mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
77 lines
1.6 KiB
C++
77 lines
1.6 KiB
C++
//
|
|
// FILE: AsyncAnalog.cpp
|
|
// AUTHOR: Rob Tillaart
|
|
// VERSION: 0.2.0
|
|
// DATE: 2018-09-05
|
|
// PURPOSE: Async version of analogRead, prevent blocking wait
|
|
// URL: https://github.com/RobTillaart/AsyncAnalog
|
|
|
|
|
|
#include "AsyncAnalog.h"
|
|
|
|
|
|
#if defined(ARDUINO_ARCH_AVR)
|
|
|
|
AsyncAnalog::AsyncAnalog(const uint8_t pin)
|
|
{
|
|
_pin = pin;
|
|
#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
|
|
if (_pin >= 54) _pin -= 54;
|
|
#else
|
|
if (_pin >= 14) _pin -= 14;
|
|
#endif
|
|
}
|
|
|
|
|
|
void AsyncAnalog::start()
|
|
{
|
|
#if defined(ADCSRB) && defined(MUX5)
|
|
// the MUX5 bit of ADCSRB selects whether we're reading from channels
|
|
// 0 to 7 (MUX5 low) or 8 to 15 (MUX5 high).
|
|
ADCSRB = (ADCSRB & ~(1 << MUX5)) | (((_pin >> 3) & 0x01) << MUX5);
|
|
#endif
|
|
|
|
#if defined(ADMUX)
|
|
// set the analogue reference (high two bits of ADMUX) and select the
|
|
// channel (low 4 bits). this also sets ADLAR (left-adjust result)
|
|
// to 0 (the default).
|
|
ADMUX = (DEFAULT << 6) | (_pin & 0x07);
|
|
#endif
|
|
|
|
sbi(ADCSRA, ADSC);
|
|
}
|
|
|
|
|
|
bool AsyncAnalog::ready()
|
|
{
|
|
// ADSC is cleared when the conversion finishes
|
|
bool _ready = bit_is_set(ADCSRA, ADSC) == 0;
|
|
|
|
if (_ready) // calculate the measurement
|
|
{
|
|
// ADCL has to be read first.
|
|
// Doing so locks both ADCL and ADCH until ADCH is read.
|
|
// Reading ADCL second would cause the results of each conversion to
|
|
// be discarded as ADCL and ADCH would be locked when it completed.
|
|
uint16_t lo = ADCL;
|
|
uint16_t hi = ADCH;
|
|
// Combine two parts.
|
|
_lastValue = (hi * 256) + lo;
|
|
}
|
|
return _ready;
|
|
}
|
|
|
|
|
|
uint16_t AsyncAnalog::value()
|
|
{
|
|
return _lastValue;
|
|
}
|
|
|
|
#else
|
|
|
|
|
|
#endif // ARDUINO_ARCH_AVR
|
|
|
|
|
|
// -- END OF FILE --
|