Arduino MQTT消息发布订阅

1、在Arduino IDE的库管理器中安装PubSubClient库。

2、包含<PubSubClient.h>。测试例子。

#include <SPI.h>
#include <WiFi.h>
#include <PubSubClient.h>

/***************************************************************************
 * Internet Connectivity Setup - Variables & Functions
 **************************************************************************/
 
char ssid[] = "CMCC-Chanpin";  // 无线网络 Network SSID (name) 
char pass[] = "chanpinxue";    // 密码

int keyIndex = 0;                 // Network Key Index Number 
                                  // (needed only for WEP)
 
int status = WL_IDLE_STATUS;

WiFiClient client;

void connectToInternet()
{
  status = WiFi.status();
  
  // Check for the presence of the shield
  if (status == WL_NO_SHIELD) 
  {
    Serial.println("[ERROR] WiFi Shield Not Present");
    // Do nothing
    while (true);
  }

  // Attempt to connect to WPA/WPA2 Wifi network
  while ( status != WL_CONNECTED) 
  {
    Serial.print("[INFO] Attempting Connection - WPA SSID: ");
    Serial.println(ssid);

    status = WiFi.begin(ssid, pass);
  }

  // Connection successful
  Serial.print("[INFO] Connection Successful");
  Serial.print("");  
  printConnectionInformation();
  Serial.println("-----------------------------------------------");
  Serial.println("");  
}

void printConnectionInformation() 
{
  // Print Network SSID
  Serial.print("[INFO] SSID: ");
  Serial.println(WiFi.SSID());

  // Print Router's MAC address
  byte bssid[6];
  WiFi.BSSID(bssid);
  Serial.print("[INFO] BSSID: ");
  Serial.print(bssid[5], HEX);
  Serial.print(":");
  Serial.print(bssid[4], HEX);
  Serial.print(":");
  Serial.print(bssid[3], HEX);
  Serial.print(":");
  Serial.print(bssid[2], HEX);
  Serial.print(":");
  Serial.print(bssid[1], HEX);
  Serial.print(":");
  Serial.println(bssid[0], HEX);

  // Print received signal strength
  long rssi = WiFi.RSSI();
  Serial.print("[INFO] Signal Strength (RSSI): ");
  Serial.println(rssi);

  // Print encryption type
  byte encryption = WiFi.encryptionType();
  Serial.print("[INFO] Encryption Type: ");
  Serial.println(encryption, HEX);

  // Print WiFi Shield's IP address
  IPAddress ip = WiFi.localIP();
  Serial.print("[INFO] IP Address: ");
  Serial.println(ip);

  // Print MAC address
  byte mac[6];
  WiFi.macAddress(mac);
  Serial.print("[INFO] MAC Address: ");
  Serial.print(mac[5], HEX);
  Serial.print(":");
  Serial.print(mac[4], HEX);
  Serial.print(":");
  Serial.print(mac[3], HEX);
  Serial.print(":");
  Serial.print(mac[2], HEX);
  Serial.print(":");
  Serial.print(mac[1], HEX);
  Serial.print(":");
  Serial.println(mac[0], HEX);
}

/***************************************************************************
 * Data Publish - Variables & Functions
 **************************************************************************/

// IP address of the Mosquitto server
char server[] = {"192.168.124.5"};
int port = 1883;
char topic[] = {"demo/testMessage"};
char mqt_username[]= {"jzh"};
char mqt_password[]= {"111111"};

PubSubClient pubSubClient(server, 1883, callback, client);

void callback(char* topic, byte* payload, unsigned int length)
{
  // Print payload
  String payloadContent = String((char *)payload);
  Serial.println("[INFO] Payload: " + payloadContent);  
}

/***************************************************************************
 * Standard Arduino Functions - setup(), loop()
 **************************************************************************/

void setup() 
{
  // Initialize serial port
  Serial.begin(9600);
  
  // Connect Arduino to internet
  connectToInternet();    
  
  //Connect MQTT Broker
  Serial.println("[INFO] Connecting to MQTT Broker");

  // 匿名链接
  // pubSubClient.connect("arduinoClient", mqt_username, mqt_password)) 

  // 通过账号、密码连接 add by jzh 2020-12-19
  // client端标识符 用户账号 用户密码
  if (pubSubClient.connect("arduinoClient", mqt_username, mqt_password)) 
  {
    Serial.println("[INFO] Connection to MQTT Broker Successfull");
    
    pubSubClient.subscribe(topic);
    Serial.println("[INFO] Successfully Subscribed to MQTT Topic ");

    Serial.println("[INFO] Publishing to MQTT Broker");
    pubSubClient.publish(topic, "Test Message");
  }
  else
  {
    Serial.println("[INFO] Connection to MQTT Broker Failed");
  }  
}

void loop() 
{  
  // Wait for messages from MQTT broker
  pubSubClient.loop();
}