ESP8266でMQTTブローカを経由したmyThingsメッセージを受け取る

esp8266_mqtt_sub.ino

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <aJSON.h>

const char* ssid     = "WIFI_SSID";
const char* password = "WIFI_PASS";

const char* mqtt_server = "MESHBLU";
const char* mqtt_clientid = "esp8266";
const char* mqtt_topic = "MESHBLU_ACTION_UUID";
const char* mqtt_user = "MESHBLU_ACTION_UUID";
const char* mqtt_passwd = "MESHBLU_ACTION_PASS";

WiFiClient client;
PubSubClient mqtt(client);

void setup() {
  Serial.begin(115200);
  delay(10);

  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());

  mqtt.setServer(mqtt_server, 1883);
  mqtt.setCallback(callback);
}

void loop() {
  connect_mqtt();
  mqtt.loop();
}

void callback(char* topic, byte* payload, unsigned int length) {
  char buffer[1000];
  snprintf(buffer, sizeof(buffer), "%s", payload);
  Serial.println(buffer);
  aJsonObject* jsonObj = aJson.parse(buffer);
  aJsonObject* d = aJson.getObjectItem(jsonObj, "data");
  aJsonObject* pl = aJson.getObjectItem(d, "payload");
  String msg = String(pl->valuestring);
  Serial.println(String("\t") + msg);
}

void connect_mqtt() {
  if (mqtt.connected()) {
    return;
  }
  mqtt.connect(mqtt_clientid, mqtt_user, mqtt_passwd);
  while (!mqtt.connected()) {
    Serial.println("failed to connect to mqtt broker");
    mqtt.disconnect();
    delay(2000);
    mqtt.connect(mqtt_clientid, mqtt_user, mqtt_passwd);
  }
  Serial.println("succeeded to connect to mqtt broker");
  mqtt.subscribe(mqtt_topic);
}