diff options
| -rw-r--r-- | pwm.c | 110 | ||||
| -rw-r--r-- | pwm.h | 7 |
2 files changed, 75 insertions, 42 deletions
@@ -1,51 +1,73 @@ /* LED pwm, uses timer0 - * XXX: this works, but we should use non-linear steps */ #include <avr/io.h> #include <avr/interrupt.h> #include <stdbool.h> +#include <assert.h> +#include <stdlib.h> #include "speaker.h" +#include "pwm.h" -#define PWM_STEPS 16 +#define PWM_LED_COUNT 6 -/* inverse brightness; 0 is max brightness, PWM_STEPS off */ -static uint8_t invbrightness[6]; -static uint8_t count = 0; +/* max count for blinks */ +static uint8_t blink[6]; +static uint8_t comphit = 0; +static uint8_t state = 0; +/* PORTB and PORTB values */ +static uint8_t val[2]; +static uint8_t init[2]; -ISR(TIMER0_COMPA_vect) { - if (count == 0) { - /* switch off all LEDs */ - PORTB = PORTB & ~((1 << PB6) | (1 << PB7)); - PORTD = PORTD & ~((1 << PD2) | (1 << PD3) | (1 << PD4) | (1 << PD5)); +static uint8_t ledToArray (const uint8_t i) { + assert (i < PWM_LED_COUNT); + if (i >= 2) { + return 1; } else { - uint8_t pb = 0, pd = 0; - if (count > invbrightness[0]) { - pb |= (1 << PB6); - } - if (count > invbrightness[1]) { - pb |= (1 << PB7); - } - if (count > invbrightness[2]) { - pd |= (1 << PD2); - } - if (count > invbrightness[3]) { - pd |= (1 << PD3); - } - if (count > invbrightness[4]) { - pd |= (1 << PD4); + 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]; +} + +/* All LEDs are off for state % 2 == 0 (off state) or state >= 7 (end of blink + * sequence), setting blink[i] = state*2 causes LED i to blink state times + */ +ISR(TIMER0_COMPA_vect) { + ++comphit; + /* divide by 13 to get ~10 Hz timer */ + if (comphit >= 13) { + comphit = 0; + ++state; + if (state == 10) { + state = 0; } - if (count > invbrightness[5]) { - pd |= (1 << PD5); + val[0] = init[0]; + val[1] = init[1]; + if (state == 8 || state % 2 == 0) { + /* end of blink/off state */ + } else { + for (uint8_t i = 0; i < PWM_LED_COUNT; i++) { + if (state < blink[i]) { + val[ledToArray (i)] |= (1 << ledToShift(i)); + } + } } - /* actually set them */ - PORTB |= pb; - PORTD |= pd; } - ++count; - if (count >= PWM_STEPS) { - count = 0; + + if (comphit % 2 == 0) { + /* switch off: we can’t just set to 0 here, since PB6 is used by + * speaker */ + PORTB = PORTB & ~((1 << PB6) | (1 << PB7)); + PORTD = PORTD & ~((1 << PD2) | (1 << PD3) | (1 << PD4) | (1 << PD5)); + } else { + PORTB |= val[0]; + PORTD |= val[1]; } } @@ -60,14 +82,13 @@ void pwmStart () { /* reset timer value */ TCNT0 = 0; /* set ctc timer0 (part 1) */ - TCCR0A = 0; + TCCR0A = (1 << WGM01); /* enable compare match interrupt */ TIMSK0 = (1 << OCIE0A); - /* compare value; interrupt on every tick */ - OCR0A = 0; - /* io clock with 8 prescaler (>8 is too slow and starts flickering); ctc - * (part 2) */ - TCCR0B = (1 << CS01) | (1 << WGM02); + /* compare value */ + OCR0A = 255; + /* io clock with prescaler 256; ctc (part 2) */ + TCCR0B = (1 << CS02) | (0 << CS01) | (0 << CS00); } void pwmStop () { @@ -75,7 +96,14 @@ void pwmStop () { TCCR0B = 0; } -void pwmSetBrightness (const uint8_t i, const uint8_t b) { - invbrightness[i] = b; +void pwmSetBlink (const uint8_t i, const uint8_t value) { + assert (i < PWM_LED_COUNT); + if (value == PWM_BLINK_ON) { + /* permanently switch on LED */ + init[ledToArray (i)] |= (1 << ledToShift (i)); + } else { + init[ledToArray (i)] &= ~(1 << ledToShift (i)); + blink[i] = value*2; + } } @@ -5,7 +5,12 @@ void pwmInit (); void pwmStart (); void pwmStop (); -void pwmSetBrightness (const uint8_t i, const uint8_t b); +void pwmSetBlink (const uint8_t, const uint8_t); + +/* LED on (no blink) */ +#define PWM_BLINK_ON UINT8_MAX +/* LED off */ +#define PWM_BLINK_OFF 0 #endif /* PWM_H */ |