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/* Copyright 2015 Jack Humbert
*
* 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 2 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 "analog.h"
static uint8_t aref = ADC_REF_POWER;
void analogReference(uint8_t mode) {
aref = mode & (_BV(REFS1) | _BV(REFS0));
}
int16_t analogReadPin(pin_t pin) {
return adc_read(pinToMux(pin));
}
uint8_t pinToMux(pin_t pin) {
switch (pin) {
// clang-format off
#if defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
case F0: return 0; // ADC0
case F1: return _BV(MUX0); // ADC1
case F2: return _BV(MUX1); // ADC2
case F3: return _BV(MUX1) | _BV(MUX0); // ADC3
case F4: return _BV(MUX2); // ADC4
case F5: return _BV(MUX2) | _BV(MUX0); // ADC5
case F6: return _BV(MUX2) | _BV(MUX1); // ADC6
case F7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // ADC7
default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
#elif defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
case F0: return 0; // ADC0
case F1: return _BV(MUX0); // ADC1
case F4: return _BV(MUX2); // ADC4
case F5: return _BV(MUX2) | _BV(MUX0); // ADC5
case F6: return _BV(MUX2) | _BV(MUX1); // ADC6
case F7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // ADC7
case D4: return _BV(MUX5); // ADC8
case D6: return _BV(MUX5) | _BV(MUX0); // ADC9
case D7: return _BV(MUX5) | _BV(MUX1); // ADC10
case B4: return _BV(MUX5) | _BV(MUX1) | _BV(MUX0); // ADC11
case B5: return _BV(MUX5) | _BV(MUX2); // ADC12
case B6: return _BV(MUX5) | _BV(MUX2) | _BV(MUX0); // ADC13
default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
#elif defined(__AVR_ATmega32A__)
case A0: return 0; // ADC0
case A1: return _BV(MUX0); // ADC1
case A2: return _BV(MUX1); // ADC2
case A3: return _BV(MUX1) | _BV(MUX0); // ADC3
case A4: return _BV(MUX2); // ADC4
case A5: return _BV(MUX2) | _BV(MUX0); // ADC5
case A6: return _BV(MUX2) | _BV(MUX1); // ADC6
case A7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // ADC7
default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
#elif defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)
case C0: return 0; // ADC0
case C1: return _BV(MUX0); // ADC1
case C2: return _BV(MUX1); // ADC2
case C3: return _BV(MUX1) | _BV(MUX0); // ADC3
case C4: return _BV(MUX2); // ADC4
case C5: return _BV(MUX2) | _BV(MUX0); // ADC5
// ADC7:6 not present in DIP package and not shared by GPIO pins
default: return _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
#endif
// clang-format on
}
return 0;
}
int16_t adc_read(uint8_t mux) {
uint16_t low;
// Enable ADC and configure prescaler
ADCSRA = _BV(ADEN) | ADC_PRESCALER;
#if defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
// High speed mode and ADC8-13
ADCSRB = _BV(ADHSM) | (mux & _BV(MUX5));
#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
// High speed mode only
ADCSRB = _BV(ADHSM);
#endif
// Configure mux input
#if defined(MUX4)
ADMUX = aref | (mux & (_BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0)));
#else
ADMUX = aref | (mux & (_BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0)));
#endif
// Start the conversion
ADCSRA |= _BV(ADSC);
// Wait for result
while (ADCSRA & _BV(ADSC))
;
// Must read LSB first
low = ADCL;
// Must read MSB only once!
low |= (ADCH << 8);
// turn off the ADC
ADCSRA &= ~(1 << ADEN);
return low;
}
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