Changes between Version 5 and Version 6 of ControlSystems/SoftwareTeam/Training/WPILib/CommandBasedProgramming

Timestamp:

Dec 17, 2019, 12:45:22 AM (6 years ago)

Author:

David Albert

Comment:

--

ControlSystems/SoftwareTeam/Training/WPILib/CommandBasedProgramming

@@ -20 +20 @@
 !ScreenStepsLive has a very good example of how a program might look if programmed for !TimedRobot and then the same program converted to !CommandRobot; you should review it [https://wpilib.screenstepslive.com/s/currentCS/m/cpp/l/241906-converting-a-simple-autonomous-program-to-a-command-based-autonomous-program here]
 
+The following is an example of a very simple Command Based Robot that has a single subsystem consisting of a servo motor with two positions: Open, Closed and they are selected using the A and B buttons on a gamepad.  Replace the template files with:
+
+RobotMap.java:
+{{{
+package frc.robot;
+public class RobotMap {
+  public static int SERVO_PORT = 0;   // PWM port for servo motor
+  public static int OPEN_BUTTON = 1;  // A button opens mechanism
+  public static int CLOSE_BUTTON = 2; // B button closes mechanism
+}
+}}}
+
+Add ServoSubsystem.java under subsystems:
+{{{
+package frc.robot.subsystems;
+
+import edu.wpi.first.wpilibj.command.Subsystem;
+import edu.wpi.first.wpilibj.Servo;
+
+public class ServoSubsystem extends Subsystem {
+  private Servo servo;
+
+  private static ServoSubsystem instance = null;
+
+  private ServoSubsystem() {
+      servo = new Servo(0);
+  }
+
+  // Singleton design pattern
+  public static ServoSubsystem getInstance() {
+      if (instance == null) {
+          instance = new ServoSubsystem();
+      }
+      return instance;
+  }
+
+  public void setAngle(double degrees) {
+    servo.setAngle(degrees);
+  }
+
+  @Override
+  public void initDefaultCommand() {
+    // Set the default command for a subsystem here.
+    // setDefaultCommand(new MySpecialCommand());
+  }
+}
+}}}
+
+Add OpenCommand.java and CloseCommand.java under commands:
+OpenCommand.java:
+{{{
+package frc.robot.commands;
+
+import edu.wpi.first.wpilibj.command.Command;
+import frc.robot.Robot;
+
+public class OpenCommand extends Command {
+  public OpenCommand() {
+    requires(Robot.m_servo);
+  }
+
+  @Override
+  protected boolean isFinished() {
+    System.out.println("Open Pressed.");
+    Robot.m_servo.setAngle(30); // set servo to open position
+    return true;
+  }
+}
+}}}
+
+CloseCommand.java:
+{{{
+package frc.robot.commands;
+
+import edu.wpi.first.wpilibj.command.Command;
+import frc.robot.Robot;
+
+public class CloseCommand extends Command {
+  public CloseCommand() {
+    requires(Robot.m_servo);
+  }
+
+  @Override
+  protected boolean isFinished() {
+    System.out.println("Close Pressed.");
+    Robot.m_servo.setAngle(120);
+    return true;
+  }
+}
+}}}
+
+OI.java:
+{{{
+package frc.robot;
+
+import edu.wpi.first.wpilibj.XboxController;
+import edu.wpi.first.wpilibj.buttons.Button;
+import edu.wpi.first.wpilibj.buttons.JoystickButton;
+import frc.robot.RobotMap;
+import frc.robot.commands.*;
+
+public class OI {
+  XboxController xbox = new XboxController(0);
+  Button openButton = new JoystickButton(xbox, RobotMap.OPEN_BUTTON);
+  Button closeButton = new JoystickButton(xbox, RobotMap.CLOSE_BUTTON);
+
+  public OI() {
+    openButton.whenPressed(new OpenCommand());
+    closeButton.whenPressed(new CloseCommand());
+  }
+}
+}}}
+
+Robot.java:
+{{{
+package frc.robot;
+
+import edu.wpi.first.wpilibj.TimedRobot;
+import edu.wpi.first.wpilibj.command.Scheduler;
+import frc.robot.subsystems.ServoSubsystem;
+
+public class Robot extends TimedRobot {
+  public static ServoSubsystem m_servo = ServoSubsystem.getInstance();
+  public static OI m_oi;
+
+  @Override
+  public void robotInit() {
+    m_oi = new OI();
+  }
+
+  @Override
+  public void disabledPeriodic() {
+    Scheduler.getInstance().run();
+  }
+
+  /**
+   * This function is called periodically during autonomous.
+   */
+  @Override
+  public void autonomousPeriodic() {
+    Scheduler.getInstance().run();
+  }
+
+  @Override
+  public void teleopPeriodic() {
+    Scheduler.getInstance().run();
+  }
+}
+}}}
 
 === How it works ===