1 | /*
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2 | Basic MQTT example
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3 |
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4 | This sketch demonstrates the basic capabilities of the library.
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5 | It connects to an MQTT server then:
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6 | - publishes "hello world" to the topic "outTopic"
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7 | - subscribes to the topic "inTopic", printing out any messages
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8 | it receives. NB - it assumes the received payloads are strings not binary
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9 |
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10 | It will reconnect to the server if the connection is lost using a blocking
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11 | reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
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12 | achieve the same result without blocking the main loop.
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13 |
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14 | */
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15 |
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16 | #include <SPI.h>
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17 | #include <Ethernet.h>
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18 | #include <PubSubClient.h>
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19 |
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20 | // Update these with values suitable for your network.
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21 | byte mac[] = { 0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED };
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22 | IPAddress ip(172, 16, 0, 100);
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23 | IPAddress server(172, 16, 0, 2);
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24 |
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25 | void callback(char* topic, byte* payload, unsigned int length) {
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26 | Serial.print("Message arrived [");
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27 | Serial.print(topic);
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28 | Serial.print("] ");
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29 | for (int i=0;i<length;i++) {
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30 | Serial.print((char)payload[i]);
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31 | }
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32 | Serial.println();
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33 | }
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34 |
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35 | EthernetClient ethClient;
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36 | PubSubClient client(ethClient);
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37 |
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38 | void reconnect() {
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39 | // Loop until we're reconnected
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40 | while (!client.connected()) {
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41 | Serial.print("Attempting MQTT connection...");
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42 | // Attempt to connect
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43 | if (client.connect("arduinoClient")) {
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44 | Serial.println("connected");
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45 | // Once connected, publish an announcement...
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46 | client.publish("outTopic","hello world");
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47 | // ... and resubscribe
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48 | client.subscribe("inTopic");
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49 | } else {
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50 | Serial.print("failed, rc=");
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51 | Serial.print(client.state());
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52 | Serial.println(" try again in 5 seconds");
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53 | // Wait 5 seconds before retrying
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54 | delay(5000);
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55 | }
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56 | }
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57 | }
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58 |
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59 | void setup()
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60 | {
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61 | Serial.begin(57600);
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62 |
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63 | client.setServer(server, 1883);
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64 | client.setCallback(callback);
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65 |
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66 | Ethernet.begin(mac, ip);
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67 | // Allow the hardware to sort itself out
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68 | delay(1500);
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69 | }
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70 |
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71 | void loop()
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72 | {
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73 | if (!client.connected()) {
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74 | reconnect();
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75 | }
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76 | client.loop();
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77 | }
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