CapSenseImpl.java

/*
 * Copyright 2013 Ytai Ben-Tsvi. All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 *    1. Redistributions of source code must retain the above copyright notice, this list of
 *       conditions and the following disclaimer.
 *
 *    2. Redistributions in binary form must reproduce the above copyright notice, this list
 *       of conditions and the following disclaimer in the documentation and/or other materials
 *       provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ARSHAN POURSOHI OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation are those of the
 * authors and should not be interpreted as representing official policies, either expressed
 * or implied.
 */
package ioio.lib.impl;

import java.io.IOException;

import ioio.lib.api.CapSense;
import ioio.lib.api.exception.ConnectionLostException;
import ioio.lib.impl.IncomingState.InputPinListener;

class CapSenseImpl extends AbstractPin implements CapSense, InputPinListener {
    private static final float CHARGE = 89.1f; // In [pC] units.
    private static final float SAMPLE_PERIOD_MS = 16.f;
    private float value_;
    private long sampleCount_ = 0;
    private float coef_;

    CapSenseImpl(IOIOImpl ioio, ResourceManager.Resource pin, float filterCoef)
            throws ConnectionLostException {
        super(ioio, pin);
        setFilterCoef(filterCoef);
    }

    @Override
    synchronized public void setValue(int value) {
        assert (value >= 0 && value < 1024);
        final float fVal = value / 1023.f;
        if (sampleCount_ == 0) {
            value_ = fVal;
        } else {
            value_ = fVal * (1.f - coef_) + value_ * coef_;
        }
        ++sampleCount_;
        notifyAll();
    }

    @Override
    synchronized public float read() throws InterruptedException,
            ConnectionLostException {
        checkState();
        while (sampleCount_ == 0) {
            safeWait();
        }
        final float voltage = 3.3f * value_;
        return CHARGE / voltage;
    }

    @Override
    public synchronized float readSync() throws InterruptedException, ConnectionLostException {
        checkState();
        final long initialSampleCount = sampleCount_;
        // Wait for sample count to increase.
        while (sampleCount_ == initialSampleCount) {
            safeWait();
        }
        final float voltage = 3.3f * value_;
        return CHARGE / voltage;
    }

    @Override
    public synchronized void waitOver(float threshold) throws ConnectionLostException,
            InterruptedException {
        while (read() <= threshold) {
            wait();
        }
    }

    @Override
    public synchronized void waitOverSync(float threshold) throws ConnectionLostException, InterruptedException {
        while (readSync() <= threshold) {
            wait();
        }
    }

    @Override
    public synchronized void waitUnder(float threshold)
            throws ConnectionLostException, InterruptedException {
        while (read() >= threshold) {
            wait();
        }
    }

    @Override
    public synchronized void waitUnderSync(float threshold) throws ConnectionLostException, InterruptedException {
        while (readSync() >= threshold) {
            wait();
        }
    }

    @Override
    public synchronized void close() {
        checkClose();
        try {
            ioio_.protocol_.setCapSenseSampling(pin_.id, false);
        } catch (IOException e) {
        }
        super.close();
    }

    @Override
    public synchronized void setFilterCoef(float t)
            throws ConnectionLostException {
        // We define t as the time it takes for an impulse response to fade to
        // 0.1.
        coef_ = (float) Math.pow(0.1, SAMPLE_PERIOD_MS / t);
    }
}