#include <avr/io.h>
#include <util/delay.h>
#include <stdlib.h>

#define RS PD0
#define EN PD1
#define D4 PD4
#define D5 PD5
#define D6 PD6
#define D7 PD7

int col[2] = {0,64};
volatile uint16_t adc_result = 0;

void lcd_init(void)
{
  DDRD |= (1 << RS) | (1 << EN) | (1 << D4) | (1 << D5) | (1 << D6) | (1 << D7);
  _delay_ms(20);
  send_command(0x33);
  send_command(0x32);
  send_command(0x28);
  send_command(0x0E);
  send_command(0x06);
  send_command(0x01);
  _delay_ms(50);
}

void adc_init(void)
{
  ADMUX |= (1 << REFS0);
  ADCSRA |= (1 << ADEN) | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
}

void send_command(unsigned char command)
{
  PORTD = ((PORTD & 0x03) | (command & 0xF0));
  PORTD &= ~(1 << RS);
  PORTD |= (1 << EN);
  _delay_ms(1);
  PORTD &= ~(1 << EN);
  _delay_ms(200);
  PORTD = ((PORTD & 0x03) | (command & 0x0F) << 4);
  PORTD |= (1 << EN);
  _delay_ms(1);
  PORTD &= ~(1 << EN);
  _delay_ms(2);
}

void send_data(unsigned char data)
{
  PORTD = ((PORTD & 0x03) | (data & 0xF0));
  PORTD |= (1 << RS);
  PORTD |= (1 << EN);
  _delay_ms(1);
  PORTD &= ~(1 << EN);
  _delay_ms(200);
  PORTD = ((PORTD & 0x03) | (data & 0x0F) << 4);
  PORTD |= (1 << EN);
  _delay_ms(1);
  PORTD &= ~(1 << EN);
  _delay_ms(2);
}

void send_string(char *string)
{
  while(*string != '\0')
  {
    send_data(*string++);
  }
}

void set_cursor(uint8_t x,uint8_t y)
{
  send_command(0x80 + x + col[y]);
}

float read_temp(uint8_t channel)
{
  unsigned int adc_value;
  float temp;
  adc_value = adc_read(channel);
  //temp = adc_value * (5.0 / 1023.0);
  temp = (adc_value * 500) / 1024.0;
  return temp;
}

uint16_t adc_read(uint8_t channel)
{
  ADMUX |= ((ADMUX & 0xF0) | (channel & 0x0F));
  ADCSRA |= (1 << ADSC);
  while(ADCSRA & (1 << ADSC));
  return ADCW;
}

void send_result(uint16_t result)
{
  char buffer[16];
  itoa(result,buffer,10);
  send_string(buffer);
}

void lcd_clear(void)
{
  send_command(0x01);
}

int main(void)
{
  uint16_t value;
  adc_init();
  lcd_init();
  set_cursor(0,0);
  send_string("thermo");
  set_cursor(0,1);
  while(1)
  {
    value = read_temp(0);
    send_result(value);
    _delay_ms(500);
    lcd_clear();
  }
  return 0;
}