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IOIOLib/src/ioio/lib/api/DigitalInput.java
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IOIOLib/src/ioio/lib/api/DigitalInput.java
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/*
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* Copyright 2011 Ytai Ben-Tsvi. All rights reserved.
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*
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*
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* Redistribution and use in source and binary forms, with or without modification, are
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* permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this list of
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* conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice, this list
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* of conditions and the following disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ARSHAN POURSOHI OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* The views and conclusions contained in the software and documentation are those of the
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* authors and should not be interpreted as representing official policies, either expressed
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* or implied.
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*/
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package ioio.lib.api;
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import ioio.lib.api.exception.ConnectionLostException;
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/**
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* A pin used for digital input.
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* <p>
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* A digital input pin can be used to read logic-level signals. DigitalInput
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* instances are obtained by calling {@link IOIO#openDigitalInput(Spec)}.
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* <p>
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* The value of the pin is obtained by calling {@link #read()}. It is also
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* possible for the client to block until a certain level is sensed, by using
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* {@link #waitForValue(boolean)}.
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* <p>
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* The instance is alive since its creation. The first {@link #read()} call
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* block for a few milliseconds until the initial value is updated. If the
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* connection with the IOIO drops at any point, the instance transitions to a
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* disconnected state, in which every attempt to use the pin (except
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* {@link #close()}) will throw a {@link ConnectionLostException}. Whenever
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* {@link #close()} is invoked the instance may no longer be used. Any resources
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* associated with it are freed and can be reused.
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* <p>
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* Typical usage:
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*
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* <pre>
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* DigitalInput button = ioio.openDigitalInput(10); // used an external pull-up
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* button.waitForValue(false); // wait for press
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* ...
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* button.close(); // pin 10 can now be used for something else.
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* </pre>
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*/
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public interface DigitalInput extends Closeable {
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/**
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* A digital input pin specification, used when opening digital inputs.
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*/
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static public class Spec {
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/** Input pin mode. */
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public enum Mode {
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/**
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* Pin is floating. When the pin is left disconnected the value
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* sensed is undefined. Use this mode when an external pull-up or
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* pull-down resistor is used or when interfacing push-pull type
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* logic circuits.
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*/
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FLOATING,
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/**
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* Internal pull-up resistor is used. When the pin is left
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* disconnected, a logical "HIGH" (true) will be sensed. This is
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* useful for interfacing with open drain circuits or for
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* interacting with a switch connected between the pin and ground.
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*/
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PULL_UP,
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/**
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* Internal pull-down resistor is used. When the pin is left
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* disconnected, a logical "LOW" (false) will be sensed. This is
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* useful for interacting with a switch connected between the pin
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* and Vdd.
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*/
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PULL_DOWN
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}
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/** The pin number, as labeled on the board. */
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public int pin;
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/** The pin mode. */
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public Mode mode;
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/**
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* Constructor.
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*
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* @param pin
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* Pin number, as labeled on the board.
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* @param mode
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* Pin mode.
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*/
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public Spec(int pin, Mode mode) {
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this.pin = pin;
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this.mode = mode;
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}
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/** Shorthand for Spec(pin, Mode.FLOATING). */
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public Spec(int pin) {
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this(pin, Mode.FLOATING);
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}
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}
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/**
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* Read the value sensed on the pin. May block for a few milliseconds if
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* called right after creation of the instance. If this is a problem, the
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* calling thread may be interrupted.
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*
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* @return True for logical "HIGH", false for logical "LOW".
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* @throws InterruptedException
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* The calling thread has been interrupted.
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* @throws ConnectionLostException
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* The connection with the IOIO has been lost.
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*/
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public boolean read() throws InterruptedException, ConnectionLostException;
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/**
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* Block until a desired logical level is sensed. The calling thread can be
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* interrupted for aborting this operation.
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*
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* @param value
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* The desired logical level. true for "HIGH", false for "LOW".
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* @throws InterruptedException
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* The calling thread has been interrupted.
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* @throws ConnectionLostException
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* The connection with the IOIO has been lost.
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*/
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public void waitForValue(boolean value) throws InterruptedException,
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ConnectionLostException;
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}
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