Timer

Introduction

The VEX AIR Drone Controller’s timer keeps track of elapsed time from the start of a project. It can be used to measure how long something takes or reset for new timing operations.

Below is a list of all available methods:

Action – Control the timer.

• reset – Resets the timer to zero.

Getter – Report the current timer value.

• time – Returns how much time has passed.

Callback – Trigger functions after a delay.

• event – Registers a function to be called after a specified number of milliseconds.

Constructor - Create a Timer to track time.

• Timer - Create a new timer object that can be used with these methods.

Action

reset

reset sets the timer to zero. This can be used to time additional sections of code within the same project.

Usage:
timer.reset()

Parameters	Description
	This method has no parameters.

# Display the time the drone takes to climb upwards.
drone.take_off(500)
timer.reset()
drone.climb_for(UP, 500)
controller.screen.print("Time elapsed: ")
controller.screen.print(timer.time(SECONDS))
drone.land()

Getter

time

time returns the time since the timer was last reset as a decimal. The timer is automatically reset at the start of a project.

Usage:
timer.time(units)

Parameters	Description
units	The unit that represents the time: MSEC (default) – milliseconds, or SECONDS

# Display the time in two units.
while True:
    controller.screen.clear_screen()
    controller.screen.set_cursor(1, 1)
    controller.screen.print("Time: {} ms".format(timer.time(MSEC)))
    controller.screen.next_row()
    controller.screen.print("Time: {:.2f} s".format(timer.time(SECONDS)))
    wait(50, MSEC)

Callback

event

event calls a function after a specified amount of time passes.

Usage:

timer.event(callback, delay, arg)

Parameters	Description
callback	A function to execute when the timer event occurs.
delay	The delay before the function is called, in milliseconds.
arg	Optional. A tuple containing arguments to pass to the callback function. See Using Events with Parameters for more information.

# Create a function to play a looping sound.
def on_timer():
    controller.sound.play(LOOPING)

# Play the sound after 4 seconds (4000 mS).
timer.event(on_timer, 4000)

Constructor

Timer

Timer creates a new timer. A Timer object will immediately begin counting the moment it is created and will work with all timer methods.

Usage:
Timer()

Parameter	Description
	This constructor has no parameters.

# Display 2 timers with a 2 second difference.
wait(2, SECONDS)

stopwatch = Timer()

while True:
    controller.screen.clear_screen()

    controller.screen.set_cursor(1, 1)
    controller.screen.print("Timer: ")
    controller.screen.print(timer.time(SECONDS))

    controller.screen.set_cursor(4, 1)
    controller.screen.print("Stopwatch: ")
    controller.screen.print(stopwatch.time(SECONDS))

    wait(0.1, SECONDS)