arduino兼容的硬件平台。PubSubClient库允许Arduino设备连接到MQTT服务器发布和订阅MQTT主题实现与其他设备或服务的通信。 在使用PubSubClient库时需要将其包含在Arduino项目中并配置MQTT服务器的地址、端口、客户端ID等参数。然后可以使用库提供的函数来建立MQTT连接、发布消息到特定的主题以及订阅并处理接收到的消息。 除了PubSubClient库之外还有其他一些MQTT库可供选择但PubSubClient因其易用性和稳定性而广受欢迎。需要根据具体需求和项目环境选择适合的MQTT库。 安装完库可查看官方的示例代码查看方法如下
官方示例代码如下
/*Basic ESP8266 MQTT exampleThis sketch demonstrates the capabilities of the pubsub library in combinationwith the ESP8266 board/library.It connects to an MQTT server then:- publishes hello world to the topic outTopic every two seconds- subscribes to the topic inTopic, printing out any messagesit receives. NB - it assumes the received payloads are strings not binary- If the first character of the topic inTopic is an 1, switch ON the ESP Led,else switch it offIt will reconnect to the server if the connection is lost using a blockingreconnect function. See the mqtt_reconnect_nonblocking example for how toachieve the same result without blocking the main loop.To install the ESP8266 board, (using Arduino 1.6.4):- Add the following 3rd party board manager under File - Preferences - Additional Boards Manager URLs:http://arduino.esp8266.com/stable/package_esp8266com_index.json- Open the Tools - Board - Board Manager and click install for the ESP8266- Select your ESP8266 in Tools - Board
*/#include ESP8266WiFi.h
#include PubSubClient.h// Update these with values suitable for your network.const char* ssid ........;
const char* password ........;
const char* mqtt_server broker.mqtt-dashboard.com;WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg 0;
#define MSG_BUFFER_SIZE (50)
char msg[MSG_BUFFER_SIZE];
int value 0;void setup_wifi() {delay(10);// We start by connecting to a WiFi networkSerial.println();Serial.print(Connecting to );Serial.println(ssid);WiFi.mode(WIFI_STA);WiFi.begin(ssid, password);while (WiFi.status() ! WL_CONNECTED) {delay(500);Serial.print(.);}randomSeed(micros());Serial.println();Serial.println(WiFi connected);Serial.println(IP address: );Serial.println(WiFi.localIP());
}void callback(char* topic, byte* payload, unsigned int length) {Serial.print(Message arrived [);Serial.print(topic);Serial.print(] );for (int i 0; i length; i) {Serial.print((char)payload[i]);}Serial.println();// Switch on the LED if an 1 was received as first characterif ((char)payload[0] 1) {digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level// but actually the LED is on; this is because// it is active low on the ESP-01)} else {digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH}}void reconnect() {// Loop until were reconnectedwhile (!client.connected()) {Serial.print(Attempting MQTT connection...);// Create a random client IDString clientId ESP8266Client-;clientId String(random(0xffff), HEX);// Attempt to connectif (client.connect(clientId.c_str())) {Serial.println(connected);// Once connected, publish an announcement...client.publish(outTopic, hello world);// ... and resubscribeclient.subscribe(inTopic);} else {Serial.print(failed, rc);Serial.print(client.state());Serial.println( try again in 5 seconds);// Wait 5 seconds before retryingdelay(5000);}}
}void setup() {pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an outputSerial.begin(115200);setup_wifi();client.setServer(mqtt_server, 1883);client.setCallback(callback);
}void loop() {if (!client.connected()) {reconnect();}client.loop();unsigned long now millis();if (now - lastMsg 2000) {lastMsg now;value;snprintf (msg, MSG_BUFFER_SIZE, hello world #%ld, value);Serial.print(Publish message: );Serial.println(msg);client.publish(outTopic, msg);}
}
二、代码设计
代码设计思路 1.包含库在Arduino项目中包含必要的库文件特别是MQTT库如pubsubclient。 2.WiFi设置设置ESP8266连接到指定的WiFi网络所需的SSID和密码。 3.MQTT服务器设置配置MQTT服务器的地址、端口以及任何必要的认证信息如用户名和密码。 4.回调函数设置MQTT连接、发布和订阅的回调函数以便处理与MQTT服务器的通信。 5.初始化和连接在setup()函数中初始化MQTT客户端并尝试连接到MQTT服务器。 6.消息处理在loop()函数中处理MQTT消息例如发布消息到特定的主题或响应订阅的主题消息。
测试代码如下
#include ESP8266WiFi.h
#include PubSubClient.h // WiFi设置
const char* ssid yourSSID;
const char* password yourPASSWORD; // MQTT服务器设置
const char* mqtt_server yourMQTTServer;
const int mqtt_port 1883;
const char* mqtt_client_id ESP8266Client;
const char* mqtt_topic your/topic; //
unsigned long lastMsg 0;WiFiClient espClient;
PubSubClient client(espClient); void setup_wifi() { delay(10); // 连接到WiFi网络 Serial.print(Connecting to ); Serial.println(ssid); WiFi.begin(ssid, password); while (WiFi.status() ! WL_CONNECTED) { delay(500); Serial.print(.); } Serial.println(); Serial.println(WiFi connected); Serial.print(IP address: ); Serial.println(WiFi.localIP());
} void reconnect() { // Loop until were reconnected while (!client.connected()) { Serial.print(Attempting MQTT connection...); // 连接到MQTT服务器 if (client.connect(mqtt_client_id)) { Serial.println(connected); // 一旦连接订阅主题 client.subscribe(mqtt_topic); } else { delay(5000); } }
} void callback(char* topic, byte* payload, unsigned int length) { // 处理接收到的消息 Serial.print(Message arrived [); Serial.print(topic); Serial.print(] ); for (int i 0; i length; i) { Serial.print((char)payload[i]); } Serial.println();
} void setup() { Serial.begin(115200); setup_wifi(); client.setServer(mqtt_server, mqtt_port); client.setCallback(callback);
} void loop() { if (!client.connected()) { reconnect(); } client.loop(); // 每隔一段时间发布一条消息到MQTT主题 long now millis(); if (now - lastMsg 2000) { lastMsg now; char msg[50]; snprintf(msg, 50, hello world at %ld, now); client.publish(mqtt_topic, msg); }
} 请确保上述代码中的yourSSID、yourPASSWORD、yourMQTTServer、your/topic替换为实际的SSID、密码、MQTT服务器地址和主题。 这个示例代码首先设置了WiFi连接然后连接到MQTT服务器。一旦连接成功它将订阅一个MQTT主题。在loop()函数中它周期性地发布消息到该主题并处理从该主题接收到的任何消息。 此外MQTT服务器的地址、端口和凭据如果需要的话应根据实际的MQTT服务器配置进行调整。如MQTT服务器需要用户名和密码PubSubClient库也提供了设置这些的方法。 上传成功后打开串口监视器来查看ESP8266与MQTT服务器的通信日志。
三、测试结果
MQTT的参数配置如下
// MQTT服务器设置
const char* mqtt_server broker.mqtt-dashboard.com;
const int mqtt_port 1883;
const char* mqtt_client_id ESP8266Client0326;
const char* mqtt_topic test/topic; esp8266模块运行串口打印如下 更换其它服务器进行测试如下
