# 3.19 Button Control LED

## 3.19.1 Overview

In this project, we control the ON/OFF of the LED via an AD button. The LED will light up if we press the button and it goes off when we press the button again.

## 3.19.2 Code Flow

![t150](./media/t150.png)

## 3.19.3 Code Blocks

Blocks in ![](./media/operators.png):

1. ![t149](./media/t149.png) is used to determine whether two values are equal. If yes, it returns true; otherwise, it returns false.

For more details, please visit [Blocks Reference | MicroBlocks Wiki](https://wiki.microblocks.fun/en/reference_manual#operators)

## 3.19.4 Test Code

You can manually build blocks, or directly open the code file we provide: `3-19-Button Control LED.ubp`. If you have any questions about how to open code files or upload code, please back to `1.9 Upload Code`.

**Build code blocks:**

1. In ![](./media/control.png), drag ![](./media/t1.png) and ![](./media/t2.png) to the script area, and stack them together.

![t34](./media/t34.png)

2. In ![](./media/variables.png), declare a variable named `item`.
3. ![t52](./media/t52.png) determines whether the red button is pressed.

![t152](./media/t152.png)

4. Check if `item` = 0. If yes, red LED turns on and set `item` to 1 . If not, red LED turns off and set `item` to 0. At last, add a delay of 300ms.

![t153](./media/t153.png)

## 3.19.5 Test Result

Connect the coding box to the MicroBlocks via USB or Bluetooth, and click ![t59](./media/t59.png) to upload the code to the coding box. Press the red button and the red LED lights up; press it again and the LED goes off.