I can't establish a connection with my NodeMCU and MQTT server.
I am getting an error of:
Attempting MQTT connection...failed, rc=-2 try again in 5 seconds
Every topic name, nodes and other variables are assigned from the given video: Referred video
Below is the code:
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Change the credentials below, so your ESP8266 connects to your router
const char* ssid = "Wifi";
const char* password = "Wifi123";
// Change the variable to your Raspberry Pi IP address, so it connects to your MQTT broker
const char* mqtt_server = "192.168.1.38";
// Initializes the espClient. You should change the espClient name if you have multiple ESPs running in your home automation system
WiFiClient espClient22;
PubSubClient client(espClient22);
// Lamp - LED - GPIO 4 = D2 on ESP-12E NodeMCU board
const int led = 4;
//Connect your NodeMCU to your router
void setup_wifi() {
delay(10);
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(100);
Serial.print(".");
}
Serial.println("");
Serial.print("WiFi connected - NodeMCU IP address: ");
Serial.println(WiFi.localIP());
}
// This functions is executed when some device publishes a message to a topic that your NodeMCU is subscribed to
void callback(String topic, byte* message, unsigned int length) {
Serial.print("Message arrived on topic: ");
Serial.print(topic);
Serial.print(". Message: ");
String messageInfo;
for (int i = 0; i < length; i++) {
Serial.print((char)message[i]);
messageInfo += (char)message[i];
}
Serial.println();
// If a message is received on the topic room/lamp, you check if the message is either on or off. Turns the lamp GPIO according to the message
if(topic=="room/light"){
Serial.print("Changing Room Light to ");
if(messageInfo == "on"){
digitalWrite(led, HIGH);
Serial.print("On");
}
else if(messageInfo == "off"){
digitalWrite(led, LOW);
Serial.print("Off");
}
}
Serial.println();
}
// This functions reconnects your ESP8266 to your MQTT broker
// Change the function below if you want to subscribe to more topics with your ESP8266
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
if (client.connect("ESP8266Client22")) {
Serial.println("connected");
// Subscribe or resubscribe to a topic
// You can subscribe to more topics (to control more LEDs in this example)
client.subscribe("room/light");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
// The setup function sets your ESP GPIOs to Outputs, starts the serial communication at a baud rate of 115200
// Sets your mqtt broker and sets the callback function
// The callback function is what receives messages and actually controls the LEDs
void setup() {
pinMode(led, OUTPUT);
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
// For this project, you don't need to change anything in the loop function. Basically it ensures that the NodeMCU is connected to MQTT broker
void loop() {
if (!client.connected()) {
reconnect();
}
if(!client.loop())
client.connect("ESP8266Client22");
}
