- FRC Game Manual
- FRC Game Q&A

# Creating a Robot Program

Once everything is installed, we’re ready to create a robot program. WPILib comes with several templates for robot programs. Use of these templates is highly recommended for new users; however, advanced users are free to write their own robot code from scratch.

## Choosing a Base Class

To start a project using one of the WPILib robot program templates, users must first choose a base class for their robot. Users subclass these base classes to create their primary `Robot` class, which controls the main flow of the robot program. There are various choices available for the base class:

### TimedRobot

Documentation: Java - C++

Source: Java - C++

The `TimedRobot` class is the base class recommended for most users. It provides control of the robot program through a collection of `init()`, `periodic()`, and `exit()` methods, which are called by WPILib during specific robot states (e.g. autonomous or teleoperated). During these calls, your code typically polls each input device and acts according to the data it receives. For instance, you would typically determine the position of the joystick and state of the joystick buttons on each call and act accordingly. The `TimedRobot` class also provides an example of retrieving autonomous routines through SendableChooser (Java/ C++)

Note

A TimedRobot Skeleton template is available that removes some informative comments and the autonomous example. You can use this if you’re already familiar with TimedRobot. The example shown below is of TimedRobot Skeleton.

JAVA

     7import edu.wpi.first.wpilibj.TimedRobot;
     8
     9/**
    10 * The methods in this class are called automatically corresponding to each mode, as described in
    11 * the TimedRobot documentation. If you change the name of this class or the package after creating
    12 * this project, you must also update the Main.java file in the project.
    13 */
    14public class Robot extends TimedRobot {
    15  /**
    16   * This function is run when the robot is first started up and should be used for any
    17   * initialization code.
    18   */
    19  public Robot() {}
    20
    21  @Override
    22  public void robotPeriodic() {}
    23
    24  @Override
    25  public void autonomousInit() {}
    26
    27  @Override
    28  public void autonomousPeriodic() {}
    29
    30  @Override
    31  public void teleopInit() {}
    32
    33  @Override
    34  public void teleopPeriodic() {}
    35
    36  @Override
    37  public void disabledInit() {}
    38
    39  @Override
    40  public void disabledPeriodic() {}
    41
    42  @Override
    43  public void testInit() {}
    44
    45  @Override
    46  public void testPeriodic() {}
    47
    48  @Override
    49  public void simulationInit() {}
    50
    51  @Override
    52  public void simulationPeriodic() {}
    53}

C++

     5#include "Robot.h"
     6
     7Robot::Robot() {}
     8void Robot::RobotPeriodic() {}
     9
    10void Robot::AutonomousInit() {}
    11void Robot::AutonomousPeriodic() {}
    12
    13void Robot::TeleopInit() {}
    14void Robot::TeleopPeriodic() {}
    15
    16void Robot::DisabledInit() {}
    17void Robot::DisabledPeriodic() {}
    18
    19void Robot::TestInit() {}
    20void Robot::TestPeriodic() {}
    21
    22void Robot::SimulationInit() {}
    23void Robot::SimulationPeriodic() {}
    24
    25#ifndef RUNNING_FRC_TESTS
    26int main() {
    27  return frc::StartRobot<Robot>();
    28}
    29#endif

Periodic methods are called every 20 ms by default. This can be changed by calling the superclass constructor with the new desired update rate.

Danger

Changing your robot rate can cause some unintended behavior (loop overruns). Teams can also use Notifiers to schedule methods at a custom rate.

JAVA

    public Robot() {
      super(0.03); // Periodic methods will now be called every 30 ms.
    }

C++

    Robot() : frc::TimedRobot(30_ms) {}

### Timeslice Robot

Documentation: Java - C++

Source: Java - C++

The `TimesliceRobot` class extends the `TimedRobot` framework to provide more control over the scheduling of periodic functions. It allows users to allocate specific time slices to different robot operations, running them sequentially within a defined period (typically shorter than TimedRobot’s default 20ms). This class is recommended for users who need more precise timing control and consistent starting times for their robot’s periodic functions.

`TimesliceRobot` provides the same `init()`, `periodic()`, and `exit()` methods as `TimedRobot`, but adds the ability to schedule additional periodic functions with custom allocations. This allows for more efficient use of processing time and can lead to improved performance which can make odometry and estimators more accurate and controller outputs change more consistently.

### RobotBase

Documentation: Java - C++

Source: Java - C++

The `RobotBase` class is the most minimal base-class offered, and is generally not recommended for direct use. No robot control flow is handled for the user; everything must be written from scratch inside the `startCompetition()` method. The template by default showcases how to process the different operation modes (teleop, auto, etc).

Note

A `RobotBase Skeleton` template is available that offers a blank `startCompetition()` method.

### Command Robot

The `Command Robot` framework adds to the basic functionality of a `Timed Robot` by automatically polling inputs and converting the raw input data into events. These events are tied to user code, which is executed when the event is triggered. For instance, when a button is pressed, code tied to the pressing of that button is automatically called and it is not necessary to poll or keep track of the state of that button directly. The `Command Robot` framework makes it easier to write compact easy-to-read code with complex behavior, but requires an additional up-front time investment from a programmer in order to understand how the Command Robot framework works.

Teams using `Command Robot` should see the Command-Based Programming Tutorial.

### Romi

Teams using a Romi should use the `Romi - Timed` or `Romi - Command Bot` template.

#### Romi - Timed

The `Romi - Timed` template provides a `RomiDrivetrain` class that exposes an `arcadeDrive(double xaxisSpeed, double zaxisRotate)` method. It’s up to the user to feed this arcadeDrive function.

This class also provides functions for retrieving and resetting the Romi’s onboard encoders.

#### Romi - Command Bot

The `Romi - Command Bot` template provides a `RomiDrivetrain` subsystem that exposes an `arcadeDrive(double xaxisSpeed, double zaxisRotate)` method. It’s up to the user to feed this arcadeDrive function.

This subsystem also provides functions for retrieving and resetting the Romi’s onboard encoders.

### Not Using a Base Class

If desired, users can omit a base class entirely and simply write their program in a `main()` method, as they would for any other program. This is highly discouraged - users should not “reinvent the wheel” when writing their robot code - but it is supported for those who wish to have absolute control over their program flow.

Warning

Users should not modify the `main()` method of a robot program unless they are absolutely sure of what they are doing.

## Creating a New WPILib Project

Once we’ve decided on a base class, we can create our new robot project. Bring up the Visual Studio Code command palette with ``Ctrl`+`Shift`+`P``. Then, type “WPILib” into the prompt. Since all WPILib commands start with “WPILib”, this will bring up the list of WPILib-specific VS Code commands. Now, select the Create a new project command:

This will bring up the “New Project Creator Window:”

The elements of the New Project Creator Window are explained below:

1. Project Type: The kind of project we wish to create. This can be an example project, or one of the project templates provided by WPILib. Templates exist for each of the robot base classes. Additionally, a template exists for Command-based projects, which are built on the `TimedRobot` base class but include a number of additional features - this type of robot program is highly recommended for new teams.

2. Language: This is the language (C++ or Java) that will be used for this project.

3. Base Folder: If this is a template project, this specifies the type of template that will be used.

4. Project Location: This determines the folder in which the robot project will be located.

5. Project Name: The name of the robot project. This also specifies the name that the project folder will be given if the Create New Folder box is checked.

6. Create a New Folder: If this is checked, a new folder will be created to hold the project within the previously-specified folder. If it is not checked, the project will be located directly in the previously-specified folder. An error will be thrown if the folder is not empty and this is not checked.

7. Team Number: The team number for the project, which will be used for package names within the project and to locate the robot when deploying code.

8. Enable Desktop Support: Enables unit test and simulation support (see Introduction to Robot Simulation).

   - Java: This option has no effect and can be left checked or unchecked

   - C++: Checking this option enables desktop compilation, which is required for simulation and unit tests

   - Romi/XRP: This option has no effect for Romi and XRP templates and can be left checked or unchecked

   Note

   While WPILib fully supports desktop builds, some third-party vendor libraries may not. If a library doesn’t support desktop compilation, your C++ code may not compile or may crash when running simulation.

Once all the above have been configured, click “Generate Project” and the robot project will be created.

Note

Any errors in project generation will appear in the bottom right-hand corner of the screen.

Warning

Creating projects on OneDrive is not supported as OneDrive’s caching interferes with the build system. Some Windows installations put the Documents and Desktop folders on OneDrive by default.

An example after all options are selected is shown below.

## Opening The New Project

After successfully creating your project, VS Code will give the option of opening the project as shown below. We can choose to do that now or later by typing ``Ctrl`+`K`` then ``Ctrl`+`O`` (or just ``Command`+`O`` on macOS) and select the folder where we saved our project.

Once opened we will see the project hierarchy on the left. Double clicking on the file will open that file in the editor.

## C++ Configurations (C++ Only)

For C++ projects, there is one more step to set up IntelliSense. Whenever we open a project, we should get a pop-up in the bottom right corner asking to refresh C++ configurations. Click “Yes” to set up IntelliSense.