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 + 3)
10 #define ZERO_ADC (N_PWMLEDS + 4)
12 #define NUM_ADCS ZERO_ADC
15 unsigned char read_zero_log : 2;
16 unsigned char read_drop_log : 2;
17 unsigned char read_keep_log : 4;
18 } adc_params[NUM_ADCS] = {
19 { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 1
20 { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 2
21 { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 3
22 { 0, 1, 3 }, // ambient
23 { 0, 1, 0 }, // battery
24 { 0, 1, 0 }, // gain20
25 { 0, 1, 0 }, // buttons
28 volatile static unsigned char current_adc;
29 static uint16_t adc_sum, zero_count, drop_count, read_count, n_reads_log;
30 #define ADC1_GAIN20_OFFSET_SHIFT 6
31 static uint16_t adc1_gain20_offset;
34 static void setup_mux(unsigned char n)
36 /* ADC numbering: PWM LEDs first, then others, zero at the end */
38 case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
39 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0);
41 case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
42 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
44 case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
45 ADMUX = _BV(REFS1) | _BV(MUX2);
47 case AMBIENT_ADC: // ambient light: 1.1V, ADC5 (PA6), single-ended
48 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
50 case BATTERY_ADC: // batt voltage: 1.1V, ADC6 (PA7), single-ended
51 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
53 case ADC1_GAIN20: // gain stage offset: 1.1V, ADC1,1, gain 20
54 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
56 case BUTTON_ADC: // buttons: 1.1V, ADC3, single-ended
57 PORTA |= _BV(PA3); // +5V to the voltage splitter
58 ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0);
60 case ZERO_ADC: // zero: 1.1V, ADC1 (PA1), single-ended
61 ADMUX = _BV(REFS1) | _BV(MUX0);
66 static void start_next_adc()
71 // TODO: kick the watchdog here.
72 current_adc = NUM_ADCS-1;
75 // we use the last iteration of zero_count to set up the MUX
76 // to its final destination, hence the "1 +" below:
77 if (adc_params[current_adc].read_zero_log)
78 zero_count = 1 + (1 << (adc_params[current_adc].read_zero_log-1));
82 if (adc_params[current_adc].read_drop_log)
83 drop_count = 1 << (adc_params[current_adc].read_drop_log - 1);
87 read_count = 1 << adc_params[current_adc].read_keep_log;
88 n_reads_log = adc_params[current_adc].read_keep_log;
90 // set up mux, start one-shot conversion
94 setup_mux(current_adc);
100 * Single synchronous ADC conversion.
101 * Has to be called with IRQs disabled (or with the ADC IRQ disabled).
103 static uint16_t read_adc_sync()
107 ADCSRA |= _BV(ADSC); // start the conversion
109 // wait for the conversion to finish
110 while((ADCSRA & _BV(ADIF)) == 0)
114 ADCSRA |= _BV(ADIF); // clear the IRQ flag
122 current_adc = NUM_ADCS;
124 ADCSRA = _BV(ADEN) // enable
125 | _BV(ADPS1) | _BV(ADPS0) // CLK/8 = 125 kHz
126 // | _BV(ADPS2) // CLK/16 = 62.5 kHz
128 // ADCSRB |= _BV(GSEL); // gain 8 or 32
130 // Disable digital input on all bits used by ADC
131 DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D) | _BV(ADC3D)
132 | _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D);
134 // 1.1V, ADC1,1, gain 20
135 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
137 /* Do first conversion and drop the result */
140 adc1_gain20_offset = 0;
142 for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) {
143 adc1_gain20_offset += read_adc_sync()
144 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
147 ADCSRA |= _BV(ADIE); // enable IRQ
158 static void adc1_gain20_adc(uint16_t adcsum)
161 adc1_gain20_offset += adcsum
162 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
165 ISR(ADC_vect) { // IRQ handler
166 uint16_t adcval = ADCW;
169 if (zero_count > 1) {
174 setup_mux(current_adc);
181 ADCSRA |= _BV(ADSC); // drop this one, start the next
194 * Now we have performed read_count measurements and have them
198 // For inputs with gain, subtract the measured gain stage offset
199 if (current_adc < 2) {
200 uint16_t offset = adc1_gain20_offset
201 >> (ADC1_GAIN20_OFFSET_SHIFT - n_reads_log);
203 if (adc_sum > offset)
209 switch (current_adc) {
213 pwmled_adc(current_adc, adc_sum);
216 ambient_adc(adc_sum);
219 battery_adc(adc_sum);
225 adc1_gain20_adc(adcval);