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 static uint16_t adc1_gain20_offset_x16;
17 static void inline setup_mux(unsigned char n)
19 /* ADC numbering: PWM LEDs first, then ambient light sensor, battery sensor */
21 case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
22 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0);
23 sum_shift = 3; // 8 measurements
25 case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
26 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
27 sum_shift = 3; // 8 measurements
29 case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
30 ADMUX = _BV(REFS1) | _BV(MUX2);
31 sum_shift = 2; // 4 measurements
33 case 3: // ambient light: 1.1V, ADC5 (PA6), single-ended
34 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
35 sum_shift = 0; // 1 measurement
37 case 4: // batt voltage: 1.1V, ADC6 (PA7), single-ended
38 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
39 sum_shift = 0; // 1 measurement
41 case 5: // gain stage offset: 1.1V, ADC1,1, gain 20
42 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
43 sum_shift = 3; // 8 measurements
48 adc_vals = 1 << sum_shift;
51 static void start_next_adc()
53 if (current_adc > 0) {
55 // set up mux, start one-shot conversion
56 setup_mux(current_adc);
59 current_adc = NUM_ADCS;
60 // TODO: kick the watchdog here.
67 current_adc = NUM_ADCS;
69 ADCSRA = _BV(ADEN) // enable
70 | _BV(ADPS1) | _BV(ADPS0) // CLK/8 = 125 kHz
71 // | _BV(ADPS2) // CLK/16 = 62.5 kHz
73 // ADCSRB |= _BV(GSEL); // gain 8 or 32
75 // Disable digital input on all bits used by ADC
76 DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D)
77 | _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D);
79 // 1.1V, ADC1,1, gain 20
80 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
83 /* Do first conversion and drop the result */
84 while ((ADCSRA & _BV(ADIF)) == 0)
86 ADCSRA |= _BV(ADIF); // clear the IRQ flag
88 adc1_gain20_offset_x16 = 0;
90 for (i = 0; i < 16; i++) {
93 while ((ADCSRA & _BV(ADIF)) == 0)
95 adc1_gain20_offset_x16 += ADCW;
97 ADCSRA |= _BV(ADIF); // clear the IRQ flag
100 ADCSRA |= _BV(ADIE); // enable IRQ
109 ISR(ADC_vect) { // IRQ handler
110 uint16_t adcval = ADCW;
113 // start the next conversion immediately
116 if (adc_vals < (1 << sum_shift))
117 // drop the first conversion, use all others
125 // Now handle the (1 << sum_shift) measurements
127 adcval = adc_sum >> sum_shift;
129 if (current_adc == ADC1_GAIN20) {
131 adc1_gain20_offset_x16 += adcval
132 - (adc1_gain20_offset_x16 >> 4);
133 } else if (current_adc == 0 || current_adc == 1) {
134 uint16_t offset = adc1_gain20_offset_x16 >> 4;
135 if (adcval >= offset)
141 if (current_adc < N_PWMLEDS)
142 pwmled_adc(current_adc, adcval);
143 if (current_adc == AMBIENT_ADC)
145 if (current_adc == BATTERY_ADC)
151 void timer_start_adcs()
153 if (current_adc == NUM_ADCS) // Don't start if in progress