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@jbott jbott/yun_mqtt.ino
Last active Oct 29, 2016

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/*
Basic MQTT example
This sketch demonstrates the basic capabilities of the library.
It connects to an MQTT server then:
- publishes "hello world" to the topic "outTopic"
- subscribes to the topic "inTopic", printing out any messages
it receives. NB - it assumes the received payloads are strings not binary
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.
*/
#include <ArduinoJson.h>
#include <Bridge.h>
#include <YunClient.h>
#include <PubSubClient.h>
IPAddress server(192, 168, 0, 100);
String hostname;
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();
}
YunClient yun;
PubSubClient client(yun);
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect(hostname.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("outTopic","hello world");
// ... and resubscribe
client.subscribe("inTopic");
} 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()
{
Serial.begin(9600);
client.setServer(server, 1883);
client.setCallback(callback);
Bridge.begin();
Process p;
p.runShellCommand("hostname");
hostname += "arduino-";
hostname += p.readString();
}
void loop()
{
if (!client.connected()) {
reconnect();
}
client.loop();
StaticJsonBuffer<200> jsonBuffer;
JsonObject& root = jsonBuffer.createObject();
root["unit"] = "F";
root["data"] = 73;
String string_status;
root.printTo(string_status);
client.publish("sensor/front/temp", string_status.c_str());
delay(2000);
}
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