Miscellany

/* Written 2007    by Matthias Bolte and Aiko Christ*/#include <avr/io.h>#include <avr/iotn2313.h>#include <avr/interrupt.h>#include <stdint.h>#define DDB0 0#define DDB1 1#define DDB2 2#define PB0 0#define PB1 1#define PB2 2typedef struct pwm_global_s {	uint8_t cycles;} pwm_global_t;typedef struct pwm_led_s {	uint8_t offcycles;	uint8_t port;} pwm_led_t;typedef struct fade_s {	uint8_t cur;	uint8_t dir[3];	uint8_t speed[3];} fade_t;// define and init structpwm_global_t pwm_global = {0};pwm_led_t pwm_led[3] = {{255,PB0},{96,PB1},{128,PB2}};fade_t fade = {0,{0,0,0},{2,1,2}};void pwm_handler() {	pwm_led_t* led;	uint8_t i;	for (i=0;i<3;++i) {		led = &pwm_led[i];		if (!pwm_global.cycles && led->offcycles != 0) {			PORTB &= ~(1 << led->port);		}		else if (pwm_global.cycles == led->offcycles && led->offcycles < 255){			PORTB |= (1 << led->port);		}	}}void fade_handler() {	pwm_led_t* led_p;	fade_t* fade_p;	uint8_t speed;	uint8_t i;	for (i=0;i<3;++i) {		led_p = &pwm_led[i];		fade_p = &fade;		speed = fade_p->speed[i];		if (fade_p->dir[i] == 1) {			if (led_p->offcycles > speed - 1)				led_p->offcycles -=  speed;			else {				led_p->offcycles +=  speed;				fade_p->dir[i] = 0;			}		}		else {			if (led_p->offcycles < 256 - speed)				led_p->offcycles +=  speed;			else {				led_p->offcycles -=  speed;				fade_p->dir[i] = 1;				fade_p->cur = (fade_p->cur + 1) % 3;			}		}	}}ISR(TIMER1_COMPA_vect) {	++pwm_global.cycles;	if (!pwm_global.cycles)		fade_handler();	pwm_handler();}int main(void) {		DDRB |= (1 << DDB0) | (1 << DDB1) | (1 << DDB2);	TCCR1A = 0;	TCCR1B = (1 << WGM12) | (1 << CS10);   	OCR1A = (unsigned short) ((unsigned long) 1024 + 256);    TIMSK |= (1 << OCIE1A);	sei();	while(1) {	}		return 0;}