MEMO PROJECT (DROWSINESS DETECTOR DEVICE)

battery.h

#ifndef __BATTERY_H__
#define __BATTERY_H__

#include <Arduino.h>

// ADC Configuration
#define BATTERY_PIN          34  // GPIO34 = ADC1_CH6
#define VOLTAGE_DIVIDER_RATIO 2.0  // 47kΩ / (47kΩ + 47kΩ) = 0.5 (so 1/0.5 = 2.0)
#define ADC_SAMPLES          20   // Must be odd number for true median
#define VOLTAGE_OFFSET            0.2463  // Offset for calibration

float read_battery_voltage() {
    // Array to store multiple readings
    int raw_values[ADC_SAMPLES] = {0};
    
    // Take multiple samples
    for (int i = 0; i < ADC_SAMPLES; i++) {
        raw_values[i] = analogRead(BATTERY_PIN);
        delay(1); // Small delay between readings
    }
    
    // Simple insertion sort for median
    for (int i = 1; i < ADC_SAMPLES; i++) {
        int temp = raw_values[i];
        int j = i - 1;
        while (j >= 0 && raw_values[j] > temp) {
            raw_values[j+1] = raw_values[j];
            j--;
        }
        raw_values[j+1] = temp;
    }
    
    // Get median value
    int median_raw = raw_values[ADC_SAMPLES / 2];
    
    // Convert to voltage (ESP32 ADC reference is 3.3V with 12-bit resolution = 4096)
    float voltage = (median_raw * 3.3f) / 4095.0f;
    
    // Apply voltage divider factor 
    voltage *= VOLTAGE_DIVIDER_RATIO;
    
    // Optional: Apply calibration formula if you have one
    voltage = voltage * 1.00005 + VOLTAGE_OFFSET; // Example calibration formula

    if(voltage <VOLTAGE_OFFSET*1.1) {
        voltage = 0;
    }
    
    return voltage;
}

void init_adc() {
    // Configure ADC
    analogReadResolution(12);  // 12-bit resolution
    analogSetPinAttenuation(BATTERY_PIN, ADC_11db); // For input up to 3.3V
}

#endif // __BATTERY_H__

memo_drowsiness_detector_basic_IO.cpp

#include <Arduino.h>  
#include "battery.h"

#define VIBRATION_PIN 14 // GPIO14 for vibration motor control


void setup() { 
  Serial.begin(115200);  

  init_adc();
  pinMode(VIBRATION_PIN, OUTPUT); // Set vibration pin as output

}

void loop() { 
  float voltage = read_battery_voltage();


  static unsigned long last_print = 0;
  if (millis() - last_print > 1000) { // Print every second
    last_print = millis();
    Serial.printf("Battery Voltage: %.2f V\n", voltage);  
  }


  digitalWrite(VIBRATION_PIN, (millis() %3000<200 ? HIGH : LOW));
}