X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?p=bike-lights.git;a=blobdiff_plain;f=firmware%2Fadc.c;h=5f7849fb1128ed47414f71fd1072dddab68e3e80;hp=ba30e5ca632c01e8064323d460ce3324fa7dc23a;hb=eb2f91ea7806fd8f5b9a5597fcf5c13855911d71;hpb=68424ad19806bd6f0b857e878bf632cf5851e7c5

diff --git a/firmware/adc.c b/firmware/adc.c
index ba30e5c..5f7849f 100644
--- a/firmware/adc.c
+++ b/firmware/adc.c
@@ -1,5 +1,6 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
+#include <util/atomic.h>
 
 #include "lights.h"
 
@@ -12,7 +13,9 @@ volatile static unsigned char current_adc;
 static uint16_t adc_sum;
 static unsigned char sum_shift;
 static unsigned char adc_vals;
-static uint16_t adc1_gain20_offset_x16;
+#define ADC1_GAIN20_OFFSET_SHIFT	6
+static uint16_t adc1_gain20_offset;
+static unsigned char handler_running;
 
 static void inline setup_mux(unsigned char n)
 {
@@ -20,15 +23,15 @@ static void inline setup_mux(unsigned char n)
 	switch (n) {
 	case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
 		ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0);
-		sum_shift = 3; // 8 measurements
+		sum_shift = PWMLED_ADC_SHIFT;
 		break;
 	case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
 		ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
-		sum_shift = 3; // 8 measurements
+		sum_shift = PWMLED_ADC_SHIFT;
 		break;
 	case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
 		ADMUX = _BV(REFS1) | _BV(MUX2);
-		sum_shift = 2; // 4 measurements
+		sum_shift = PWMLED_ADC_SHIFT;
 		break;
 	case 3: // ambient light: 1.1V, ADC5 (PA6), single-ended
 		ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
@@ -40,7 +43,7 @@ static void inline setup_mux(unsigned char n)
 		break;
 	case 5: // gain stage offset: 1.1V, ADC1,1, gain 20
 		ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
-		sum_shift = 3; // 8 measurements
+		sum_shift = 0; // 1 measurement
 		break;
 	}
 
@@ -50,21 +53,42 @@ static void inline setup_mux(unsigned char n)
 
 static void start_next_adc()
 {
-	if (current_adc > 0) {
+	if (current_adc > 0)
 		current_adc--;
-		// set up mux, start one-shot conversion
-		setup_mux(current_adc);
-		ADCSRA |= _BV(ADSC);
-	} else {
-		current_adc = NUM_ADCS;
+	else
 		// TODO: kick the watchdog here.
-	}
+		current_adc = NUM_ADCS-1;
+
+	// set up mux, start one-shot conversion
+	setup_mux(current_adc);
+	ADCSRA |= _BV(ADSC);
+}
+
+/*
+ * Single synchronous ADC conversion.
+ * Has to be called with IRQs disabled (or with the ADC IRQ disabled).
+ */
+static uint16_t read_adc_sync()
+{
+	uint16_t rv;
+
+	ADCSRA |= _BV(ADSC); // start the conversion
+
+	// wait for the conversion to finish
+	while((ADCSRA & _BV(ADIF)) == 0)
+		;
+
+	rv = ADCW;
+	ADCSRA |= _BV(ADIF); // clear the IRQ flag
+
+	return rv;
 }
 
 void init_adc()
 {
 	unsigned char i;
 	current_adc = NUM_ADCS;
+	handler_running = 0;
 
 	ADCSRA = _BV(ADEN)			// enable
 		| _BV(ADPS1) | _BV(ADPS0)	// CLK/8 = 125 kHz
@@ -78,26 +102,20 @@ void init_adc()
 
 	// 1.1V, ADC1,1, gain 20
 	ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
-	ADCSRA |= _BV(ADSC);
 
 	/* Do first conversion and drop the result */
-	while ((ADCSRA & _BV(ADIF)) == 0)
-		;
-	ADCSRA |= _BV(ADIF); // clear the IRQ flag
-
-	adc1_gain20_offset_x16 = 0;
-
-	for (i = 0; i < 16; i++) {
-		ADCSRA |= _BV(ADSC);
+	read_adc_sync();
 
-		while ((ADCSRA & _BV(ADIF)) == 0)
-			;
-		adc1_gain20_offset_x16 += ADCW;
+	adc1_gain20_offset = 0;
 
-		ADCSRA |= _BV(ADIF); // clear the IRQ flag
+	for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) {
+		adc1_gain20_offset += read_adc_sync()
+			- (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
 	}
 
 	ADCSRA |= _BV(ADIE); // enable IRQ
+
+	start_next_adc();
 }
 
 void susp_adc()
@@ -128,31 +146,39 @@ ISR(ADC_vect) { // IRQ handler
 
 	if (current_adc == ADC1_GAIN20) {
 		// running average
-		adc1_gain20_offset_x16 += adcval
-			- (adc1_gain20_offset_x16 >> 4);
+		adc1_gain20_offset += adcval
+			- (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
 	} else if (current_adc == 0 || current_adc == 1) {
-		uint16_t offset = adc1_gain20_offset_x16 >> 4;
-		if (adcval >= offset)
-			adcval -= offset;
+		uint16_t offset = adc1_gain20_offset
+			>> (ADC1_GAIN20_OFFSET_SHIFT - sum_shift);
+		if (adc_sum > offset)
+			adc_sum -= offset;
 		else
-			adcval = 0;
+			adc_sum = 0;
 	}
 
-	if (current_adc < N_PWMLEDS)
-		pwmled_adc(current_adc, adcval);
-	if (current_adc == AMBIENT_ADC)
-		ambient_adc(adcval);
-	if (current_adc == BATTERY_ADC)
-		battery_adc(adcval);
-	
-	start_next_adc();
-}
+	if (handler_running & (1 << current_adc)) {
+		log_byte(0xB0 + current_adc);
+
+		// drop the result, what else to do?
 
-void timer_start_adcs()
-{
-	if (current_adc == NUM_ADCS) // Don't start if in progress
 		start_next_adc();
-	else
-		log_byte(0x99);
+	} else {
+		unsigned char current_adc_copy = current_adc;
+		uint16_t adc_sum_copy = adc_sum;
+
+		start_next_adc();
+
+		handler_running |= (1 << current_adc_copy);
+		NONATOMIC_BLOCK(NONATOMIC_FORCEOFF) {
+			if (current_adc_copy < N_PWMLEDS)
+				pwmled_adc(current_adc_copy, adc_sum_copy);
+			if (current_adc_copy == AMBIENT_ADC)
+				ambient_adc(adc_sum_copy);
+			if (current_adc_copy == BATTERY_ADC)
+				battery_adc(adc_sum_copy);
+		}
+		handler_running &= ~(1 << current_adc_copy);
+	}
 }