Alternate Siren Lights with Code Car

Alternate the sirens like a police car on the road. Play with the speed and build on with your own code.

Code

The code below already works and is ready to upload! Upload the code to Code Car and see what happens. Then, you'll 'take apart' the code to learn what each piece of the program does.

Walkthrough Videos

Watch the videos for line-by-line explanation of how the example program works. Then you'll be ready to make some changes of your own!

Challenges

How many can you complete? Change the code according to the challenges below. Upload your code to see the effect when you're finished. Complete a challenge? Check it off the list!

Change the speed of the sirens so that they blink 10 times per second. What's the delay() value?

Add the headlight and tail light to your alternating pattern. Can you get only one light to be on at a time? Remember to look for patterns.

Can you write code that turns on LED 4, then 5, then 6, then 7 and then turns off LED 4, then 5, then 6, then 7? Can you add a one second delay between each light change?

Concepts

These are the new code concepts covered in this example program. To become a great coder, read through these concepts to learn new vocabulary.

New Concept: Imagining and Visualizing

As your code gets more complex, it may be helpful to find ways to visualize what you want to do before putting into coding terms. In the final challenge of this example program, you might want to write down "4 on, wait, 5 on, wait, 6 on, wait....." and so on, before 'translating' your idea into the code terms "digitalWrite()" and "delay". Especially as you're getting used to the syntax of coding, take some time to visualize and imagine how you want your code to work before you start typing.

New Concept: Breaking it Down

You learned in the last project to look for patterns in existing code. In this program, you may have created your own patterns, starting with figuring out how to turn on and off one LED light. Maybe you used the 'copy/paste' commands on your keyboard or maybe you typed out each line of code. In either case, it will help you become a better programmer if you try to think about the repeating actions and patterns you want your code to run. Once you build the first piece, all you have to do it copy it and make small changes, like the pin number of an LED light.

Quiz

If you're having trouble, try to run an experimental program or look at the example code to help you find the answer.

When you have a coding challenge that you're not sure how to complete, a good first step might be to ____________________ . Hint: there is more than one right answer!

Draw a sketch of what you want the Code Car to do when the challenge is complete.
Draw a timeline on paper that shows what the program should do at each step of the loop.
Write the code steps down in your own words (called pseudocode) before translating to code terms.
Start writing code as fast as you can. The answer will reveal itself.

The void loop of this program only contains 2 different functions. Which of these is not included in the void loop?

digitalWrite();
delay();
pinMode();

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