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diff --git a/source/lang/api/analogread.rst b/source/lang/api/analogread.rst deleted file mode 100644 index 6665a94..0000000 --- a/source/lang/api/analogread.rst +++ /dev/null @@ -1,119 +0,0 @@ -.. highlight:: cpp - -.. _lang-analogread: - -.. _lang-api-analogread: - -analogRead() -============ - -Used to perform ADC conversion. - -.. contents:: Contents - :local: - -Library Documentation ---------------------- - -.. doxygenfunction:: analogRead - -Discussion ----------- - -Reads the value from the specified analog pin. The Maple boards -contain 16-channel, 12-bit analog to digital converters. This means -that a converter will map input voltages between 0 and 3.3 volts into -integer values between 0 and 4095. However, a number of factors -interfere with getting full accuracy and precision. For more -information, see :ref:`adc`. - -Before calling analogRead() on a pin, that pin must first be -configured for analog input, using :ref:`lang-pinMode`. You only have -to do this once, so it's usually done in :ref:`lang-setup`\ . - -Parameter Discussion --------------------- - -The pin parameter is the number of the analog input pin to read from. -The pins which support analog to digital conversion have ``AIN`` -listed underneath their number on your board's silkscreen. These pin -numbers are available to your program in the :ref:`boardADCPins -<lang-board-values-adc-pins>` board-specific array. The number of -pins which are capable of analog to digital conversion on your board -is given by the ``BOARD_NR_ADC_PINS`` constant. These values are -documented for each board in the :ref:`Board Hardware Documentation -<index-boards>` pages. - -.. note:: Pin 3 is not marked ``AIN`` on the silkscreen for Maple - revisions through Rev 5; however **it does work** as an analog - input pin. - -Note ----- - -If the analog input pin is not connected to anything, the value -returned by ``analogRead()`` will fluctuate due to a number of reasons -(like the values of the other analog inputs, how close your hand is to -the board, etc.) in a "random" way. - -Example -------- - -:: - - int analogPin = 3; // Potentiometer wiper (middle terminal) connected - // to analog pin 3. outside leads to ground and +3.3V. - // You may have to change this value if your board - // cannot perform ADC conversion on pin 3. - - int val = 0; // variable to store the value read - - void setup() { - pinMode(analogPin, INPUT_ANALOG); // set up pin for analog input - } - - void loop() { - val = analogRead(analogPin); // read the input pin - SerialUSB.println(val); // print the value, for debugging with - // a serial monitor - } - -Arduino Compatibility ---------------------- - -The Arduino board contains a 6 channel (8 channels on the Mini and -Nano, 16 on the Mega), 10-bit analog to digital converter with an -input voltage range of 0V--5V. This means that it will map input -voltages between 0 and 5 volts (which is **larger** than Maple's range -of 0V-3.3V) into integer values between 0 and 1023 (which is -**smaller** than the Maple's range of 0--4095). - -This yields a theoretical resolution between readings of: 5 volts / -1024 units or .0049 volts (4.9 mV) per unit on Arduino boards, which -is larger, and thus less precise, than Maple's 0.0008 volts (0.8 mV). - -If your program expects Arduino-style 10-bit ADC, you can :ref:`right -shift <lang-bitshift>` the value of a Maple readout by 2, like so:: - - // right shift means that the result will be between 0 and 1023; - // be aware that you're losing a lot of precision if you do this - int adc_reading = analogRead(pin) >> 2; - -.. FIXME [0.1.0] Mention that Native can do analogReference() - -On the Arduino, the input range and resolution can be changed using -the `analogReference() -<http://arduino.cc/en/Reference/AnalogReference>`_ function. Because -of hardware restrictions, this function is not available on the Maple -and Maple RET6 Edition. If your inputs lie in a different voltage -range than 0V--3.3V, you'll need to bring them into that range before -using ``analogRead()``. See the :ref:`ADC reference <adc-range>` for -more information. - -See Also --------- - -- :ref:`ADC tutorial <adc>` -- `(Arduino) Tutorial: Analog Input Pins <http://arduino.cc/en/Tutorial/AnalogInputPins>`_ - -.. include:: /arduino-cc-attribution.txt |