pxt-calliope/docs/blocks/on-start.md

# @extends

## #exstart

In this example, ``on start`` sets a dimmer brightness on the screen and the button handler shows a string.

```blocks
input.onButtonEvent(Button.A, input.buttonEventValue(ButtonEvent.Down), () => {
    basic.showString("Hello!")
})
led.setBrightness(50)
```