HDD clock

//___________________ Librairies & defines __________________//
#include <avr/io.h>
#include <util/delay.h>
#include <stdlib.h>
#include <avr/interrupt.h>
#include <stdio.h>
//RTC libs
#include <Wire.h>
#include <RTClib.h>


#ifndef F_CPU
#define F_CPU           16000000UL  // 16 MHz
#endif


// frequencion division
#define FREQ_DIV_8      (F_CPU / 8)
// #of ticks / millisec
#define MILLITICK       (FREQ_DIV_8 * .001)


//______________________ Constants and global variables_______________//
const int  divisions = 180;  //a multiple of 60 to simplyfy the positioning

volatile byte LED [divisions+1]; //Array with positions where the leds should light up. in bytes so we can clock it directly in the portB register

// _____________period of the rotation of the disk
int period;
// ______________volatile so it will be accessible in the IRS routine
volatile int positionCounter = 0;

//____________RTC declareren
RTC_DS1307 RTC;

volatile boolean update; //variable to trigger update

void setup()
{

  Serial.begin(115200);
  Serial.println("serial is set");
  //______________ RTC opzetten_____________//
 // Wire.begin();
  //RTC.begin();

 delay(50);
  Serial.println("rtc is set");
delay(50);
  //________________    Set I/O ports   ______________//

  DDRL=255 ;   //PL4 pin 45 as output for servo
  DDRB=255;      // pin 51 - 52 - 53 as ooutput for portb
  DDRD=0;
  Serial.println("IO is set");
delay(50);
  //___________________Init Timers_______________________//
 cli(); //disable timers


  //**********          PWM for Servo (ESC)     ****************//

  TCCR5A = (1 << COM5B1); // timer5: phase & frequency correct - pwm Clear OC1B on Compare Match
  TCCR5B = (1 << WGM53)  | (1 << CS51); //prescaler 8

  ICR5 = 20000; // 20ms
  OCR5B= 1500; // 1.5ms
  Serial.println("servo is set");
  delay(50);
  //***************      Timers for disk position     *****************//

  // setup timer0 - 8bit, --> to drive the leds
  TCCR2A = 0;
  TCCR2B = 0;
  // select CTC mode:  clear timer on compare match mode
  TCCR2A = (1<< WGM21);
  // select prescaler clk / 8
  TCCR2B= (1<< CS21);
  // enable compare interrupt
  TIMSK2 = (1<<OCIE2A);

  // setup timer1 - 16bit to count the rotations and calculate the period
  TCCR3B = 0;
  TCCR3A = 0; // A1 registering p134
  // select prescaler clk / 8
  TCCR3B=(1<< CS31);
  // reset timer
  TCNT3 = 0;
  // enable overflow interrupt
  TIMSK3=(1<< TOIE3);
  Serial.println("timer1 is set");
  delay(50);
  // stel PIN2( arduino D-input) falling edge interrupt
  EICRA |= _BV(ISC21);
  EIMSK |= _BV(INT2);
  Serial.println("int2 is set");
  delay(50);
  // set the rotational period to 0

  period = 0;

  // setup timer3 - 16bit, --> to drive time keeping function
  TCCR4A = 0;
  TCCR4B = 0;
  // select CTC mode:  clear timer on compare match mode
  TCCR4A = (1<< WGM41);
  // select prescaler clk / 1024
  TCCR4B= (1<< CS40)|(1<<CS42);
  // enable compare interrupt
  TIMSK4 = (1<<OCIE4A);

  OCR4A=6250; //400ms
  Serial.println("timer4 is set");
  delay(50);
 sei(); //reenable interrupts
  Serial.begin(9600);
Serial.println("timers are set");
delay(50);


  for(int i =0; i<divisions;i++){  //Set all bytes in the array to zero
    LED[positionCounter]=0;
  }
  Serial.println("array is empty");
  //Getting out of settings mode of the ESC & Testing leds
  PORTB=0b00000001;
  _delay_ms(5000);
  PORTB=0b00000010;
  OCR5B = 2000;
  _delay_ms(2000);
  PORTB=0b00000100;
  OCR5B = 1000;
  _delay_ms(2000);
  OCR5B = 2000;
  PORTB=0b00000000;



}
void loop()
  {


    if(update){
      DateTime now = RTC.now();
      int hours=now.hour()%12; //getting the time from 0 to 11 instead of 24 hours
      int minutes= now.minute();
      int seconds= now.second();

      for(int i =0; i<divisions;i++){  //clear the whole array
        LED[positionCounter]=0;
      }
        LED[hours*15] |= 4;
        LED[minutes*3] |= 2;
        LED[seconds*3] |= 1;

      }
      update=false;


  }



ISR(INT2_vect)   //Sensor interrupt routine
{
  // period = nuber of ticks since last interrupt
  period = TCNT3;
  // if period < than to millis no rotation is possible --> discard value
  // disk 7500 rpm --> 125rps -->8 millis /rotation
  if(period <(2 * MILLITICK))
  {
    return;
  }
  //reset timer to zero
  TCNT3 = 0;
  //8bit timer0 generates an interrupt / division --> time between interrupts = period/divisions
  TCNT2 = 0;
  OCR2A = (period / divisions);
  positionCounter = 25;  // set position to 25. sensor is rotated 37° to the length axis of the disk.
}




ISR(TIMER2_COMPA_vect) { //timer interrupt routine
  positionCounter = ((positionCounter + 1) % divisions); //position with modulo division
  PORTB=LED[positionCounter]; //getting the led values of the current position and clocking them in the portB output register.
}

ISR(TIMER4_COMPA_vect) { //timer interrupt routine
 update=true;
}