Light Sensor Sets 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.

/* Use the light sensor to control the color of the LED strip */ #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(A2,INPUT); //light sensor } void loop() { int color = analogRead(A2); //create variable called color that is an integer (whole number) with a starting value equal to the reading from port A2 color = map(color,0,1023,0,299); //map the analogReadings (0-1023) to the color values the LED strip can show (0-299) //Now the light reading of 0 = 0 on the color reading. light reading 1023 = 299 color. light reading 512 = 150 color. strip.setPixel(strip.ALL,color); //set all pixels to a color determined by the 'color' variable strip.draw(); //send the setPixel data to the strip } // (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 permanently set on Code Lab.

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

This graphic represents how some values from the light sensor will be 'mapped' onto the pixel colors of the LED strip.

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!

Using 15 strip.setPixel functions, try to rewrite the code so that every odd-numbered pixel is using the color variable for its color and every even-numbered pixel is using a number value for the color. This will make half of your light strip responsive to the light sensor and half of it steady as a single color. Here’s an example of how the code will look:
strip.setPixel(0,200);
strip.setPixel(1,color);
….

Adjust the fourth and fifth arguments in the map function to change how wide the range of colors are that can display on the LED strip.

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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