Have you noticed when some programs are either loading or executing, they display text on the screen that tells you what is happening? Many programmers add a message line before every operation, where they say what their program is doing.
This way, they can easily find a problem if such appears. This is called debugging and we will learn how to apply it by printing messages on the brick display.
The command for printing text is ev3.screen.draw_text() and it requires three input parameters:
Here's an example of how you can output the message "thinking" on the screen for 5 seconds:
# Create your objects here. ev3 = EV3Brick() # Write your program here. ev3.screen.draw_text(40, 50, "thinking") wait(5000)
Upon execution of the program, the brick display should look something like this:
Here the text is set to appear at 40 pixels to the right, which is why it appears to be at the center of the screen. Furthermore, the text is set to be 50 pixels down.
If you wish to clear the displayed text from the screen, you can use the following command:
ev3.screen.clear()
This command clears the entire display.
This Tutorial is used in the following courses and lessons
The course introduces students to the programming language Python. We use LEGO Mindstorms EV3 Robots. Python is a popular programming language. It could be used for introducing students to programming, for academic studies, for developing machine learning algorithms and as a general-purpose language.
During the course, students learn how to read and how to develop Python programs. They use an Integrated Development Environment called Visual Studio Code. Robots are programmed to perform interesting and funny tasks like "bringing you water". The level ends with competition on a playing field with boxes.
Returning feedback to students is important. We try to return feedback constantly in the classes. You should also try to return feedback in a structured way - in a form of a digit. Today you will have to grade your students following this article.