Controls

Introduction

The Control blocks in VEXcode AIM manage the flow of a project by handling loops, conditions, delays, and stopping execution. Below is a list of available blocks:

• wait – Pauses execution for a specific duration.

• wait until – Pauses execution until a specified condition is met.

• repeat – Repeats enclosed blocks a specific number of times.

• forever – Repeats enclosed blocks indefinitely.

• repeat until – Repeats enclosed blocks until a condition is met.

• while – Repeats enclosed blocks while a condition remains true.

• if – Runs enclosed blocks if a condition is true.

• if / else – Runs one set of blocks if a condition is true, otherwise runs another.

• if / else if / else – Runs different sets of blocks depending on multiple conditions.

• break – Exits a repeat, forever, repeat until, or while loop immediately.

• stop project – Ends the execution of the project.

wait

The wait block pauses for a specific amount of time before moving to the next block.

wait stack block

    wait (1) seconds

Parameters	Description
time	The amount of time to wait, as a positive integer or decimal in seconds.

Example

When started, moves forward for one second, then stops all movement.

    when started :: hat events
    [Move forward for one second, then stop.]
    move [forward v]
    wait (1) seconds
    stop all movement

wait Until

The wait until block pauses execution until a specified condition is met before proceeding to the next block.

wait until stack block

    wait until <>

Parameters	Description
condition	The condition that must be met before moving on to the next block.

Example

When started, moves forward until the screen is pressed, then stops all movement.

    when started :: hat events
    [Move forward until screen pressed, then stop.]
    move [forward v]
    wait until <screen pressed?>
    stop all movement

repeat

The repeat block runs the blocks inside it a set number of times.

repeat c block

    repeat [10]
    end

Parameters	Description
times	A whole number that sets how many times the repeat block runs.

Example

    when started :: hat events
    [Move in a square path.]
    repeat [4]
        move [forward v] for [50] [mm v] ▶
        turn [right v] for [90] degrees ▶
    end

forever

The forever block keeps running the blocks inside it again and again without stopping.

forever c block

    forever
    end

Parameters	Description
	This block has no parameters.

Example

When started, continuously moves in a square path by moving forward 50 mm and turning right 90 degrees in an infinite loop.

    when started :: hat events
    [Move in a square path forever.]
    forever
        move [forward v] for [50] [mm v] ▶
        turn [right v] for [90] degrees ▶
    end

repeat until

The repeat until block executes the enclosed blocks repeatedly while the condition evaluates as False.

repeat until block

    repeat until <>
    end

Parameters	Description
condition	An expression or variable that is evaluated before each iteration. If it evaluates as: False - The loop continues True - The loop stops

Example

When started, keeps all LEDs red until the screen is pressed, then turns them off.

    when started :: hat events
    [Repeat until the screen is pressed before turning off the LEDs.]
    repeat until <screen pressed?>
        set [lightall v] LED color to [red v]
    end
    set [lightall v] LED color to [off v]

while

The while block executes the enclosed blocks repeatedly while the condition evaluates as True.

while c block

    while <>
    end

Parameters	Description
condition	An expression or variable that is evaluated before each iteration. If it evaluates as: True - The loop continues False - The loop stops

Example

When started, moves forward for 200 mm while keeping all LEDs green. The LEDs turn off after movement stops.

    when started :: hat events
    [Keep the LEDs green while the robot is moving.]
    move [forward v] for [200] [mm v] ◀ and don't wait
    while <move active?>
        set [lightall v] LED color to [green v]
    end
    set [lightall v] LED color to [off v]

if

The if block executes the enclosed block of code if the condition evaluates as True.

if block

    if <> then
    end

Parameters	Description
condition	An expression or variable that is evaluated when the statement runs. If it evaluates as: True - The code inside the if block executes False - The block is skipped

Example

When started, continuously checks if the screen is pressed. If pressed, the robot kicks an object with medium force.

    when started :: hat events
    [Kick when the screen is pressed.]
    forever
        if <screen pressed?> then
            kick object [medium v]
        end
    end

if / else

The if / else block determines which enclosed block of code runs based on whether the condition evaluates as True or False.

if then else block

    if <> then
    else
    end

Parameters	Description
condition	An expression or variable that is evaluated when the statement runs. If it evaluates as: True - The code inside the if block executes False - The code inside the else block executes instead

Example

When started, continuously checks if the screen is pressed. If pressed, displays an excited emoji looking forward; otherwise, displays a bored emoji looking forward.

    when started :: hat events
    [Show one emoji when the screen is touched and a different one when it's not.]
    forever
        if <screen pressed?> then
            show [emoji_excited v] looking [forward v]
        else
            show [emoji_bored v] looking [forward v]
        end
    end

if / else if / else

The if / else if / else block structure selects which enclosed block of code runs based on conditions:

• if runs its block of code if the condition evaluates as True.

• else if checks additional conditions only if all previous conditions evaluated as False. Multiple else if statements can be used.

• else runs its block of code only if none of the previous conditions evaluated as True.

if else if else block

    if <> then
    else if <> then
    else 
    end

Parameters	Description
condition	An expression or variable that is evaluated when the statement runs. The first condition that evaluates as: True - Determines which block of code executes False - If none are True, the else block of code runs

Example

When the controller’s axis 1 position changes, moves forward if pushed forward, moves in reverse if pulled backward, and stops when neutral.

    when Controller axis [1 v] is changed :: hat events
    [Move the robot forward or reverse based on the position of the joystick.]
    if <(controller axis [1 v] position) [math_greater_than v] [0]> then
        move [forward v]
    else if <(controller axis [1 v] position) [math_less_than v] [0]> then
        move [reverse v]
    else
        stop all movement
    end

break

The break block exits a loop immediately.

break stack block

    break

Parameters	Description
	This block has no parameters.

Example

When started, flashes LEDs red and green every 0.5 seconds until the screen is pressed, then stops.

    when started :: hat events
    [Flash LEDs until the screen is pressed.]
    forever
        set [lightall v] LED color to [red v]
        wait [0.5] seconds
        set [lightall v] LED color to [green v]
        wait [0.5] seconds
        if <screen pressed?> then
            break
        end
    end

stop project

The stop project block ends a running project.

stop project block

    stop project

Parameters	Description
	This block has no parameters.

Example

When started, flashes LEDs red and green every 0.5 seconds until the screen is pressed, then stops the project.

    when started :: hat events
    [Stop the project once the screen is pressed.]
    forever
        set [lightall v] LED color to [red v]
        wait [0.5] seconds
        set [lightall v] LED color to [green v]
        wait [0.5] seconds
        if <screen pressed?> then
            stop project
        end
    end