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=6db036af530b124e8aec9db50e668b6802d669a9;hp=d0ee1c40f3377f17e40bd1f7662d662f72f8034f;hb=1f28156058ed3af9e87afdc60d631ca5a47eb2cb;hpb=5090774fd8ca593d3b247b099b3b6a40e837475e

diff --git a/firmware/adc.c b/firmware/adc.c
index d0ee1c4..6db036a 100644
--- a/firmware/adc.c
+++ b/firmware/adc.c
@@ -6,35 +6,35 @@
 #define AMBIENT_ADC N_PWMLEDS
 #define BATTERY_ADC (N_PWMLEDS + 1)
 #define ADC1_GAIN20 (N_PWMLEDS + 2)
+#define BUTTON_ADC  (N_PWMLEDS + 2)
 
-#define NUM_ADCS 6
+#define NUM_ADCS 7
 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 void inline setup_mux(unsigned char n)
 {
-	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
+		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);
-		sum_shift = 0; // 1 measurement
+		sum_shift = 3; // 3 measurements
 		break;
 	case 4: // batt voltage: 1.1V, ADC6 (PA7), single-ended
 		ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
@@ -42,7 +42,12 @@ 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;
+	case 6: // buttons: 1.1V, ADC3, single-ended
+		PORTA |= _BV(PA3); // +5V to the voltage splitter
+		ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0);
+		sum_shift = 0;
 		break;
 	}
 
@@ -52,15 +57,35 @@ 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()
@@ -75,33 +100,25 @@ void init_adc()
 	// ADCSRB |= _BV(GSEL); // gain 8 or 32
 
 	// Disable digital input on all bits used by ADC
-	DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D)
+	DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D) | _BV(ADC3D)
 		| _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D);
 
 	// 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;
+	read_adc_sync();
 
-	for (i = 0; i < 16; i++) {
-		ADCSRA |= _BV(ADSC);
-
-		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
 
-	ADCSRA &= ~_BV(ADEN); // disable until needed
+	start_next_adc();
 }
 
 void susp_adc()
@@ -116,8 +133,6 @@ ISR(ADC_vect) { // IRQ handler
 	if (adc_vals)
 		// start the next conversion immediately
 		ADCSRA |= _BV(ADSC);
-	else
-		ADCSRA &= ~_BV(ADEN); // the last one, disable ADC
 
 	if (adc_vals < (1 << sum_shift))
 		 // drop the first conversion, use all others
@@ -134,29 +149,26 @@ 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);
+		pwmled_adc(current_adc, adc_sum);
 	if (current_adc == AMBIENT_ADC)
-		ambient_adc(adcval);
+		ambient_adc(adc_sum);
 	if (current_adc == BATTERY_ADC)
 		battery_adc(adcval);
+	if (current_adc == BUTTON_ADC)
+		button_adc(adcval);
 	
 	start_next_adc();
 }
 
-void timer_start_adcs()
-{
-	if (current_adc == NUM_ADCS) // Don't start if in progress
-		start_next_adc();
-}
-