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authorLars-Dominik Braun <lars@6xq.net>2014-06-10 16:23:50 +0200
committerLars-Dominik Braun <lars@6xq.net>2014-06-10 16:23:50 +0200
commit3362013554bd40ce17894f67b3b8dcf568ccdb5c (patch)
treec3dfaf8025f779dcb8d40e416d488f1e144ada5f
parentb442ffba40cef5fa5a5e1bd6c13b5e30b06b28e2 (diff)
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pwm: Implement blink
Still flickers a little bit, might have to increase frequency…
-rw-r--r--pwm.c110
-rw-r--r--pwm.h7
2 files changed, 75 insertions, 42 deletions
diff --git a/pwm.c b/pwm.c
index eaaa5af..e0042fd 100644
--- a/pwm.c
+++ b/pwm.c
@@ -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;
+ }
}
diff --git a/pwm.h b/pwm.h
index eeb93c6..399a099 100644
--- a/pwm.h
+++ b/pwm.h
@@ -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 */