Programming basics

Programming basics¶

FRC robots are typically programmed in Java, C++, or LabVIEW using the WPILib libraries provided by FIRST.

Control loops and modes¶

The robot program usually includes:

• Disabled – robot is not allowed to move.
• Autonomous – robot runs pre-programmed routines without driver input.
• Teleoperated (teleop) – drivers control the robot with gamepads/joysticks.

Many teams structure code around:

• Subsystems – code modules for mechanisms (drivetrain, intake, arm, etc.).
• Commands – actions that use one or more subsystems (drive, shoot, follow path).

Sensors and feedback¶

Common sensors:

• Encoders – measure wheel or joint rotation, used for distance and position.
• Gyros/IMUs – measure heading and orientation, used for driving straight and path following.
• Limit switches / beam breaks – detect end stops or game pieces.
• Cameras – used with vision libraries (e.g., PhotonVision, Limelight) for target tracking.

Feedback control (like PID) helps mechanisms reach and hold positions, speeds, or angles.

Safety and reliability¶

Good practices:

• Always honor safety interlocks (e.g., disable shooter when doors are open).
• Add current limits and software limits to protect hardware.
• Log important data (sensor readings, states) to help debug problems at events.