Press a Button for a Random LED Strip Color

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 the entire LED strip a random color when you press a button */ #include "LEDStrip.h" //The LEDStrip.h library gives your code access to special functions exclusive to the LED Strip LEDStrip strip = LEDStrip(50, 13, 12); //Set up the strip by defining how many pixels (50) and which pins of the microchip are used (always 13 and 12 on Code Lab) void setup() { pinMode(8,INPUT_PULLUP); //button } void loop() { if(digitalRead(8)==LOW){ //if the button on port 2 is pressed... strip.setPixel(strip.ALL,random(0,300)); //Set the entire strip (strip.ALL) to a random color including 0-299 strip.draw(); //send the setPixel data to the strip to be displayed delay(250); //delay 250 milliseconds so the 'if' statement isn't checked again before you release the button } } // (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!

Video Notes for Code Lab Users:

You will use “50” instead of “15” as the first argument in your LEDStrip function.
The second and third arguments of the LEDStrip function (13 and 12) do not need to change. These connections are are permanently set on Code Lab.
Your button is on port 8, not port 2 as the video says.

Use this spectrum to estimate the color values you'll need for your 'setPixel' arguments to achieve your favorite color!

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!

Delete the delay(250); code inside the void loop. Predict what will happen when you upload it, then see if you’re right!

Change the first argument of the strip.setPixel function so that instead of turning all of the pixels to a random color, this program only changes one pixel to a new random color.

Building on the last challenge, copy/paste the strip.setPixel function inside the ‘if’ statement and change the argument that determines which pixel is lit up. Now you can have multiple pixels on the strip that change color when the button is pressed. Here’s an example of what that might look like:
strip.setPixel(0,random(0,300));
strip.setPixel(1,random(0,300));
strip.setPixel(2,random(0,300));

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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