Sensor Publisher rev_01

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    - Project: Sensor Publisher
    - Source Code NOT compiled for: Arduino Nano ESP32
    - Source Code created on: 2025-08-04 13:11:08

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/****** SYSTEM REQUIREMENTS *****/
/****** SYSTEM REQUIREMENT 1 *****/
    /* Send the MAX30100 sensor's SpO2 and heart rate */
    /* variables via MQTT to a specified broker, ensuring */
    /* data is transmitted only when new readings are */
    /* available, using the MAX30100_milan library */
    /* functions. */
/****** END SYSTEM REQUIREMENTS *****/

/* START CODE */
/****** DEFINITION OF LIBRARIES *****/
#include <Wire.h>
#include <MAX30100_milan.h>       // Using the MAX30100_milan library
#include <WiFi.h>
#include <PubSubClient.h>         // MQTT library

/****** FUNCTION PROTOTYPES *****/
void setup(void);
void loop(void);
void reconnect(); // MQTT reconnect function

/***** DEFINITION OF DIGITAL INPUT PINS *****/
const uint8_t BMP_MAX30100_INT_PIN_D2 = 2;

/***** DEFINITION OF I2C PINS *****/
const uint8_t BMP_MAX30100_I2C_PIN_SDA_A4 = A4;
const uint8_t BMP_MAX30100_I2C_PIN_SCL_A5 = A5;

/****** DEFINITION OF LIBRARIES CLASS INSTANCES*****/
MAX30100_milan max30100Sensor;  // Instantiate MAX30100 sensor object

// MQTT broker details
const char* mqtt_server = "your.mqtt.broker.address"; // Replace with your broker address
const int mqtt_port = 1883; // Default MQTT port
const char* mqtt_user = "your_username"; // If needed
const char* mqtt_password = "your_password"; // If needed

WiFiClient espClient;
PubSubClient client(espClient);

// Variables to hold sensor data
volatile bool newDataAvailable = false;
uint16_t lastSpO2 = 0;
uint16_t lastHeartRate = 0;

// Callback when a beat is detected
void onBeatDetected() {
  Serial.println("Beat detected");
}

// Connect to WiFi network
void setup_wifi() {
  delay(10);
  Serial.println();
  Serial.print("Connecting to WiFi...");
  WiFi.begin("your_SSID", "your_PASSWORD"); // Replace with your WiFi credentials

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

// Reconnect to MQTT broker
void reconnect() {
  // Loop until reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP32Client", mqtt_user, mqtt_password)) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(BMP_MAX30100_INT_PIN_D2, INPUT_PULLUP);

  // Initialize WiFi
  setup_wifi();

  // Initialize MQTT
  client.setServer(mqtt_server, mqtt_port);

  // Initialize MAX30100 sensor
  if (!max30100Sensor.begin()) {
    Serial.println("Failed to initialize MAX30100 sensor");
    while (1);
  }
  max30100Sensor.setMode(MAX30100_MODE_SPO2_HR);
  max30100Sensor.setLedsCurrent(MAX30100_LED_CURR_50MA, MAX30100_LED_CURR_50MA);
  max30100Sensor.setOnBeatDetectedCallback(onBeatDetected);
}

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

  max30100Sensor.update();

  uint16_t ir, red;
  if (max30100Sensor.getRawValues(&ir, &red)) {
    // Read SpO2 and Heart Rate
    uint16_t currentSpO2 = max30100Sensor.getSpO2();
    uint16_t currentHR = max30100Sensor.getHeartRate();

    // Check if new data is different from last sent data
    if (currentSpO2 != lastSpO2 || currentHR != lastHeartRate) {
      lastSpO2 = currentSpO2;
      lastHeartRate = currentHR;

      // Prepare JSON payload
      String payload = "{";
      payload += "\"SpO2\": " + String(currentSpO2) + ",";
      payload += "\"HeartRate\": " + String(currentHR);
      payload += "}";

      // Publish to MQTT topic
      if (client.publish("sensor/heart_rate_spo2", payload.c_str())) {
        Serial.println("Data sent: " + payload);
      } else {
        Serial.println("Failed to send data");
      }
    }
  }

  delay(100); // Adjust delay as needed
}