2 #include <avr/interrupt.h>
3 #include <util/atomic.h>
7 #define AMBIENT_ADC N_PWMLEDS
8 #define BATTERY_ADC (N_PWMLEDS + 1)
9 #define ADC1_GAIN20 (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;
18 static unsigned char handler_running;
20 static void inline setup_mux(unsigned char n)
22 /* ADC numbering: PWM LEDs first, then ambient light sensor, battery sensor */
24 case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
25 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0);
26 sum_shift = PWMLED_ADC_SHIFT;
28 case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
29 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
30 sum_shift = PWMLED_ADC_SHIFT;
32 case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
33 ADMUX = _BV(REFS1) | _BV(MUX2);
34 sum_shift = PWMLED_ADC_SHIFT;
36 case 3: // ambient light: 1.1V, ADC5 (PA6), single-ended
37 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
38 sum_shift = 3; // 3 measurements
40 case 4: // batt voltage: 1.1V, ADC6 (PA7), single-ended
41 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
42 sum_shift = 0; // 1 measurement
44 case 5: // gain stage offset: 1.1V, ADC1,1, gain 20
45 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
46 sum_shift = 0; // 1 measurement
51 adc_vals = 1 << sum_shift;
54 static void start_next_adc()
59 // TODO: kick the watchdog here.
60 current_adc = NUM_ADCS-1;
62 // set up mux, start one-shot conversion
63 setup_mux(current_adc);
68 * Single synchronous ADC conversion.
69 * Has to be called with IRQs disabled (or with the ADC IRQ disabled).
71 static uint16_t read_adc_sync()
75 ADCSRA |= _BV(ADSC); // start the conversion
77 // wait for the conversion to finish
78 while((ADCSRA & _BV(ADIF)) == 0)
82 ADCSRA |= _BV(ADIF); // clear the IRQ flag
90 current_adc = NUM_ADCS;
93 ADCSRA = _BV(ADEN) // enable
94 | _BV(ADPS1) | _BV(ADPS0) // CLK/8 = 125 kHz
95 // | _BV(ADPS2) // CLK/16 = 62.5 kHz
97 // ADCSRB |= _BV(GSEL); // gain 8 or 32
99 // Disable digital input on all bits used by ADC
100 DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D)
101 | _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D);
103 // 1.1V, ADC1,1, gain 20
104 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
106 /* Do first conversion and drop the result */
109 adc1_gain20_offset = 0;
111 for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) {
112 adc1_gain20_offset += read_adc_sync()
113 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
116 ADCSRA |= _BV(ADIE); // enable IRQ
127 ISR(ADC_vect) { // IRQ handler
128 uint16_t adcval = ADCW;
131 // start the next conversion immediately
134 if (adc_vals < (1 << sum_shift))
135 // drop the first conversion, use all others
143 // Now handle the (1 << sum_shift) measurements
145 adcval = adc_sum >> sum_shift;
147 if (current_adc == ADC1_GAIN20) {
149 adc1_gain20_offset += adcval
150 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
151 } else if (current_adc == 0 || current_adc == 1) {
152 uint16_t offset = adc1_gain20_offset
153 >> (ADC1_GAIN20_OFFSET_SHIFT - sum_shift);
154 if (adc_sum > offset)
160 if (handler_running & (1 << current_adc)) {
161 log_byte(0xB0 + current_adc);
163 // drop the result, what else to do?
167 unsigned char current_adc_copy = current_adc;
168 uint16_t adc_sum_copy = adc_sum;
172 handler_running |= (1 << current_adc_copy);
173 NONATOMIC_BLOCK(NONATOMIC_FORCEOFF) {
174 if (current_adc_copy < N_PWMLEDS)
175 pwmled_adc(current_adc_copy, adc_sum_copy);
176 if (current_adc_copy == AMBIENT_ADC)
177 ambient_adc(adc_sum_copy);
178 if (current_adc_copy == BATTERY_ADC)
179 battery_adc(adc_sum_copy);
181 handler_running &= ~(1 << current_adc_copy);