MQTT client program not showing any results with Arduino

DHCP does work with the standard Ethernet shield, I have used it on many occasions

You may want to also check you DHCP server ?

regards

Peter

Hi Peter Oakes,

  Thanks..That and many others can also be added as reasons..

   I have given these lessons learnt from my side since I didnt have issues with DHCP server...

I didnt press the Ethernet shield properly..Also,I had a faulty Ethernet shield..

#include <SPI.h>

#include <PubSubClient.h>

#include <Ethernet.h>

// Pins

// Analog 0 is the input pin

// Variables

const int Tempin = 0;

int value;

float temp,tempC;

String pubstring;

unsigned long time;

char message_buffer[100];

// Network Settings

// MAC address of ethernet shield

// Look for it on a sticket at the bottom of the shield.

// Old Arduino Ethernet Shields or clones may not have a dedicated MAC address. Set any hex values here.

byte MAC_ADDRESS[] = {  0x78, 0x45, 0xC4, 0xAA, 0xE5, 0x6F };

// IP address of MQTT server

//byte MQTT_SERVER[] = {0,0,0,0};

//byte ip[] = {10,107,1,115};

EthernetClient ethClient;

PubSubClient client;

void setup()

{ 

  // Initilize serial link for debugging

  Serial.begin(9600);

  Ethernet.begin(MAC_ADDRESS);

  Serial.print("Local IP=");

  Serial.println(Ethernet.localIP());

  client  = PubSubClient("0.0.0.0", 1883, callback, ethClient);

}

void loop()

{

  if (!client.connected())

  {

    //client.connect("clientID", "mqtt_username", "mqtt_password");

    client.connect("sfo-arduino");

    client.publish("sfo/arduino/alive", "I'm alive!");

  }

  else{

    client.connect("arduino/temperature");

    Serial.println("here i am connected");

    }

  //tempC = dtostrf(tempF,5,2,message_buffer);

  // Publish sensor reading every X milliseconds

  if (millis() > (time + 5000)) {

    time = millis();

    value = analogRead(Tempin);

    temp = (value/1024.0)*5000;

    tempC = temp/10;

    pubstring = String(tempC);

     pubstring.toCharArray(message_buffer, pubstring.length() + 1);

    client.publish("arduino/temperature",message_buffer);

    //Serial.println("published!");

    //Serial.println(message_buffer);

}

  // MQTT client loop processing

  client.loop();

}

// Handles messages arrived on subscribed topic(s)

void callback(char* topic, byte* payload, unsigned int length) {

}

hey i am trying a project on reading lm35 temperature sensor and publish in a mqtt broker using arduino.. I am stuck at subscribe mid1:0 after which it starts pinging..may i know what am i doing wrong here??

Thanks in advance..kindly reply asap

Did you set the server address?

Clem

As per what clem57 said, the server address is not set for starters "client  = PubSubClient("0.0.0.0", 1883, callback, ethClient);" does not contain a valid server address even if it is a local MQTT server

second error is

if (!client.connected())

  {....

client.connect("sfo-arduino");

....

else

{

....

client.connect("arduino/temperature");

....

}

if the first connect failed, what makes you think the else clause is going to work ???

hey thanks for ur suggestions and i have updated my code like this..and i found that my arduino and mqtt is still not getting connected returning rc as -2..here is the code..any idea what is the problem??

float temp;

int tempPin = 0;

#include <SPI.h>

#include <Ethernet.h>

#include <PubSubClient.h>

// Update these with values suitable for your network.

byte mac[] = { 0x78, 0x45, 0xC4, 0xAA, 0xE5, 0x6F };

IPAddress ip(192, 168, 1, 108);

IPAddress server(192, 168, 1, 100);

char buff[3];

void callback(char* topic, byte* payload, unsigned int length)

{

temp = analogRead(tempPin);

  temp = temp * 0.48828125;

Serial.print("TEMPRATURE");

  Serial.print(temp);

  Serial.print("*C");

  Serial.println();

  dtostrf(temp,4,3,buff);

}

EthernetClient ethClient;

PubSubClient client(ethClient);

void reconnect() {

// Loop until we're reconnected

while (!client.connected()) {

Serial.print("Attempting MQTT connection...");

// Attempt to connect

if (client.connect("arduinoClient"))

{ Serial.println("connected");

// Once connected, publish an announcement...

client.publish("/home/temperature","alive");

// ... and resubscribe

client.subscribe("/home/temperature"); }

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);

Ethernet.begin(mac, ip);

// Allow the hardware to sort itself out

delay(1500); }

void loop()

{ if (!client.connected())

{ reconnect();

} client.loop();

}

hey guys mqtt_basic program itself is failing for me...and arduino mqtt function almost always fails..any ideas??

kindly reply asap

arduino mqtt connection*

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