# ButtoncontrolLED
In this example, we will use a push-button to control the LED.
The input signal will change as you press the button. Thus, you can set LED status according to different input states.
## What you need
* SwiftIO board
* Button
* Jumper wires
### Kits that meet the experimental conditions:
* [Maker Kit for SwiftIO](https://www.madmachine.io/product-page/maker-kit-for-swiftio)
## Circuit
There is an onboard RGB LED. Please apply **low** voltage to light it.
The button has four legs. The two legs on same side are interconnected.
* Connect the leg on left side to 3.3V pin.
* Connect the leg on right side to digital pin D10.
In default mode, the digital pin reads `false`. When you press the button, the two points on the button will be connected. And the value of pin will be `true`.
So please be sure you connected the button in a right way.
## Code
Here comes the code. You can find the example code at the bottom left corner of IDE:  > SimpleIO > ButtoncontrolLED.
```swift
// Read the input signal controlled by a button to turn on and off the LED.
// Import the library to enable everything in it, like relevant classes and methods.
// This is first step for your coding process.
import SwiftIO
// Declare a constant. You may choose any descriptive name you like.
// Initialize the onboard red LED.
// The Id of onboard LED should be capitalized.
let red = DigitalOut(Id.RED)
// Initialize a digital input pin D10 the button is connected to.
let button = DigitalIn(Id.D10)
// Allow the button to control the LED all the time.
while true {
// Check the state of button.
// If it is pressed, the value will be true and then turn off the LED.
// Modify the code according to your button if necessary.
if button.read() {
red.write(false)
} else {
red.write(true)
}
}
```
## Instruction
`DigitalIn` class is intended to detect the state of a digital input pin. The input value is either `true`(1) or `false`(0). The `.read()` function reads the value from a digital input pin.
If you have the experience with Arduino, you may notice there's no pull-down resistor on the button. That's because the SwiftIO Board already provides a pull-down function. Reference the `DigitalIn` class for more information.
## See Also
* [Id](https://swiftioapi.madmachine.io/Enums/Id.html) - Enumerations of all the pins on the board.
* [DigitalIn](https://swiftioapi.madmachine.io/Classes/DigitalIn.html) - Detect the state of a digital input pin. The input value is either true (1) or false (0).
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