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/* LED pwm, uses timer0
*/
#include "common.h"
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include "speaker.h"
#include "pwm.h"
static uint8_t count = 0;
static uint8_t toggle[PWM_MAX_BRIGHTNESS][2];
/* led bitfield, indicating which ones are leds */
static const uint8_t bits[2] = {(1 << PB6) | (1 << PB7),
(1 << PD2) | (1 << PD3) | (1 << PD4) | (1 << PD5)};
static void allLedsOff () {
PORTB &= ~bits[0];
PORTD &= ~bits[1];
}
ISR(TIMER0_COMPA_vect) {
/* the 16th+ state is always ignored/force-off */
if (count >= PWM_MAX_BRIGHTNESS-1) {
allLedsOff ();
} else {
PORTB ^= toggle[count][0];
PORTD ^= toggle[count][1];
}
/* 16 steps */
count = (count+1) & (PWM_MAX_BRIGHTNESS-1);
}
static uint8_t ledToArray (const uint8_t i) {
assert (i < PWM_LED_COUNT);
if (i >= 2) {
return 1;
} else {
return 0;
}
}
static uint8_t ledToShift (const uint8_t i) {
assert (i < PWM_LED_COUNT);
static const uint8_t shifts[] = {PB6, PB7, PD2, PD3, PD4, PD5};
return shifts[i];
}
#if 0
static void ledOff (const uint8_t i) {
assert (i < PWM_LED_COUNT);
if (ledToArray (i) == 0) {
PORTB = PORTB & ~(1 << ledToShift (i));
} else {
PORTD = PORTD & ~(1 << ledToShift (i));
}
}
#endif
void pwmInit () {
/* set led1,led2 to output */
DDRB |= (1 << PB6) | (1 << PB7);
/* set led3,led4,led5,led6 to output */
DDRD |= (1 << PD2) | (1 << PD3) | (1 << PD4) | (1 << PD5);
memset (toggle, 0, sizeof (toggle));
}
void pwmStart () {
count = 0;
/* reset timer value */
TCNT0 = 0;
/* set ctc timer0 (part 1) */
TCCR0A = (1 << WGM01);
/* enable compare match interrupt */
TIMSK0 = (1 << OCIE0A);
/* compare value */
OCR0A = 255;
/* io clock with prescaler 64; ctc (part 2) */
TCCR0B = (0 << CS02) | (1 << CS01) | (1 << CS00);
}
void pwmStop () {
/* zero clock source */
TCCR0B = 0;
allLedsOff ();
}
/* Set LED brightness
*
* We could switch off interrupts here. Instead use pwmStart/Stop.
*/
void pwmSet (const uint8_t i, const uint8_t value) {
assert (i < PWM_LED_COUNT);
const uint8_t array = ledToArray (i);
const uint8_t bit = 1 << ledToShift (i);
/* disable all toggles */
for (uint8_t j = 0; j < PWM_MAX_BRIGHTNESS; j++) {
toggle[j][array] &= ~bit;
}
uint8_t toggleat;
if (value < PWM_MAX_BRIGHTNESS) {
toggleat = PWM_MAX_BRIGHTNESS-value;
} else {
/* max brightness */
toggleat = 0;
}
toggle[toggleat][array] |= bit;
}
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