Debouncer.java

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.
 
package org.wpilib.math.filter;
 
import org.wpilib.math.util.MathSharedStore;

public class Debouncer {
  public enum DebounceType {
    RISING,
    FALLING,
    BOTH
  }
 
  private double m_debounceTime;
  private DebounceType m_debounceType;
  private boolean m_baseline;
 
  private double m_prevTime;

  public Debouncer(double debounceTime, DebounceType type) {
    m_debounceTime = debounceTime;
    m_debounceType = type;
 
    resetTimer();
 
    m_baseline = m_debounceType == DebounceType.FALLING;
  }

  public Debouncer(double debounceTime) {
    this(debounceTime, DebounceType.RISING);
  }
 
  private void resetTimer() {
    m_prevTime = MathSharedStore.getTimestamp();
  }
 
  private boolean hasElapsed() {
    return MathSharedStore.getTimestamp() - m_prevTime >= m_debounceTime;
  }

  public boolean calculate(boolean input) {
    if (input == m_baseline) {
      resetTimer();
    }
 
    if (hasElapsed()) {
      if (m_debounceType == DebounceType.BOTH) {
        m_baseline = input;
        resetTimer();
      }
      return input;
    } else {
      return m_baseline;
    }
  }

  public void setDebounceTime(double time) {
    m_debounceTime = time;
  }

  public double getDebounceTime() {
    return m_debounceTime;
  }

  public void setDebounceType(DebounceType type) {
    m_debounceType = type;
 
    m_baseline = m_debounceType == DebounceType.FALLING;
  }

  public DebounceType getDebounceType() {
    return m_debounceType;
  }
}