Commands

NextFTC v2 has no command framework of its own. The robot module uses Ivy, Pedro Pathing’s command library. Ivy is a simple command library inpsired by WPILib and NextFTC v1, so if you’ve written WPILib commands or NextFTC v1 commands, Ivy’s Command will look about the same.

This page covers only the parts of Ivy you touch through the robot module. Sequential and parallel groups, Command.build(), and the rest live in Ivy’s documentation.

Building commands from a mechanism

Most commands come from Mechanism.instant and Mechanism.infinite. Both call Ivy’s Commands.instant/Commands.infinite and then requiring(this), which tells the scheduler the command owns that mechanism’s hardware.

Kotlin

class Intake : Mechanism {
    val motor = NextMotor("intakeMotor")

    fun run() = infinite { motor.throttle = 1.0 }
    fun stop() = instant { motor.throttle = 0.0 }
}

Java

public class Intake implements Mechanism {
    NextMotor motor = new NextMotor("intakeMotor");

    public Command run() { return infinite(() -> motor.setThrottle(1.0)); }
    public Command stop() { return instant(() -> motor.setThrottle(0.0)); }
}

instant runs its action once and finishes on the same loop. infinite re-runs its action every loop and never finishes on its own, so something has to cancel it. That makes infinite the right choice for anything fed by gamepad input, where the value changes every loop.

Sequencing Commands in Kotlin

Anything with steps in it, like raise the arm, wait, then open the claw, can be written as a coroutine command instead of a nest of sequential and parallel groups. This command is only available in Kotlin, but it can call Java methods and use Java classes.

Starting, checking, and cancelling

Three Command methods from Ivy come up outside of triggers: schedule() hands the command to the scheduler, cancel() stops it early, and isScheduled reports whether it’s running right now.

NextFTC provides Triggers, which start and stop commands based on gamepad input, mechanism or sensor state, or other conditions.

Learn more

Sequences, parallel groups, custom commands written from scratch, and the Scheduler API are all in Ivy’s documentation.