Controls#
Introduction#
The Control blocks in VEXcode AIR manage the flow of a project by handling loops, conditions, and delaying blocks from running.
A loop is when a computer repeats the same step or group of steps over and over until it is told to stop. A condition is a rule the computer checks to decide what to do next. For example, the drone can fly forward when a controller button is pressed.
Below is a list of available blocks:
wait — Pauses blocks from running for a specific duration.
wait until — Pauses blocks from running until a specified condition is met.
repeat — Repeats a set of blocks a specific number of times.
forever — Repeats a set of blocks indefinitely.
repeat until — Repeats a set of blocks until a condition is met.
while — Repeats a set of blocks while a condition remains true.
if — Runs a set of 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 loop immediately.
stop project — Ends the project.
wait#
The wait stack block pauses blocks from running for a specific amount of time before moving to the next block.
wait (1) seconds
Parameters |
Description |
|---|---|
time |
The amount of time to wait, as a positive whole number or decimal in seconds. |
Example
when started
[Fly for 1 second.]
take off to (500) [mm v] ▶
wait [1] seconds
land ▶
wait until#
The wait until stack block pauses blocks from running until a specified condition is met before moving to the next block.
wait until <>
Parameters |
Description |
|---|---|
condition |
The condition that must be met before moving on to the next block. If it evaluates as:
|
Example
when started
[Hover at 200 mm.]
take off to [500] [mm v] ▶
climb [down v]
wait until <(distance [downward v] range in [mm v]) [math_less_than v] [200]>
hover
wait (3) seconds
land ▶
repeat#
The repeat C block runs the blocks inside it a set number of times.
repeat [10]
end
Parameters |
Description |
|---|---|
times |
A whole number that sets how many times the repeat block runs. |
Example
when started
[Move back and forth four times then land.]
take off to [500] [mm v] ▶
repeat (4)
move [forward v] for (500) [mm v] ▶
wait (1) seconds
move [backward v] for (500) [mm v] ▶
wait (1) seconds
end
land ▶
forever#
The forever C block keeps running the blocks inside it again and again without stopping.
forever
end
Parameters |
Description |
|---|---|
This block has no parameters. |
Example
when started
[Move with controller.]
take off to [500] [mm v] ▶
forever
move with controller
end
repeat until#
The repeat until C block runs the blocks inside it repeatedly while the specified condition is not met.
repeat until <>
end
Parameters |
Description |
|---|---|
condition |
An expression or variable that is checked before each loop. If it is False, the blocks continue repeating. If it is True, the loop will stop. |
Example
when started
[Move with controller until button 7 is pressed.]
take off to [500] [mm v] ▶
repeat until <controller button [7 v] pressed?>
move with controller
end
land ▶
while#
The while C block runs the blocks inside repeatedly while the specified condition is met.
while <>
end
Parameters |
Description |
|---|---|
condition |
An expression or variable that is checked before each loop. If it is True, the blocks continue repeating. If it is False, the loop will stop. |
Example
when started
[Hover at 200 mm.]
take off to [500] [mm v] ▶
while <(distance [downward v] range in [mm v]) [math_greater_than v] [200]>
climb [down v]
end
hover
wait (3) seconds
land ▶
if#
The if C block runs the blocks inside if the condition is True.
if <> then
end
Parameters |
Description |
|---|---|
condition |
An expression or variable that is checked when the statement runs. If it is True, the blocks inside the if block will run. If it is False, the blocks are skipped over. |
Example
when started
[Take a picture when button 5 is pressed.]
take off to [500] [mm v] ▶
forever
move with controller
if <controller button [5 v] pressed?> then
capture image on [forward v] camera
end
end
if / else#
The if / else C block determines which set of blocks runs based on whether the condition is True or False.
if <> then
else
end
Parameters |
Description |
|---|---|
condition |
An expression or variable that is checked when the statement runs. If it is True, the blocks inside the if block will run. If it is False, it will runs the blocks inside the else block. |
Example
when started
[Climb when the left joystick is moved up.]
take off to [500] [mm v] ▶
forever
if <(controller axis [1 v] position) [math_greater_than v] [0]> then
climb [up v]
else
hover
end
if / else if / else#
The if / else if / else expandable C block selects which set of blocks 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 <> then
else if <> then
else
end
Parameters |
Description |
|---|---|
condition |
An expression or variable that is checked when the statement runs. The first condition that is True runs that set of blocks. If all conditions evaluate as False, the blocks inside the else block will run. |
Example
when started
[Move the drone up or down based on the position of the joystick.]
take off to [500] [mm v] ▶
forever
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
hover
end
end
break#
The break stack block exits a loop immediately. This block can be used inside repeat, repeat until, while, and forever blocks. Break is useful when a loop needs to stop early based on something that happens during the project, like a button being pressed or a sensor detecting an object.
break
Parameters |
Description |
|---|---|
This block has no parameters. |
Example
when started
[Land when button 5 is pressed.]
take off to [500] [mm v] ▶
forever
move with controller
if <controller button [5 v] pressed?> then
break
end
end
land ▶
stop project#
The stop project stack block ends a running project.
stop project :: control cap
Parameters |
Description |
|---|---|
This block has no parameters. |
Example
when started
[Stop motors after landing.]
take off to [500] [mm v] ▶
wait [1] seconds
land ▶
stop project