From 918f7a82545a1fb7c5a505abe797d7849e3f3d71 Mon Sep 17 00:00:00 2001
From: "Jan \"Yenya\" Kasprzak" <kas@fi.muni.cz>
Date: Mon, 3 Jun 2013 17:52:14 +0200
Subject: [PATCH] adc: use only active pwmleds, on-demand switching of other
 channels

---
 firmware/adc.c    | 56 ++++++++++++++++++++++++++++-------------------
 firmware/lights.h |  1 +
 2 files changed, 35 insertions(+), 22 deletions(-)

diff --git a/firmware/adc.c b/firmware/adc.c
index c6b113d..1dbedfc 100644
--- a/firmware/adc.c
+++ b/firmware/adc.c
@@ -6,8 +6,10 @@
 // pwmleds are measured continuously (when active)
 #define AMBIENT_ADC N_PWMLEDS		// measured every jiffy (16 Hz)
 #define BUTTON_ADC  (N_PWMLEDS + 1)	// measured every jiffy (16 Hz)
+#define FIRST_16HZ_ADC	BUTTON_ADC
 #define BATTERY_ADC (N_PWMLEDS + 2)	// once per second
 #define ADC1_GAIN20 (N_PWMLEDS + 3)	// once per second
+#define FIRST_1S_ADC	ADC1_GAIN20
 #define ZERO_ADC    (N_PWMLEDS + 4)	// must be last
 
 #define NUM_ADCS	ZERO_ADC
@@ -26,7 +28,9 @@ struct {
 	{ 0, 1, 0 },			// gain20
 };
 
-volatile static unsigned char current_adc, current_slow_adc;
+volatile unsigned char adc_is_on;
+
+volatile static unsigned char current_adc, slow_adcs_wanted;
 static uint16_t adc_sum, zero_count, drop_count, read_count, n_reads_log;
 #define ADC1_GAIN20_OFFSET_SHIFT	6
 static uint16_t adc1_gain20_offset;
@@ -66,25 +70,30 @@ static void setup_mux(unsigned char n)
 
 static void start_next_adc()
 {
-	if (current_adc == 0) {
-		if (current_slow_adc > N_PWMLEDS) {
-			// read one of the non-PWMLED ADCs
-			current_adc = --current_slow_adc;
-		} else {
-			// no more non-PWMLEDs to do, start with PWMLEDs
-			current_adc = N_PWMLEDS-1;
-		}
-	} else if (current_adc >= N_PWMLEDS) {
-		// one of the non-PWMLED ADCs just finished, skip to PWMLEDs.
-		current_adc = N_PWMLEDS-1;
-	} else {
-		// next PWMLED
+	if (slow_adcs_wanted) {
+		current_adc = slow_adcs_wanted;
+		slow_adcs_wanted = 0;
+		goto found;
+	}
+
+	if (current_adc > N_PWMLEDS) {
 		current_adc--;
+		goto found;
 	}
 
-#if 0
-	log_byte(0x90 + current_adc); // debug ADC switching
-#endif
+	if (!TIMER1_IS_ON()) {
+		adc_is_on = 0;
+		return;
+	}
+
+	do {
+		if (!current_adc)
+			current_adc = N_PWMLEDS;
+		--current_adc;
+	} while (!PWM_IS_ON(current_adc));
+
+found:
+	adc_is_on = 1;
 
 	adc_sum = 0;
 	// we use the last iteration of zero_count to set up the MUX
@@ -113,11 +122,14 @@ static void start_next_adc()
 
 void timer_start_slow_adcs()
 {
-	if (current_slow_adc > N_PWMLEDS) { // Don't start if in progress
-		log_byte(0x80 + current_slow_adc);
+	if ((jiffies & 0x000F) == 0) {
+		slow_adcs_wanted = FIRST_1S_ADC;
 	} else {
-		current_slow_adc = NUM_ADCS;
-		// TODO: kick the watchdog here
+		slow_adcs_wanted = FIRST_16HZ_ADC;
+	}
+
+	if (!adc_is_on) {
+		start_next_adc();
 	}
 }
 
@@ -144,8 +156,8 @@ static uint16_t read_adc_sync()
 void init_adc()
 {
 	unsigned char i;
-	current_slow_adc = NUM_ADCS;
 	current_adc = 0;
+	adc_is_on = 1;
 
 	ADCSRA = _BV(ADEN)			// enable
 		| _BV(ADPS1) | _BV(ADPS0)	// CLK/8 = 125 kHz
diff --git a/firmware/lights.h b/firmware/lights.h
index 72b719b..41ee4d6 100644
--- a/firmware/lights.h
+++ b/firmware/lights.h
@@ -29,6 +29,7 @@ void inline log_word(uint16_t word) { }
 void init_adc();
 void susp_adc();
 void timer_start_slow_adcs();
+extern volatile unsigned char adc_is_on;
 
 /* pwm.c */
 /*
-- 
2.39.3