001// Copyright (c) FIRST and other WPILib contributors.
002// Open Source Software; you can modify and/or share it under the terms of
003// the WPILib BSD license file in the root directory of this project.
004
005package edu.wpi.first.wpilibj;
006
007import static edu.wpi.first.util.ErrorMessages.requireNonNullParam;
008
009import edu.wpi.first.hal.FRCNetComm.tResourceType;
010import edu.wpi.first.hal.HAL;
011import edu.wpi.first.util.sendable.Sendable;
012import edu.wpi.first.util.sendable.SendableBuilder;
013import edu.wpi.first.util.sendable.SendableRegistry;
014
015/**
016 * Handle operation of an analog accelerometer. The accelerometer reads acceleration directly
017 * through the sensor. Many sensors have multiple axis and can be treated as multiple devices. Each
018 * is calibrated by finding the center value over a period of time.
019 */
020public class AnalogAccelerometer implements Sendable, AutoCloseable {
021  private AnalogInput m_analogChannel;
022  private double m_voltsPerG = 1.0;
023  private double m_zeroGVoltage = 2.5;
024  private final boolean m_allocatedChannel;
025
026  /** Common initialization. */
027  private void initAccelerometer() {
028    HAL.report(tResourceType.kResourceType_Accelerometer, m_analogChannel.getChannel() + 1);
029    SendableRegistry.addLW(this, "Accelerometer", m_analogChannel.getChannel());
030  }
031
032  /**
033   * Create a new instance of an accelerometer.
034   *
035   * <p>The constructor allocates desired analog channel.
036   *
037   * @param channel The channel number for the analog input the accelerometer is connected to
038   */
039  public AnalogAccelerometer(final int channel) {
040    this(new AnalogInput(channel), true);
041    SendableRegistry.addChild(this, m_analogChannel);
042  }
043
044  /**
045   * Create a new instance of Accelerometer from an existing AnalogChannel. Make a new instance of
046   * accelerometer given an AnalogChannel. This is particularly useful if the port is going to be
047   * read as an analog channel as well as through the Accelerometer class.
048   *
049   * @param channel The existing AnalogInput object for the analog input the accelerometer is
050   *     connected to
051   */
052  public AnalogAccelerometer(final AnalogInput channel) {
053    this(channel, false);
054  }
055
056  private AnalogAccelerometer(final AnalogInput channel, final boolean allocatedChannel) {
057    requireNonNullParam(channel, "channel", "AnalogAccelerometer");
058    m_allocatedChannel = allocatedChannel;
059    m_analogChannel = channel;
060    initAccelerometer();
061  }
062
063  /** Delete the analog components used for the accelerometer. */
064  @Override
065  public void close() {
066    SendableRegistry.remove(this);
067    if (m_analogChannel != null && m_allocatedChannel) {
068      m_analogChannel.close();
069    }
070    m_analogChannel = null;
071  }
072
073  /**
074   * Return the acceleration in Gs.
075   *
076   * <p>The acceleration is returned units of Gs.
077   *
078   * @return The current acceleration of the sensor in Gs.
079   */
080  public double getAcceleration() {
081    if (m_analogChannel == null) {
082      return 0.0;
083    }
084    return (m_analogChannel.getAverageVoltage() - m_zeroGVoltage) / m_voltsPerG;
085  }
086
087  /**
088   * Set the accelerometer sensitivity.
089   *
090   * <p>This sets the sensitivity of the accelerometer used for calculating the acceleration. The
091   * sensitivity varies by accelerometer model. There are constants defined for various models.
092   *
093   * @param sensitivity The sensitivity of accelerometer in Volts per G.
094   */
095  public void setSensitivity(double sensitivity) {
096    m_voltsPerG = sensitivity;
097  }
098
099  /**
100   * Set the voltage that corresponds to 0 G.
101   *
102   * <p>The zero G voltage varies by accelerometer model. There are constants defined for various
103   * models.
104   *
105   * @param zero The zero G voltage.
106   */
107  public void setZero(double zero) {
108    m_zeroGVoltage = zero;
109  }
110
111  @Override
112  public void initSendable(SendableBuilder builder) {
113    builder.setSmartDashboardType("Accelerometer");
114    builder.addDoubleProperty("Value", this::getAcceleration, null);
115  }
116}