Waiting for Button Input

You may have noticed that your code runs immediately after uploading it. This is nice sometimes, but sometimes you aren’t coding in the same place you will be running your code, and the robot suddenly driving itself off the table isn’t an ideal result. In order to have the code run on command, we can use the on board buttons to tell the code when to run.

The XRP has a button which you can read from code. To make it easy, XRPLib has a built in function which will wait for the button to be pressed for you.

Python

from XRPLib.defaults import *
from time import sleep

board.wait_for_button()
sleep(1)
drivetrain.straight(20)

Blockly

This function is part of board since the button is on the XRP’s main controller board.

This code will wait until the button is pressed, and then wait an additional 1 second (for you to get your finger out of the way) and then start driving.

There is also a function which lets you read the current state of the button without waiting for it:

board.is_button_pressed()

You could use this function as the condition for a while loop if you wanted to do something more complicated with the button than just waiting for it.