- FRC Game Manual
- FRC Game Q&A

# Choosing an Autonomous Program

Often teams have more than one autonomous program, either for competitive reasons or for testing new software. Programs often vary by adding things like time delays, different strategies, etc. The methods to choose the strategy to run usually involves switches, joystick buttons, knobs, or other hardware based inputs.

With the SmartDashboard you can simply display a widget on the screen to choose the autonomous program that you would like to run. And with command based programs, that program is encapsulated in one of several commands. This article shows how to select an autonomous program with only a few lines of code and a nice looking user interface, with examples for both TimedRobot and Command-Based Robots.

## TimedRobot

Note

The code snippets shown below are part of the TimedRobot template (Java, C++):

### Creating SendableChooser Object

In `Robot.java` / `Robot.h`, create a variable to hold a reference to a `SendableChooser` object. Two or more auto modes can be added by creating strings to send to the chooser. Using the `SendableChooser`, one can choose between them. In this example, `Default` and `My Auto` are shown as options. You will also need a variable to store which auto has been chosen, `m_autoSelected`.

Java

      private static final String kDefaultAuto = "Default";
      private static final String kCustomAuto = "My Auto";
      private String m_autoSelected;
      private final SendableChooser<String> m_chooser = new SendableChooser<>();

C++

      frc::SendableChooser<std::string> m_chooser;
      const std::string kAutoNameDefault = "Default";
      const std::string kAutoNameCustom = "My Auto";
      std::string m_autoSelected;

Python

    import wpilib
    self.defaultAuto = "Default"
    self.customAuto = "My Auto";
    self.chooser = wpilib.SendableChooser()

### Setting Up Options

The chooser allows you to pick from a list of defined elements, in this case the strings we defined above. In the `Robot` constructor, add your options created as strings above using `setDefaultOption` or `addOption`. `setDefaultOption` will be the one selected by default when the dashboard starts. The `putData` function will push it to the dashboard on your driver station computer.

Java

      public Robot() {
        m_chooser.setDefaultOption("Default Auto", kDefaultAuto);
        m_chooser.addOption("My Auto", kCustomAuto);
        SmartDashboard.putData("Auto choices", m_chooser);
      }

C++

    Robot::Robot() {
      m_chooser.SetDefaultOption(kAutoNameDefault, kAutoNameDefault);
      m_chooser.AddOption(kAutoNameCustom, kAutoNameCustom);
      frc::SmartDashboard::PutData("Auto Modes", &m_chooser);
    }

Python

    from wpilib import SmartDashboard
    self.chooser.setDefaultOption("Default Auto", self.defaultAuto)
    self.chooser.addOption("My Auto", self.customAuto)
    SmartDashboard.putData("Auto choices", self.chooser)

### Running Autonomous Code

Now, in `autonomousInit` and `autonomousPeriodic`, you can use the `m_autoSelected` variable to read which option was chosen, and change what happens during the autonomous period.

Java

      @Override
      public void autonomousInit() {
        m_autoSelected = m_chooser.getSelected();
        System.out.println("Auto selected: " + m_autoSelected);
      }

      /** This function is called periodically during autonomous. */
      @Override
      public void autonomousPeriodic() {
        switch (m_autoSelected) {
          case kCustomAuto:
            // Put custom auto code here
            break;
          case kDefaultAuto:
          default:
            // Put default auto code here
            break;
        }
      }

C++

    void Robot::AutonomousInit() {
      m_autoSelected = m_chooser.GetSelected();
      wpi::print("Auto selected: {}\n", m_autoSelected);

      if (m_autoSelected == kAutoNameCustom) {
        // Custom Auto goes here
      } else {
        // Default Auto goes here
      }
    }

    void Robot::AutonomousPeriodic() {
      if (m_autoSelected == kAutoNameCustom) {
        // Custom Auto goes here
      } else {
        // Default Auto goes here
      }
    }

Python

    def autonomousInit(self):
       self.autoSelected = self.chooser.getSelected()
       print("Auto selected: " + self.autoSelected)
    def autonomousPeriodic(self):
       match self.autoSelected:
          case self.customAuto:
             # Put custom auto code here
          case _:
             # Put default auto code here

## Command-Based

Note

The code snippets shown below are part of the HatchbotTraditional example project (Java, C++, Python):

### Creating the SendableChooser Object

In `RobotContainer`, create a variable to hold a reference to a `SendableChooser` object. Two or more commands can be created and stored in new variables. Using the `SendableChooser`, one can choose between them. In this example, `SimpleAuto` and `ComplexAuto` are shown as options.

Java

      // A simple auto routine that drives forward a specified distance, and then stops.
      private final Command m_simpleAuto =
          new DriveDistance(
              AutoConstants.kAutoDriveDistanceInches, AutoConstants.kAutoDriveSpeed, m_robotDrive);

      // A complex auto routine that drives forward, drops a hatch, and then drives backward.
      private final Command m_complexAuto = new ComplexAuto(m_robotDrive, m_hatchSubsystem);

      // A chooser for autonomous commands
      SendableChooser<Command> m_chooser = new SendableChooser<>();

C++ (using raw pointers)

      // The autonomous routines
      DriveDistance m_simpleAuto{AutoConstants::kAutoDriveDistanceInches,
                                 AutoConstants::kAutoDriveSpeed, &m_drive};
      ComplexAuto m_complexAuto{&m_drive, &m_hatch};

      // The chooser for the autonomous routines
      frc::SendableChooser<frc2::Command*> m_chooser;

C++ (using `CommandPtr`)

      // The autonomous routines
      frc2::CommandPtr m_simpleAuto = autos::SimpleAuto(&m_drive);
      frc2::CommandPtr m_complexAuto = autos::ComplexAuto(&m_drive, &m_hatch);

      // The chooser for the autonomous routines
      frc::SendableChooser<frc2::Command*> m_chooser;

Python

            # A simple auto routine that drives forward a specified distance, and then stops.
            self.simpleAuto = DriveDistance(
                constants.kAutoDriveDistanceInches, constants.kAutoDriveSpeed, self.drive
            )

            # A complex auto routine that drives forward, drops a hatch, and then drives backward.
            self.complexAuto = ComplexAuto(self.drive, self.hatch)

            # Chooser
            self.chooser = wpilib.SendableChooser()

### Setting up SendableChooser

Imagine that you have two autonomous programs to choose between and they are encapsulated in commands `SimpleAuto` and `ComplexAuto`. To choose between them:

In `RobotContainer`, create a `SendableChooser` object and add instances of the two commands to it. There can be any number of commands, and the one added as a default (`setDefaultOption`), becomes the one that is initially selected. Notice that each command is included in an `setDefaultOption()` or `addOption()` method call on the `SendableChooser` instance.

Java

        // Add commands to the autonomous command chooser
        m_chooser.setDefaultOption("Simple Auto", m_simpleAuto);
        m_chooser.addOption("Complex Auto", m_complexAuto);

C++ (using raw pointers)

      // Add commands to the autonomous command chooser
      m_chooser.SetDefaultOption("Simple Auto", &m_simpleAuto);
      m_chooser.AddOption("Complex Auto", &m_complexAuto);

C++ (using `CommandPtr`)

      // Add commands to the autonomous command chooser
      // Note that we do *not* move ownership into the chooser
      m_chooser.SetDefaultOption("Simple Auto", m_simpleAuto.get());
      m_chooser.AddOption("Complex Auto", m_complexAuto.get());

Python

            # Add commands to the autonomous command chooser
            self.chooser.setDefaultOption("Simple Auto", self.simpleAuto)
            self.chooser.addOption("Complex Auto", self.complexAuto)

Then, publish the chooser to the dashboard:

Java

    // Put the chooser on the dashboard
    SmartDashboard.putData(m_chooser);

C++

    // Put the chooser on the dashboard
    frc::SmartDashboard::PutData(&m_chooser);

Python

    from wpilib import SmartDashboard
    # Put the chooser on the dashboard
    SmartDashboard.putData(chooser)

### Starting an Autonomous Command

In `Robot.java`, when the autonomous period starts, the `SendableChooser` object is polled to get the selected command and that command must be scheduled.

Java

      public Command getAutonomousCommand() {
        return m_chooser.getSelected();
      }

      public void autonomousInit() {
        m_autonomousCommand = m_robotContainer.getAutonomousCommand();

        // schedule the autonomous command (example)
        if (m_autonomousCommand != null) {
          m_autonomousCommand.schedule();
        }
      }

C++ (Source)

    frc2::Command* RobotContainer::GetAutonomousCommand() {
      // Runs the chosen command in autonomous
      return m_chooser.GetSelected();
    }

    void Robot::AutonomousInit() {
      m_autonomousCommand = m_container.GetAutonomousCommand();

      if (m_autonomousCommand != nullptr) {
        m_autonomousCommand->Schedule();
      }
    }

Python

        def getAutonomousCommand(self) -> commands2.Command:
            return self.chooser.getSelected()

        def autonomousInit(self) -> None:
            """This autonomous runs the autonomous command selected by your RobotContainer class."""
            self.autonomousCommand = self.container.getAutonomousCommand()

            if self.autonomousCommand:
                self.autonomousCommand.schedule()

### Running the Scheduler during Autonomous

In `Robot.java`, this will run the scheduler every driver station update period (about every 20ms) and cause the selected autonomous command to run. In Python the scheduler runs automatically when `TimedCommandRobot` is used.

Note

Running the scheduler can occur in the `autonomousPeriodic()` function or `robotPeriodic()`, both will function similarly in autonomous mode.

Java

    49  @Override
    50  public void robotPeriodic() {
    51    CommandScheduler.getInstance().run();
    52  }

C++ (Source)

    29void Robot::RobotPeriodic() {
    30  frc2::CommandScheduler::GetInstance().Run();
    31}

### Canceling the Autonomous Command

In `Robot.java`, when the teleop period begins, the autonomous command will be canceled.

Java

    87  @Override
    88  public void teleopInit() {
    89    // This makes sure that the autonomous stops running when
    90    // teleop starts running. If you want the autonomous to
    91    // continue until interrupted by another command, remove
    92    // this line or comment it out.
    93    if (m_autonomousCommand != null) {
    94      m_autonomousCommand.cancel();
    95    }
    96  }

C++ (Source)

    56void Robot::TeleopInit() {
    57  // This makes sure that the autonomous stops running when
    58  // teleop starts running. If you want the autonomous to
    59  // continue until interrupted by another command, remove
    60  // this line or comment it out.
    61  if (m_autonomousCommand != nullptr) {
    62    m_autonomousCommand->Cancel();
    63    m_autonomousCommand = nullptr;
    64  }
    65}

Python

    51    def teleopInit(self) -> None:
    52        # This makes sure that the autonomous stops running when
    53        # teleop starts running. If you want the autonomous to
    54        # continue until interrupted by another command, remove
    55        # this line or comment it out.
    56        if self.autonomousCommand:
    57            self.autonomousCommand.cancel()

### SmartDashboard Display

When the SmartDashboard is run, the choices from the `SendableChooser` are automatically displayed. You can simply pick an option before the autonomous period begins and the corresponding command will run.