Please help me, i should finish this project as soon
I want to make project monitoring using ESP8266, MQTT, and Node-RED dashboard
but I have an issue that my serial monitors showing cannot connected to MQTT
"Failed to connect to MQTT broker, rc=-2"
I try to test my mqtt in CMD using Sub and Pub, i send some text and it works well. but in my project it's failed.
here is my code:
#include <Wire.h>
#include <Adafruit_MLX90614.h>
#include <Wire.h>
#include "MAX30100_PulseOximeter.h"
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Replace with your Wi-Fi credentials
const char* ssid = "mywifi";
const char* password = "password";
// Replace with your MQTT broker IP address
const char* mqttServer = "127.0.0.1";
const int mqttPort = 1883;
// Replace with your MQTT topics
const char* mqttTopicTemp = "sensors/temperature";
const char* mqttTopicOxygen = "sensors/oxygen";
WiFiClient espClient;
PubSubClient client(espClient);
Adafruit_MLX90614 mlx = Adafruit_MLX90614();
PulseOximeter pox;
void onHeartRateBeatDetected()
{
float hr = pox.getHeartRate();
Serial.print("Heart rate:");
Serial.println(hr);
}
void setup() {
Serial.begin(115200);
// Connect to Wi-Fi
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("Connecting to WiFi...");
}
Serial.println("Connected to WiFi");
// Connect to MQTT broker
client.setServer(mqttServer, mqttPort);
while (!client.connected()) {
if (client.connect("ESP8266Client")) {
Serial.println("Connected to MQTT broker");
}
else {
Serial.print("Failed to connect to MQTT broker, rc=");
Serial.println(client.state());
delay(2000);
}
}
// Initialize sensors
mlx.begin();
pox.begin();
// Set up a callback for pulse detection
pox.setOnBeatDetectedCallback(onHeartRateBeatDetected);
}
void loop() {
// Read temperature from MLX90614 sensor
float temperature = mlx.readObjectTempC();
// Convert temperature to string
String tempPayload = String(temperature);
// Publish temperature to MQTT topic
client.publish(mqttTopicTemp, tempPayload.c_str());
// Update pulse oximeter
pox.update();
// Read oxygen level from MAX30100 sensor
if (pox.begin()) {
float oxygen = pox.getSpO2();
// Convert oxygen level to string
String oxygenPayload = String(oxygen);
// Publish oxygen level to MQTT topic
client.publish(mqttTopicOxygen, oxygenPayload.c_str());
}
delay(1000); // Adjust the delay based on your needs
}
I actually don't know where can i get the MQTT IP server, but i'm pretty sure that's the correct IP. because i tried to send a simple message using MQTT in terminal and it works well.
Presumably you have Node RED running on your PC, then?
No.
Again, 127.0.0.1 refers to the device where it is running - so, unless your MQTT server is running on the ESP8266, you will need something else.
Your sketch needs the IP address of the system where your MQTT server is running.
If your MQTT server is running on your PC, then that will be the IP address of your PC.
You can get the IP address of your PC by typing ipconfig at a command prompt on that PC.
Is your ESP8266 actually on the same network as your PC?
Yes
since the code has function
// Connect to Wi-Fi
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("Connecting to WiFi...");
}
Serial.println("Connected to WiFi");
There are a lot of pieces to this project you have to get working independently first before putting it altogether.
I would recommend you get your mosquitto broker running, set up a publisher and client on the same machine and get that working. This is without node-red and arduino. That gets the mqtt broker working. Then get node-red working with the broker. Set up node-red as a client and use the same publisher. Once you get that working get the arduino involved.
I took me a good few days to understand and getting all that to work when I first used mqtt.
Good luck, it will take some time.
