PWM interfacing with ATMEGA Code

// program to change brightness of an LED
// demonstration of PWM

#include <avr/io.h>
#include <util/delay.h>

// initialize PWM
void pwm_init()
{
// initialize timer0 in PWM mode
TCCR0 |= (1<<WGM00)|(1<<COM01)|(1<<WGM01)|(1<<CS00);

// make sure to make OC0 pin (pin PB3 for atmega32) as output pin
DDRB |= (1<<PB3);
}

void main()
{
uint8_t brightness;

// initialize timer0 in PWM mode
pwm_init();

// run forever
while(1)
{
// increasing brightness
for (brightness = 0; brightness < 255; ++brightness)
{
// set the brightness as duty cycle
OCR0 = brightness;

// delay so as to make the user "see" the change in brightness
_delay_ms(10);
}

// decreasing brightness
for (brightness = 255; brightness > 0; --brightness)
{
// set the brightness as duty cycle
OCR0 = brightness;

// delay so as to make the user "see" the change in brightness
_delay_ms(10);
}

// repeat this forever
}
}