// #include "RTClib.h"
#define DS1307_ADDR 0x68 // I2C address of DS1307 RTC

// DS1307 register addresses
#define DS1307_SECONDS 0x00
#define DS1307_MINUTES 0x01
#define DS1307_HOURS   0x02
#define DS1307_DAY     0x03
#define DS1307_DATE    0x04
#define DS1307_MONTH   0x05
#define DS1307_YEAR    0x06
#define DS1307_CONTROL 0x07



void setup () {
  Serial.begin(9600);
  i2c_init();
  // Set date and time (hours, minutes, seconds)
  ds1307_set_time(11, 49, 0);

}

void loop () {
  uint8_t hours, minutes, seconds;
  // Get current time (hours, minutes, seconds)
  ds1307_get_time(&hours, &minutes, &seconds);
  Serial.print(hours);
  Serial.print(" : ");
  Serial.print(minutes);
  Serial.print(" : ");
  Serial.println(seconds);
  delay(1000);
}

// I2C Initialization
void i2c_init() {
  // Set prescaler to 1 (TWPS0 = 0, TWPS1 = 0)
  TWSR &= ~(1 << TWPS0);
  TWSR &= ~(1 << TWPS1);

  // Set SCL frequency to desired value (e.g., 100 kHz)
  TWBR = ((F_CPU / 100000UL) - 16) / 2;

  // Enable TWI module
  TWCR |= (1 << TWEN);
}

// I2C Start Condition
void i2c_start() {
  TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN); // Start condition
  while (!(TWCR & (1 << TWINT))); // Wait for start condition to be transmitted
}

// I2C Stop Condition
void i2c_stop() {
  TWCR = (1 << TWINT) | (1 << TWSTO) | (1 << TWEN); // Stop condition
  while (TWCR & (1 << TWSTO)); // Wait for stop condition to complete
}

// I2C Send Data
void i2c_send(uint8_t data) {
  TWDR = data; // Load data into TWI data register
  TWCR = (1 << TWINT) | (1 << TWEN); // Start transmission
  while (!(TWCR & (1 << TWINT))); // Wait for transmission to complete
}

// I2C Receive Data with ACK
uint8_t i2c_receive_ack() {
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWEA); // Enable ACK and start reception
  while (!(TWCR & (1 << TWINT))); // Wait for data reception to complete
  return TWDR; // Return received data
}

// I2C Receive Data with NACK
uint8_t i2c_receive_nack() {
  TWCR = (1 << TWINT) | (1 << TWEN); // Don't send ACK, start reception
  while (!(TWCR & (1 << TWINT))); // Wait for data reception to complete
  return TWDR; // Return received data
}


// Function to read a register from DS1307 RTC
uint8_t ds1307_read(uint8_t reg) {
  uint8_t data;

  // Start condition
  i2c_start();

  // Send device address + write bit
  i2c_send(DS1307_ADDR << 1);

  // Send register address
  i2c_send(reg);

  // Restart condition
  i2c_start();

  // Send device address + read bit
  i2c_send((DS1307_ADDR << 1) | 1);

  // Receive data
  data = i2c_receive_nack();

  // Stop condition
  i2c_stop();

  return data;
}

// Function to write to a register in DS1307 RTC
void ds1307_write(uint8_t reg, uint8_t data) {
  // Start condition
  i2c_start();

  // Send device address + write bit
  i2c_send(DS1307_ADDR << 1);

  // Send register address
  i2c_send(reg);

  // Send data
  i2c_send(data);

  // Stop condition
  i2c_stop();
}

// Function to read current time from DS1307 RTC
void ds1307_get_time(uint8_t *hours, uint8_t *minutes, uint8_t *seconds) {
  *seconds = ds1307_read(DS1307_SECONDS);
  *minutes = ds1307_read(DS1307_MINUTES);
  *hours = ds1307_read(DS1307_HOURS);
}

// Function to set current time in DS1307 RTC
void ds1307_set_time(uint8_t hours, uint8_t minutes, uint8_t seconds) {
  ds1307_write(DS1307_SECONDS, seconds);
  ds1307_write(DS1307_MINUTES, minutes);
  ds1307_write(DS1307_HOURS, hours);
}