76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
#include "analog.h"
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#include "temp.h"
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#include <avr/interrupt.h>
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/* OR-combined mask of all channels */
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#undef DEFINE_TEMP_SENSOR
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#define DEFINE_TEMP_SENSOR(name, type, pin) | (((type == TT_THERMISTOR) || (type == TT_AD595)) ? 1 << (pin) : 0)
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static const uint8_t analog_mask = 0
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#include "config.h"
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;
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#undef DEFINE_TEMP_SENSOR
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static uint8_t adc_counter;
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static volatile uint16_t adc_result[8] __attribute__ ((__section__ (".bss")));
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void analog_init() {
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if (analog_mask > 0) {
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#ifdef PRR
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PRR &= ~MASK(PRADC);
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#elif defined PRR0
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PRR0 &= ~MASK(PRADC);
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#endif
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ADMUX = REFERENCE;
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// ADC frequency must be less than 200khz or we lose precision. At 16MHz system clock, we must use the full prescale value of 128 to get an ADC clock of 125khz.
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ADCSRA = MASK(ADEN) | MASK(ADPS2) | MASK(ADPS1) | MASK(ADPS0);
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adc_counter = 0;
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AIO0_DDR &= ~analog_mask;
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DIDR0 = analog_mask & 0x3F;
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// now we start the first conversion and leave the rest to the interrupt
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ADCSRA |= MASK(ADIE) | MASK(ADSC);
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} /* analog_mask > 0 */
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}
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ISR(ADC_vect, ISR_NOBLOCK) {
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// emulate free-running mode but be more deterministic about exactly which result we have, since this project has long-running interrupts
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if (analog_mask > 0) {
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adc_result[ADMUX & 0x0F] = ADC;
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// find next channel
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do {
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adc_counter++;
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adc_counter &= 0x07;
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} while ((analog_mask & (1 << adc_counter)) == 0);
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// start next conversion
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ADMUX = (adc_counter) | REFERENCE;
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ADCSRA |= MASK(ADSC);
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}
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}
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uint16_t analog_read(uint8_t channel) {
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if (analog_mask > 0) {
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uint16_t r;
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uint8_t sreg;
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// save interrupt flag
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sreg = SREG;
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// disable interrupts
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cli();
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// atomic 16-bit copy
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r = adc_result[channel];
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// restore interrupt flag
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SREG = sreg;
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return r;
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} else {
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return 0;
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}
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}
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