MQTT Subscribe not working

[hemalbavisi]

I am very new to ESP8266 and MQTT. So Apologies if I haven't done it properly. I am using test.mosquitto.org server and trying to publish and subscribe the data. I am able to publish the data but subscribe part is not working. Nevertheless, I have tested subscribe part between two mobile and I am able to receive the data but I am not getting any data in the callback routine though I subscribed explicitly in the code. I have attached my code for your reference.

`

include <ESP8266WiFi.h>

include <PubSubClient.h>

define wifi_ssid ""

define wifi_password ""

define mqtt_server "test.mosquitto.org"

define mqtt_user "test"

define mqtt_password "test"

define topic1 "SmartIOT/Temperature"

define topic2 "SmartIOT/Humidity"

define topic3 "SmartIOT/Switch"

void callback(char* topic, byte* payload, unsigned int length); WiFiClient espClient; PubSubClient client(mqtt_server, 1883, callback, espClient); void setup() { Serial.begin(115200); setup_wifi(); //client.setServer(mqtt_server, 1883); client.subscribe(topic3); }

// Callback function void callback(char* topic, byte* payload, unsigned int length) { // In order to republish this payload, a copy must be made // as the orignal payload buffer will be overwritten whilst // constructing the PUBLISH packet. Serial.println("Incoming data : "); Serial.println(topic); //Serial.println(payload); // Allocate the correct amount of memory for the payload copy byte* p = (byte*)malloc(length); // Copy the payload to the new buffer memcpy(p,payload,length); //client.publish("outTopic", p, length); // Free the memory free(p); }

void setup_wifi() { delay(10); // We start by connecting to a WiFi network Serial.println(); Serial.print("Connecting to "); Serial.println(wifi_ssid); WiFi.begin(wifi_ssid, wifi_password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); Serial.println("IP address: "); Serial.println(WiFi.localIP());

} void reconnect() { // Loop until we're reconnected while (!client.connected()) { Serial.print("Attempting MQTT connection..."); // Attempt to connect if (client.connect("TestMQTT")) { //* See //NOTE below Serial.println("connected");

    } else {
        Serial.print("failed, rc=");
        Serial.print(client.state());
        Serial.println(" try again in 5 seconds");
        // Wait 5 seconds before retrying
        delay(5000);
    }
}

} //NOTE: if a user/password is used for MQTT connection use: //if(client.connect("TestMQTT", mqtt_user, mqtt_password)) { void pubMQTT(String topic,float topic_val){ Serial.print("Newest topic " + topic + " value:"); Serial.println(String(topic_val).c_str()); client.publish(topic.c_str(), String(topic_val).c_str(), true); } //Variables used in loop() long lastMsg = 0; float t1 = 75.5; float t2 = 50.5; void loop() { if (!client.connected()) { reconnect(); client.subscribe(topic3); } client.loop(); //2 seconds minimum between Read Sensors and Publish long now = millis(); if (now - lastMsg > 2000) { lastMsg = now; //Read Sensors (simulate by increasing the values, range:0-90) t1 = t1>90 ? 0 : ++t1; t2 = t2>90 ? 0 : ++t2; //Publish Values to MQTT broker pubMQTT(topic1,t1); pubMQTT(topic2,t2); } } `

[hemalbavisi]

One more point -> Connection to server is frequently getting disconnected. However, I am able to see almost all the data from ESP2866 client to which my mobile application is subscribed to.

[MartijnvdB]

You did not specify that a callback should be executed when a message is received.

In setup(), after you do client.setServer(arg, arg), you specify which callback to execute, as follows:

client.setCallback(callbackName); // callback executed when message received

[hemalbavisi]

Thanks for your quick response. I posted little older code first time but then I corrected it. Please check below mentioned code

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

PubSubClient client(mqtt_server, 1883, callback, espClient);

void setup() { Serial.begin(115200); setup_wifi(); //client.setServer(mqtt_server, 1883); client.subscribe(topic3); }

Best Regards, Hemal Bavishi

From: MartijnvdB [mailto:[email protected]] Sent: 17 May 2016 11:32 To: knolleary/pubsubclient [email protected] Cc: Hemal Bavishi [email protected]; Author [email protected] Subject: Re: [knolleary/pubsubclient] MQTT Subscribe not working (#163)

You did not specify that a callback should be executed when a message is received.

In setup(), after you do client.setServer(arg, arg), you specify which callback to execute, as follows:

client.setCallback(callbackName); // callback executed when message received

— You are receiving this because you authored the thread. Reply to this email directly or view it on GitHubhttps://github.com/knolleary/pubsubclient/issues/163#issuecomment-219626975

[MartijnvdB]

Hi,

Did you uncommment the line that says:

//client.setServer(mqtt_server, 1883);

and did you add the following line after that:

client.setCallback(callback); // callback executed when message received

?

[hemalbavisi]

Yes, I commented this line as I’ve added this line on the top -> PubSubClient client(mqtt_server, 1883, callback, espClient);

Isn’t above line serve the same purpose?

Nevertheless, I can try uncommenting this line and also add the line you suggested and will get back to you.

client.setServer(mqtt_server, 1883);

client.setCallback(callback); // callback executed when message received Many Thanks!

[MartijnvdB]

PubSubClient client(mqtt_server, 1883, callback, espClient);

Hm, that should work too, indeed (according to the docs). Haven't used that one yet, myself.

[hemalbavisi]

Thanks. I'll check and revert back to you in few hours.

[hemalbavisi]

Unfortunately it doesn't work. Sometime data appears but most of the time it doesn't. What could be the problem?

[edwin-oetelaar]

Check the data flowing to the server using WireShark. Use a debugger? Write log files? Use brain?

[knolleary]

Any update?

[Kerr1st]

Hi Knolleary, Picking up the issue...Mqtt_Esp8266 example doesn't receive/serial print on inTopic (publishes outTopic fine) nor toggle LED. See Serial Output below. Two other clients connected and receive publish outTopic and published inTopics. Wemos D1 mini is ESP8266 module.

serial output: WiFi connected IP address: 192.168.1.96 Attempting MQTT connection...connected Publish message: hello world #1 Publish message: hello world #2 Publish message: hello world #3 Publish message: hello world #4 Publish message: hello world #5 Publish message: hello world #6 Publish message: hello world #7 Publish message: hello world #8 Publish message: hello world #9 Publish message: hello world #10 Publish message: hello world #11 Publish message: hello world #12 Publish message: hello world #13 Publish message: hello world #14 Publish message: hello world #15

[edwin-oetelaar]

looking at line 92 of the example ; https://github.com/knolleary/pubsubclient/blob/master/examples/mqtt_esp8266/mqtt_esp8266.ino

check the return value of the subscribe call client.subscribe("inTopic");

maybe it gives an error?? ( == false) for some reason.

good luck, Edwin

On Tue, Nov 29, 2016 at 5:40 AM, Kerr1st [email protected] wrote:

Hi Knolleary, Picking up the issue...Mqtt_Esp8266 example doesn't receive/serial print on inTopic (publishes outTopic fine) nor toggle LED. See Serial Output below. Two other clients connected and receive publish outTopic and published inTopics. Wemos D1 mini is ESP8266 module.

serial output: WiFi connected IP address: 192.168.1.96 Attempting MQTT connection...connected Publish message: hello world #1 Publish message: hello world #2 Publish message: hello world #3 Publish message: hello world #4 Publish message: hello world #5 Publish message: hello world #6 Publish message: hello world #7 Publish message: hello world #8 Publish message: hello world #9 Publish message: hello world #10 Publish message: hello world #11 Publish message: hello world #12 Publish message: hello world #13 Publish message: hello world #14 Publish message: hello world #15

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[fdrevet]

Hi there, here is my experience with ESP8266 (01 and 12 models) and MQTT using PubSubClient.

The publishing works quite well and is also reliable (with an ESP8266-12), but the subscribing is just a real pain (IMO !)... for me the subscribe method mostly returns 0, "randomly" and very few times it returns 1... same behaviour with 3 ESP8266-12 modules...

Note : I'm using "EasyIot Cloud" MQTT server, dunno if it can be the reason ! I'll try a local MQTT server and send the result here.

[hudanar]

Hi there, iam using 2 Wemos D1 R2, 1 for publisher and 1 for subscriber. connected to mosquitto broker on my pc, but everytime publisher publish message, the subscriber got disconneted and reconnecting to the broker, so the subscriber never get the message from the publisher, anyone know how to fix that?

[knolleary]

@hudanar please don't ask your own questions on other issues.

My guess is you are using the same clientid for both clients and they are kicking each other off the broker. Make use you give each client a unique id

[hatfieldr]

Hi Nick I have a similar problem using PubSubClient. It connects to wifi & to MQTT server & publishes fine but does not receive subscribe data. I have an ESP8266-01 connected to Arduino Mega (with level conversions) Code:

#include <WiFiEsp.h>
#include <WiFiEspClient.h>
#include <WiFiEspUdp.h>
//#include "SoftwareSerial.h"
#include <PubSubClient.h>

IPAddress server(192,168,1,xxx);
char ssid[] = "xxxxxxxxx";           // your network SSID (name)
char pass[] = "xxxxxxxxxx";           // your network password
int status = WL_IDLE_STATUS;   // the Wifi radio's status


// Initialize the Ethernet client object
WiFiEspClient espClient;

PubSubClient client(espClient);

//SoftwareSerial soft(2,3); // RX, TX
void setup() {
  // initialize serial for debugging
  Serial.begin(115200);
  // initialize serial for ESP module
  Serial1.begin(115200);
  // initialize ESP module
  WiFi.init(&Serial1);

  // check for the presence of the shield
  if (WiFi.status() == WL_NO_SHIELD) {
    Serial.println("WiFi shield not present");
    // don't continue
    while (true);
  }

  // attempt to connect to WiFi network
  while ( status != WL_CONNECTED) {
    Serial.print("Attempting to connect to WPA SSID: ");
    Serial.println(ssid);
    // Connect to WPA/WPA2 network
    status = WiFi.begin(ssid, pass);
  }

  // you're connected now, so print out the data
  Serial.println("You're connected to the network");

  //connect to MQTT server
  client.setServer(server, 1883);
  client.setCallback(callback);
}

//print any message received for subscribed topic
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++) {
   char receivedChar = (char)payload[i]; 
    Serial.print(receivedChar);
    if (receivedChar == '0')
    Serial.println("Off");
    if (receivedChar == '1')
    Serial.println("On");
    
  }
  Serial.println();
}

void loop() {
  // put your main code here, to run repeatedly:
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect, just a name to identify the client
    if (client.connect("AMega","xxxxxx","xxxxxxxxxxx")) {
      Serial.println("connected");
      // Once connected, publish an announcement...
 //  client.publish("Hello World");
      // ... and resubscribe
      client.subscribe("switch");
      
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

This connects to WiFi fine & to an MQTT server running on a raspberry Pi It posts to the Pi but does not receive subscribed messages. I also have an MQTT client on my android phone. This communicates fine with the RPi Again the Arduino can publish to my phone but cannot receive with subscribe

I am not sure where to go next? Any help would be appreciated

Richard

[fdrevet]

Hi Richard,

Your code seems to be OK.

Which MQTT broker are you using on your Raspberry ?

Does the subscribe("switch") call is successfully returning 1 ?

I had a lot of headache making my ESP8266-12 working (mainly with EasyIOT MQTT broker... in fact...) but now it's OK with my Raspberry hosting a Mosquitto MQTT broker.

Best regards,

Florian

2017-01-05 23:13 GMT+01:00 hatfieldr [email protected]:

Hi Nick I have a similar problem using PubSubClient. It connects to wifi & to MQTT server & publishes fine but does not receive subscribe data. I have an ESP8266-01 connected to Arduino Mega (with level conversions) Code:

#include <WiFiEsp.h> #include <WiFiEspClient.h> #include <WiFiEspUdp.h> //#include "SoftwareSerial.h" #include <PubSubClient.h>

IPAddress server(192,168,1,xxx); char ssid[] = "xxxxxxxxx"; // your network SSID (name) char pass[] = "xxxxxxxxxx"; // your network password int status = WL_IDLE_STATUS; // the Wifi radio's status

// Initialize the Ethernet client object WiFiEspClient espClient;

PubSubClient client(espClient);

//SoftwareSerial soft(2,3); // RX, TX void setup() { // initialize serial for debugging Serial.begin(115200); // initialize serial for ESP module Serial1.begin(115200); // initialize ESP module WiFi.init(&Serial1);

// check for the presence of the shield if (WiFi.status() == WL_NO_SHIELD) { Serial.println("WiFi shield not present"); // don't continue while (true); }

// attempt to connect to WiFi network while ( status != WL_CONNECTED) { Serial.print("Attempting to connect to WPA SSID: "); Serial.println(ssid); // Connect to WPA/WPA2 network status = WiFi.begin(ssid, pass); }

// you're connected now, so print out the data Serial.println("You're connected to the network");

//connect to MQTT server client.setServer(server, 1883); client.setCallback(callback); }

//print any message received for subscribed topic 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++) { char receivedChar = (char)payload[i]; Serial.print(receivedChar); if (receivedChar == '0') Serial.println("Off"); if (receivedChar == '1') Serial.println("On");

} Serial.println(); }

void loop() { // put your main code here, to run repeatedly: if (!client.connected()) { reconnect(); } client.loop(); }

void reconnect() { // Loop until we're reconnected while (!client.connected()) { Serial.print("Attempting MQTT connection..."); // Attempt to connect, just a name to identify the client if (client.connect("AMega","xxxxxx","xxxxxxxxxxx")) { Serial.println("connected"); // Once connected, publish an announcement... // client.publish("Hello World"); // ... and resubscribe client.subscribe("switch");

} else { Serial.print("failed, rc="); Serial.print(client.state()); Serial.println(" try again in 5 seconds"); // Wait 5 seconds before retrying delay(5000); }

} }

This connects to WiFi fine & to an MQTT server running on a raspberry Pi It posts to the Pi but does not receive subscribed messages. I also have an MQTT client on my android phone. This communicates fine with the RPi Again the Arduino can publish to my phone but cannot receive with subscribe

I am not sure where to go next? Any help would be appreciated

Richard

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[hatfieldr]

Hi Florian Thanks for replying I am using a Mosquitto MQTT broker (1.4.10) on the RPi (3) It's part of the emonpi software from the OpenEnergyMonitor group. The arduino sketch publishes fine to the RPi and to the client on my android phone (MQTT Client App) The phone communicates both ways with the RPi But the arduino shetch does not appear to receive anything from either my phone or the RPi with client.subscribe("") The arduino stays "connected" but nothing happens! It does automatically disconnect after about 30 seconds & then reconnects to the MQTT broker

I am at a loss as to what to try next! Any suggestions gratefully received!

Regards

Richard

[fdrevet]

Hi Richard,

I'm using Mosquitto without any issue (Raspberry B model 2) I had a lot of problems with random connections and subscriptions, but it was coming from my Wifi router (Livebox, just a shame) now I'm using a WRT54GL and it works like a charm. => dunno what Wifi access point you're using but I guess you're connecting to your raspberry through your Wifi router ? Did you tried to connect from your phone (wifi access point) for exemple ? (you will need a NAT rule to access it from the outside)

As I previously asked it to you, did you checked the subscribe("switch") return ? (should be 0 if it don't succeed to subscribe) Also, did you tried to make a retry logic ? (I think the subscribe method should fails)

Best regards,

Florian

[hatfieldr]

Hi Florian

I have a BT router, all my current experiments are on my home network, I don't think its a router problem. The mosquitto server on my Pi 3 seems to work fine with other devices (eg the MQTT client on my android phone) client.subscribe("switch",0) returns 1 so I guess "subscribe" may be working & the problem is with callback? no messages for topic "switch" seem to be received I have tried lots of different message formats

would love to solve it! Its holding up my project!

Regards

Richard

[fdrevet]

Hi Richard,

I was asking you about the router because my smartphones was perfectly working (connect, subscribe, publish), but my ESP8266 was rarely and randomly working.

It's very strange that subscribe() returns 1 and if you don't receive anything on callback method.

I'm calling setCallback() before setServer(), don't know if it can change anything...

You seems to have a working broker, but have you tried mosquitto_pub mosquitto_sub batch calls directly on your Raspberry ?

If you want, I can send to you my working code by mail, if it can helps.

Florian

[hatfieldr]

Hi Florian My sketch is based on one of the examples so I guess it has the right format. The broker on the Pi seems to be working fine .... it communicates with the client on my android phone both ways... I wondered if there was any way of "sniffing" communication with the ESP8266? when I fist connected the ESP to my arduino mega I used 10K & 20K resitors in the voltage dividers on the mega output lines ..... this resulted in very erratic transmission at 115200 baud but when I used 1k & 2K resistors it connected to wifi & the MQTT broker fine....

I'm not sure what to try next....

Regards Richard

[slavino]

Hi, if your issues are only HW related give it a try with Logic Level converter 3V3/5V (example: http://www.ebay.com/itm/2-Channel-Way-Bi-directional-Logic-Level-Shifter-Converter-5V-3-3V-TTL-Module-/121736138032?var=&hash=item1c580a0d30:m:mGYrmVBtrJ153d9DsH5Ld6g). ArduinoMega has 5V logic and ESP8266 should be 3V3 only.

[hatfieldr]

Hi I do know about the different voltages! my issues are not related to level shifting I originally used resistive dividers to shit levels, I now use a level shifter. It made no difference. The arduino communicates fine with the ESP. It logs on to the network & the MQTT broker It publishes fine & subscribe() returns 1 but no messages are received for the subscribed topic....

[slavino]

Ah, got it now - sorry for misunderstanding... Then off-topic reaction: What about bypassing the issue for now with regular querying the channel for retained messages?

[hatfieldr]

Update 2

command line publish on the Rpi works fine $mosquitto_pub -u 'xxxxx' -P 'xxxxxxx' -t 'switch' -m '1switchon' This is received on my android mqtt client but not the arduino

I have tried installing mosquitto on my PC.... The results are exactly the same!

I have tried an ESP8266-12 with the Mega with the same result It connects to the WiFi network & to the MQTT broker, It publishes fine client.subscribe() returns true but no messages are received

Desperate for an answer............ Any help appreciated.....,......

Richard

[tororm]

Hi @hatfieldr ,

I was tidying up some working code and I experienced the same issue. I believe I'm on to something, but it's too late for me to investigate further. My mqtt payload looks like this: {"desired_hysterisis":0,"desired_temp": 50,"desired_humidity":20,"desired_FanOn":off,"desired_FanBreak":5.0}

However, try as I may, the callback is not entered. Subscribe Status is 1.

I then change the payload to something simple like 'Hello'.

It arrives!

Hoping this helps. I will do some more testing in coming days.

Edit: scratch that. Changing the QOS to 1 and waiting for a few loops results in the message arriving.

[hatfieldr]

I solved the problem by calling: if (!client.connected()) reconnect(); & client.loop(); every 100 ms instead of every loop If you are not flashing the code to the ESP but are using an arduino connected to the ESP via serial I think the problem is calling these functions every loop causes the serial interface to be overwhelmed with status messages blocking the incoming message. I am a newbie programmer especially with the ESP & MQTT so I'm not sure................ But my setup is now working (After a week of tearing my hair out!!) Richard

[anupam19]

Have you used escape characters for "" ? ie "desired_temp"

On Mon, Jan 30, 2017 at 5:20 PM, tororm [email protected] wrote:

Hi @hatfieldr https://github.com/hatfieldr ,

I was tidying up some working code and I experienced the same issue. I believe I'm on to something, but it's too late for me to investigate further. My mqtt payload looks like this: {"desired_hysterisis":0,"desired_temp": 50,"desired_humidity":20," desired_FanOn":off,"desired_FanBreak":5.0}

However, try as I may, the callback is not entered. Subscribe Status is 1.

I then change the payload to something simple like 'Hello'.

It arrives!

Hoping this helps. I will do some more testing in coming days.

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[anupam19]

Yup, without a reconnect function, connection drop happens with frequent streaming. It is due to hardware failure. Can not process big payloads at such faster rate

On Mon, Jan 30, 2017 at 6:08 PM, hatfieldr [email protected] wrote:

I solved the problem by calling: if (!client.connected()) reconnect(); & client.loop(); every 100 ms instead of every loop If you are not flashing the code to the ESP but are using an arduino connected to the ESP via serial I think the problem is calling these functions every loop causes the serial interface to be overwhelmed with status messages blocking the incoming message. I am a newbie programmer especially with the ESP & MQTT so I'm not sure................ But my setup is now working (After a week of tearing my hair out!!) Richard

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