117 lines
4.4 KiB
C
117 lines
4.4 KiB
C
/* Copyright 2015 Jack Humbert
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "analog.h"
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static uint8_t aref = ADC_REF_POWER;
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void analogReference(uint8_t mode) {
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aref = mode & (_BV(REFS1) | _BV(REFS0));
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}
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int16_t analogReadPin(pin_t pin) {
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return adc_read(pinToMux(pin));
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}
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uint8_t pinToMux(pin_t pin) {
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switch (pin) {
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// clang-format off
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#if defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
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case F0: return 0; // ADC0
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case F1: return _BV(MUX0); // ADC1
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case F2: return _BV(MUX1); // ADC2
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case F3: return _BV(MUX1) | _BV(MUX0); // ADC3
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case F4: return _BV(MUX2); // ADC4
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case F5: return _BV(MUX2) | _BV(MUX0); // ADC5
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case F6: return _BV(MUX2) | _BV(MUX1); // ADC6
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case F7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // ADC7
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default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
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#elif defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
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case F0: return 0; // ADC0
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case F1: return _BV(MUX0); // ADC1
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case F4: return _BV(MUX2); // ADC4
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case F5: return _BV(MUX2) | _BV(MUX0); // ADC5
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case F6: return _BV(MUX2) | _BV(MUX1); // ADC6
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case F7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // ADC7
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case D4: return _BV(MUX5); // ADC8
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case D6: return _BV(MUX5) | _BV(MUX0); // ADC9
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case D7: return _BV(MUX5) | _BV(MUX1); // ADC10
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case B4: return _BV(MUX5) | _BV(MUX1) | _BV(MUX0); // ADC11
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case B5: return _BV(MUX5) | _BV(MUX2); // ADC12
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case B6: return _BV(MUX5) | _BV(MUX2) | _BV(MUX0); // ADC13
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default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
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#elif defined(__AVR_ATmega32A__)
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case A0: return 0; // ADC0
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case A1: return _BV(MUX0); // ADC1
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case A2: return _BV(MUX1); // ADC2
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case A3: return _BV(MUX1) | _BV(MUX0); // ADC3
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case A4: return _BV(MUX2); // ADC4
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case A5: return _BV(MUX2) | _BV(MUX0); // ADC5
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case A6: return _BV(MUX2) | _BV(MUX1); // ADC6
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case A7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // ADC7
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default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
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#elif defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)
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case C0: return 0; // ADC0
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case C1: return _BV(MUX0); // ADC1
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case C2: return _BV(MUX1); // ADC2
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case C3: return _BV(MUX1) | _BV(MUX0); // ADC3
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case C4: return _BV(MUX2); // ADC4
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case C5: return _BV(MUX2) | _BV(MUX0); // ADC5
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// ADC7:6 not present in DIP package and not shared by GPIO pins
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default: return _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0); // 0V
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#endif
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// clang-format on
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}
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return 0;
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}
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int16_t adc_read(uint8_t mux) {
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uint16_t low;
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// Enable ADC and configure prescaler
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ADCSRA = _BV(ADEN) | ADC_PRESCALER;
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#if defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
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// High speed mode and ADC8-13
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ADCSRB = _BV(ADHSM) | (mux & _BV(MUX5));
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#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
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// High speed mode only
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ADCSRB = _BV(ADHSM);
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#endif
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// Configure mux input
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#if defined(MUX4)
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ADMUX = aref | (mux & (_BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0)));
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#else
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ADMUX = aref | (mux & (_BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0)));
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#endif
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// Start the conversion
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ADCSRA |= _BV(ADSC);
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// Wait for result
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while (ADCSRA & _BV(ADSC))
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;
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// Must read LSB first
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low = ADCL;
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// Must read MSB only once!
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low |= (ADCH << 8);
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// turn off the ADC
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ADCSRA &= ~(1 << ADEN);
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return low;
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}
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