#include <avr/io.h>
#include <avr/interrupt.h>
unsigned char Hex_Data [] = {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D,
                0x07, 0x7F, 0x67, 0x77, 0x7C, 0x39, 0x5E, 0x79, 0x71};
unsigned  adc_value = 0;
int I_flag = 1;
#define BIT(b)  (1<<(b))

#define SEQ_COUNT_MAX   16 // hex numbers
#define SW1             3  // PB.3
#define SW2             2  // PB.2
#define SEG_DP          1  // PB.1
#define SEG_G           0  // PB.0
#define BIT_G           0x40 // Bit 7
#define PORTD_OFFSET    0x02 // Skip PORTD[0-1]
#define MIN_DELAY 250

/*
PORTD.[2-7] drive the display bits [a-f]
PORTB.0 drives display bit "g"
PORTB.0 drives display bit "dp" (decimal point)

The display has a common anode, therefore the ports need to
be driven low to activate a segment (i.e., invert the pattern)

PORT A0 senses a potentiometer that spans 0V to 5V; The ADC 
can be used to measure the position on a scale of 0 - 1023
*/
 
int main(void)
{
  DDRD = 0xff;	// output
  DDRB = 0x03; // output on pb.1 and pb.2
  
	PORTB = 0x0c; // pb.3, pb.4 pull up
  int index = 0; 
  unsigned char comp;
  ADCSRA = 0x8F;  //enable ADC, enable interrupts, prescale 128
  ADMUX = 0x60;   //VCC ref, ADC on channel 0 (pin A0), left justify bits
  ADCSRA |=(1<<ADSC); //start conversion
  sei();              //enable global interrupt
  while(1)
  {
    if(I_flag)    //check if ADC data ready
    {
    ADCSRA |=(1<<ADSC); //reset ADC
    I_flag = 0;         //clear flag
    }
    //PORTD = adc_value << PORTD_OFFSET;
    comp = ~Hex_Data[index];
    PORTD = comp << PORTD_OFFSET;

    if ( (comp & (1<<6)) ==(1<<6))// if the bit is set on the data, then set it on the port
      PORTB |= 1;
    else                          //otherwise clear bit
      PORTB &= ~1;
   if ( (comp & (1<<7)) ==(1<<7))
      PORTB |= (1<<1);
    else
      PORTB &= ~(1<<1);

    if (PINB & (1<<SW2))
    {
      index++;        //increment index
      if (index >=16)// make sure index only has values 0-15 for hexidemical
      {
        index = 0;
      }
      if(PINB &(1<<SW1)) //delay 1 sec when switch 1 is high
      {
        timer_delay(1000);
      }
      else
      {
        
        //map adc_value to .25s - 1.25s, and delay that time
        timer_delay((((int)adc_value*1000)/16)+MIN_DELAY);
      }
    }
    else
    {
      index = adc_value;
    }

  }
}
void timer_delay(unsigned msecs){
	TCNT1 = 0xffff -(0x0010 * msecs); //timer counts down, take max
	TCCR1A = 0x00;
	TCCR1B = 0x05;
	while((TIFR1 &(1<<TOV1))==0);
	TCCR1B = 0;
	TIFR1 = 1<<TOV1;
}

ISR(ADC_vect)
{
  adc_value = ADCH >>4;//take 4 MSB
  I_flag = 1;         //set flag for main loop
}