altos: Use simpler debounce logic for buttonstelelaunchtwo

Instead of waiting for a while after the transition to decide if it
has stuck, signal the event right away and then ignore other
transitions for the debounce interval.

This seems to work just as reliably, but has the benefit of
eliminating button latency at press time.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 31 insertions, 21 deletions

diff --git a/src/drivers/ao_button.c b/src/drivers/ao_button.c
index cdf07352..8e7dead7 100644
--- a/src/drivers/ao_button.c
+++ b/src/drivers/ao_button.c
@@ -18,7 +18,6 @@
 #include <ao.h>
 #include <ao_button.h>
 #include <ao_exti.h>
-#include <ao_debounce.h>
 #if AO_EVENT
 #include <ao_event.h>
 #define ao_button_queue(b,v)	ao_event_put_isr(AO_EVENT_BUTTON, b, v)
@@ -26,9 +25,14 @@
 #define ao_button_queue(b,v)
 #endif
 
-#define AO_BUTTON_DEBOUNCE_HOLD	10
+#define AO_BUTTON_DEBOUNCE_INTERVAL	AO_MS_TO_TICKS(50)
 
-static struct ao_debounce	ao_button_debounce[AO_BUTTON_COUNT];
+struct ao_button_state {
+	AO_TICK_TYPE	time;
+	uint8_t		value;
+};
+
+static struct ao_button_state	ao_button_state[AO_BUTTON_COUNT];
 
 #define port(q)	AO_BUTTON_ ## q ## _PORT
 #define bit(q) AO_BUTTON_ ## q
@@ -38,10 +42,8 @@ static struct ao_debounce	ao_button_debounce[AO_BUTTON_COUNT];
 #define ao_button_value(b)	!ao_gpio_get(port(b), bit(b), pin(b))
 
 static uint8_t
-_ao_button_get(struct ao_debounce *debounce)
+_ao_button_get(uint8_t b)
 {
-	uint8_t	b = debounce - ao_button_debounce;
-
 	switch (b) {
 #if AO_BUTTON_COUNT > 0
 	case 0: return ao_button_value(0);
@@ -63,22 +65,31 @@ _ao_button_get(struct ao_debounce *debounce)
 }
 
 static void
-_ao_button_set(struct ao_debounce *debounce, uint8_t value)
+_ao_button_check(uint8_t b)
 {
-	uint8_t b = debounce - ao_button_debounce;
-
-	ao_button_queue(b, value);
-}
+	uint8_t	value = _ao_button_get(b);
 
+	if (value != ao_button_state[b].value) {
+		AO_TICK_TYPE	now = ao_time();
 
-#define ao_button_update(b)	ao_button_do(b, ao_gpio_get(port(b), bit(b), pin(b)))
+		if ((now - ao_button_state[b].time) >= AO_BUTTON_DEBOUNCE_INTERVAL) {
+			ao_button_state[b].value = value;
+			ao_button_queue(b, value);
+		}
+		ao_button_state[b].time = now;
+	}
+}
 
 static void
-ao_button_debounce_init(struct ao_debounce *debounce) {
-	ao_debounce_config(debounce,
-			   _ao_button_get,
-			   _ao_button_set,
-			   AO_BUTTON_DEBOUNCE_HOLD);
+_ao_button_init(uint8_t b)
+{
+	uint8_t	m = ao_arch_irqsave();
+	uint8_t value = _ao_button_get(b);
+	ao_button_state[b].value = value;
+	ao_button_state[b].time = ao_time();
+	ao_button_queue(b, value);
+	ao_arch_irqrestore(m);
+
 }
 
 static void
@@ -87,17 +98,17 @@ ao_button_isr(void)
 	uint8_t	b;
 
 	for (b = 0; b < AO_BUTTON_COUNT; b++)
-		_ao_debounce_start(&ao_button_debounce[b]);
+		_ao_button_check(b);
 }
 
 #define init(b) do {							\
-		ao_button_debounce_init(&ao_button_debounce[b]);	\
 		ao_enable_port(port(b));				\
 									\
 		ao_exti_setup(port(b), bit(b),				\
 			      AO_BUTTON_MODE|AO_EXTI_MODE_FALLING|AO_EXTI_MODE_RISING|AO_EXTI_PRIORITY_MED, \
-			      ao_button_isr);			\
+			      ao_button_isr);				\
 		ao_exti_enable(port(b), bit(b));			\
+		_ao_button_init(b);					\
 	} while (0)
 
 void
@@ -118,5 +129,4 @@ ao_button_init(void)
 #if AO_BUTTON_COUNT > 4
 	init(4);
 #endif
-	ao_debounce_init();
 }