BASH

1$ docker run -it -p 1883:1883 -p 9001:9001 eclipse-mosquitto:1.4.8

C++

1/*
2 Basic ESP8266 MQTT example
3 This sketch demonstrates the capabilities of the pubsub library in combination
4 with the ESP8266 board/library.
5 It connects to an MQTT server then:
6  - publishes "hello world" to the topic "outTopic" every two seconds
7  - subscribes to the topic "inTopic", printing out any messages
8    it receives. NB - it assumes the received payloads are strings not binary
9  - If the first character of the topic "inTopic" is an 1, switch ON the ESP Led,
10    else switch it off
11 It will reconnect to the server if the connection is lost using a blocking
12 reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
13 achieve the same result without blocking the main loop.
14 To install the ESP8266 board, (using Arduino 1.6.4+):
15  - Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
16       http://arduino.esp8266.com/stable/package_esp8266com_index.json
17  - Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
18  - Select your ESP8266 in "Tools -> Board"
19*/
20
21/**/
22
23#include <ESP8266WiFi.h>
24#include <PubSubClient.h>
25
26// Update these with values suitable for your network.
27
28const char* ssid = "........";
29const char* password = "........";
30const char* mqtt_server = "broker.mqtt-dashboard.com";
31
32WiFiClient espClient;
33PubSubClient client(espClient);
34unsigned long lastMsg = 0;
35#define MSG_BUFFER_SIZE	(50)
36char msg[MSG_BUFFER_SIZE];
37int value = 0;
38
39void setup_wifi() {
40
41  delay(10);
42  // We start by connecting to a WiFi network
43  Serial.println();
44  Serial.print("Connecting to ");
45  Serial.println(ssid);
46
47  WiFi.mode(WIFI_STA);
48  WiFi.begin(ssid, password);
49
50  while (WiFi.status() != WL_CONNECTED) {
51    delay(500);
52    Serial.print(".");
53  }
54
55  randomSeed(micros());
56
57  Serial.println("");
58  Serial.println("WiFi connected");
59  Serial.println("IP address: ");
60  Serial.println(WiFi.localIP());
61}
62
63void callback(char* topic, byte* payload, unsigned int length) {
64  Serial.print("Message arrived [");
65  Serial.print(topic);
66  Serial.print("] ");
67  for (int i = 0; i < length; i++) {
68    Serial.print((char)payload[i]);
69  }
70  Serial.println();
71
72  // Switch on the LED if an 1 was received as first character
73  if ((char)payload[0] == '1') {
74    digitalWrite(BUILTIN_LED, LOW);   // Turn the LED on (Note that LOW is the voltage level
75    // but actually the LED is on; this is because
76    // it is active low on the ESP-01)
77  } else {
78    digitalWrite(BUILTIN_LED, HIGH);  // Turn the LED off by making the voltage HIGH
79  }
80
81}
82
83void reconnect() {
84  // Loop until we're reconnected
85  while (!client.connected()) {
86    Serial.print("Attempting MQTT connection...");
87    // Create a random client ID
88    String clientId = "ESP8266Client-";
89    clientId += String(random(0xffff), HEX);
90    // Attempt to connect
91    if (client.connect(clientId.c_str())) {
92      Serial.println("connected");
93      // Once connected, publish an announcement...
94      client.publish("outTopic", "hello world");
95      // ... and resubscribe
96      client.subscribe("inTopic");
97    } else {
98      Serial.print("failed, rc=");
99      Serial.print(client.state());
100      Serial.println(" try again in 5 seconds");
101      // Wait 5 seconds before retrying
102      delay(5000);
103    }
104  }
105}
106
107void setup() {
108  pinMode(BUILTIN_LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
109  Serial.begin(115200);
110  setup_wifi();
111  client.setServer(mqtt_server, 1883);
112  client.setCallback(callback);
113}
114
115void loop() {
116
117  if (!client.connected()) {
118    reconnect();
119  }
120  client.loop();
121
122  unsigned long now = millis();
123  if (now - lastMsg > 2000) {
124    lastMsg = now;
125    ++value;
126    snprintf (msg, MSG_BUFFER_SIZE, "hello world #%ld", value);
127    Serial.print("Publish message: ");
128    Serial.println(msg);
129    client.publish("outTopic", msg);
130  }
131}