pxt-microbit/docs/reference/input/light-level.md

Light Level

Find the light level (how bright or dark it is) where you are. The light level 0 means darkness and 255 means bright light. The @boardname@ measures the light around it by using some of the LEDs on the LED screen.

The first time you use it, this function will say 0. After that, it will say the real light level. This is because the light sensor (the part that can find the light level) has to be turned on first.

input.lightLevel();

Returns

• a Number that means a light level from 0 (dark) to 255 (bright).

Example: show light level

When you press button B on the microbit, this program shows the light level on the LED screen.

input.onButtonPressed(Button.B, () => {
    let level = input.lightLevel()
    basic.showNumber(level)
})

Example: chart light level

This program shows the light level with a bar chart on the @boardname@ screen. If you carry the @boardname@ around to different places with different light levels, the bar chart will change.

basic.forever(() => {
    led.plotBarGraph(input.lightLevel(), 255)
})

See also

acceleration, compass-heading