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)
9 #define BUTTON_ADC (N_PWMLEDS + 2)
12 volatile static unsigned char current_adc;
13 static uint16_t adc_sum;
14 static unsigned char sum_shift;
15 static unsigned char adc_vals;
16 #define ADC1_GAIN20_OFFSET_SHIFT 6
17 static uint16_t adc1_gain20_offset;
19 static void inline setup_mux(unsigned char n)
21 /* ADC numbering: PWM LEDs first, then ambient light sensor, battery sensor */
23 case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
24 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0);
25 sum_shift = PWMLED_ADC_SHIFT;
27 case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
28 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
29 sum_shift = PWMLED_ADC_SHIFT;
31 case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
32 ADMUX = _BV(REFS1) | _BV(MUX2);
33 sum_shift = PWMLED_ADC_SHIFT;
35 case 3: // ambient light: 1.1V, ADC5 (PA6), single-ended
36 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
37 sum_shift = 3; // 3 measurements
39 case 4: // batt voltage: 1.1V, ADC6 (PA7), single-ended
40 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
41 sum_shift = 0; // 1 measurement
43 case 5: // gain stage offset: 1.1V, ADC1,1, gain 20
44 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
45 sum_shift = 0; // 1 measurement
47 case 6: // buttons: 1.1V, ADC3, single-ended
48 PORTA |= _BV(PA3); // +5V to the voltage splitter
49 ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0);
55 adc_vals = 1 << sum_shift;
58 static void start_next_adc()
63 // TODO: kick the watchdog here.
64 current_adc = NUM_ADCS-1;
66 // set up mux, start one-shot conversion
67 setup_mux(current_adc);
72 * Single synchronous ADC conversion.
73 * Has to be called with IRQs disabled (or with the ADC IRQ disabled).
75 static uint16_t read_adc_sync()
79 ADCSRA |= _BV(ADSC); // start the conversion
81 // wait for the conversion to finish
82 while((ADCSRA & _BV(ADIF)) == 0)
86 ADCSRA |= _BV(ADIF); // clear the IRQ flag
94 current_adc = NUM_ADCS;
96 ADCSRA = _BV(ADEN) // enable
97 | _BV(ADPS1) | _BV(ADPS0) // CLK/8 = 125 kHz
98 // | _BV(ADPS2) // CLK/16 = 62.5 kHz
100 // ADCSRB |= _BV(GSEL); // gain 8 or 32
102 // Disable digital input on all bits used by ADC
103 DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D) | _BV(ADC3D)
104 | _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D);
106 // 1.1V, ADC1,1, gain 20
107 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
109 /* Do first conversion and drop the result */
112 adc1_gain20_offset = 0;
114 for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) {
115 adc1_gain20_offset += read_adc_sync()
116 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
119 ADCSRA |= _BV(ADIE); // enable IRQ
130 ISR(ADC_vect) { // IRQ handler
131 uint16_t adcval = ADCW;
134 // start the next conversion immediately
137 if (adc_vals < (1 << sum_shift))
138 // drop the first conversion, use all others
146 // Now handle the (1 << sum_shift) measurements
148 adcval = adc_sum >> sum_shift;
150 if (current_adc == ADC1_GAIN20) {
152 adc1_gain20_offset += adcval
153 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
154 } else if (current_adc == 0 || current_adc == 1) {
155 uint16_t offset = adc1_gain20_offset
156 >> (ADC1_GAIN20_OFFSET_SHIFT - sum_shift);
157 if (adc_sum > offset)
163 if (current_adc < N_PWMLEDS)
164 pwmled_adc(current_adc, adc_sum);
165 if (current_adc == AMBIENT_ADC)
166 ambient_adc(adc_sum);
167 if (current_adc == BATTERY_ADC)
169 if (current_adc == BUTTON_ADC)