X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?p=tinyboard.git;a=blobdiff_plain;f=projects%2Fstep-up%2Fadc.c;fp=projects%2Fstep-up%2Fadc.c;h=ef714777011f1af24d171bb44cdd0d6461ac6b0e;hp=0000000000000000000000000000000000000000;hb=edebb613b2f867d4f8473747744f329cb30e38fe;hpb=5aa70c4eca2337027c5ca5ece45c0031b95026ef diff --git a/projects/step-up/adc.c b/projects/step-up/adc.c new file mode 100644 index 0000000..ef71477 --- /dev/null +++ b/projects/step-up/adc.c @@ -0,0 +1,256 @@ +#include +#include + +#include "lights.h" + +#define AMBIENT_ADC N_PWMLEDS +#define BATTERY_ADC (N_PWMLEDS + 1) +#define ADC1_GAIN20 (N_PWMLEDS + 2) +#define BUTTON_ADC (N_PWMLEDS + 3) +#define ZERO_ADC (N_PWMLEDS + 4) + +#define NUM_ADCS ZERO_ADC + +struct { + unsigned char read_zero_log : 2; + unsigned char read_drop_log : 2; + unsigned char read_keep_log : 4; +} adc_params[NUM_ADCS] = { + { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 1 + { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 2 + { 0, 1, PWMLED_ADC_SHIFT }, // pwmled 3 + { 0, 1, AMBIENT_ADC_SHIFT }, // ambient + { 0, 1, 0 }, // battery + { 0, 1, 0 }, // gain20 + { 0, 1, 0 }, // buttons +}; + +volatile static unsigned char current_adc, current_slow_adc; +static uint16_t adc_sum, zero_count, drop_count, read_count, n_reads_log; +#define ADC1_GAIN20_OFFSET_SHIFT 6 +static uint16_t adc1_gain20_offset; + + +static void setup_mux(unsigned char n) +{ + /* ADC numbering: PWM LEDs first, then others, zero at the end */ + switch (n) { + case 0: // pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 20 + ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX1) | _BV(MUX0); + break; + case 1: // pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20 + ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1); + break; + case 2: // pwmled 3: 1.1V, ADC4 (PA5), single-ended + ADMUX = _BV(REFS1) | _BV(MUX2); + break; + case AMBIENT_ADC: // ambient light: 1.1V, ADC5 (PA6), single-ended + ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX0); + break; + case BATTERY_ADC: // batt voltage: 1.1V, ADC6 (PA7), single-ended + ADMUX = _BV(REFS1) | _BV(MUX2) | _BV(MUX1); + break; + case ADC1_GAIN20: // gain stage offset: 1.1V, ADC1,1, gain 20 + ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0); + break; + case BUTTON_ADC: // buttons: 1.1V, ADC3, single-ended + PORTA |= _BV(PA3); // +5V to the voltage splitter + ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0); + break; + case ZERO_ADC: // zero: 1.1V, ADC1 (PA1), single-ended + ADMUX = _BV(REFS1) | _BV(MUX0); + break; + } +} + +static void start_next_adc() +{ + if (current_adc == 0) { + if (current_slow_adc > N_PWMLEDS) { + // read one of the non-PWMLED ADCs + current_adc = --current_slow_adc; + } else { + // no more non-PWMLEDs to do, start with PWMLEDs + current_adc = N_PWMLEDS-1; + } + } else if (current_adc >= N_PWMLEDS) { + // one of the non-PWMLED ADCs just finished, skip to PWMLEDs. + current_adc = N_PWMLEDS-1; + } else { + // next PWMLED + current_adc--; + } + +#if 0 + log_byte(0x90 + current_adc); // debug ADC switching +#endif + + adc_sum = 0; + // we use the last iteration of zero_count to set up the MUX + // to its final destination, hence the "1 +" below: + if (adc_params[current_adc].read_zero_log) + zero_count = 1 + (1 << (adc_params[current_adc].read_zero_log-1)); + else + zero_count = 1; + + if (adc_params[current_adc].read_drop_log) + drop_count = 1 << (adc_params[current_adc].read_drop_log - 1); + else + drop_count = 0; + + read_count = 1 << adc_params[current_adc].read_keep_log; + n_reads_log = adc_params[current_adc].read_keep_log; + + // set up mux, start one-shot conversion + if (zero_count > 1) + setup_mux(ZERO_ADC); + else + setup_mux(current_adc); + + ADCSRA |= _BV(ADSC); +} + +void timer_start_slow_adcs() +{ + if (current_slow_adc > N_PWMLEDS) { // Don't start if in progress + log_byte(0x80 + current_slow_adc); + } else { + current_slow_adc = NUM_ADCS; + // TODO: kick the watchdog here + } +} + +/* + * Single synchronous ADC conversion. + * Has to be called with IRQs disabled (or with the ADC IRQ disabled). + */ +static uint16_t read_adc_sync() +{ + uint16_t rv; + + ADCSRA |= _BV(ADSC); // start the conversion + + // wait for the conversion to finish + while((ADCSRA & _BV(ADIF)) == 0) + ; + + rv = ADCW; + ADCSRA |= _BV(ADIF); // clear the IRQ flag + + return rv; +} + +void init_adc() +{ + unsigned char i; + current_slow_adc = NUM_ADCS; + current_adc = 0; + + ADCSRA = _BV(ADEN) // enable + | _BV(ADPS1) | _BV(ADPS0) // CLK/8 = 125 kHz + // | _BV(ADPS2) // CLK/16 = 62.5 kHz + ; + // ADCSRB |= _BV(GSEL); // gain 8 or 32 + + // Disable digital input on all bits used by ADC + DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D) | _BV(ADC3D) + | _BV(ADC4D) | _BV(ADC5D) | _BV(ADC6D); + + // 1.1V, ADC1,1, gain 20 + ADMUX = _BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX0); + + /* Do first conversion and drop the result */ + read_adc_sync(); + + adc1_gain20_offset = 0; + + for (i = 0; i < (1 << ADC1_GAIN20_OFFSET_SHIFT); i++) { + adc1_gain20_offset += read_adc_sync() + - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT); + } + + ADCSRA |= _BV(ADIE); // enable IRQ + + start_next_adc(); +} + +void susp_adc() +{ + ADCSRA = 0; + DIDR0 = 0; +} + +static void adc1_gain20_adc(uint16_t adcsum) +{ + // running average + adc1_gain20_offset += adcsum + - (adc1_gain20_offset >> ADC1_GAIN20_OFFSET_SHIFT); +} + +ISR(ADC_vect) { // IRQ handler + uint16_t adcval = ADCW; + + if (zero_count) { + if (zero_count > 1) { + ADCSRA |= _BV(ADSC); + zero_count--; + return; + } else { + setup_mux(current_adc); + zero_count = 0; + /* fall through */ + } + } + + if (drop_count) { + ADCSRA |= _BV(ADSC); // drop this one, start the next + drop_count--; + return; + } + + if (read_count) { + ADCSRA |= _BV(ADSC); + adc_sum += adcval; + read_count--; + return; + } + + /* + * Now we have performed read_count measurements and have them + * in adc_sum. + */ + + // For inputs with gain, subtract the measured gain stage offset + if (current_adc < 2) { + uint16_t offset = adc1_gain20_offset + >> (ADC1_GAIN20_OFFSET_SHIFT - n_reads_log); + + if (adc_sum > offset) + adc_sum -= offset; + else + adc_sum = 0; + } + + switch (current_adc) { + case 0: + case 1: + case 2: + pwmled_adc(current_adc, adc_sum); + break; + case AMBIENT_ADC: + ambient_adc(adc_sum); + break; + case BATTERY_ADC: + battery_adc(adc_sum); + break; + case BUTTON_ADC: + button_adc(adc_sum); + break; + case ADC1_GAIN20: + adc1_gain20_adc(adcval); + break; + } + + start_next_adc(); +} +