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Adc.cpp
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Adc.cpp
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/*
* Abstraction layer for the ATmega328p ADC
* Non-blocking read the ADC output as an alternative
* to the blocking analogRead() method.
*
* This source file can be found under:
* http://www.github.com/arduino-library/Adc
*
* Please visit:
* http://www.microfarad.de
* http://www.github.com/microfarad-de
* http://www.github.com/arduino-library
*
* Copyright (C) 2019 Karim Hraibi (khraibi at gmail.com)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "Adc.h"
#include <assert.h>
AdcClass Adc;
void AdcClass::initialize (AdcPrescaler_t prescaler, AdcReference_t reference, uint16_t avgSamples, uint8_t numPins, AdcPin_t *adcPins) {
this->reference = reference;
assert (numPins <= ADC_NUM_PINS);
this->numPins = numPins;
this->avgSamples = avgSamples;
for (uint8_t i = 0; i < numPins; i++) {
this->adcPins[i] = adcPins[i];
}
ADCSRA = _BV (ADEN); // turn ADC on
ADCSRA |= prescaler ;
}
void AdcClass::start (AdcPin_t adcPin) {
uint8_t pin;
if (working) return;
pin = (uint8_t)adcPin;
ADMUX = reference | (pin & 0x07); // select reference and input port
bitSet (ADCSRA, ADSC); // start a conversion
working = true;
}
int16_t AdcClass::readVal (void) {
int16_t rv;
// the ADC clears the bit when done
if (bit_is_clear(ADCSRA, ADSC) && working) {
rv = ADC; // read result
working = false;
return rv;
}
else {
return -1;
}
}
bool AdcClass::readAll (void) {
int16_t adcVal;
AdcPin_t pin = adcPins[pinIdx];
// Start a new ADC measurement
start (pin);
// Check if ADC finished detecting the value
adcVal = readVal ();
// ADC finished
if (adcVal >= 0) {
if (avgCount == 0) result[pin] = 0;
result[pin] += adcVal;
if (avgCount == avgSamples - 1) result[pin] = result[pin] / avgSamples;
pinIdx++;
if (pinIdx >= numPins) {
pinIdx = 0;
avgCount++;
if (avgCount >= avgSamples) {
avgCount = 0;
return true;
}
}
}
return false;
}