2 #include <avr/interrupt.h>
6 // pwmleds are measured continuously (when active)
7 #define AMBIENT_ADC N_PWMLEDS // measured every jiffy (16 Hz)
8 #define BUTTON_ADC (N_PWMLEDS + 1) // measured every jiffy (16 Hz)
9 #define BATTERY_ADC (N_PWMLEDS + 2) // once per second
10 #define ADC1_GAIN20 (N_PWMLEDS + 3) // once per second
11 #define ZERO_ADC (N_PWMLEDS + 4) // must be last
13 #define NUM_ADCS ZERO_ADC
16 unsigned char read_zero_log : 2;
17 unsigned char read_drop_log : 2;
18 unsigned char read_keep_log : 4;
19 } adc_params[NUM_ADCS] = {
20 { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 1
21 { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 2
22 { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 3
23 { 0, 1, AMBIENT_ADC_SHIFT }, // ambient
24 { 0, 1, 0 }, // buttons
25 { 0, 1, 0 }, // battery
26 { 0, 1, 0 }, // gain20
29 volatile static unsigned char current_adc, current_slow_adc;
30 static uint16_t adc_sum, zero_count, drop_count, read_count, n_reads_log;
31 #define ADC1_GAIN20_OFFSET_SHIFT 6
32 static uint16_t adc1_gain20_offset;
35 static void setup_mux(unsigned char n)
37 /* ADC numbering: PWM LEDs first, then others, zero at the end */
39 case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20
40 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0);
42 case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20
43 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
45 case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended
46 ADMUX = _BV(REFS1) | _BV(MUX2);
48 case AMBIENT_ADC: // ambient light: 1.1V, ADC5 (PA6), single-ended
49 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0);
51 case BUTTON_ADC: // buttons: 1.1V, ADC3, single-ended
52 PORTA |= _BV(PA3); // +5V to the voltage splitter
53 ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0);
55 case BATTERY_ADC: // batt voltage: 1.1V, ADC6 (PA7), single-ended
56 ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1);
58 case ADC1_GAIN20: // gain stage offset: 1.1V, ADC1,1, gain 20
59 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
61 case ZERO_ADC: // zero: 1.1V, ADC1 (PA1), single-ended
62 ADMUX = _BV(REFS1) | _BV(MUX0);
67 static void start_next_adc()
69 if (current_adc == 0) {
70 if (current_slow_adc > N_PWMLEDS) {
71 // read one of the non-PWMLED ADCs
72 current_adc = --current_slow_adc;
74 // no more non-PWMLEDs to do, start with PWMLEDs
75 current_adc = N_PWMLEDS-1;
77 } else if (current_adc >= N_PWMLEDS) {
78 // one of the non-PWMLED ADCs just finished, skip to PWMLEDs.
79 current_adc = N_PWMLEDS-1;
86 log_byte(0x90 + current_adc); // debug ADC switching
90 // we use the last iteration of zero_count to set up the MUX
91 // to its final destination, hence the "1 +" below:
92 if (adc_params[current_adc].read_zero_log)
93 zero_count = 1 + (1 << (adc_params[current_adc].read_zero_log-1));
97 if (adc_params[current_adc].read_drop_log)
98 drop_count = 1 << (adc_params[current_adc].read_drop_log - 1);
102 read_count = 1 << adc_params[current_adc].read_keep_log;
103 n_reads_log = adc_params[current_adc].read_keep_log;
105 // set up mux, start one-shot conversion
109 setup_mux(current_adc);
114 void timer_start_slow_adcs()
116 if (current_slow_adc > N_PWMLEDS) { // Don't start if in progress
117 log_byte(0x80 + current_slow_adc);
119 current_slow_adc = NUM_ADCS;
120 // TODO: kick the watchdog here
125 * Single synchronous ADC conversion.
126 * Has to be called with IRQs disabled (or with the ADC IRQ disabled).
128 static uint16_t read_adc_sync()
132 ADCSRA |= _BV(ADSC); // start the conversion
134 // wait for the conversion to finish
135 while((ADCSRA & _BV(ADIF)) == 0)
139 ADCSRA |= _BV(ADIF); // clear the IRQ flag
147 current_slow_adc = NUM_ADCS;
150 ADCSRA = _BV(ADEN) // enable
151 | _BV(ADPS1) | _BV(ADPS0) // CLK/8 = 125 kHz
152 // | _BV(ADPS2) // CLK/16 = 62.5 kHz
154 // ADCSRB |= _BV(GSEL); // gain 8 or 32
156 // Disable digital input on all bits used by ADC
157 DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D) | _BV(ADC3D)
158 | _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D);
160 // 1.1V, ADC1,1, gain 20
161 ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0);
163 /* Do first conversion and drop the result */
166 adc1_gain20_offset = 0;
168 for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) {
169 adc1_gain20_offset += read_adc_sync()
170 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
173 ADCSRA |= _BV(ADIE); // enable IRQ
184 static void adc1_gain20_adc(uint16_t adcsum)
187 adc1_gain20_offset += adcsum
188 - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT);
191 ISR(ADC_vect) { // IRQ handler
192 uint16_t adcval = ADCW;
195 if (zero_count > 1) {
200 setup_mux(current_adc);
207 ADCSRA |= _BV(ADSC); // drop this one, start the next
220 * Now we have performed read_count measurements and have them
224 // For inputs with gain, subtract the measured gain stage offset
225 if (current_adc < 2) {
226 uint16_t offset = adc1_gain20_offset
227 >> (ADC1_GAIN20_OFFSET_SHIFT - n_reads_log);
229 if (adc_sum > offset)
235 switch (current_adc) {
239 pwmled_adc(current_adc, adc_sum);
242 ambient_adc(adc_sum);
248 battery_adc(adc_sum);
251 adc1_gain20_adc(adcval);