glucosemonitor.ino

/**
 * NON-INVASIVE GLUCOSE MONITOR – FINAL VERSION
 * Hardware:
 *  - ESP32 DevKit
 *  - MAX30102 / MAX30105
 *  - SSD1306 OLED (128x64)
 */

#include <Wire.h>
#include "MAX30105.h"
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "model_coefficients.h"

// ================= DISPLAY =================
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// ================= SENSOR =================
MAX30105 particleSensor;

// ================= CONFIG =================
#define SAMPLE_RATE 100
#define BUFFER_SIZE 200
#define FEATURE_INTERVAL 5000

float irBuffer[BUFFER_SIZE];
float redBuffer[BUFFER_SIZE];
unsigned long timeBuffer[BUFFER_SIZE];
int bufferIndex = 0;

unsigned long lastFeatureTime = 0;
float lastGlucosePrediction = 0;

// ================= ML PREDICTION =================
float predictGlucose(float ratio, float variability, float slope) {
  float z_ratio = (ratio - mean_ratio) / std_ratio;
  float z_variability = (variability - mean_variability) / std_variability;
  float z_slope = (slope - mean_slope) / std_slope;

  float glucose =
    intercept +
    coeff_ratio * z_ratio +
    coeff_variability * z_variability +
    coeff_slope * z_slope;

  return glucose;
}

// ================= UTILS =================
float mean(float *buf, int n) {
  float s = 0;
  for (int i = 0; i < n; i++) s += buf[i];
  return s / n;
}

// ================= SETUP =================
void setup() {
  Serial.begin(115200);
  Wire.begin(18, 19);

  // OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED not found");
    while (1);
  }

  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("Glucose Monitor");
  display.println("Initializing...");
  display.display();

  // MAX30102
  if (!particleSensor.begin(Wire, I2C_SPEED_FAST)) {
    Serial.println("MAX30102 not found");
    while (1);
  }

  particleSensor.setup(
    0x1F,     // LED brightness
    4,        // sample avg
    2,        // red + IR
    SAMPLE_RATE,
    411,      // pulse width
    4096      // ADC range
  );

  delay(2000);
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("Place finger");
  display.display();

  Serial.println("System Ready");
}

// ================= LOOP =================
void loop() {
  // Capture PPG
  if (bufferIndex < BUFFER_SIZE) {
    irBuffer[bufferIndex] = particleSensor.getIR();
    redBuffer[bufferIndex] = particleSensor.getRed();
    timeBuffer[bufferIndex] = millis();
    bufferIndex++;
    delay(1000 / SAMPLE_RATE);
    return;
  }

  // Shift buffer
  for (int i = 1; i < BUFFER_SIZE; i++) {
    irBuffer[i - 1] = irBuffer[i];
    redBuffer[i - 1] = redBuffer[i];
    timeBuffer[i - 1] = timeBuffer[i];
  }
  bufferIndex = BUFFER_SIZE - 1;

  // Feature extraction every interval
  if (millis() - lastFeatureTime > FEATURE_INTERVAL) {
    lastFeatureTime = millis();

    float irMean = mean(irBuffer, BUFFER_SIZE);
    float redMean = mean(redBuffer, BUFFER_SIZE);

    if (irMean < 50000) {
      display.clearDisplay();
      display.setCursor(0, 0);
      display.println("No Finger");
      display.display();
      return;
    }

    // Feature 1: Ratio
    float ratio = irMean / redMean;

    // Feature 2: Variability (RMSSD)
    float var = 0;
    for (int i = 1; i < BUFFER_SIZE; i++) {
      float d = irBuffer[i] - irBuffer[i - 1];
      var += d * d;
    }
    var = sqrt(var / (BUFFER_SIZE - 1));

    // Feature 3: Slope
    int maxI = 0, minI = 0;
    float maxV = irBuffer[0], minV = irBuffer[0];
    for (int i = 1; i < BUFFER_SIZE; i++) {
      if (irBuffer[i] > maxV) { maxV = irBuffer[i]; maxI = i; }
      if (irBuffer[i] < minV) { minV = irBuffer[i]; minI = i; }
    }

    float slope = 0;
    if (maxI > minI) {
      slope = (maxV - minV) /
              (timeBuffer[maxI] - timeBuffer[minI]) * 1000.0;
    }

    // ================= ML PREDICTION =================
    float glucose = predictGlucose(ratio, var, slope);
    lastGlucosePrediction = glucose;

    // ================= OUTPUT =================
    Serial.print("Glucose: ");
    Serial.print(glucose, 1);
    Serial.println(" mg/dL");

    display.clearDisplay();
    display.setCursor(0, 0);
    display.setTextSize(1);
    display.println("Predicted Glucose");
    display.setTextSize(2);
    display.setCursor(0, 20);
    display.print(glucose, 1);
    display.println(" mg/dL");
    display.display();
  }
}