Skip to content


Sunlight sensor

Beginner | MakeCode, Python | Light sensor | Input/output, Light, Relational operators, Selection, Weather & climate

Step 1: Make it

What is it?

Turn the LED display into a sensor to make your micro:bit react to light.

micro:bit reacting to sunlight falling on it by showing a sun icon on its LED display

How it works

  • As well as working as an output, the LEDs on your micro:bit can also work as an input device light sensor, measuring the amount of light falling on them.
  • This means that micro:bit programs can make different things happen depending on how light or dark it is.
  • The program uses an ‘if… else’ statement to show the sun image only if the light level is greater than (>) a certain level. This is known as selection – selecting when different things happen.
  • Flash this program onto your micro:bit and shine a light source, like a torch, daylight or bright ceiling light on to the micro:bit, and you should see the sun appear.
  • Cover the micro:bit with your hand and the sun icon should vanish.
  • If it doesn’t work, try making the 100 number smaller to suit the lighting where you are.
  • You can read more background information about how the micro:bit light sensor works here.

What you need

  • micro:bit (or MakeCode simulator)
  • MakeCode or Python editor
  • battery pack (optional)
  • a light source and something to cover the micro:bit with – your hand will do!

Step 2: Code it

1from microbit import *
3while True:
4    if display.read_light_level() > 100:
6        "90909:"
7        "09990:"
8        "99999:"
9        "09990:"
10        "90909"))
11    else:
12        display.clear()

Step 3: Improve it

  • Show a different picture, like a moon or star, when it’s dark.
  • Show an animated sun when light falls on your micro:bit.
  • Turn this project into a night-light by making it light up the micro:bit’s display when it goes dark.