Gamepad Controls in FTC

beginner65 min

Understanding the Gamepad API

FTC robots are controlled using gamepads. The gamepad1 and gamepad2 objects provide access to all the buttons, sticks, triggers, and dpad controls. Knowing how to use these inputs is essential for effective TeleOp programming.

For a full list of gamepad fields, see FTC Docs: Gamepad Input.

Gamepad Input Reference

Analog: left_stick_x, left_stick_y, right_stick_x, right_stick_y, left_trigger, right_trigger
Digital: a, b, x, y, dpad_up, dpad_down, dpad_left, dpad_right, left_bumper, right_bumper, start, back

Example: Reading Analog and Digital Inputs

This snippet shows how to read both analog and digital inputs from gamepad1.

// Analog inputs
double drive = -gamepad1.left_stick_y;
double turn = gamepad1.right_stick_x;
double lift = gamepad1.right_trigger - gamepad1.left_trigger;
// Digital inputs
boolean openClaw = gamepad1.a;
boolean closeClaw = gamepad1.b;
boolean slowMode = gamepad1.left_bumper;

Advanced Gamepad Techniques: Button Toggles and State Machines

Some mechanisms, like claws or arms, need to change state with a single button press, not just while held. This is called a toggle. Edge detection lets you trigger an action only when a button is pressed, not held.

Example: Button Toggle with Edge Detection (Advanced)

private boolean lastA = false;
private boolean clawOpen = false;
private void controlClaw() {
    if (gamepad1.a && !lastA) {
        clawOpen = !clawOpen;
        clawServo.setPosition(clawOpen ? 1.0 : 0.0);
    }
    lastA = gamepad1.a;
}

Combining Inputs for Complex Actions

Sometimes you want to require multiple buttons or stick positions for a single action (e.g., safety interlocks, macros). Use logical operators to combine inputs.

Example: Combined Input for Safety

if (gamepad1.left_bumper && gamepad1.a) {
    // Only run this if both are pressed
    armMotor.setPower(1.0);
}

Multi-Driver Support (gamepad1 vs. gamepad2)

FTC allows two drivers, each with their own gamepad. Assign different subsystems to each gamepad for better teamwork.

Example: Assigning Subsystems to Gamepads

// gamepad1 drives, gamepad2 operates arm
double leftPower = -gamepad1.left_stick_y;
double rightPower = -gamepad1.right_stick_y;
leftDrive.setPower(leftPower);
rightDrive.setPower(rightPower);
if (gamepad2.a) {
    armMotor.setPower(1.0);
}

Implementing Slow/Precision Mode

Precision driving is important for tasks like aligning with game elements. Use a button to reduce drive speed for more control.

Example: Slow Mode Toggle

double speed = gamepad1.left_bumper ? 0.3 : 1.0;
double leftPower = -gamepad1.left_stick_y * speed;
double rightPower = -gamepad1.right_stick_y * speed;
leftDrive.setPower(leftPower);
rightDrive.setPower(rightPower);

Macros and Automation

Macros automate repetitive tasks, improving driver efficiency. For example, pressing a button to run a sequence of actions.

Example: Simple Macro

if (gamepad1.x && !lastX) {
    // Run a macro: open claw, move arm
    clawServo.setPosition(1.0);
    armMotor.setPower(1.0);
    sleep(500);
    armMotor.setPower(0.0);
}
lastX = gamepad1.x;

Best Practices for Advanced Controls

Keep your control logic clean and readable. Use clear variable names and comments. Test each advanced feature separately before combining them.

Practice Exercise: Gamepad Mapping and Advanced Controls

Write code to control a drive train with the left stick, a lift with the bumpers, and a claw with buttons A/B. Implement a toggle for the claw using edge detection. Add a slow mode, a macro, and assign subsystems to different gamepads.

Map drive motors, a lift motor, and a claw servo.
Read analog and digital inputs from gamepad1.
Implement edge detection for the claw toggle.
Add a slow mode for precision driving.
Create a macro that runs a sequence of actions.
Assign subsystems to different gamepads.

Map drive motors, a lift motor, and a claw servo.

                  // In your OpMode class
DcMotor leftDrive = hardwareMap.get(DcMotor.class, "left_drive");
DcMotor rightDrive = hardwareMap.get(DcMotor.class, "right_drive");
DcMotor liftMotor = hardwareMap.get(DcMotor.class, "lift_motor");
Servo clawServo = hardwareMap.get(Servo.class, "claw_servo");
// Make sure these names match your robot configuration!

Read analog and digital inputs from gamepad1.

                  // Analog inputs
double leftPower = -gamepad1.left_stick_y; // Drive forward/backward
double rightPower = -gamepad1.right_stick_y; // Drive right side
// Digital inputs
boolean liftUp = gamepad1.right_bumper;
boolean liftDown = gamepad1.left_bumper;
boolean openClaw = gamepad1.a;
boolean closeClaw = gamepad1.b;

Implement edge detection for the claw toggle.

                  // Place these at the top of your OpMode class
boolean lastA = false;
boolean clawOpen = false;

// In your main loop
if (gamepad1.a && !lastA) {
    clawOpen = !clawOpen; // Toggle claw state
    clawServo.setPosition(clawOpen ? 1.0 : 0.0);
}
lastA = gamepad1.a; // Update last state after checking
// This ensures the toggle only happens once per button press.

Add a slow mode for precision driving.

                  double speed = gamepad1.left_bumper ? 0.3 : 1.0;
double leftPower = -gamepad1.left_stick_y * speed;
double rightPower = -gamepad1.right_stick_y * speed;
leftDrive.setPower(leftPower);
rightDrive.setPower(rightPower);

Create a macro that runs a sequence of actions.

                  if (gamepad1.x && !lastX) {
    // Run a macro: open claw, move arm
    clawServo.setPosition(1.0);
    armMotor.setPower(1.0);
    sleep(500);
    armMotor.setPower(0.0);
}
lastX = gamepad1.x;

Assign subsystems to different gamepads.

                  // gamepad1 drives, gamepad2 operates arm
double leftPower = -gamepad1.left_stick_y;
double rightPower = -gamepad1.right_stick_y;
leftDrive.setPower(leftPower);
rightDrive.setPower(rightPower);
if (gamepad2.a) {
    armMotor.setPower(1.0);
}