Added Ultrasonic example program in Java and C++, updated examples XML.

Change-Id: I510bef33d8565d124894d926d6634b04b1b6ca28

eclipse-plugins/edu.wpi.first.wpilib.plugins.java/resources/templates/examples/Ultrasonic/src/org/usfirst/frc/team190/robot/Robot.java

@@ -0,0 +1,65 @@
+
+package org.usfirst.frc.team190.robot;
+
+import edu.wpi.first.wpilibj.CANTalon;
+import edu.wpi.first.wpilibj.SampleRobot;
+import edu.wpi.first.wpilibj.RobotDrive;
+import edu.wpi.first.wpilibj.AnalogInput;
+
+/**
+ * This is a sample program demonstrating how to use an ultrasonic sensor and proportional 
+ * control to maintain a set distance from an object.
+ */
+
+public class Robot extends SampleRobot {
+    AnalogInput ultrasonic; //ultrasonic sensor
+    RobotDrive myRobot;
+    
+    final int ultrasonicChannel = 3; //analog input pin
+    
+    //channels for motors
+    final int leftMotorChannel = 1;
+    final int rightMotorChannel = 0;
+    final int leftRearMotorChannel = 3;
+    final int rightRearMotorChannel = 2;
+    
+    int holdDistance = 12; //distance in inches the robot wants to stay from an object
+    final double valueToInches = 0.125; //factor to convert sensor values to a distance in inches
+    final double pGain = 0.05; //proportional speed constant
+
+ 
+    public Robot() {
+	//make objects for the sensor and the drive train
+	ultrasonic = new AnalogInput(ultrasonicChannel);   
+        myRobot = new RobotDrive(new CANTalon(leftMotorChannel), new CANTalon(leftRearMotorChannel), 
+        	new CANTalon(rightMotorChannel), new CANTalon(rightRearMotorChannel));
+    }
+
+    /**
+     * Runs during autonomous.
+     */
+    public void autonomous() {
+
+    }
+
+    /**
+     * Tells the robot to drive to a set distance (in inches) from an object using proportional control.
+     */
+    public void operatorControl() {
+
+	double currentDistance; //distance measured from the ultrasonic sensor values
+	double currentSpeed; //speed to set the motor
+	
+	while (isOperatorControl() && isEnabled()) {
+            currentDistance = ultrasonic.getValue()*valueToInches; //sensor returns a value from 0-4095 that is scaled to inches 
+            currentSpeed = (holdDistance - currentDistance)*pGain; //convert distance error to a motor speed
+            myRobot.drive(currentSpeed, 0); //drive robot 
+	}
+    }
+
+    /**
+     * Runs during test mode
+     */
+    public void test() {
+    }
+}

eclipse-plugins/edu.wpi.first.wpilib.plugins.java/resources/templates/examples/examples.xml

@@ -141,6 +141,25 @@
   </files>
   </example>
 
+  
+   <example>
+  <name>Ultrasonic</name>
+  <description>Demonstrate maintaining a set distance using an ultrasonic sensor. </description>
+  <tags>
+    <tag>Sensors</tag>
+    <tag>Complete List</tag>
+    <tag>Robot and Motor</tag>
+    <tag>CAN</tag>
+  </tags>
+  <packages>
+    <package>src/$package-dir</package>
+  </packages>
+  <files>
+    <file source="examples/Ultrasonic/src/org/usfirst/frc/team190/robot/Robot.java"
+      destination="src/$package-dir/Robot.java"></file>
+  </files>
+  </example>
+
 
  <example>
   <name>Motor Controller</name>