구차니의 잡동사니 모음

#include "avr/io.h"
#include "avr/interrupt.h"

volatile unsigned int sv1_high, sv1_low, sv1_flag, sv1_range, sec;
volatile unsigned char Bout;

ISR(TIMER0_OVF_vect)
{
	if(sv1_flag == 0)
	{
		if(sv1_low == 1250)
		{
			if(sec > 49)	sec = 0;
			else			sec++;

			sv1_flag = 1;
			sv1_low = 0;
			Bout = 0xFF;
//			Bout = Bout | 0x08;
		}
		else
		{
			sv1_low++;
		}
	}
	else
	{
		sv1_high++;
		if(sv1_high > sv1_range)
		{
			sv1_flag = 0;
			sv1_high = 0;
			Bout = 0x00;
//			Bout = Bout & ~0x08;
		}
		TCNT0 = 0;
	}
}

int main(void)
{
	SREG = 0x80;

	DDRF = 0xFF;
	DDRC = 0xFF;

	TIMSK = 1 << TOIE0;
	TCNT0 = 0x00;
	TCCR0 = 0x01;

	sei();

	for(;;)
	{
		// 1msec = 62.5
#if 1
		PORTF = 0x01;
		sec = 0;
		sv1_range = 32; // 0 degree
		while(sec < 49)
		{
			PORTC = Bout;
		}
#endif
#if 0
		PORTF = 0x05;
		sec = 0;
		sv1_range = 76; // 90 degree
		while(sec < 49)
		{
			PORTC = Bout;
		}
#endif
#if 1
		PORTF = 0x15;
		sec = 0;
		sv1_range = 112; // 180 degree
		while(sec < 49)
		{
			PORTC = Bout;
		}
#endif
#if 0
		PORTF = 0x05;
		sec = 0;
		sv1_range = 76; // 90 degree
		while(sec < 49)
		{
			PORTC = Bout;
		}
#endif
	}
}

Normal Mode

The simplest mode of operation is the normal mode (WGM01:0 = 0). In this mode the counting
direction is always up (incrementing), and no counter clear is performed. The counter simply
overruns when it passes its maximum 8-bit value (TOP = 0xFF) and then restarts from the bot-
tom (0x00). In normal operation the Timer/Counter overflow flag (TOV0) will be set in the same
timer clock cycle as the TCNT0 becomes zero. The TOV0 flag in this case behaves like a ninth
bit, except that it is only set, not cleared. However, combined with the timer overflow interrupt
that automatically clears the TOV0 flag, the timer resolution can be increased by software. There
are no special cases to consider in the normal mode, a new counter value can be written anytime.
The output compare unit can be used to generate interrupts at some given time. Using the output
compare to generate waveforms in normal mode is not recommended, since this will occupy
too much of the CPU time.