#include <Wire.h>

void setup() {
  Wire.setClock(100000);
  Wire.begin();
  Serial.begin(115200);

  // checking the I2c device on the line
  byte error, address;
  int nDevices;

  Serial.println("Scanning...");

  nDevices = 0;
  for(address = 1; address < 127; address++ )
  {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0)
    {
      Serial.print("I2C device found at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.print(address,HEX);
      Serial.println("  !");

      nDevices++;
    }
    else if (error==4)
    {
      Serial.print("Unknow error at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");


 // setting up 
   // Reset device by common 0x00 call
  Wire.beginTransmission(0x40);
  Wire.write(0x06);
  Serial.println(Wire.endTransmission());
  delay(500);
  
  // Read the value from the register 0x00 - should return 0 as default
  Wire.beginTransmission(0x40);
  Wire.write(0x20);
  Serial.println(Wire.endTransmission());
  Wire.requestFrom(0x40, 1);
  if (Wire.available() == 1) {
    int value = Wire.read();
    Serial.println(value);
  }
  delay(100);

  // Write a value to the register 0x00 - 0xA7 - 1010 0111 : AIN2AGND, GAIN 0, 20SPS, Cont mode, External ref
  Wire.beginTransmission(0x40);
  Wire.write(0x40);
  Wire.write(0xA7);
  Serial.println(Wire.endTransmission());
  delay(100);

  // Read the value from the register 0x00 - should return 0xA7 = 0d167
  Wire.beginTransmission(0x40);
  Wire.write(0x20);
  Serial.println(Wire.endTransmission());
  Wire.requestFrom(0x40, 1);
  if (Wire.available() == 1) {
    int value = Wire.read();
    Serial.println(value);
  }
  delay(100);

  // Start conversion
  Wire.beginTransmission(0x40);
  Wire.write(0x08);
  Serial.println(Wire.endTransmission());
  delay(1000);

}

void loop() {

// // Start conversion
//   Wire.beginTransmission(0x40);
//   Wire.write(0x08);
//   // Wire.write(0x41);
//   Serial.println(Wire.endTransmission());
//   delay(100);

//Read data by cmd
  uint16_t value;
  // Reading data by cmd
  Wire.beginTransmission(0x40);
  Wire.write(0x10);
  Wire.endTransmission(false);
  Serial.print("Number of bytes requested :"); Serial.println(Wire.requestFrom(0x40, 2));
  Serial.println();
  byte value_1 = Wire.read();
  byte value_2 = Wire.read();

  Serial.print("Byte 0:"); Serial.println(value_1);
  Serial.print("Byte 1:"); Serial.println(value_2);

  value = (value_1 << 8 | value_2);
  if (value > 0x7FFF) 
  {
    value = 0x0;
  }
  //Serial.println(value);
  float voltage = 5.0 * (float(value) / 32767) * 1; 
  Serial.print("Vin :"); Serial.println(voltage);
  Serial.println();

  delay(1000);
}