Though the following example uses the Circuit Playground Express to demonstrate, the code works exactly the same way with the Circuit Playground Bluefruit. Simply copy the code and follow along with your Circuit Playground Bluefruit!

The Circuit Playground Express can see you! OK, not really. That would be creepy. 

But, it can sense light and dark, as well as colors and even your pulse!!

The Light Sensor in the upper left of the board (look for the eye icon) is a phototransistor. Here's how to use it as a light sensor:

# Circuit Playground Light Sensor
# Reads the on-board light sensor and graphs the brightness with NeoPixels

import time
import board
import neopixel
import analogio
import simpleio

pixels = neopixel.NeoPixel(board.NEOPIXEL, 10, brightness=.05, auto_write=False)
pixels.fill((0, 0, 0))

light = analogio.AnalogIn(board.LIGHT)

while True:
    # light value remapped to pixel position
    peak = simpleio.map_range(light.value, 2000, 62000, 0, 9)

    for i in range(0, 9, 1):
        if i <= peak:
            pixels[i] = (0, 255, 0)
            pixels[i] = (0, 0, 0)


Copy and paste that code into a text editor and then save it to your Circuit Playground Express as

The code reads the light sensor and then lights up the NeoPixels like a bar graph depending on the light level. Try waving your hand over it, or shining it with a flashlight to see it change!

This guide was first published on Sep 12, 2019. It was last updated on Sep 12, 2019.

This page (Playground Light Sensor) was last updated on Oct 18, 2021.

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