pwm.h:
----------------------------------
#ifndef PWM_
#define PWM_
#include <stdint.h>

#define NOFPWMS 1  // number of pwm channels


void pwmned();
void InitPwm();
void setPwmValue(int clr, int value);


// A pwm channel is one pin, on a port, with it's own pwm value. 

struct pwm_channel {
uint8_t *port;
uint8_t pin;
volatile uint8_t state;
uint8_t value; // 0-255 brightness
};

#endif /*PWM_*/


pwm.c:
-------------------------------------------------
#include "pwm.h"
#include <avr/io.h>

static volatile struct pwm_channel pwms[NOFPWMS];
static struct pwm_channel default_pwmc;

void InitPwm() { // initialize the pwm channels
	default_pwmc.port = &PORTB;
	default_pwmc.pin = PB0;
	default_pwmc.state = 0;
	default_pwmc.value = 0;

	for (int a = 0; a<NOFPWMS; a++)
		pwms[a] = default_pwmc;

	pwms[0].pin=PB0;
	
}


void pwmned() {
	struct pwm_channel *most;
	for (int i = 0; i<NOFPWMS; i++) {
		most = &pwms[i];

		if (most->state==255) {
			*most->port |= (1<<most->pin);
			most->state=0;
		}
		
		if (most->value==most->state) {
			*most->port &= ~(1<<most->pin);

		}

		most->state++;

	}

}

void setPwmValue(int clr, int value) {
	pwms[clr].value = value;

}


usage:
--------------------------------
pwms is an array of  "pwm_channel"s. Each item of it needs to be set after InitPwm().