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Arduino on ESP32 でMQTTの実験をしてみる　その３：ESP32からPublishする

arduino mqtt

shuzo-kino.hateblo.jp
のシリーズです。
いよいよ、今回から

実際のところ

動作環境

スクリプト

arduino向けMQTTクライアント"pubsubclient"のesp2866向けサンプルをベースにします。
pubsubclient/mqtt_esp8266.ino at master · knolleary/pubsubclient · GitHub
ESP32になってから"WiFi.h"を直に使えるようになったので注意して下さい。

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

// Update these with values suitable for your network.

const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASS";
const char* mqtt_server = "YOUR_ACCOUNT/IP";

WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;

void setup_wifi() {

  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  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 reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a random client ID
    String clientId = "ESP32Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect
    if (client.connect(clientId.c_str())) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish("msg/comment", "Coming Packets");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  pinMode(BUILTIN_LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
}

void loop() {

  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  long now = millis();
  if (now - lastMsg > 2000) {
    lastMsg = now;
    ++value;
    snprintf (msg, 75, "hello world #%ld", value);
    Serial.print("Publish message: ");
    Serial.println(msg);
    client.publish("msg/comment", msg);
  }
}

動作ログ

Arduino側のシリアルにはこんな感じでログが出ます

Connecting to YOURSSID
.....
WiFi connected
IP address: 
YOUR_ACCOUNT/IP
Attempting MQTT connection...connected
Publish message: hello world #1
Publish message: hello world #2
Publish message: hello world #3
Publish message: hello world #4
...

mosquittoの方には、こんな感じで接続情報がきます

1507644406: New connection from YOUR_ACCOUNT/IP on port 1883.
1507644406: New client connected from YOUR_ACCOUNT/IP as ESP32Client-1f85 (c1, k15).

subscriberはこんな塩梅

$ mosquitto_sub -h YOUR_ACCOUNT/IP -t msg/comment -q 1
hello world #1
hello world #2
...

参考もと

GitHub - knolleary/pubsubclient: A client library for the Arduino Ethernet Shield that provides support for MQTT.
ESP32で現在時刻を取得する（これが一番良いと思います） – AutumnColor.com