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=4213ef56bc01b5114ee2c76f6ef16dfce1e7158d;hb=1f28156058ed3af9e87afdc60d631ca5a47eb2cb;hpb=dd1738d1117607d5a47050274d805748b11f48d1

diff --git a/firmware/adc.c b/firmware/adc.c
index 4213ef5..6db036a 100644
--- a/firmware/adc.c
+++ b/firmware/adc.c
@@ -6,8 +6,9 @@
 #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;
@@ -43,6 +44,11 @@ static void inline setup_mux(unsigned char n)
 		ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
 		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;
 	}
 
 	adc_sum = 0;
@@ -62,6 +68,26 @@ static void start_next_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;
@@ -74,29 +100,20 @@ 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
+	read_adc_sync();
 
 	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 += read_adc_sync()
 			- (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
-
-		ADCSRA |= _BV(ADIF); // clear the IRQ flag
 	}
 
 	ADCSRA |= _BV(ADIE); // enable IRQ
@@ -149,6 +166,8 @@ ISR(ADC_vect) { // IRQ handler
 		ambient_adc(adc_sum);
 	if (current_adc == BATTERY_ADC)
 		battery_adc(adcval);
+	if (current_adc == BUTTON_ADC)
+		button_adc(adcval);
 	
 	start_next_adc();
 }