altos: Simplify quadrature tracking

Set the timer to 200Hz for a 5ms debounce interval. Then, simply look
for transitions ending in both bits in the encoder being off, which
indicates the the encoder is resting in a detent. If bit '2' is
turning off, the encoder was rotated clockwise, otherwise the encoder
was rotated counter clockwise.

This is a lot more reliable, although still not perfect.

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

3 files changed, 33 insertions, 43 deletions

diff --git a/src/drivers/ao_quadrature.c b/src/drivers/ao_quadrature.c
index d07488d0..66a77dfa 100644
--- a/src/drivers/ao_quadrature.c
+++ b/src/drivers/ao_quadrature.c
@@ -22,11 +22,7 @@
 #include <ao_event.h>
 
 __xdata int32_t ao_quadrature_count[AO_QUADRATURE_COUNT];
-static uint8_t	ao_quadrature_state[AO_QUADRATURE_COUNT];
-static int8_t	ao_quadrature_raw[AO_QUADRATURE_COUNT];
-
-#define BIT(a,b)	((a) | ((b) << 1))
-#define STATE(old_a, old_b, new_a, new_b)	(((BIT(old_a, old_b) << 2) | BIT(new_a, new_b)))
+static uint8_t  ao_quadrature_state[AO_QUADRATURE_COUNT];
 
 #define port(q)	AO_QUADRATURE_ ## q ## _PORT
 #define bita(q) AO_QUADRATURE_ ## q ## _A
@@ -54,51 +50,29 @@ _ao_quadrature_queue(uint8_t q, int8_t step)
 	ao_wakeup(&ao_quadrature_count[q]);
 }
 
-static const int8_t	step[16] = {
-	[STATE(0,0,0,0)] = 0,
-	[STATE(0,0,0,1)] = -1,
-	[STATE(0,0,1,0)] = 1,
-	[STATE(0,0,1,1)] = 0,
-	[STATE(0,1,0,0)] = 1,
-	[STATE(0,1,1,0)] = 0,
-	[STATE(0,1,1,1)] = -1,
-	[STATE(1,0,0,0)] = -1,
-	[STATE(1,0,0,1)] = 0,
-	[STATE(1,0,1,0)] = 0,
-	[STATE(1,0,1,1)] = 1,
-	[STATE(1,1,0,0)] = 0,
-	[STATE(1,1,0,1)] = 1,
-	[STATE(1,1,1,0)] = -1,
-	[STATE(1,1,1,1)] = 0
-};
 
 static void
-_ao_quadrature_set(uint8_t q, uint8_t value) {
-	uint8_t v;
-	
-	v = ao_quadrature_state[q] & 3;
-	value = value & 3;
+_ao_quadrature_set(uint8_t q, uint8_t new) {
+	uint8_t	old = ao_quadrature_state[q];
 
-	if (v == value)
-		return;
-	
-	ao_quadrature_state[q] = (v << 2) | value;
-
-	ao_quadrature_raw[q] += step[ao_quadrature_state[q]];
-	if (value == 0) {
-		if (ao_quadrature_raw[q] == 4)
+	if (old != new && new == 0) {
+		if (old & 2)
 			_ao_quadrature_queue(q, 1);
-		else if (ao_quadrature_raw[q] == -4)
+		else if (old & 1)
 			_ao_quadrature_queue(q, -1);
-		ao_quadrature_raw[q] = 0;
 	}
+	ao_quadrature_state[q] = new;
 }
 
 static void
 ao_quadrature_isr(void)
 {
+#if AO_QUADRATURE_COUNT > 0
 	_ao_quadrature_set(0, _ao_quadrature_get(0));
+#endif
+#if AO_QUADRATURE_COUNT > 1
 	_ao_quadrature_set(1, _ao_quadrature_get(1));
+#endif
 }
 
 int32_t
@@ -120,6 +94,8 @@ static void
 ao_quadrature_test(void)
 {
 	uint8_t	q;
+	int32_t	c;
+	uint8_t	s;
 
 	ao_cmd_decimal();
 	q = ao_cmd_lex_i;
@@ -127,10 +103,18 @@ ao_quadrature_test(void)
 		ao_cmd_status = ao_cmd_syntax_error;
 		return;
 	}
-	printf ("count %d state %x raw %d\n",
-		ao_quadrature_count[q],
-		ao_quadrature_state[q],
-		ao_quadrature_raw[q]);
+
+	c = -10000;
+	s = 0;
+	while (ao_quadrature_count[q] != 10) {
+		if (ao_quadrature_count[q] != c ||
+		    ao_quadrature_state[q] != s) {
+			c = ao_quadrature_count[q];
+			s = ao_quadrature_state[q];
+			printf ("count %3d state %2x\n", c, s);
+			flush();
+		}
+	}
 #if 0
 	for (;;) {
 		int32_t	c;
diff --git a/src/stm/ao_fast_timer.c b/src/stm/ao_fast_timer.c
index d61b40c9..9a73eb51 100644
--- a/src/stm/ao_fast_timer.c
+++ b/src/stm/ao_fast_timer.c
@@ -88,7 +88,11 @@ void stm_tim6_isr(void)
 #define TIMER_23467_SCALER 1
 #endif
 
-#define TIMER_10kHz	((AO_PCLK1 * TIMER_23467_SCALER) / 10000)
+#ifndef FAST_TIMER_FREQ
+#define FAST_TIMER_FREQ	10000
+#endif
+
+#define TIMER_FAST	((AO_PCLK1 * TIMER_23467_SCALER) / FAST_TIMER_FREQ)
 
 void
 ao_fast_timer_init(void)
@@ -100,7 +104,7 @@ ao_fast_timer_init(void)
 		/* Turn on timer 6 */
 		stm_rcc.apb1enr |= (1 << STM_RCC_APB1ENR_TIM6EN);
 
-		stm_tim6.psc = TIMER_10kHz;
+		stm_tim6.psc = TIMER_FAST;
 		stm_tim6.arr = 9;
 		stm_tim6.cnt = 0;
 
diff --git a/src/telelco-v0.2/ao_pins.h b/src/telelco-v0.2/ao_pins.h
index 62f221a1..609e5494 100644
--- a/src/telelco-v0.2/ao_pins.h
+++ b/src/telelco-v0.2/ao_pins.h
@@ -72,6 +72,8 @@
 #define PACKET_HAS_SLAVE	0
 #define PACKET_HAS_MASTER	0
 
+#define FAST_TIMER_FREQ		200	/* 5ms for debouncing */
+
 /*
  * Radio is a cc1120 connected via SPI
  */