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This bundle wraps Pi4j (http://pi4j.com) that wraps the native code Wiring Pi (http://wiringpi.com). It wraps these libraries to make them OSGi friendly and allow them to work together with the OSGi enRoute IoT circuit library (osgi.enroute.iot.circuit). The bundle will first use Pi4J to detect on what hardware it runs. If it runs on an appropriate type, it will register a component that can be configured with Metatype. The Metatype defines a full blown configuration template for all the Pi's functions. The GPIO's are registered as components for the circuit. Regardless of the success of the configuration, this bundle will also register a GpioController service, which is the main Pi4J class.

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package com.pi4j.wiringpi;

/*
 * #%L
 * **********************************************************************
 * ORGANIZATION  :  Pi4J
 * PROJECT       :  Pi4J :: Java Library (Core)
 * FILENAME      :  SoftPwm.java  
 * 
 * This file is part of the Pi4J project. More information about 
 * this project can be found here:  http://www.pi4j.com/
 * **********************************************************************
 * %%
 * Copyright (C) 2012 - 2015 Pi4J
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program 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 Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * .
 * #L%
 */


import com.pi4j.util.NativeLibraryLoader;

/**
 * 
 * WiringPi includes a software-driven PWM handler capable of outputting a PWM signal on any of the
 * Raspberry Pi's GPIO pins.
 * 
 * 
 * 
 * There are some limitations. To maintain a low CPU usage, the minimum pulse width is 100uS. That
 * combined with the default suggested range of 100 gives a PWM frequency of 100Hz. You can lower
 * the range to get a higher frequency, at the expense of resolution, or increase to get more
 * resolution, but that will lower the frequency. If you change the pulse-width in the drive code,
 * then be aware that at delays of less than 100uS wiringPi does it in a software loop, which means
 * that CPU usage will rise dramatically, and controlling more than one pin will be almost
 * impossible.
 * 
 * 
 * 
 * Also note that while the routines run themselves at a higher and real-time priority, Linux can
 * still affect the accuracy of the generated signal.
 * 
 * 
 * 
 * However, within these limitations, control of a light/LED or a motor is very achievable.
 * 
 * 
 * 
 *  You must initialize wiringPi with one of wiringPiSetup() or wiringPiSetupGpio() functions
 * beforehand. wiringPiSetupSys() is not fast enough, so you must run your programs with sudo. 
 * 
 * 
 * 
 * Before using the Pi4J library, you need to ensure that the Java VM in configured with access to
 * the following system libraries:
 * 

 * pi4j
 * wiringPi
 * pthread
 * 
 *  This library depends on the wiringPi native system library.
 (developed by
 * Gordon Henderson @ http://wiringpi.com/)
 * 
 * 
 * 
 * @see http://www.pi4j.com/
 * @see http://wiringpi.com/reference/software-pwm-library/
 * @author Robert Savage (http://www.savagehomeautomation.com)
 */
public class SoftPwm {

    // private constructor 
    private SoftPwm() {
        // forbid object construction 
    }
    
    static {
        // Load the platform library
        NativeLibraryLoader.load("libpi4j.so");
    }

    /**
     * int softPwmCreate (int pin, int initialValue, int pwmRange);
     * 
     * 
     * This creates a software controlled PWM pin. You can use any GPIO pin and the pin numbering
     * will be that of the wiringPiSetup function you used. Use 100 for the pwmRange, then the value
     * can be anything from 0 (off) to 100 (fully on) for the given pin.
     * 
     *
     * @see http://wiringpi.com/reference/software-pwm-library/
     * 
     * @param pin The GPIO pin to use as a PWM pin.
     *            
     * @param value The value to initialize the PWM pin (between 0 (off) to 100 (fully
     *            on))
     * @param range The maximum range. Use 100 for the pwmRange.
     * @return The return value is 0 for success. Anything else and you should check the global
     *         errno variable to see what went wrong.
     */
    public static native int softPwmCreate(int pin, int value, int range);

    /**
     * void softPwmWrite (int pin, int value);
     * 
     * 
     * This updates the PWM value on the given pin. The value is checked to be in-range and pins
     * that haven't previously been initialized via softPwmCreate will be silently ignored.
     * 
     *
     * @see http://wiringpi.com/reference/software-pwm-library/
     *
     * @param pin The GPIO pin to use as a PWM pin.
     * @param value The value to initialize the PWM pin (between 0 (off) to 100 (fully
     *            on))
     */
    public static native void softPwmWrite(int pin, int value);
}