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-rw-r--r--platforms/avr/drivers/analog.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/platforms/avr/drivers/analog.c b/platforms/avr/drivers/analog.c
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+++ b/platforms/avr/drivers/analog.c
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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 <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)); }
+
+// Arduino compatible pin input
+int16_t analogRead(uint8_t pin) {
+#if defined(__AVR_ATmega32U4__)
+ // clang-format off
+ static const uint8_t PROGMEM pin_to_mux[] = {
+ //A0 A1 A2 A3 A4 A5
+ //F7 F6 F5 F4 F1 F0
+ 0x07, 0x06, 0x05, 0x04, 0x01, 0x00,
+ //A6 A7 A8 A9 A10 A11
+ //D4 D7 B4 B5 B6 D6
+ 0x20, 0x22, 0x23, 0x24, 0x25, 0x21
+ };
+ // clang-format on
+ if (pin >= 12) return 0;
+ return adc_read(pgm_read_byte(pin_to_mux + pin));
+#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__) || defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)
+ if (pin >= 8) return 0;
+ return adc_read(pin);
+#else
+ return 0;
+#endif
+}
+
+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;
+}