#include <Wire.h>
#include <Adafruit_ADS1X15.h>

// Create an instance of the ADS1115 class
Adafruit_ADS1115 ads;

// Global variables to set expected voltages
float expectedVoltageA0 = 3.3; // Expected voltage on A0
float expectedVoltageA1 = 5.0; // Expected voltage on A1
float expectedVoltageA2 = 0.0; // Expected voltage on A2 (Set to 0 if not used)
float expectedVoltageA3 = 0.0; // Expected voltage on A3 (Set to 0 if not used)

// Uncomment the appropriate line based on where the ADDR pin is connected
// #define ADS1115_ADDRESS 0x48  // ADDR pin connected to GND
// #define ADS1115_ADDRESS 0x49  // ADDR pin connected to VDD
// #define ADS1115_ADDRESS 0x4A  // ADDR pin connected to SDA
// #define ADS1115_ADDRESS 0x4B  // ADDR pin connected to SCL

// Function to determine the appropriate gain setting based on expected voltage
adsGain_t chooseGain(float maxVoltage) {
  if (maxVoltage <= 0.256) {
    return GAIN_SIXTEEN; // ±0.256V
  } else if (maxVoltage <= 0.512) {
    return GAIN_EIGHT; // ±0.512V
  } else if (maxVoltage <= 1.024) {
    return GAIN_FOUR; // ±1.024V
  } else if (maxVoltage <= 2.048) {
    return GAIN_TWO; // ±2.048V
  } else if (maxVoltage <= 4.096) {
    return GAIN_ONE; // ±4.096V
  } else {
    return GAIN_TWOTHIRDS; // ±6.144V
  }
}

void setup(void)
{
  Serial.begin(9600);
  Wire.begin(); // Start I2C communication

  if (!ads.begin(ADS1115_ADDRESS)) {
    Serial.println("Failed to initialize ADS1115!");
    while (1);
  }

  // Choose the correct gain based on the highest expected voltage
  float maxExpectedVoltage = max(max(expectedVoltageA0, expectedVoltageA1),
                                 max(expectedVoltageA2, expectedVoltageA3));
  ads.setGain(chooseGain(maxExpectedVoltage));

  Serial.println("ADS1115 initialized successfully.");
}

void loop(void)
{
  int16_t adc0, adc1, adc2, adc3;
  float voltage0, voltage1, voltage2, voltage3;

  // Read ADC values from each channel
  adc0 = ads.readADC_SingleEnded(0); // Reading from A0
  delay(5); // Small delay to ensure stable reading
  adc1 = ads.readADC_SingleEnded(1); // Reading from A1
  delay(5);
  adc2 = ads.readADC_SingleEnded(2); // Reading from A2
  delay(5);
  adc3 = ads.readADC_SingleEnded(3); // Reading from A3
  delay(5);

  // Get the selected gain for voltage conversion
  float gainFactor = 0.0;
  switch (ads.getGain()) {
    case GAIN_TWOTHIRDS: gainFactor = 0.1875; break; // ±6.144V
    case GAIN_ONE: gainFactor = 0.125; break; // ±4.096V
    case GAIN_TWO: gainFactor = 0.0625; break; // ±2.048V
    case GAIN_FOUR: gainFactor = 0.03125; break; // ±1.024V
    case GAIN_EIGHT: gainFactor = 0.015625; break; // ±0.512V
    case GAIN_SIXTEEN: gainFactor = 0.0078125; break; // ±0.256V
  }

  // Convert ADC readings to voltage
  voltage0 = adc0 * gainFactor / 1000.0; // Convert mV to V
  voltage1 = adc1 * gainFactor / 1000.0;
  voltage2 = adc2 * gainFactor / 1000.0;
  voltage3 = adc3 * gainFactor / 1000.0;

  // Print the voltage values
  Serial.print("A0 Voltage: "); Serial.print(voltage0); Serial.println(" V");
  Serial.print("A1 Voltage: "); Serial.print(voltage1); Serial.println(" V");
  Serial.print("A2 Voltage: "); Serial.print(voltage2); Serial.println(" V");
  Serial.print("A3 Voltage: "); Serial.print(voltage3); Serial.println(" V");

  delay(1000);
}