/*Ej 5.5 Generate a ramp with constant acceleration for a stepper motor,
starting from rest and reaching 1000 pulses per second, in increments of 50 pulses
per second approximately every 100 ms.

Speed	|50	|100	|150	|200	…				|1000
Time	|0	|100ms	|200ms	| 300ms					|
*/

#define F_CPU 16000000UL

#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdint.h>

#define OSCILLATOR			PORTB1					/*Oscillator PIN*/
#define FREQ_STEP			5						/*Frequency step in steps per 100 miliseconds*/
#define TIME_STEP			100						/*Time step between changes of the frequency*/
#define MAX_FREQ_FACTOR		20						/*Maximum factor of frequency for the maximum freq*/

volatile uint8_t _freq_factor = 1;					/*Frequency factor of step frecuency*/

unsigned char _timer1_setup(void);
unsigned char _timer0_init(void);
unsigned char _timer1_init(void);


int main(void){
	DDRB = (1 << OSCILLATOR);	/*Stes oscillator as an output*/
	
	sei();
	_timer1_setup();
	_timer0_init();
	_timer1_init();
	
	while(1){
		
	}
}

unsigned char _timer1_setup(void){
	TCCR1B = (1 << WGM12);					/*CTC Mode*/
	TCCR1A = (1 << COM1A0);					/*Toggle Mode*/
	
	OCR1A = F_CPU/FREQ_STEP/160 - 1;		/*First set OCR1A for the initial frequency*/
	
	TIFR1 |= (1 << OCF1A);					/*Clears flag OCR1A interrupt on TOP*/
	TIMSK1 |= (1 << OCIE1A);				/*Enable Interrupt on OC1A*/
	
	return 1;
}
unsigned char _timer0_init(void){
	TCCR0B = (3 << CS01);			/*External clock con falling edge*/
	TCCR0A |= (1 << WGM01);			/*CTC Mode*/
	TIFR0 |= (1 << OCF0A);			/*Clears OC flag*/
	TIMSK0 |= (1 << OCIE0A);		/*Output compare interrupt enabled*/
	OCR0A = FREQ_STEP;				/*0CR0A value for the initial frequency*/
	
	return 1;
}
unsigned char _timer1_init(void){
	TCCR1B |= (1 << CS11);					/*8 factor prescaler*/
	return 1;
}
ISR(TIMER0_COMPA_vect){
	_freq_factor++;										/*factor for next freqency*/
	OCR1A = F_CPU/FREQ_STEP/160/_freq_factor - 1;		/*new frecuency*/
	OCR0A = _freq_factor*FREQ_STEP;
	
	if (_freq_factor == MAX_FREQ_FACTOR){
		/*When maximum frequency is reached*/	
		TIFR0 |= (1 << OCF0A);							/*Turns off the flag*/
		TIMSK0 &= ~(1 << OCIE0A);						/*Disables the interrupt*/
	}
}