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 = 3; // 8 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);
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;
// 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
if (current_adc < N_PWMLEDS)
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);