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