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Documentation Index

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FRC Academy lessons use WPILib’s Command-Based architecture — specifically CommandXboxController for button-to-command binding and RunCommand/InstantCommand for inline motor control. This page covers the three command classes you’ll encounter in every FRC Academy lesson.

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edu.wpi.first.wpilibj2.command.*

The command package in wpilibj2 is the heart of the Command-Based programming model. Instead of polling button states in a periodic() loop, you bind commands directly to controller triggers — WPILib schedules them automatically.

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CommandXboxController

Full class: edu.wpi.first.wpilibj2.command.CommandXboxController CommandXboxController is a modern wrapper extending XboxController with Trigger-based event binding. Rather than reading getBButton() in a loop and writing if statements, you call .b() once and attach a command to it — the scheduler handles the rest. Constructor: 
new CommandXboxController(int port)
port is 0 for the driver controller or 1 for the operator controller (matches the USB port index in the Driver Station). Button Trigger methods — each returns a Trigger object you can chain commands onto:
MethodButton
.a()A face button
.b()B face button
.x()X face button
.y()Y face button
.leftBumper()Left bumper (LB)
.rightBumper()Right bumper (RB)
.leftTrigger()Left trigger axis (LT)
.rightTrigger()Right trigger axis (RT)
.start()Start button
.back()Back / Select button
Trigger binding methods — chain these onto any button Trigger:
MethodBehavior
.whileTrue(Command command)Runs the command continuously while the button is held
.onTrue(Command command)Runs the command once when the button is first pressed
.onFalse(Command command)Runs the command once when the button is released
.toggleOnTrue(Command command)Toggles the command on or off each time the button is pressed
Axis read methods — for use directly in RunCommand lambdas:
MethodReturnsDescription
.getLeftY()doubleLeft stick Y axis (−1.0 to 1.0, up = negative)
.getLeftX()doubleLeft stick X axis
.getRightY()doubleRight stick Y axis
.getRightX()doubleRight stick X axis
Example — Activate Motor lesson (from FRC Academy): 
operatorController.b()
    .whileTrue(new RunCommand(() -> m_motor.set(0.5)))
    .onFalse(new InstantCommand(() -> m_motor.set(0.0)));

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RunCommand

Full class: edu.wpi.first.wpilibj2.command.RunCommand RunCommand executes an inline lambda function repeatedly until terminated by an external signal (such as a button being released). It wraps any Runnable — including motor set() calls — so you can use it directly with Trigger binding. Constructors: 
new RunCommand(Runnable toRun)
new RunCommand(Runnable toRun, Subsystem... requirements)
The optional Subsystem requirements argument registers this command with the scheduler so it interrupts other commands using the same subsystem. Example — arcade drive inside a RunCommand: 
new RunCommand(() -> {
    double speed = -driverController.getLeftY();
    double turn = driverController.getLeftX();
    m_leftMotor.set(speed + turn);
    m_rightMotor.set(speed - turn);
})

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InstantCommand

Full class: edu.wpi.first.wpilibj2.command.InstantCommand InstantCommand runs an assigned code block exactly once, then finishes immediately. The scheduler marks it complete on the same loop tick it starts. This makes it perfect for one-shot actions where you don’t want the command to linger. Constructor: 
new InstantCommand(Runnable toRun)
Common use cases:
  • Stopping a motor when a button is released
  • Resetting a sensor or encoder
  • Toggling a solenoid state
Example: 
new InstantCommand(() -> m_motor.set(0.0))

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whileTrue vs onFalse Pattern

The motor-hold pattern is used throughout every FRC Academy motor lesson. It pairs .whileTrue() and .onFalse() on the same button to create a clean hold-to-run, release-to-stop behavior: 
// While button B is held: run motor at 50%
// When button B is released: stop motor
operatorController.b()
    .whileTrue(new RunCommand(() -> m_motor.set(0.5)))
    .onFalse(new InstantCommand(() -> m_motor.set(0.0)));
When the button is released, WPILib interrupts the whileTrue command automatically, then immediately fires the .onFalse() command. The stop InstantCommand runs once, sets the motor to 0.0, and finishes on the same scheduler cycle it starts. The result is a motor that runs at full speed exactly while the button is held and stops cleanly the moment the driver lets go.
FRC Academy uses simplified RobotContainer-style structures directly inside Robot.java for teaching clarity. In a full robot project, motors and their associated commands are usually wrapped in dedicated Subsystem classes, and binding is done inside a RobotContainer class passed to the CommandScheduler.

WPILib Core

TimedRobot, XboxController, DriverStation, PWMSparkMax, and the MotorController interface.

REV Robotics

SparkMax, SparkMaxConfig, MotorType, and the REV hardware configuration API.

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