Events

Introduction

The Events blocks in VEXcode 123 allow for event-driven coding, enabling different parts of a project to run in response to triggers such as project start, received events, or user interactions.

Below is a list of available blocks:

• when started – Executes the attached stack of blocks when the project starts.

• when I receive event – Runs the attached stack when a specific event is broadcast.

• broadcast event – Triggers an event without pausing execution.

• broadcast event and wait – Triggers an event and pauses execution until the event’s tasks complete.

when started

The when started block runs its stack when the project begins. You can have multiple when started blocks to run multiple stacks of blocks at once.

The When started hat block.

    when started :: hat events

parameter	description
	This block has no parameters.

Example

aria-description goes here

  when started :: hat events
  [Drive forward then stop.]
  drive [forward v]    
  wait (2) seconds
  stop driving

when I receive event

The when I receive event block starts a stack when a matching event is broadcast. You can have multiple when I receive event blocks to run multiple stacks of blocks at once.

The When I receive event hat block.

    when I receive [my_event v]

parameter	description
event	The event to be triggered. Users can select an existing event, create a new one, rename the selected event, or delete it.

Example

aria-description goes here

  when started :: hat events
  [Turn LED green while the robot moves.]
  broadcast [square_drive v]  
  glow [green v]
  when I receive [square_drive v] :: hat events
  [Move in a square pattern.]
  repeat [4]
  drive [forward v] for [100] [mm v]
  turn [right v] for [90] degrees

broadcast event

The broadcast event block triggers any matching when I receive event hat block. It does not pause the execution of the stack and continues running the next block immediately.

The Broadcast event stack block.

    broadcast [message1 v]

parameter	description
event	The event to trigger. Users can select an existing event, create a new one, rename the selected event, or delete it.

Example

aria-description goes here

  when started :: hat events
  [Turn LED green while the robot moves.]
  broadcast [square_drive v]  
  glow [green v]
  when I receive [square_drive v] :: hat events
  [Move in a square pattern.]
  repeat [4]
  drive [forward v] for [100] [mm v]
  turn [right v] for [90] degrees

broadcast event and wait

The broadcast event and wait block triggers an event, then pauses execution of the current stack until all triggered when I receive event block stacks have completed.

The Broadcast event and wait stack block.

    broadcast [message1 v] and wait

parameter	description
event	The event to trigger. Users can select an existing event, create a new one, rename the selected event, or delete it.

Example

aria-description goes here

  when started :: hat events
  [Turn LED green after robot is done moving.]
  broadcast [square_drive v] and wait
  glow [green v]
  when I receive [square_drive v] :: hat events
  [Move in a square pattern.]
  repeat [4]
  drive [forward v] for [100] [mm v]
  turn [right v] for [90] degrees