X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?a=blobdiff_plain;f=firmware%2Fadc.c;h=fa0782c4248c6ee67917901cc1340dedfefea087;hb=ee55592455c9628ca21142449d4b5918a59151fe;hp=8bc171a390bd684ba79a345c39f377bb909cbbd2;hpb=35a6047369df5398282c6e1f2ec03976e6af76e4;p=bike-lights.git

diff --git a/firmware/adc.c b/firmware/adc.c
index 8bc171a..fa0782c 100644
--- a/firmware/adc.c
+++ b/firmware/adc.c
@@ -5,17 +5,18 @@
 
 #define AMBIENT_ADC N_PWMLEDS
 #define BATTERY_ADC (N_PWMLEDS + 1)
+#define ADC1_GAIN20 (N_PWMLEDS + 2)
 
-#define NUM_ADCS 5
+#define NUM_ADCS 6
 volatile static unsigned char current_adc;
 static uint16_t adc_sum;
 static unsigned char sum_shift;
 static unsigned char adc_vals;
+#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
@@ -38,6 +39,10 @@ static void inline setup_mux(unsigned char n)
 		ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
 		sum_shift = 0; // 1 measurement
 		break;
+	case 5: // gain stage offset: 1.1V, ADC1,1, gain 20
+		ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
+		sum_shift = 0; // 1 measurement
+		break;
 	}
 
 	adc_sum = 0;
@@ -59,6 +64,7 @@ static void start_next_adc()
 
 void init_adc()
 {
+	unsigned char i;
 	current_adc = NUM_ADCS;
 
 	ADCSRA = _BV(ADEN)			// enable
@@ -71,15 +77,29 @@ void init_adc()
 	DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D)
 		| _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
-	ADCSRA |= _BV(ADIE); // enable IRQ
 
-	ADCSRA &= ~_BV(ADEN); // disable until needed
+	adc1_gain20_offset = 0;
+
+	for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) {
+		ADCSRA |= _BV(ADSC);
+
+		while ((ADCSRA & _BV(ADIF)) == 0)
+			;
+		adc1_gain20_offset += ADCW
+			- (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
+
+		ADCSRA |= _BV(ADIF); // clear the IRQ flag
+	}
+
+	ADCSRA |= _BV(ADIE); // enable IRQ
 }
 
 void susp_adc()
@@ -94,8 +114,6 @@ 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
@@ -110,8 +128,21 @@ ISR(ADC_vect) { // IRQ handler
 
 	adcval = adc_sum >> sum_shift;
 
+	if (current_adc == ADC1_GAIN20) {
+		// running average
+		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
+			>> (ADC1_GAIN20_OFFSET_SHIFT - sum_shift);
+		if (adc_sum > offset)
+			adc_sum -= offset;
+		else
+			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);
 	if (current_adc == BATTERY_ADC)
@@ -124,5 +155,9 @@ void timer_start_adcs()
 {
 	if (current_adc == NUM_ADCS) // Don't start if in progress
 		start_next_adc();
+#if 0
+	else
+		log_byte(0x99);
+#endif
 }