//the scale factor of TMP36 (temperature sensor) is 10 mV/°C with a 500 mV offset to allow for negative temperatures
#include <Wire.h>
#include <math.h>

// the analog pin number connected to the TMP36
#define slaveAddr 0x08

// defining global flags as actual registers
#define RD_REG_TEMP_INT_CEL    0x00
#define RD_REG_TEMP_FRA_CEL    0x01
#define RD_REG_TEMP_INT_FAR    0x02
#define RD_REG_TEMP_FRA_FAR    0x03

//define the analog port that is used on Arduino Dock 2
int sensorPin = A0;

//Byte that is being receiving
byte recvData;

//Global variables of the temperature to be accessible at any time
int celsiusInt;
int celsiusFrac;
int fahrenheitInt;
int fahrenheitFrac;

void setup()
{
  //received data from the Master
  recvData = 0xff;

  //initializing serial communication with the Omega2 for sending sensor data
  Serial.begin(9600);

  // initializing i2c interface
  Wire.begin(slaveAddr);
  Wire.onReceive(receiveEvent);
  Wire.onRequest(requestEvent);
}

void receiveEvent(int bytesReceived)
{
  // loop through all received bytes
  for (int i = 0; i < bytesReceived; i++)
  {
    if (i == 0)
    {
      // only store the very first received byte
      recvData = Wire.read();
    }
    else
    {
      // make sure to read the rest of the bytes to clear the i2c buffer
      Wire.read();
    }
  }
}

//Function definision for requesting the values from the slave (ATmega) and transfer it over to the master (Omega).
//We can only send one value at a time
void requestEvent()
{
    if (recvData == RD_REG_TEMP_INT_CEL)
    {
      Wire.write((byte)celsiusInt);
    }
    else if (recvData == RD_REG_TEMP_FRA_CEL)
    {
      Wire.write((byte)celsiusFrac);
    }
    else if (recvData == RD_REG_TEMP_INT_FAR)
    {
      Wire.write((byte)fahrenheitInt);
    }
    else if (recvData == RD_REG_TEMP_FRA_FAR)
    {
      Wire.write((byte)fahrenheitFrac);
    }
    else
    {
      Wire.write(0xff);
    }
}

float ReadSensor()
{
  // getting the voltage reading from the temperature sensor
  int reading = analogRead(sensorPin);
  // convert the analog reading (0 to 1023) to voltage (0 - 5V)
  float voltage = (float)reading * 5.0;
  voltage /= 1024.0;
  return (voltage);
}

float convertVoltTocelsius(float voltage)
{
  float temperatureC = (voltage - 0.5) * 100;
  return (temperatureC);
}

float convertCelcToFahrenheit (float temperatureC)
{
  float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;
  return (temperatureF);
}

//A function definition to get an Integer part of the reading
//e.g. you get a value of 26.73. This function returns 26 as you can only send one byte at a time
int GetInteger (float inputFloat)
{
  int intPart=(int)inputFloat;
  return intPart;
}

//A function definition to get a Fractional part of the reading
//e.g. you get a value of 26.73. This function returns 73 as you can only send one byte at a time
int GetFractional(float inputFloat)
{
  float frac = (inputFloat-GetInteger(inputFloat))+0.05; // +0.05 is added to either round up or down the end result
  frac = frac*100;
  return (int)frac;
}

void loop()
{
  float voltage_reading = ReadSensor();
  float celsius = convertVoltTocelsius(voltage_reading);
  float fahrenheit = convertCelcToFahrenheit(celsius);
  //functions to get Integer and Fractional part of celsius and Fahrenheit values
  celsiusInt = GetInteger(celsius);
  celsiusFrac = GetFractional(celsius);

  fahrenheitInt = GetInteger(fahrenheit);
  fahrenheitFrac = GetFractional(fahrenheit);
  /* This is optional feature to see the values that are correspondin to Celsius and Fahrenheit
  Serial.print("Celcius Integer: "); Serial.println(celsiusInt);
  Serial.print("Celcius Fractional: "); Serial.println(celsiusFrac);
  Serial.print("Fahrenheit Integer: "); Serial.println(fahrenheitInt);
  Serial.print("Fahrenheit Fractional: "); Serial.println(fahrenheitFrac);
  */
  delay(1000); // delay between sensor reads
}