001 /*----------------------------------------------------------------------------*/
002 /* Copyright (c) FIRST 2008-2012. All Rights Reserved. */
003 /* Open Source Software - may be modified and shared by FRC teams. The code */
004 /* must be accompanied by the FIRST BSD license file in the root directory of */
005 /* the project. */
006 /*----------------------------------------------------------------------------*/
007
008 package edu.wpi.first.wpilibj;
009
010 import edu.wpi.first.wpilibj.communication.UsageReporting;
011 import edu.wpi.first.wpilibj.livewindow.LiveWindow;
012 import edu.wpi.first.wpilibj.parsing.IDevice;
013 import edu.wpi.first.wpilibj.tables.ITable;
014 import edu.wpi.first.wpilibj.tables.ITableListener;
015
016 /**
017 * Standard hobby style servo.
018 *
019 * The range parameters default to the appropriate values for the Hitec HS-322HD servo provided
020 * in the FIRST Kit of Parts in 2008.
021 */
022 public class Servo extends PWM implements IDevice {
023
024 private static final double kMaxServoAngle = 170.0;
025 private static final double kMinServoAngle = 0.0;
026
027 /**
028 * Common initialization code called by all constructors.
029 *
030 * InitServo() assigns defaults for the period multiplier for the servo PWM control signal, as
031 * well as the minimum and maximum PWM values supported by the servo.
032 */
033 private void initServo() {
034 setBounds(2.27, 0, 0, 0, .743);
035 setPeriodMultiplier(PeriodMultiplier.k4X);
036
037 LiveWindow.addActuator("Servo", getModuleNumber(), getChannel(), this);
038 UsageReporting.report(UsageReporting.kResourceType_Servo, getChannel(), getModuleNumber()-1);
039 }
040
041 /**
042 * Constructor that assumes the default digital module.
043 *
044 * @param channel The PWM channel on the digital module to which the servo is attached.
045 */
046 public Servo(final int channel) {
047 super(channel);
048 initServo();
049 }
050
051 /**
052 * Constructor that specifies the digital module.
053 *
054 * @param slot The slot in the chassis that the digital module is plugged into.
055 * @param channel The PWM channel on the digital module to which the servo is attached.
056 */
057 public Servo(final int slot, final int channel) {
058 super(slot, channel);
059 initServo();
060 }
061
062 /**
063 * Set the servo position.
064 *
065 * Servo values range from 0.0 to 1.0 corresponding to the range of full left to full right.
066 *
067 * @param value Position from 0.0 to 1.0.
068 */
069 public void set(double value) {
070 setPosition(value);
071 }
072
073 /**
074 * Get the servo position.
075 *
076 * Servo values range from 0.0 to 1.0 corresponding to the range of full left to full right.
077 *
078 * @return Position from 0.0 to 1.0.
079 */
080 public double get() {
081 return getPosition();
082 }
083
084 /**
085 * Set the servo angle.
086 *
087 * Assume that the servo angle is linear with respect to the PWM value (big assumption, need to test).
088 *
089 * Servo angles that are out of the supported range of the servo simply "saturate" in that direction
090 * In other words, if the servo has a range of (X degrees to Y degrees) than angles of less than X
091 * result in an angle of X being set and angles of more than Y degrees result in an angle of Y being set.
092 *
093 * @param degrees The angle in degrees to set the servo.
094 */
095 public void setAngle(double degrees) {
096 if (degrees < kMinServoAngle) {
097 degrees = kMinServoAngle;
098 } else if (degrees > kMaxServoAngle) {
099 degrees = kMaxServoAngle;
100 }
101
102 setPosition(((degrees - kMinServoAngle)) / getServoAngleRange());
103 }
104
105 /**
106 * Get the servo angle.
107 *
108 * Assume that the servo angle is linear with respect to the PWM value (big assumption, need to test).
109 * @return The angle in degrees to which the servo is set.
110 */
111 public double getAngle() {
112 return getPosition() * getServoAngleRange() + kMinServoAngle;
113 }
114
115 private double getServoAngleRange() {
116 return kMaxServoAngle - kMinServoAngle;
117 }
118
119 /*
120 * Live Window code, only does anything if live window is activated.
121 */
122 public String getSmartDashboardType(){
123 return "Servo";
124 }
125 private ITable m_table;
126 private ITableListener m_table_listener;
127
128 /**
129 * {@inheritDoc}
130 */
131 public void initTable(ITable subtable) {
132 m_table = subtable;
133 updateTable();
134 }
135
136 /**
137 * {@inheritDoc}
138 */
139 public void updateTable() {
140 if (m_table != null) {
141 m_table.putNumber("Value", get());
142 }
143 }
144
145 /**
146 * {@inheritDoc}
147 */
148 public void startLiveWindowMode() {
149 m_table_listener = new ITableListener() {
150 public void valueChanged(ITable itable, String key, Object value, boolean bln) {
151 set(((Double) value).doubleValue());
152 }
153 };
154 m_table.addTableListener("Value", m_table_listener, true);
155 }
156
157 /**
158 * {@inheritDoc}
159 */
160 public void stopLiveWindowMode() {
161 // TODO: Broken, should only remove the listener from "Value" only.
162 m_table.removeTableListener(m_table_listener);
163 }
164 }