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authorLars-Dominik Braun <lars@6xq.net>2014-08-05 15:57:39 +0200
committerLars-Dominik Braun <lars@6xq.net>2014-08-05 15:57:39 +0200
commitf4e36ee188a084e3103e43914d18bbe889fd4025 (patch)
tree6754d070180ec365cc9f750db985425be252cebc
parentf76d64e8db03c56c45afbbb60da801d7a801d460 (diff)
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pwm: Add brightness control
-rw-r--r--pwm.c100
-rw-r--r--pwm.h9
2 files changed, 55 insertions, 54 deletions
diff --git a/pwm.c b/pwm.c
index a504c36..0d0b28d 100644
--- a/pwm.c
+++ b/pwm.c
@@ -7,21 +7,32 @@
#include <avr/interrupt.h>
#include <stdbool.h>
#include <stdlib.h>
+#include <string.h>
#include "speaker.h"
#include "pwm.h"
-/* 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];
+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 ledOff () {
- PORTB = PORTB & ~((1 << PB6) | (1 << PB7));
- PORTD = PORTD & ~((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) {
@@ -39,49 +50,27 @@ static uint8_t ledToShift (const uint8_t i) {
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 == 12) {
- state = 0;
- }
- val[0] = init[0];
- val[1] = init[1];
- if (state >= 10 || 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));
- }
- }
- }
- }
-
- if (comphit % 2 == 0) {
- ledOff ();
+#if 0
+static void ledOff (const uint8_t i) {
+ assert (i < PWM_LED_COUNT);
+ if (ledToArray (i) == 0) {
+ PORTB = PORTB & ~(1 << ledToShift (i));
} else {
- PORTB |= val[0];
- PORTD |= val[1];
+ 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 () {
- comphit = 0;
- state = 0;
+ count = 0;
/* reset timer value */
TCNT0 = 0;
/* set ctc timer0 (part 1) */
@@ -90,24 +79,35 @@ void pwmStart () {
TIMSK0 = (1 << OCIE0A);
/* compare value */
OCR0A = 255;
- /* io clock with prescaler 256; ctc (part 2) */
- TCCR0B = (1 << CS02) | (0 << CS01) | (0 << CS00);
+ /* io clock with prescaler 64; ctc (part 2) */
+ TCCR0B = (0 << CS02) | (1 << CS01) | (1 << CS00);
}
void pwmStop () {
/* zero clock source */
TCCR0B = 0;
- ledOff ();
+ allLedsOff ();
}
-void pwmSetBlink (const uint8_t i, const uint8_t value) {
+/* 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);
- if (value == PWM_BLINK_ON) {
- /* permanently switch on LED */
- init[ledToArray (i)] |= (1 << ledToShift (i));
+ 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 {
- init[ledToArray (i)] &= ~(1 << ledToShift (i));
- blink[i] = value*2;
+ /* max brightness */
+ toggleat = 0;
}
+ toggle[toggleat][array] |= bit;
}
diff --git a/pwm.h b/pwm.h
index f170573..96deaae 100644
--- a/pwm.h
+++ b/pwm.h
@@ -5,13 +5,14 @@
void pwmInit ();
void pwmStart ();
void pwmStop ();
-void pwmSetBlink (const uint8_t, const uint8_t);
+void pwmSet (const uint8_t, const uint8_t);
-/* LED on (no blink) */
-#define PWM_BLINK_ON UINT8_MAX
+/* LED on (max brightness) */
+#define PWM_ON UINT8_MAX
/* LED off */
-#define PWM_BLINK_OFF 0
+#define PWM_OFF 0
#define PWM_LED_COUNT 6
+#define PWM_MAX_BRIGHTNESS 8
#endif /* PWM_H */