pxt-calliope/docs/projects/light-level-meter.md

Light Level Meter

Use this program to graph the light level. Press A to scroll the value on the screen.

let reading = 0
basic.forever(() => {
    reading = input.lightLevel()
    led.plotBarGraph(
        reading,
        255
    )
    if (input.buttonIsPressed(Button.A)) {
        basic.showNumber(reading)
    }
})