#include <avr/io.h>
#include <avr/interrupt.h>

#define TWI_FREQ   100000
#define SLA_ADDRES 104

#ifndef F_CPU
#define F_CPU        16000000UL
#endif // !F_CPU

#ifndef TWI_FREQ
#define TWI_FREQ     100000
#endif // !TWI_FREQ

#ifndef I2C
#define I2C

void i2c_initialise(void)
{
  // Set pre-scalers in TWPS1 TWPS0 (no pre-scaling)
  TWSR = 0B00000000;
  // Set bit rate
  TWBR = ((F_CPU / TWI_FREQ) - 16) / 2;
  // Writing a logic one to this bit shuts down the TWI by stopping the clock to the module. When waking up the TWI again, the TWI should be re initialized to ensure proper operation
  PRR &= (0 << PRTWI);
  // Enable TWI and interrupt
  TWCR = (1 << TWIE) | (1 << TWEN);
}

void i2c_start(void)
{
  // Send start condition
  TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
  // Wait until the TWI is ready for the next operation
  while (!(TWCR & (1 << TWINT)));
}

void i2c_send_sla_adress(uint8_t addres)
{
  // Write SLA+R/W in TWI data register
  TWDR = addres;
  // Enable TWI and clear interrupt flag
  TWCR = (1 << TWINT) | (1 << TWEN);
  // Wait until TWI finish its current job
  while (!(TWCR & (1 << TWINT)));
}

void i2c_send_data(uint8_t data)
{
  // Copy data in TWI data register
  TWDR = data;
  TWCR = (1 << TWINT) | (1 << TWEN);
  // Wait until TWI finish its current job
  while (!(TWCR & (1 << TWINT)));
}

void ic2_stop(void)
{
  // Send start condition
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
  // Wait until the TWI is ready for the next operation
  while (!(TWCR & (1 << TWSTO)));
}

void i2c_Ack(void)
{
  // Enable TWI and clear interrupt flag
  TWCR = (1 << TWEN) | (1 << TWINT) | (1 << TWEA);
  // Wait until TWI finish its current job
  while (!(TWCR&(1 << TWINT)));
}

void i2c_Nack(void)
{
  // Enable TWI and clear interrupt flag
  TWCR = (1 << TWEN) | (1 << TWINT);
  // Wait until TWI finish its current job
  while (!(TWCR&(1 << TWINT)));
}

uint8_t i2c_get_data(uint8_t sla_address, uint8_t register_address)
{
  i2c_start();
  // Write mode.
  i2c_send_sla_adress(sla_address << 1);
  i2c_send_data(register_address);
  i2c_start();
  // Read mode.
  i2c_send_sla_adress((sla_address << 1) | 0B00000001);
  i2c_Nack();
  ic2_stop();
  return TWDR;
}

#endif // !I2C

float temp;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  i2c_initialise();
  i2c_start();
  i2c_send_sla_adress(SLA_ADDRES << 1);
  i2c_send_data(58);
  i2c_start();
  i2c_send_sla_adress((SLA_ADDRES << 1) | 0B00000001);
  i2c_Ack(); // Address 0.
  Serial.println(TWDR, DEC);

  i2c_Ack(); // Address 1.
  Serial.println(TWDR, DEC);

  i2c_Ack(); // Address 2.
  Serial.println(TWDR, DEC);

  i2c_Ack(); // Address 3.
  Serial.println(TWDR, DEC);

  ic2_stop(); // Address 7.

}

void loop() {
  // put your main code here, to run repeatedly:
  temp = i2c_get_data(SLA_ADDRES, 8) + (i2c_get_data(SLA_ADDRES, 9) / 10 );
  Serial.print(temp, DEC);
  Serial.print("°C\n");


}