Add DutyCycleEncoder and AnalogEncoder (#2040)

wpilibj/src/main/java/edu/wpi/first/wpilibj/AnalogEncoder.java

@@ -0,0 +1,158 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. 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.hal.SimDevice;
+import edu.wpi.first.hal.SimDouble;
+import edu.wpi.first.wpilibj.AnalogTriggerOutput.AnalogTriggerType;
+import edu.wpi.first.wpilibj.smartdashboard.SendableBuilder;
+import edu.wpi.first.wpilibj.smartdashboard.SendableRegistry;
+
+/**
+ * Class for supporting continuous analog encoders, such as the US Digital MA3.
+ */
+public class AnalogEncoder implements Sendable, AutoCloseable {
+  private final AnalogInput m_analogInput;
+  private AnalogTrigger m_analogTrigger;
+  private Counter m_counter;
+  private double m_positionOffset;
+  private double m_distancePerRotation = 1.0;
+  private double m_lastPosition;
+
+  protected SimDevice m_simDevice;
+  protected SimDouble m_simPosition;
+
+  /**
+   * Construct a new AnalogEncoder attached to a specific AnalogInput.
+   *
+   * @param analogInput the analog input to attach to
+   */
+  public AnalogEncoder(AnalogInput analogInput) {
+    m_analogInput = analogInput;
+    init();
+  }
+
+  private void init() {
+    m_analogTrigger = new AnalogTrigger(m_analogInput);
+    m_counter = new Counter();
+
+    m_simDevice = SimDevice.create("AnalogEncoder", m_analogInput.getChannel());
+
+    if (m_simDevice != null) {
+      m_simPosition = m_simDevice.createDouble("Position", false, 0.0);
+    }
+
+    // Limits need to be 25% from each end
+    m_analogTrigger.setLimitsVoltage(1.25, 3.75);
+    m_counter.setUpSource(m_analogTrigger, AnalogTriggerType.kRisingPulse);
+    m_counter.setDownSource(m_analogTrigger, AnalogTriggerType.kFallingPulse);
+
+    SendableRegistry.addLW(this, "Analog Encoder", m_analogInput.getChannel());
+  }
+
+  /**
+   * Get the encoder value since the last reset.
+   *
+   * <p>This is reported in rotations since the last reset.
+   *
+   * @return the encoder value in rotations
+   */
+  public double get() {
+    if (m_simPosition != null) {
+      return m_simPosition.get();
+    }
+
+    // As the values are not atomic, keep trying until we get 2 reads of the same
+    // value. If we don't within 10 attempts, warn
+    for (int i = 0; i < 10; i++) {
+      double counter = m_counter.get();
+      double pos = m_analogInput.getVoltage();
+      double counter2 = m_counter.get();
+      double pos2 = m_analogInput.getVoltage();
+      if (counter == counter2 && pos == pos2) {
+        double position = counter + pos - m_positionOffset;
+        m_lastPosition = position;
+        return position;
+      }
+    }
+
+    DriverStation.reportWarning(
+        "Failed to read Analog Encoder. Potential Speed Overrun. Returning last value", false);
+    return m_lastPosition;
+  }
+
+  /**
+   * Get the offset of position relative to the last reset.
+   *
+   * <p>getPositionInRotation() - getPositionOffset() will give an encoder absolute
+   * position relative to the last reset. This could potentially be negative,
+   * which needs to be accounted for.
+   *
+   * @return the position offset
+   */
+  public double getPositionOffset() {
+    return m_positionOffset;
+  }
+
+  /**
+   * Set the distance per rotation of the encoder. This sets the multiplier used
+   * to determine the distance driven based on the rotation value from the
+   * encoder. Set this value based on the how far the mechanism travels in 1
+   * rotation of the encoder, and factor in gearing reductions following the
+   * encoder shaft. This distance can be in any units you like, linear or angular.
+   *
+   * @param distancePerRotation the distance per rotation of the encoder
+   */
+  public void setDistancePerRotation(double distancePerRotation) {
+    m_distancePerRotation = distancePerRotation;
+  }
+
+  /**
+   * Get the distance per rotation for this encoder.
+   *
+   * @return The scale factor that will be used to convert rotation to useful
+   *         units.
+   */
+  public double getDistancePerRotation() {
+    return m_distancePerRotation;
+  }
+
+  /**
+   * Get the distance the sensor has driven since the last reset as scaled by the
+   * value from {@link #setDistancePerRotation(double)}.
+   *
+   * @return The distance driven since the last reset
+   */
+  public double getDistance() {
+    return get() * getDistancePerRotation();
+  }
+
+  /**
+   * Reset the Encoder distance to zero.
+   */
+  public void reset() {
+    m_counter.reset();
+    m_positionOffset = m_analogInput.getVoltage();
+  }
+
+  @Override
+  public void close() {
+    m_counter.close();
+    m_analogTrigger.close();
+    if (m_simDevice != null) {
+      m_simDevice.close();
+    }
+  }
+
+  @Override
+  public void initSendable(SendableBuilder builder) {
+    builder.setSmartDashboardType("AbsoluteEncoder");
+    builder.addDoubleProperty("Distance", this::getDistance, null);
+    builder.addDoubleProperty("Distance Per Rotation", this::getDistancePerRotation, null);
+  }
+}

wpilibj/src/main/java/edu/wpi/first/wpilibj/DutyCycle.java

@@ -28,6 +28,8 @@ public class DutyCycle implements Sendable, AutoCloseable {
   // Explicitly package private
   final int m_handle;
 
+  private final DigitalSource m_source;
+
   /**
    * Constructs a DutyCycle input from a DigitalSource input.
    *
@@ -39,6 +41,7 @@ public class DutyCycle implements Sendable, AutoCloseable {
     m_handle = DutyCycleJNI.initialize(digitalSource.getPortHandleForRouting(),
         digitalSource.getAnalogTriggerTypeForRouting());
 
+    m_source = digitalSource;
     int index = getFPGAIndex();
     HAL.report(tResourceType.kResourceType_DutyCycle, index + 1);
     SendableRegistry.addLW(this, "Duty Cycle", index);
@@ -107,6 +110,10 @@ public class DutyCycle implements Sendable, AutoCloseable {
     return DutyCycleJNI.getFPGAIndex(m_handle);
   }
 
+  public int getSourceChannel() {
+    return m_source.getChannel();
+  }
+
   @Override
   public void initSendable(SendableBuilder builder) {
     builder.setSmartDashboardType("Duty Cycle");

wpilibj/src/main/java/edu/wpi/first/wpilibj/DutyCycleEncoder.java

@@ -0,0 +1,219 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. 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.hal.SimBoolean;
+import edu.wpi.first.hal.SimDevice;
+import edu.wpi.first.hal.SimDouble;
+import edu.wpi.first.wpilibj.AnalogTriggerOutput.AnalogTriggerType;
+import edu.wpi.first.wpilibj.smartdashboard.SendableBuilder;
+import edu.wpi.first.wpilibj.smartdashboard.SendableRegistry;
+
+/**
+ * Class for supporting duty cycle/PWM encoders, such as the US Digital MA3 with
+ * PWM Output, the CTRE Mag Encoder, the Rev Hex Encoder, and the AM Mag
+ * Encoder.
+ */
+public class DutyCycleEncoder implements Sendable, AutoCloseable {
+  private final DutyCycle m_dutyCycle;
+  private boolean m_ownsDutyCycle;
+  private AnalogTrigger m_analogTrigger;
+  private Counter m_counter;
+  private int m_frequencyThreshold = 100;
+  private double m_positionOffset;
+  private double m_distancePerRotation = 1.0;
+  private double m_lastPosition;
+
+  protected SimDevice m_simDevice;
+  protected SimDouble m_simPosition;
+  protected SimBoolean m_simIsConnected;
+
+  /**
+   * Construct a new DutyCycleEncoder attached to an existing DutyCycle object.
+   *
+   * @param dutyCycle the duty cycle to attach to
+   */
+  public DutyCycleEncoder(DutyCycle dutyCycle) {
+    m_dutyCycle = dutyCycle;
+    init();
+  }
+
+  /**
+   * Construct a new DutyCycleEncoder attached to a DigitalSource object.
+   *
+   * @param source the digital source to attach to
+   */
+  public DutyCycleEncoder(DigitalSource source) {
+    m_ownsDutyCycle = true;
+    m_dutyCycle = new DutyCycle(source);
+    init();
+  }
+
+  private void init() {
+    m_analogTrigger = new AnalogTrigger(m_dutyCycle);
+    m_counter = new Counter();
+
+    m_simDevice = SimDevice.create("DutyCycleEncoder", m_dutyCycle.getFPGAIndex());
+
+    if (m_simDevice != null) {
+      m_simPosition = m_simDevice.createDouble("Position", false, 0.0);
+      m_simIsConnected = m_simDevice.createBoolean("Connected", false, true);
+    }
+
+    m_analogTrigger.setLimitsDutyCycle(0.25, 0.75);
+    m_counter.setUpSource(m_analogTrigger, AnalogTriggerType.kRisingPulse);
+    m_counter.setDownSource(m_analogTrigger, AnalogTriggerType.kFallingPulse);
+
+    SendableRegistry.addLW(this, "DutyCycle Encoder", m_dutyCycle.getSourceChannel());
+  }
+
+  /**
+   * Get the encoder value since the last reset.
+   *
+   * <p>This is reported in rotations since the last reset.
+   *
+   * @return the encoder value in rotations
+   */
+  public double get() {
+    if (m_simPosition != null) {
+      return m_simPosition.get();
+    }
+
+    // As the values are not atomic, keep trying until we get 2 reads of the same
+    // value
+    // If we don't within 10 attempts, error
+    for (int i = 0; i < 10; i++) {
+      double counter = m_counter.get();
+      double pos = m_dutyCycle.getOutput();
+      double counter2 = m_counter.get();
+      double pos2 = m_dutyCycle.getOutput();
+      if (counter == counter2 && pos == pos2) {
+        double position = counter + pos - m_positionOffset;
+        m_lastPosition = position;
+        return position;
+      }
+    }
+
+    DriverStation.reportWarning(
+        "Failed to read Analog Encoder. Potential Speed Overrun. Returning last value", false);
+    return m_lastPosition;
+  }
+
+  /**
+   * Get the offset of position relative to the last reset.
+   *
+   * <p>getPositionInRotation() - getPositionOffset() will give an encoder absolute
+   * position relative to the last reset. This could potentially be negative,
+   * which needs to be accounted for.
+   *
+   * @return the position offset
+   */
+  public double getPositionOffset() {
+    return m_positionOffset;
+  }
+
+  /**
+   * Set the distance per rotation of the encoder. This sets the multiplier used
+   * to determine the distance driven based on the rotation value from the
+   * encoder. Set this value based on the how far the mechanism travels in 1
+   * rotation of the encoder, and factor in gearing reductions following the
+   * encoder shaft. This distance can be in any units you like, linear or angular.
+   *
+   * @param distancePerRotation the distance per rotation of the encoder
+   */
+  public void setDistancePerRotation(double distancePerRotation) {
+    m_distancePerRotation = distancePerRotation;
+  }
+
+  /**
+   * Get the distance per rotation for this encoder.
+   *
+   * @return The scale factor that will be used to convert rotation to useful
+   *         units.
+   */
+  public double getDistancePerRotation() {
+    return m_distancePerRotation;
+  }
+
+  /**
+   * Get the distance the sensor has driven since the last reset as scaled by the
+   * value from {@link #setDistancePerRotation(double)}.
+   *
+   * @return The distance driven since the last reset
+   */
+  public double getDistance() {
+    return get() * getDistancePerRotation();
+  }
+
+  /**
+   * Get the frequency in Hz of the duty cycle signal from the encoder.
+   *
+   * @return duty cycle frequency in Hz
+   */
+  public int getFrequency() {
+    return m_dutyCycle.getFrequency();
+  }
+
+  /**
+   * Reset the Encoder distance to zero.
+   */
+  public void reset() {
+    m_counter.reset();
+    m_positionOffset = m_dutyCycle.getOutput();
+  }
+
+  /**
+   * Get if the sensor is connected
+   *
+   * <p>This uses the duty cycle frequency to determine if the sensor is connected.
+   * By default, a value of 100 Hz is used as the threshold, and this value can be
+   * changed with {@link #setConnectedFrequencyThreshold(int)}.
+   *
+   * @return true if the sensor is connected
+   */
+  public boolean isConnected() {
+    if (m_simIsConnected != null) {
+      return m_simIsConnected.get();
+    }
+    return getFrequency() > m_frequencyThreshold;
+  }
+
+  /**
+   * Change the frequency threshold for detecting connection used by
+   * {@link #isConnected()}.
+   *
+   * @param frequency the minimum frequency in Hz.
+   */
+  public void setConnectedFrequencyThreshold(int frequency) {
+    if (frequency < 0) {
+      frequency = 0;
+    }
+
+    m_frequencyThreshold = frequency;
+  }
+
+  @Override
+  public void close() {
+    m_counter.close();
+    m_analogTrigger.close();
+    if (m_ownsDutyCycle) {
+      m_dutyCycle.close();
+    }
+    if (m_simDevice != null) {
+      m_simDevice.close();
+    }
+  }
+
+  @Override
+  public void initSendable(SendableBuilder builder) {
+    builder.setSmartDashboardType("AbsoluteEncoder");
+    builder.addDoubleProperty("Distance", this::getDistance, null);
+    builder.addDoubleProperty("Distance Per Rotation", this::getDistancePerRotation, null);
+    builder.addBooleanProperty("Is Connected", this::isConnected, null);
+  }
+}