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=8bc171a390bd684ba79a345c39f377bb909cbbd2;hp=123dddd4dee4f319c5f536ccd3a5e817ed77c433;hb=35a6047369df5398282c6e1f2ec03976e6af76e4;hpb=87b9093fd54402618c297aaacbfa68bad80302e9

diff --git a/firmware/adc.c b/firmware/adc.c
index 123dddd..8bc171a 100644
--- a/firmware/adc.c
+++ b/firmware/adc.c
@@ -3,54 +3,63 @@
 
 #include "lights.h"
 
-/* ADC numbering: PWM LEDs first, then ambient light sensor, battery sensor */
-static unsigned char adc_mux[] = { // pwmleds should be first
-	// 0: pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
-	_BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0),
-	// 1: pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
-	_BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1),
-	// 2: pwmled 3: 1.1V, ADC4 (PA5), single-ended
-	_BV(REFS1) | _BV(MUX2),
-	// 3: ambient light: 1.1V, ADC5 (PA6), single-ended
-	_BV(REFS1) | _BV(MUX2) | _BV(MUX0),
-	// 4: batt voltage: 1.1V, ADC6 (PA7), single-ended
-	_BV(REFS1) | _BV(MUX2) | _BV(MUX1),
-};
-
 #define AMBIENT_ADC N_PWMLEDS
 #define BATTERY_ADC (N_PWMLEDS + 1)
 
-#define LAST_ADC (sizeof(adc_mux)/sizeof(adc_mux[0]))
+#define NUM_ADCS 5
 volatile static unsigned char current_adc;
-static unsigned char adc_ignore;
+static uint16_t adc_sum;
+static unsigned char sum_shift;
+static unsigned char adc_vals;
 
-static void start_next_adc()
+static void inline setup_mux(unsigned char n)
 {
-	while (current_adc > 0) {
-		--current_adc;
-
-		// test if current_adc should be measured
-		if (current_adc < N_PWMLEDS && pwmled_needs_adc(current_adc))
-			goto found;
-		if (current_adc == AMBIENT_ADC)
-			goto found;
-		// TODO battery sense, etc.
+	ADCSRA |= _BV(ADEN); // enable ADC
+
+	/* ADC numbering: PWM LEDs first, then ambient light sensor, battery sensor */
+	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
+		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
+		break;
+	case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
+		ADMUX = _BV(REFS1) | _BV(MUX2);
+		sum_shift = 3; // 8 measurements
+		break;
+	case 3: // ambient light: 1.1V, ADC5 (PA6), single-ended
+		ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
+		sum_shift = 0; // 1 measurement
+		break;
+	case 4: // batt voltage: 1.1V, ADC6 (PA7), single-ended
+		ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
+		sum_shift = 0; // 1 measurement
+		break;
 	}
 
-	// all ADCs have been handled
-	current_adc = LAST_ADC;
-	// TODO: kick the watchdog here.
-	return;
-found:
-	ADMUX = adc_mux[current_adc]; // set up mux, start one-shot conversion
-	adc_ignore = 1; // ignore first reading after mux change
-	ADCSRA |= _BV(ADSC);
+	adc_sum = 0;
+	adc_vals = 1 << sum_shift;
+}
+
+static void start_next_adc()
+{
+	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;
+		// TODO: kick the watchdog here.
+	}
 }
 
 void init_adc()
 {
-	current_adc = LAST_ADC;
-	adc_ignore = 1;
+	current_adc = NUM_ADCS;
 
 	ADCSRA = _BV(ADEN)			// enable
 		| _BV(ADPS1) | _BV(ADPS0)	// CLK/8 = 125 kHz
@@ -68,8 +77,9 @@ void init_adc()
 	while ((ADCSRA & _BV(ADIF)) == 0)
 		;
 	ADCSRA |= _BV(ADIF); // clear the IRQ flag
-
 	ADCSRA |= _BV(ADIE); // enable IRQ
+
+	ADCSRA &= ~_BV(ADEN); // disable until needed
 }
 
 void susp_adc()
@@ -81,18 +91,25 @@ void susp_adc()
 ISR(ADC_vect) { // IRQ handler
 	uint16_t adcval = ADCW;
 
-#if 0
-	log_byte(0xF3);
-	log_byte(current_adc);
-	log_word(adcval);
-#endif
-
-	if (adc_ignore) {
+	if (adc_vals)
+		// start the next conversion immediately
 		ADCSRA |= _BV(ADSC);
-		adc_ignore = 0;
+	else
+		ADCSRA &= ~_BV(ADEN); // the last one, disable ADC
+
+	if (adc_vals < (1 << sum_shift))
+		 // drop the first conversion, use all others
+		 adc_sum += adcval;
+
+	if (adc_vals) {
+		adc_vals--;
 		return;
 	}
 
+	// Now handle the (1 << sum_shift) measurements
+
+	adcval = adc_sum >> sum_shift;
+
 	if (current_adc < N_PWMLEDS)
 		pwmled_adc(current_adc, adcval);
 	if (current_adc == AMBIENT_ADC)
@@ -105,7 +122,7 @@ ISR(ADC_vect) { // IRQ handler
 
 void timer_start_adcs()
 {
-	if (current_adc == LAST_ADC) // Don't start if in progress
+	if (current_adc == NUM_ADCS) // Don't start if in progress
 		start_next_adc();
 }