Blink Row of LEDs 'Up and Back'

Code

The code in the editor below is ready to run! Plug your Code Lab in to your computer's USB port with the cable and hit 'Upload Your Code!' to see what it does. Change something in the code, like a delay or pin number. Try to add something new to the program - it's yours to tinker with! You can always press the 'Restore' button to return the code to the working example.

/* Turn on a row of LEDs, then turn them off in reverse order */ void setup(){ //combine single color LEDs with an RGB LED to fill all these ports! pinMode(2,OUTPUT); //LED pinMode(3,OUTPUT); //LED pinMode(4,OUTPUT); //LED pinMode(5,OUTPUT); //Red-Green-Blue LED color pinMode(6,OUTPUT); //Red-Green-Blue LED color pinMode(7,OUTPUT); //Red-Green-Blue LED color } void loop(){ /*create a variable named i that has a starting value of 2. Until i equals 7, run the code between the curly braces, then increase the value of the 'i' variable by 1*/ for(int i=2;i<8;i++){ digitalWrite(i,HIGH);//turn on the LED whose number is equal to 'i' delay(500); //wait 500 milliseconds (0.5 seconds) with the LED on before running the 'for' loop again } /*create a variable named i that has a starting value of 7. Until i equals 2, run the code between the curly braces, then decrease the value of the 'i' variable by 1*/ for(int i=7;i>1;i--){ digitalWrite(i,LOW); //turn off whichever LED's number is equal to 'i' delay(500); //wait 500 milliseconds (0.5 seconds) with the LED off before running the 'for' loop again } } // (c) 2021 Let's Start Coding. License: www.letsstartcoding.com/bsdlicense

Walkthrough Video

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

Challenges

Can you complete the challenges? Change the code in your code editor above. Upload your code to see the effect when you're finished. Complete a challenge? Check it off the list!

Modify the delays in the code to affect the speed.

Try to add the other RGB (red-green-blue) LED to this circuit and this program. You’ll need 3 more pinMode functions and one small change to the condition of both of the ‘for’ loops.

What happens if you add a delay between the two ‘for’ loops? Try to predict the outcome before you run an experiment to find out.

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.

Quiz

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

1. Which syntax ends the entire 'void loop' function?

semicolon ;
parentheses )
closing curly brace }

2. Which syntax ends a single code command?

semicolon ;
closing curly brace }
period .

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