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‎AsyncAnalog.cpp‎

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//
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// FILE: AsyncAnalog.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.1
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// DATE: 2018-09-05
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// PURPOSE: async version of analogRead, prevent blocking wait
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//
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// backgrounder
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// https://www.avrfreaks.net/forum/tut-c-newbies-guide-avr-adc?name=PNphpBB2&file=viewtopic&t=56429
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//
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// HISTORY:
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// 0.1.0 2018-09-05 initial version, based upon analogRead()
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// 0.1.1 2020-03-26 minor refactor
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//
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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 analog 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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return bit_is_set(ADCSRA, ADSC) == 0;
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}
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int AsyncAnalog::value()
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{
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// we have to read ADCL first; doing so locks both ADCL
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// and ADCH until ADCH is read. reading ADCL second would
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// cause the results of each conversion to be discarded,
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// as ADCL and ADCH would be locked when it completed.
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int low = ADCL;
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int high = ADCH;
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// combine the two bytes
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return (high << 8) | low;
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}
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#endif // ARDUINO_ARCH_AVR
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// -- END OF FILE --

‎AsyncAnalog.h‎

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#pragma once
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//
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// FILE: AsyncAnalog.h
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.1
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// DATE: 2018-09-05
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// PURPOSE: async version of analogRead
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// URL: https://github.com/RobTillaart/AsyncAnalog
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//
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#if !defined(ARDUINO_ARCH_AVR)
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#error “AsyncAnalog library 0.1.1 only supports boards with an AVR processor .”
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#endif
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// (ARDUINO_ARCH_SAM) future
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#include "Arduino.h"
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#include "wiring_private.h"
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#include "pins_arduino.h"
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#define ASYNCANALOG_LIB_VERSION "0.1.1"
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class AsyncAnalog
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{
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public:
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AsyncAnalog(uint8_t pin);
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void start();
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bool ready();
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int value();
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private:
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uint8_t _pin;
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};
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// -- END OF FILE --

‎LICENSE‎

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MIT License
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3-
Copyright (c) 2020 Rob Tillaart
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Copyright (c) 2018-2020 Rob Tillaart
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal

‎README.md‎

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# AsyncAnalog
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Arduino Library for async reading of an analog pin [AVR only for now]
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Arduino Library for async reading of an analog pin. **\[AVR ONLY\]**
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## Description
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AsyncAnalog is a library to read the analog port in an asynchronous way.
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This means that the user must explicitly **start** the ADC, check if it is **ready**
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and read out its **value**.
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By using this class, the user prevents the (112 uSec) blocking of the
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**analogRead()** call, and gives the user the ability to do some processing.
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The library works only for AVR boards now, other platforms might be supported in the future.
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As the UNO has only one ADC that is multiplexed, one can only read one analog pin
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in async way simultaneously.
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## Operation
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The library consists of three main function:
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* **void start()**
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* **bool ready()**
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* **int value()**
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The example **asyncAnalogTest2.ino** shows a loop of 1000 analogReads and prints
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over Serial at 115200 baud. The async test does this in less time. Note that faster
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baudrates shows an even bigger difference.
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‎examples/asyncAnalogTest/asyncAnalogTest.ino‎

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//
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// FILE: asyncAnalogTest.ino
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.1
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// DATE: 2018-09-05
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#include "AsyncAnalog.h"
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AsyncAnalog AA(A0);
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uint32_t start = 0;
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uint32_t duration = 0;
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uint16_t count = 0;
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void setup()
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{
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Serial.begin(115200);
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Serial.println("start: ");
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Serial.println(analogRead(0));
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AA.start();
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start = micros();
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}
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void loop()
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{
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// if sample ready
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if (AA.ready())
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{
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// process sample
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duration = micros() - start;
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Serial.print(duration);
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Serial.print("\t");
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Serial.print(AA.value());
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Serial.print("\t");
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Serial.print(count);
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Serial.println();
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// request a new sample
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AA.start();
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start = micros();
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count = 0;
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}
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// do other stuff here
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count++;
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}
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// END OF FILE

‎examples/asyncAnalogTest2/asyncAnalogTest2.ino‎

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//
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// FILE: asyncAnalogTest2.ino
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.0
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// DATE: 2020-03-27
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#include "AsyncAnalog.h"
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AsyncAnalog AA(A0);
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uint32_t start = 0;
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uint32_t duration = 0;
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void setup()
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{
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Serial.begin(115200);
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Serial.println("start: ");
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Serial.println(analogRead(0));
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}
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void loop()
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{
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normal_test();
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delay(1000);
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async_test();
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delay(1000);
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}
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void normal_test()
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{
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Serial.println();
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Serial.println(__FUNCTION__);
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start = micros();
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for (int i = 0; i < 1000; i++)
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{
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int x = analogRead(A0);
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Serial.println(x);
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}
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duration = micros() - start;
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Serial.print(duration);
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Serial.print("\n\n");
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}
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void async_test()
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{
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int x = 0;
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Serial.println();
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Serial.println(__FUNCTION__);
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start = micros();
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AA.start();
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for (int i = 0; i < 1000; i++)
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{
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if (AA.ready())
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{
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x = AA.value(); // read the value
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AA.start(); // request next conversion
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Serial.println(x); // print value while conversion runs in the background
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}
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}
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duration = micros() - start;
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Serial.print(duration);
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Serial.print("\n\n");
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}
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// END OF FILE

‎library.json‎

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{
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"name": "AsyncAnalog",
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"keywords": "analogRead,smooth,analog,pin,noise,reduction",
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"description": "Class for smoothing analogReads.",
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"authors":
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[
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{
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"name": "Rob Tillaart",
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"email": "Rob.Tillaart@gmail.com",
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"maintainer": true
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}
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],
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"repository":
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{
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"type": "git",
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"url": "https://github.com/RobTillaart/AsyncAnalog.git"
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},
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"version":"0.1.1",
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"frameworks": "arduino",
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"platforms": "*",
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"export": {
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"include": "AsyncAnalog"
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}
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}

‎library.properties‎

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name=AsyncAnalog
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version=0.1.1
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author=Rob Tillaart <rob.tillaart@gmail.com>
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maintainer=Rob Tillaart <rob.tillaart@gmail.com>
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sentence=Arduino Library for async reading of an analog pin
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paragraph=AVR only for now.
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category=Signal Input/Output
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url=https://github.com/RobTillaart/AsyncAnalog
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architectures=avr
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include=AsyncAnalog.h
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depends=

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