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#include <stdint.h>
#include <avr/interrupt.h>
#include <avr/io.h>
#include <avr/sleep.h>
#define max(a, b) \
({ \
__typeof__(a) _a = (a); \
__typeof__(b) _b = (b); \
_a > _b ? _a : _b; \
})
#define min(a, b) \
({ \
__typeof__(a) _a = (a); \
__typeof__(b) _b = (b); \
_a < _b ? _a : _b; \
})
// return a + (t/128)*(b-a)
static uint8_t lerp(uint8_t a, uint8_t b, uint8_t t)
{
return a + (uint8_t)(((int16_t)(b - a) * t) >> 7);
}
static void eeprom_write(uint16_t addr, uint8_t data)
{
while (EECR & _BV(EEPE))
;
EEAR = addr;
EECR = 0;
EEDR = data;
EECR |= _BV(EEMPE);
EECR |= _BV(EEPE);
}
static uint8_t eeprom_read(uint16_t addr)
{
while (EECR & _BV(EEPE))
;
EEAR = addr;
EECR = _BV(EERE);
return EEDR;
}
enum {
MODE_SOLID = 0,
MODE_PULSE,
MODE_ALTERNATE,
MODE_FAST_PULSE,
MODE_FAST_ALTERNATE,
MODE_VFAST_PULSE,
MODE_VFAST_ALTERNATE,
NUM_MODE,
};
uint16_t tickcount;
static void tick(void);
ISR(TIM0_COMPA_vect)
{
++tickcount;
tick();
}
static uint8_t mode;
ISR(PCINT0_vect)
{
static uint16_t down;
if ((PINB & _BV(PB0)) == 0) {
down = tickcount;
} else {
if (tickcount - down > 100) {
eeprom_write(0, mode);
} else {
if (++mode == NUM_MODE) {
mode = MODE_SOLID;
}
}
}
}
static uint8_t brightness;
ISR(ADC_vect)
{
brightness = ADCH;
}
static uint8_t oa_duty, ob_duty;
ISR(TIM1_OVF_vect)
{
OCR1A = min(oa_duty, 127);
OCR1B = max(255 - ob_duty, 128);
}
void tick(void)
{
ADCSRA |= _BV(ADSC);
switch (mode) {
case MODE_SOLID:
oa_duty = ob_duty = brightness >> 1;
break;
case MODE_PULSE:
case MODE_ALTERNATE:
case MODE_FAST_PULSE:
case MODE_FAST_ALTERNATE:
case MODE_VFAST_PULSE:
case MODE_VFAST_ALTERNATE: {
static uint8_t dir;
static uint8_t t;
oa_duty = lerp(0, brightness >> 1, dir ? t : 128 - t);
ob_duty = (mode & 1) ? oa_duty : ((brightness >> 1) - oa_duty);
t += mode > MODE_FAST_ALTERNATE ? 4 :
mode > MODE_ALTERNATE ? 2 :
1;
if (t >= 128) {
t = 0;
dir = !dir;
}
} break;
}
}
static void pwm_init(void)
{
TCCR1 = _BV(PWM1A) | _BV(COM1A1);
GTCCR |= _BV(PWM1B) | _BV(COM1B1) | _BV(COM1B0);
TCCR1 |= _BV(CS12);
OCR1A = 0;
OCR1B = 255;
DDRB |= _BV(PB1) | _BV(PB4);
TIMSK |= _BV(TOIE1);
}
static void adc_init(void)
{
ADMUX = _BV(ADLAR) | _BV(MUX0) | _BV(MUX1);
DIDR0 = _BV(ADC3D);
ADCSRA = _BV(ADEN) | _BV(ADIE) | _BV(ADPS2) | _BV(ADPS1);
}
static void tick_init(void)
{
GTCCR = _BV(TSM) | _BV(PSR0);
TCCR0A = _BV(WGM01);
TCCR0B = _BV(CS01) | _BV(CS00);
OCR0A = 122; // 1M/64 = 15kHz / 122 = 128 hz tick
TIMSK |= _BV(OCIE0A);
GTCCR &= _BV(TSM);
}
int main(void)
{
mode = eeprom_read(0);
if (mode >= NUM_MODE) {
mode = 0;
}
tick_init();
pwm_init();
adc_init();
DDRB &= ~_BV(PB0);
PORTB |= _BV(PB0);
GIMSK = _BV(PCIE);
PCMSK = _BV(PCINT0);
sei();
for (;;)
sleep_mode();
return (0);
}
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