From 20177f823fc0effcc9c5c389a629294c5ed367a1 Mon Sep 17 00:00:00 2001
From: "Jan \"Yenya\" Kasprzak" <kas@fi.muni.cz>
Date: Sat, 15 Dec 2012 22:21:25 +0100
Subject: [PATCH] ambient.c: ambient light hysteresis

---
 firmware/ambient.c | 61 +++++++++++++++++++++++++++++-----------------
 1 file changed, 38 insertions(+), 23 deletions(-)

diff --git a/firmware/ambient.c b/firmware/ambient.c
index 025b0c4..c6c6a65 100644
--- a/firmware/ambient.c
+++ b/firmware/ambient.c
@@ -4,49 +4,64 @@
 
 static uint16_t ambient_val;
 volatile unsigned char ambient_zone;
-static unsigned char ambient_zone_set;
 
-static uint16_t ambient_zones[] = {
-	0x0c00, 0x0d00, 0x1000, 0x1800, 0x2800, 0x2f80, 0xffff
+/* My photodiode reads 0x00C5 .. 0x033B */
+typedef struct {
+	uint16_t lo, hi;
+} ambient_zone_t;
+
+/*
+ * Note: these have to be sorted, starting with 0, ending with 0xFFFF
+ * and having small overlaps in order to provide a bit of hysteresis.
+ */
+static ambient_zone_t ambient_zones[] = {
+	{ 0x0000, 0x3120 }, // dark
+	{ 0x30f0, 0x5000 },
+	{ 0x4c00, 0x8000 },
+	{ 0x7800, 0xffff }
 };
 #define N_AMBIENT_ZONES (sizeof(ambient_zones)/sizeof(ambient_zones[0]))
 
 void init_ambient()
 {
 	ambient_val = 0;
-	ambient_zone = 0;
-	ambient_zone_set = 0;
+	ambient_zone = 1;
 }
 
 void ambient_zone_changed()
 {
+#if 1
 	log_byte(0xab);
 	log_byte(ambient_zone);
 	log_word(ambient_val);
 	log_flush();
+#endif
 
-	pattern_reload();
+	// led_set_pattern(N_PWMLEDS, status_led_pattern_select());
+	// led_set_pattern(N_PWMLEDS+1, illumination_led_pattern_select());
+	// pattern_reload();
 }
 
 void ambient_adc(uint16_t adcval)
 {
-	unsigned char newzone;
-
-	if (!ambient_zone_set)
-		ambient_val = adcval << 4;
-	else // running sum
-		ambient_val += adcval - (ambient_val >> 4);
-
-	newzone = 0;
-	while (newzone < N_AMBIENT_ZONES-1
-		&& ambient_zones[newzone] < ambient_val)
-		newzone++;
-
-	// TODO: implement hysteresis?
-	if (!ambient_zone_set || newzone != ambient_zone) {
-		ambient_zone = newzone;
-		ambient_zone_set = 1;
-		// ambient_zone_changed();
+	unsigned char old_zone = ambient_zone;
+
+	ambient_val += adcval - (ambient_val >> 6);
+
+	while (ambient_zones[ambient_zone].lo > ambient_val)
+		ambient_zone--;
+
+	while (ambient_zones[ambient_zone].hi < ambient_val)
+		ambient_zone++;
+
+#if 0
+	if (old_zone != ambient_zone) {
+		log_byte(0xab);
+		log_byte(ambient_zone);
+		log_word(adcval);
+		log_flush();
 	}
+		// ambient_zone_changed();
+#endif
 }
 
-- 
2.39.3