Arduino から MQTT サーバーにメッセージを投げます。

使用機材

項目	設定値
使用している Arduino	arduino nano
書き込みブートローダ	atmega328old
LAN シールド	ENC28J60

IPアドレス

端末	IPアドレス
ルーター	192.168.0.1
Arduino	192.168.0.117
MQTT Server	192.168.0.104

MQTT設定

MQTT	設定値
server	192.168.0.104
ポート	1883
ルーム	test
クライアントID	myArduinoID
メッセージ	Hello World from arduino

ソースコード

mqtt_pub.ino

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

EthernetClient ethClient;
PubSubClient mqttClient(ethClient);

// Function prototypes
void subscribeReceive(char* topic, byte* payload, unsigned int length);
 
byte mac[] = { 0x90, 0xA2, 0xDA, 0x0D, 0x78, 0xEE  };  
IPAddress ip(192, 168, 0, 117);
IPAddress myDns(192, 168, 0, 1);
 
// Make sure to leave out the http and slashes!
const char* server = "192.168.0.104";

void setup()
{

  // Useful for debugging purposes
  Serial.begin(9600);
  
  // Start the ethernet connection
  Ethernet.begin(mac, ip ,myDns);              
  
  // Ethernet takes some time to boot!
  delay(3000);                          
 
  // Set the MQTT server to the server stated above ^
  mqttClient.setServer(server, 1883);   
 
  if (mqttClient.connect("myArduinoID")) {
  
    Serial.println("Connection has been established, well done");
 
    // Establish the subscribe event
    mqttClient.setCallback(subscribeReceive);
  
  } else {

    Serial.println("Looks like the server connection failed...");

  }

}

void loop(){

  mqttClient.loop();
 
  mqttClient.subscribe("test");
 
  if(mqttClient.publish("test", "Hello World from arduino")){

    Serial.println("Publish message success");
  
  }else{
  
    Serial.println("Could not send message :(");

  }
 
  // Dont overload the server!
  delay(4000);

}

void subscribeReceive(char* topic, byte* payload, unsigned int length){

  Serial.print("Topic: ");
  Serial.println(topic);
 
  Serial.print("Message: ");
  for(int i = 0; i < length; i ++){
    Serial.print(char(payload[i]));
  }
  Serial.println("");

}

参考リンク