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Improve support and docs for ADC driver (#7191)

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* Improve support and docs for ADC driver

* Comment ADC channels

* Move to Makers and Modders section, and fix usage instructions

* Flesh out intro

* Superscript 328P note

* Fix pin_to_mux LUT

* Support USB64/1287 as well

* analogReadPin() defaults to 0V mux on invalid pin

* Update pinToMux() function documentation

* Dot

* Accept (some of) the `qmk cformat` changes

* Do clang-format properly

* More wording tweaks

* Link to encoder docs
This commit is contained in:
fauxpark 2019-12-08 12:11:29 +11:00 • committed by GitHub
parent f275ffbdfc
commit a8320f20f7
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4 changed files with 159 additions and 39 deletions
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110
drivers/avr/analog.c
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@ -14,24 +14,31 @@
* 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
static uint8_t aref = ADC_REF_POWER;
void analogReference(uint8_t mode) { aref = mode & 0xC0; }
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__)
static const uint8_t PROGMEM pin_to_mux[] = {0x00, 0x01, 0x04, 0x05, 0x06, 0x07, 0x25, 0x24, 0x23, 0x22, 0x21, 0x20};
// 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_AT90USB1286__)
#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__) || defined(__AVR_ATmega328P__)
if (pin >= 8) return 0;
return adc_read(pin);
#else
@ -39,20 +46,87 @@ int16_t analogRead(uint8_t pin) {
#endif
}
// Mux input
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__)
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
}
}
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!
// 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!
return (ADCH << 8) | low;
}