Control

Introduction

Control includes methods for timing, program flow, conditional logic, and project termination. These controls let you pause execution, create loops, define logic paths, and end a program. Below is a list of available controls, including methods and core Python keywords:

• wait – Pauses execution for a given number of milliseconds or seconds.

• for – Repeats code for each item in a sequence.

• if – Executes code if a condition is true.

• if/else – Runs different code depending on a condition.

• if/elif/else – Checks multiple conditions in order.

• while – Repeats code while a condition is true.

• break – Exits a loop immediately.

• quit – Ends the running project.

• pass – Placeholder used when no action is needed.

wait

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

Usage:
wait(time, units)

Parameters	Description
time	The amount of time to wait, as a positive integer.
units	The unit to represent the time: MSEC (default) – Milliseconds SECONDS

# Fly for 1 second.
drone.take_off(climb_to=500)
wait(1, SECONDS)
drone.land()

for

for iterates over a sequence (such as a list, tuple, dictionary, set, or string) or any iterable object. It executes the block of code once for each item in the sequence.

Usage:

for value in expression_list:
    pass

Parameters	Description
value	A temporary variable that stores the current element in the iteration.
expression_list	The collection of elements being looped through (e.g., list, string, range).

# Move back and forth four times then land.
drone.take_off(climb_to=500)
for i in range(4):
    drone.move_for(direction=0, distance=500, velocity=50, units=MM)
    wait(1, SECONDS)
    drone.move_for(direction=180, distance=500, velocity=50, units=MM)
    wait(1, SECONDS)
drone.land()

# Print each item in a list.
colors = ["Red", "Green", "Blue"]
for color in colors:
    controller.screen.print(color)
    controller.screen.next_row()

if

if executes the indented block of code if the condition evaluates as True.

Usage:

if condition:
    pass

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; if it evaluates as False, the block is skipped.

# Take a picture when button 5 is pressed.
drone.take_off(climb_to=500)
while True:
    # Move with controller
    drone.move_with_vectors(
        forward=controller.axis4.position(),
        rightward=controller.axis3.position(),
        upward=controller.axis1.position(),
        rotation=controller.axis2.position()
    )

    if controller.button5.pressing():
        drone.camera.capture_image(FORWARD_CAMERA)

    wait(5, MSEC)

if/else

if and else determine which indented block of code runs based on whether the condition evaluates as True or False.

Usage:

if condition:
    pass
else:
    pass

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; if it evaluates as False, the code inside the else block executes instead.

# Climb when the left joystick is moved up.
drone.take_off(climb_to=500)
while True:
    if controller.axis1.position() > 0:
        drone.climb(direction=UP, velocity=50)
    else:
        drone.hover()
    wait(5, MSEC)

if/elif/else

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

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

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

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

Usage:

if condition:
    pass
elif condition:
    pass
else:
    pass

Parameters	Description
condition	An expression or variable that is evaluated when the statement runs. The first condition that evaluates as True determines which block executes; if none are True, the else block runs.

# Move the drone up or down based on the position of the joystick.
drone.take_off(climb_to=500)
while True:
    position = controller.axis1.position()
    if position > 0:
        drone.climb(direction=UP, velocity=50)
    elif position < 0:
        drone.climb(direction=DOWN, velocity=50)
    else:
        drone.hover()
    wait(5, MSEC)

while

while repeatedly runs methods as long as the condition is True. It can also be used like a “Wait until” by adding not to the condition, as shown in the example below.

Usage:

while condition:
    pass

Parameters	Description
condition	An expression or variable that is evaluated before each iteration. If it evaluates as True, the loop continues; if it evaluates as False, the loop stops.

# Hover at 200 mm.
drone.take_off(climb_to=500)
while drone.range.get_distance(DOWNWARD_RANGE, MM) > 200:
    drone.climb(direction=DOWN, velocity=10)
drone.hover()
wait(3, SECONDS)
drone.land()

break

break exits a loop immediately.

# Land when button 5 is pressed.
drone.take_off(climb_to=500)
while True:
    # Move with controller
    drone.move_with_vectors(
        forward=controller.axis4.position(),
        rightward=controller.axis3.position(),
        upward=controller.axis1.position(),
        rotation=controller.axis2.position()
    )
    if controller.button5.pressing():
        break
    wait(5, MSEC)
drone.land()

quit

quit ends a running project.

Usage:
quit()

Parameters	Description
	This method has no parameters.

# Land when button 5 is pressed.
drone.take_off(climb_to=500)
while True:
    # Move with controller
    drone.move_with_vectors(
        forward=controller.axis4.position(),
        rightward=controller.axis3.position(),
        upward=controller.axis1.position(),
        rotation=controller.axis2.position()
    )
    if controller.button5.pressing():
        quit()
    wait(5, MSEC)
drone.land()

pass

pass is a placeholder for future code and can be used to avoid errors in empty loops, conditionals, and functions.

if condition:
    pass

def function():
    pass