2 #include <avr/interrupt.h>
6 #define AMBIENT_ADC N_PWMLEDS
7 #define BATTERY_ADC (N_PWMLEDS + 1)
8 #define ADC1_GAIN20 (N_PWMLEDS + 2)
11 volatile static unsigned char current_adc;
12 static uint16_t adc_sum;
13 static unsigned char sum_shift;
14 static unsigned char adc_vals;
15 #define ADC1_GAIN20_OFFSET_SHIFT 6
16 static uint16_t adc1_gain20_offset;
18 static void inline setup_mux(unsigned char n)
20 /* ADC numbering: PWM LEDs first, then ambient light sensor, battery sensor */
22 case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
23 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0);
24 sum_shift = PWMLED_ADC_SHIFT;
26 case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
27 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
28 sum_shift = PWMLED_ADC_SHIFT;
30 case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
31 ADMUX = _BV(REFS1) | _BV(MUX2);
32 sum_shift = PWMLED_ADC_SHIFT;
34 case 3: // ambient light: 1.1V, ADC5 (PA6), single-ended
35 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
36 sum_shift = 0; // 1 measurement
38 case 4: // batt voltage: 1.1V, ADC6 (PA7), single-ended
39 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
40 sum_shift = 0; // 1 measurement
42 case 5: // gain stage offset: 1.1V, ADC1,1, gain 20
43 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
44 sum_shift = 0; // 1 measurement
49 adc_vals = 1 << sum_shift;
52 static void start_next_adc()
57 // TODO: kick the watchdog here.
58 current_adc = NUM_ADCS-1;
60 // set up mux, start one-shot conversion
61 setup_mux(current_adc);
68 current_adc = NUM_ADCS;
70 ADCSRA = _BV(ADEN) // enable
71 | _BV(ADPS1) | _BV(ADPS0) // CLK/8 = 125 kHz
72 // | _BV(ADPS2) // CLK/16 = 62.5 kHz
74 // ADCSRB |= _BV(GSEL); // gain 8 or 32
76 // Disable digital input on all bits used by ADC
77 DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D)
78 | _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D);
80 // 1.1V, ADC1,1, gain 20
81 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
84 /* Do first conversion and drop the result */
85 while ((ADCSRA & _BV(ADIF)) == 0)
87 ADCSRA |= _BV(ADIF); // clear the IRQ flag
89 adc1_gain20_offset = 0;
91 for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) {
94 while ((ADCSRA & _BV(ADIF)) == 0)
96 adc1_gain20_offset += ADCW
97 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
99 ADCSRA |= _BV(ADIF); // clear the IRQ flag
102 ADCSRA |= _BV(ADIE); // enable IRQ
113 ISR(ADC_vect) { // IRQ handler
114 uint16_t adcval = ADCW;
117 // start the next conversion immediately
120 if (adc_vals < (1 << sum_shift))
121 // drop the first conversion, use all others
129 // Now handle the (1 << sum_shift) measurements
131 adcval = adc_sum >> sum_shift;
133 if (current_adc == ADC1_GAIN20) {
135 adc1_gain20_offset += adcval
136 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
137 } else if (current_adc == 0 || current_adc == 1) {
138 uint16_t offset = adc1_gain20_offset
139 >> (ADC1_GAIN20_OFFSET_SHIFT - sum_shift);
140 if (adc_sum > offset)
146 if (current_adc < N_PWMLEDS)
147 pwmled_adc(current_adc, adc_sum);
148 if (current_adc == AMBIENT_ADC)
150 if (current_adc == BATTERY_ADC)