/******************   Arduino Blink with potentiometer in C ******************/
#include<avr/io.h>

//#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
//#define _SFR_BYTE(n) (n)
long map(long x, long in_min, long in_max, long out_min, long out_max) {
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

void initPort()
{
  DDRB|=(1<<PB2);   //PB2 - output pin, led
  DDRD =0xff;       //A0  - inputpin
}

void initADC( void)
{
  
  ADMUX = 0;                //Select channel 0
  ADCSRA = 0xC3;            //Enable ADC & start 1st dummy
                            //conversion
                            //Set ADC module prescalar to 8
                            //critical for accurate ADC
  while (!(ADCSRA & 0x10)); //Check if conversation ready
  ADCSRA |= 0x10;           //Clear conv rdy flag - set bit
}

int main()
{
  Serial.begin(9600);
  initPort();
  initADC();
  while(1)
  {
    blink();
  }
}

void blink()
{
  
  int ledVal = 0;
  ReadADC(&ledVal, 0x00);
  ledVal = map(ledVal, 1023, 0, 0, 255);
  printVal(&ledVal);

//  in simulator tinkercad doesnt work :(
    TCCR1A = 0xA1;  //freq = int osc/64 = 1 MHz/64
                    //freq = 15.6 kHz
    TCCR1B = 0x03;  //no clock source division
    
    
    OCR1BH = 0x00;  //Init PWM duty cycle variables
    OCR1BL = (unsigned char)(ledVal);

}

void printVal(int *ledVal)
{
  Serial.print(*ledVal);      // prints 2 decimal places by default
  Serial.print('\n');
}

void ReadADC(int * result, unsigned char channel)
{
    unsigned int binary_weighted_voltage_low  = 0,
                 binary_weighted_voltage_high = 0; //weighted binary voltage

    ADMUX = channel;//Select channel
    ADCSRA |= 0x43; //Start conversion
                    //Set ADC module prescalar
                    //to 8 critical for
                    //accurate ADC results

    while (!(ADCSRA & 0x10)); //Check if conversion ready
    ADCSRA |= 0x10;           //Clear Conv rdy flag - set the bit

    binary_weighted_voltage_low = ADCL;                         //Read ADC register
    binary_weighted_voltage_high = ((unsigned int)(ADCH << 8)); //Read 8 low bits first
    *result = binary_weighted_voltage_low |                     // send 8 low bits 
              binary_weighted_voltage_high;
}