Pubsubclient: Continually reconnections

[AndyDHill]

Continual re connection and ever so often will lose connect return -4

`/*
Basic ESP8266 MQTT example

This sketch demonstrates the capabilities of the pubsub library in combination
with the ESP8266 board/library.

It connects to an MQTT server then:

• publishes "hello world" to the topic "outTopic" every two seconds
• subscribes to the topic "inTopic", printing out any messages
  it receives. NB - it assumes the received payloads are strings not binary
• If the first character of the topic "inTopic" is an 1, switch ON the ESP Led,
  else switch it off

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.

To install the ESP8266 board, (using Arduino 1.6.4+):

• Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
  http://arduino.esp8266.com/stable/package_esp8266com_index.json
• Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
• Select your ESP8266 in "Tools -> Board"

*/

include

include

// Update these with values suitable for your network.

ifdef work

const char* ssid = "SSID";
const char* password = "PASS";
const char* mqtt_server = "broker.hivemq.com";

else

const char* ssid = "SSID";
const char* password = "PASS";
const char* mqtt_server = "broker.hivemq.com";

endif

WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;

void setup() {
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
Serial.begin(9600);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}

void setup_wifi() {

delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, 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 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();

// Switch on the LED if an 1 was received as first character
if ((char)payload[0] == '1') {
digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level
// but actually the LED is on; this is because
// it is acive low on the ESP-01)
} else {
digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
}

}

void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("ESP8266Client")) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("outTopic123", "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 loop() {

if (!client.connected()) {
reconnect();
}
client.loop();

long now = millis();
if (now - lastMsg > 2000) {
lastMsg = now;
++value;
snprintf (msg, 75, "hello world #%ld", value);
Serial.print("Publish message: ");
Serial.println(msg);
client.publish("outTopic123", msg);
}
`
Output from above program

Connecting to Denserver
...
WiFi connected
IP address:
192.168.1.82
Attempting MQTT connection...connected
Publish message: hello world #1
Message arrived [inTopic] vimal
Attempting MQTT connection...connected
Message arrived [inTopic] vimal
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
Attempting MQTT connection...connected
Message arrived [inTopic] vimal
Publish message: hello world #15
Attempting MQTT connection...connected
Message arrived [inTopic] vimal
Publish message: hello world #16
Publish message: hello world #17
Publish message: hello world #18
Publish message: hello world #19
Publish message: hello world #20
Publish message: hello world #21
Publish message: hello world #22
Publish message: hello world #23
Publish message: hello world #24
Publish message: hello world #25
Publish message: hello world #26
Publish message: hello world #27
Publish message: hello world #28
Attempting MQTT connection...connected
Message arrived [inTopic] vimal
Publish message: hello world #29

Tired on a Wemos D1 ESP and on a NODEMCU 12E. both have similar problem. Always using HiveMQ public broker

Code seems to be failing to detect !client.connected() and forcing reconnect();

Andy

[AndyDHill]

SOLVED - This is due to a hard coded ClientID

if (client.connect("ESP8266Client")) {

Change this to

if (client.connect(ClientId.c_str())) {

where

String ClientId = "ESP8266_";
unsigned char mac[6];
WiFi.macAddress(mac);
ClientId += macToStr(mac);

String macToStr(const uint8_t* mac)
{
String result;
for (int i = 0; i < 6; ++i) {
result += String(mac[i], 16);
}
return result;
}

https://github.com/esp8266/Arduino/issues/313#issuecomment-104945593

[ahmedalkhabeer]

i cannot recive the signal coming from my client to my esp after it wakes up from deepsleep