Button#

Introduction#

The button class is derived from the controller base class and provides access to the IQ Controller’s buttons, allowing your robot to monitor presses to the controller’s buttons.

Access#

The controller class provides twelve button objects. Each object is an instance of the button class and can be accessed through a controller instance.

Object	Example Usage	Description
`ButtonEDown`	`Controller.ButtonEDown.pressing()`	E Down button
`ButtonEUp`	`Controller.ButtonEUp.pressing()`	E Up button
`ButtonFDown`	`Controller.ButtonFDown.pressing()`	F Down button
`ButtonFUp`	`Controller.ButtonFUp.pressing()`	F Up button
`ButtonL3`	`Controller.ButtonL3.pressing()`	L3 button (Only on the 2nd Gen Controller)
`ButtonLDown`	`Controller.ButtonLDown.pressing()`	L Down button
`ButtonLUp`	`Controller.ButtonLUp.pressing()`	L Up button
`ButtonR3`	`Controller.ButtonR3.pressing()`	R3 button (Only on the 2nd Gen Controller)
`ButtonRDown`	`Controller.ButtonRDown.pressing()`	R Down button
`ButtonRUp`	`Controller.ButtonRUp.pressing()`	R Up button

Notes#

The button object is provided by the controller. It is not constructed directly.

Member Functions#

The Button class includes the following member functions:

pressing — Returns whether or not the specified button is being pressed.
pressed — Registers a function to be called when the specified button is pressed.
released — Registers a function to be called when the specified button is released.

Before calling any button member functions, a controller instance must be created, as shown below:

// Create a controller instance
controller Controller = controller();

pressing#

Returns whether a specific controller button is currently being pressed.

Available Functions

bool pressing() const;

Parameters

This function does not accept any parameters.

Return Values

Returns an integer indicating whether the specified button is being pressed:

1 — The button is being pressed.
0 — The button is not being pressed.

Examples

This function can be called on any controller button object, for example:

Controller.ButtonEDown
Controller.ButtonEUp
Controller.ButtonFDown
Controller.ButtonFUp
Controller.ButtonL3
Controller.ButtonLDown
Controller.ButtonLUp
Controller.ButtonR3
Controller.ButtonRDown
Controller.ButtonRUp

// Turn right while RUp is pressed
while (true) {
    if (Controller.ButtonRUp.pressing()) {
        Drivetrain.turn(right);
    } else {
        Drivetrain.stop();
    }
    wait(5, msec);
}

pressed#

Registers a callback function that runs when a specific controller button is pressed.

Available Functions

void pressed( 
  void (* callback)(void) ) const;

Parameters

Parameter	Type	Description
`callback`	`void (*)(void)`	A function that is called when the specified button is pressed.

Return Values

This function does not return a value.

Examples

This function can be called on any controller button object, for example:

Controller.ButtonEDown
Controller.ButtonEUp
Controller.ButtonFDown
Controller.ButtonFUp
Controller.ButtonL3
Controller.ButtonLDown
Controller.ButtonLUp
Controller.ButtonR3
Controller.ButtonRDown
Controller.ButtonRUp

Define the callback function (outside of int main())

// Drive forward when FUp is pressed
void driveForward() {
    Drivetrain.driveFor(forward, 100, mm);
}

int main() {
  /* vexcodeInit() is only required when using VEXcode.
  Remove vexcodeInit() if compiling in VS Code. */
  vexcodeInit();

  // Call driveForward when the FUp button is pressed
  Controller.ButtonFUp.pressed(driveForward);
}

released#

Registers a callback function that runs when a specific controller button is released.

Available Functions

void released( 
  void (* callback)(void) ) const;

Parameters

Parameter	Type	Description
`callback`	`void (*)(void)`	A function that is called when the specified button is released.

Return Values

This function does not return a value.

Examples

This function can be called on any controller button object, for example:

Controller.ButtonEDown
Controller.ButtonEUp
Controller.ButtonFDown
Controller.ButtonFUp
Controller.ButtonL3
Controller.ButtonLDown
Controller.ButtonLUp
Controller.ButtonR3
Controller.ButtonRDown
Controller.ButtonRUp

Define the callback function (outside of int main())

// Drive backward when FDown is released
void backUp() {
    Drivetrain.driveFor(reverse, 100, mm);
}

int main() {
  /* vexcodeInit() is only required when using VEXcode.
  Remove vexcodeInit() if compiling in VS Code. */
  vexcodeInit();

  // Call backUp when the FDown button is released
  Controller.ButtonA.released(backUp);
}