- /* 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 <avr/io.h>
- #include <avr/pgmspace.h>
- #include <stdint.h>
- #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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