WeMosを使ってみる

RaspberryとのMQTT通信(Raspberry→WeMos)

mosquitto-clients編


これまでは、
WeMos(Publisher)--->Broker--->Raspberry(Subscriber)
を紹介しましたが、ここからは
Raspberry(Publisher)--->Broker--->WeMos(Subscriber)
を紹介します。

必要なライブラリなどはこちらのページを参照してください。

WeMos側のスケッチは以下の通りです。
MQTTクライアントライブラリに含まれている「pubsubclient\examples\mqtt_esp8266」を少しだけ変更して
「nopnop2002」で始まるトピックだけを読み込みます。
赤字の部分は自分の環境に合わせて変更してください。

/*
 Basic ESP8266 MQTT example

 This sketch demonstrates the capabilities of the pubsub library in combination
 with 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 messages
    it 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 off

 It will reconnect to the server if the connection is lost using a blocking
 reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
 achieve 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 = "アクセスポイントのSSID";
const char* password = "アクセスポイントのパス ワード";
//const char* mqtt_server = "broker.mqtt-dashboard.com";
const char* mqtt_server = "broker.hivemq.com";

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.println();
  Serial.print("Wait for WiFi...");
  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 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 character
  if ((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 acive low on the ESP-01)
  } else {
    digitalWrite(BUILTIN_LED, HIGH);  // Turn the LED off by making the voltage HIGH
  }

}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
//    if (client.connect("ESP8266Client")) {
    if (client.connect(ssid)) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish("outTopic", "hello world");
      // ... and resubscribe
//      client.subscribe("inTopic");
//      client.subscribe("#");
      client.subscribe("nopnop2002/#");
    } 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(9600);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void loop() {
  static int counter=0;

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

#if 0
  long now = millis();
  if (now - lastMsg > 1000) {
    lastMsg = now;
    counter++;
    if (counter > 10) {
      ++value;
      snprintf (msg, 75, "hello world #%ld", value);
      Serial.print("Publish message: ");
      Serial.println(msg);
      client.publish("nopnop2002", msg);
      counter=0;
    }
  }
#endif

}


このスケッチを実行するとArduino-IDEのシリアルモニターはこのように表示されます。


ここでRaspberry側から以下のコマンドを実行します。
$ mosquitto_pub -h broker.hivemq.com -p 1883 -t "nopnop2002" -m "1"
$ mosquitto_pub -h broker.hivemq.com -p 1883 -t "nopnop2002" -m "0"

WeMos側に以下が表示され、オンボードのLEDがLチカします。


ちなみに、WeMosのスケッチを以下のように変更すると、
このサーバーにPublishされる全てのトピックを見ることができます。
(前略)

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
//    if (client.connect("ESP8266Client")) {
    if (client.connect(ssid)) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish("outTopic", "hello world");
      // ... and resubscribe
//      client.subscribe("inTopic");
      client.subscribe("#");
//      client.subscribe("nopnop2002/#");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

(後略)



世界中の人が色々Publishしています。

次は、Raspberry側のPublisherをPythonで作ってみます。

続く....