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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      :  Gertboard.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;

/**
 * 
 * The Gertboard has an on-board Digital to Analog (DAC) converter and an Analog to Digital (ADC)
 * converters. These are connected via the SPI bus back to the Raspberry Pi host.
 * 
 * 
 * 
 * Each of the DAC and ADC chips has 2 channels.
 * 
 * 
 * 
 * The DAC has a resolution of 8 bits and produces an output voltage between 0 and 2.047 volts, the
 * ADC has a resolution of 10 bits and can take an input voltage between 0 and 3.3 volts.
 * 
 * 
 * 
 * Part of the wiringPi library includes code to setup and drive these chips in an easy to use
 * manner.
 * 
 * 
 * 
 * To use in a program, first you need to make sure that the 5 SPI jumpers are present on the
 * Gertboard (there are 7 in total, 5 for the SPI, 2 to connect the serial to the ATmega), the
 * photo below shows all 7 jumpers in-place.
 * 
 * 
 * 
 * Before using the Pi4J library, you need to ensure that the Java VM in configured with access to
 * the following system libraries:
 * 

 * pi4j
 * wiringPi
 * 
 *  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/dev-lib/gertboard-analog/
 * @author Robert Savage (http://www.savagehomeautomation.com)
 */
public class Gertboard {

    public static final int SPI_ADC_SPEED = 1000000;
    public static final int SPI_DAC_SPEED = 1000000;
    public static final int SPI_A2D = 0;
    public static final int SPI_D2A = 1;

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

    /**
     *  This outputs the supplied value (0-255) to the given channel (0 or 1). The output voltage is:
     * 
     * 
     * vOut = value / 255 * 2.047
     * 
     * 
     * or to find the value for a given voltage:
     * 
     *      * value = vOut / 2.047 * 255
     * 
     * 
     * @see http://wiringpi.com/dev-lib/gertboard-analog/
     * @param chan  Analog channel to write to (0 or 1).
     * @param value The output value (0-255) supplied to the given channel (0 or 1).
     */
    public static native void gertboardAnalogWrite(int chan, int value);

    /**
     *  This returns a value from 0 to 1023 representing the value on the supplied channel (0 or 1).
     * To convert this to a voltage, use the following formula:
     * 
     * 
     * vIn = value * 3.3 / 1023
     * 
     * 
     *
     * @see http://wiringpi.com/dev-lib/gertboard-analog/
     * @param chan Analog channel to read from (0 or 1).
     * @return This returns a value from 0 to 1023 representing the value on the supplied channel (0
     *         or 1).
     */
    public static native int gertboardAnalogRead(int chan);

    /**
     *  This must be called to initialize the SPI bus to communicate with the Gertboards ADC and DAC
     * chips. If the return value is < 0 then an error occurred and errno will be set appropriately.
     * 
     *
     * @see http://wiringpi.com/dev-lib/gertboard-analog/
     * @return If the return value is < 0 then an error occurred and errno will be set
     *         appropriately. If the return value is '0' or greater than the call was successful.
     */
    public static native int gertboardSPISetup();



    /**
     * 
     * This setup routine allocates 2 pins and overlays the analog to digital input pins with the digital to analog
     * output pins. So reading channel pinBase + 0 reads the first analog input channel (pin DA0 on the Gertboard),
     * and writing pinBase + 0 outputs to the first analog output channel. (Pin AD0).
     * 
     *
     * @see http://wiringpi.com/dev-lib/gertboard-analog/
     * @param pinBase pinBase is the base pin that you want the analog ports to appear as
     * @return If the return value is < 0 then an error occurred and errno will be set
     *         appropriately. If the return value is '0' or greater than the call was successful.
     */
    public static native int gertboardAnalogSetup(int pinBase);
}