LED Strip Shadow Counter

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.

/* 'Shadow counter' adds one more lit pixel to the LED strip when the light sensor 'sees' darkness */ #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) int pixelCount = 0; //create a variable named pixelCount that is an integer (whole number) with starting value of 0 void setup() { pinMode(A2,INPUT); //light sensor } void loop() { if(analogRead(A2)< 300){ //if the light reading is lower than 300... pixelCount++; //increase the value of pixelCount by 1 } strip.setPixel(pixelCount,100); //light the number of pixels equal to the pixelCount variable, with a color value of 100 strip.draw(); //send the setPixel data to the strip delay(500); //wait 500 milliseconds (0.5 seconds) between light readings so a single shadow doesn't count more than once if(pixelCount>49){ //if all 50 pixels (0-49) are lit and another shadow makes pixelCount > 49... pixelCount=0; //reset the pixelCount variable to 0 strip.clear(); //clear the lit pixels off the LED strip } //Note: You might need to adjust the 'shadow' threshold depending on how bright or dim your environment is! } // (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.
The second ‘if’ statement is going to check if all 50 of the LED pixels are on, not 14 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!

If the shadow counter is counting up without you passing a shadow over the light sensor, change the number in the first ‘if’ statement that is next to the ‘<’ sign.

Change the color value that the LED pixel displays by changing the second argument in the strip.setPixel function.

If your shadow counter is counting one quick movement as multiple ‘shadows’ or if it is not counting shadows fast enough, adjust the delay in the code to change the sensitivity.

Add a speaker to the program and make it beep once when the second if statement runs - the code that resets pixelCount to 0 - so that you get a warning when the shadow counter is resetting.

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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