pxt-calliope/docs/reference/led/brightness.md

Brightness

Find how bright the LED screen is when it is turned on.

led.brightness();

Returns

• a number that means how bright the screen is when it is turned on, from 0 (darkest) to 255 (brightest). For example, the number 127 means the screen is halfway bright when it is turned on.

Example: highest brightness

This program makes the screen completely bright when it is turned on (if it is not that way already):

if (led.brightness() < 255) {
    led.setBrightness(255)
}

See also

set brightness, fade in, fade out