diff options
author | Callum Oakley <callum@pusher.com> | 2017-08-19 10:34:45 +0100 |
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committer | Callum Oakley <callum@pusher.com> | 2017-08-19 10:34:45 +0100 |
commit | a6845036e25c4f4d936dcd12cd0ddedd2894b30e (patch) | |
tree | b23b4e8d9d757aa3c0d42be561572533ae0d126c /drivers/avr/analog.c | |
parent | 84a8aabe5bf8807595f98de44d18f6a31b892edf (diff) | |
parent | 7277f09bbadcce120f819132dec8ff7172caacc4 (diff) |
Merge branch 'master' of https://github.com/qmk/qmk_firmware
Diffstat (limited to 'drivers/avr/analog.c')
-rw-r--r-- | drivers/avr/analog.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/drivers/avr/analog.c b/drivers/avr/analog.c new file mode 100644 index 0000000000..1ec38df75d --- /dev/null +++ b/drivers/avr/analog.c @@ -0,0 +1,69 @@ +/* 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/>. + */ + +// Simple analog to digitial conversion + +#include <avr/io.h> +#include <avr/pgmspace.h> +#include <stdint.h> +#include "analog.h" + + +static uint8_t aref = (1<<REFS0); // default to AREF = Vcc + + +void analogReference(uint8_t mode) +{ + aref = mode & 0xC0; +} + + +// Arduino compatible pin input +int16_t analogRead(uint8_t pin) +{ +#if defined(__AVR_ATmega32U4__) + static const uint8_t PROGMEM pin_to_mux[] = { + 0x00, 0x01, 0x04, 0x05, 0x06, 0x07, + 0x25, 0x24, 0x23, 0x22, 0x21, 0x20}; + if (pin >= 12) return 0; + return adc_read(pgm_read_byte(pin_to_mux + pin)); +#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__) + if (pin >= 8) return 0; + return adc_read(pin); +#else + return 0; +#endif +} + +// Mux input +int16_t adc_read(uint8_t mux) +{ +#if defined(__AVR_AT90USB162__) + return 0; +#else + uint8_t low; + + ADCSRA = (1<<ADEN) | ADC_PRESCALER; // enable ADC + ADCSRB = (1<<ADHSM) | (mux & 0x20); // high speed mode + ADMUX = aref | (mux & 0x1F); // configure mux input + ADCSRA = (1<<ADEN) | ADC_PRESCALER | (1<<ADSC); // start the conversion + while (ADCSRA & (1<<ADSC)) ; // wait for result + low = ADCL; // must read LSB first + return (ADCH << 8) | low; // must read MSB only once! +#endif +} + + |