allwpilib/wpilibj/src/athena/java/edu/wpi/first/wpilibj/AnalogAccelerometer.java

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2012. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
/*----------------------------------------------------------------------------*/

package edu.wpi.first.wpilibj;

import edu.wpi.first.wpilibj.communication.FRCNetworkCommunicationsLibrary.tResourceType;
import edu.wpi.first.wpilibj.communication.UsageReporting;
import edu.wpi.first.wpilibj.livewindow.LiveWindow;
import edu.wpi.first.wpilibj.livewindow.LiveWindowSendable;
import edu.wpi.first.wpilibj.tables.ITable;


/**
 * Handle operation of an analog accelerometer. The accelerometer reads
 * acceleration directly through the sensor. Many sensors have multiple axis and
 * can be treated as multiple devices. Each is calibrated by finding the center
 * value over a period of time.
 */
public class AnalogAccelerometer extends SensorBase implements PIDSource, LiveWindowSendable {

  private AnalogInput m_analogChannel;
  private double m_voltsPerG = 1.0;
  private double m_zeroGVoltage = 2.5;
  private boolean m_allocatedChannel;
  protected PIDSourceType m_pidSource = PIDSourceType.kDisplacement;

  /**
   * Common initialization
   */
  private void initAccelerometer() {
    UsageReporting.report(tResourceType.kResourceType_Accelerometer, m_analogChannel.getChannel());
    LiveWindow.addSensor("Accelerometer", m_analogChannel.getChannel(), this);
  }

  /**
   * Create a new instance of an accelerometer.
   *
   * The constructor allocates desired analog channel.
   *$
   * @param channel The channel number for the analog input the accelerometer is
   *        connected to
   */
  public AnalogAccelerometer(final int channel) {
    m_allocatedChannel = true;
    m_analogChannel = new AnalogInput(channel);
    initAccelerometer();
  }

  /**
   * Create a new instance of Accelerometer from an existing AnalogChannel. Make
   * a new instance of accelerometer given an AnalogChannel. This is
   * particularly useful if the port is going to be read as an analog channel as
   * well as through the Accelerometer class.
   *$
   * @param channel The existing AnalogInput object for the analog input the
   *        accelerometer is connected to
   */
  public AnalogAccelerometer(AnalogInput channel) {
    m_allocatedChannel = false;
    if (channel == null)
      throw new NullPointerException("Analog Channel given was null");
    m_analogChannel = channel;
    initAccelerometer();
  }

  /**
   * Delete the analog components used for the accelerometer.
   */
  public void free() {
    if (m_analogChannel != null && m_allocatedChannel) {
      m_analogChannel.free();
    }
    m_analogChannel = null;
  }

  /**
   * Return the acceleration in Gs.
   *
   * The acceleration is returned units of Gs.
   *
   * @return The current acceleration of the sensor in Gs.
   */
  public double getAcceleration() {
    return (m_analogChannel.getAverageVoltage() - m_zeroGVoltage) / m_voltsPerG;
  }

  /**
   * Set the accelerometer sensitivity.
   *
   * This sets the sensitivity of the accelerometer used for calculating the
   * acceleration. The sensitivity varies by accelerometer model. There are
   * constants defined for various models.
   *
   * @param sensitivity The sensitivity of accelerometer in Volts per G.
   */
  public void setSensitivity(double sensitivity) {
    m_voltsPerG = sensitivity;
  }

  /**
   * Set the voltage that corresponds to 0 G.
   *
   * The zero G voltage varies by accelerometer model. There are constants
   * defined for various models.
   *
   * @param zero The zero G voltage.
   */
  public void setZero(double zero) {
    m_zeroGVoltage = zero;
  }

  /**
   * {@inheritDoc}
   */
  public void setPIDSourceType(PIDSourceType pidSource) {
    m_pidSource = pidSource;
  }

  /**
   * {@inheritDoc}
   */
  public PIDSourceType getPIDSourceType() {
    return m_pidSource;
  }

  /**
   * Get the Acceleration for the PID Source parent.
   *
   * @return The current acceleration in Gs.
   */
  public double pidGet() {
    return getAcceleration();
  }

  public String getSmartDashboardType() {
    return "Accelerometer";
  }

  /*
   * Live Window code, only does anything if live window is activated.
   */
  private ITable m_table;

  /**
   * {@inheritDoc}
   */
  public void initTable(ITable subtable) {
    m_table = subtable;
    updateTable();
  }

  /**
   * {@inheritDoc}
   */
  public ITable getTable() {
    return m_table;
  }

  /**
   * {@inheritDoc}
   */
  public void updateTable() {
    if (m_table != null) {
      m_table.putNumber("Value", getAcceleration());
    }
  }

  /**
   * Analog Channels don't have to do anything special when entering the
   * LiveWindow. {@inheritDoc}
   */
  public void startLiveWindowMode() {}

  /**
   * Analog Channels don't have to do anything special when exiting the
   * LiveWindow. {@inheritDoc}
   */
  public void stopLiveWindowMode() {}
}