ДПТ, ШИМ и плавный старт

/*******************************************

Program                 : pwm

Compiler                : AVR GCC

Chip type               : ATmega8

System Clock            : 1 MHz

*******************************************/



#include <avr/io.h>



int main(void)

{

    unsigned char i = 0;

    unsigned char j = 0;



    unsigned char flag = 0;



    unsigned char pwm = 0;



    DDRD = 0b00000001; // PD0 out

    PORTD = 0b00000000; // PD0 "0"



    for(;;)

    {

        PORTD |= 0b00000001; // PD0 "1"



        i = 0;

        while( i != 255 )

        {

            if ( i == pwm )

            {

                PORTD &= 0b11111110; // PD0 "0"

            }



            i += 1;



            // --- begin delay ---

            j = 0;

            while( j != 20 )

            {

                j += 1;

            }

            // --- end delay ---

        }



        if ( flag == 0 ) pwm += 5;

        if ( flag == 1 ) pwm -= 5;

        if ( pwm == 255 ) flag = 1;

        if ( pwm == 0 ) flag = 0;

    }



    return 0;

}