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/*
* Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* Interfaces and classes for generating width-modulated pulses - Pulse Width Modulation (PWM) - on a digital output line.
*
* In order to access and control a specific PWM channel, an application should first open and obtain an
* {@link jdk.dio.pwm.PWMChannel} instance for the PWM generator's channel the application wants to
* access and control, using its numeric ID, name, type (interface) and/or properties:
*
*
* - Using its ID
* -
*
*
* PWMChannel channel = (PWMChannel) DeviceManager.open(8);
*
*
* - Using its name and interface
* -
*
*
* PWMChannel channel = DeviceManager.open("DIMMER", PWMChannel.class, null);
*
*
*
*
*
* Once opened, an application can set the period of generated pulses using the
* {@link jdk.dio.pwm.PWMChannel#setPulsePeriod} method ; then generate pulses of a specified width or
* duty cycle by calling one of the {@link jdk.dio.pwm.PWMChannel#generate} or
* {@link jdk.dio.pwm.PWMChannel#startGeneration}.
*
*
* channel.setPulsePeriod(1000000); // Pulse period = 1 second
* channel.generate(500000, 10); // Generate 10 pulses with a width of 0.5 second
*
*
*
* When done, the application should call the {@link jdk.dio.pwm.PWMChannel#close
* PWMChannel.close} method to close PWM channel.
*
*
* channel.close();
*
*
*
* The following sample code gives an example of using the PWM channel API to progressively dim the light
* of a LED (for example) starting from its maximum intensity (100% duty cycle) in 10 successive steps of 10 seconds
* each:
*
*
* class VaryingDimmer implements GenerationRoundListener {
*
* private PWMChannel channel = null;
* private int step = 10;
*
* public void pulseGenerationCompleted(GenerationEvent event) {
* if (step > 0) {
* try {
* channel.startGeneration((channel.getPulsePeriod() / 10) * --step, 10, this);
* } catch (IOException ex) {
* // Ignored
* }
* }
* }
*
* public void start(int channelID) throws IOException, NonAvailableDeviceException, DeviceNotFoundException {
* if (channel != null) {
* throw new IllegalStateException();
* }
* channel = (PWMChannel) DeviceManager.open(channelID);
* channel.setPulsePeriod(1000000); // period = 1 second
* channel.startGeneration((channel.getPulsePeriod() / 10) * step, 10, this);
* }
*
* public void stop() throws IOException, NonAvailableDeviceException {
* if (channel != null) {
* channel.stopGeneration();
* channel.close();
* }
* }
*
* public void failed(Throwable exception, PWMChannel source) {
* // Ignored
* }
* }
*
*
*
* Because of performance issue, procedures handling PWM events, and especially event listeners, should be
* implemented to be as fast as possible.
*
* Unless otherwise noted, permission and security checks that may cause
* a {@link java.lang.SecurityException SecurityException} to be thrown must be performed
* in priority to any other checks or operations once performed the checking of the input parameters
* from which the permission target names and action lists are retrieved and assembled.
*
* Unless otherwise noted, passing a {@code null} argument to a constructor or method in any class
* or interface in this package will cause a {@link java.lang.NullPointerException NullPointerException} to be thrown.
*
* This package requires the {@link jdk.dio.gpio} package.
*
*
* @since 1.0
*/
package jdk.dio.pwm;