# 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 Test Code

### 3.19.2.1 Code Flow



![6-19-2-1](./media/6-19-2-1.png)

### 3.19.2.2 Build Code

There are two ways to upload the code: directly open the code file we provide; or manually build blocks.

**Directly open the code file we provide:**

1. Click ![](./media/j68.png) and choose `Load from your computer`

![](./media/j67.png)

2. We have already downloaded the codes on computer desktop, so open the file and choose `3-19-tableLamp.sb3`

**Manually build blocks:**

1. In ![events](./media/events.png), find ![j1](./media/j1.png) block.
2. In ![control](./media/control.png), find and place ![j2](./media/j2.png) block under ![j1](./media/j1.png).

![6-1-4-1-1](./media/6-1-4-1-1.png)

3. In ![variable](./media/variable.png), find ![j7](./media/j7.png) and put it under ![j1](./media/j1.png), name the variable to “item“ and assign to “1” as its initial value.

![6-19](./media/6-19-2-2.png)

4. In ![control](./media/control.png), put ![j25](./media/j25.png) into ![j2](./media/j2.png).
5. In ![operator](./media/operator.png), find and put ![j22](./media/j22.png) into the condition box of ![j25](./media/j25.png)

![6-19](./media/6-19-2-2-3.png)

4. In ![](./media/adkey.png), find ![j8](./media/j21.png) and put it in the left part of ![j22](./media/j22.png), and set the right part to value 3500: AD key analog value > 3500

![6-19](./media/6-19-2-2-4.png)

5. In ![control](./media/control.png), find and put block ![](./media/j16.png) into ![6-19](./media/6-19-2-2-4.png).
6. In ![operator](./media/operator.png), put ![j29](./media/j29.png) into the condition box of ![](./media/j16.png)
7. In ![variable](./media/variable.png), put ![j8](./media/j8.png) into the left part of the ![j29](./media/j29.png), and modify the right part into “1”: variable item = 1

![6-19](./media/6-19-2-2-5.png)

8. In ![](./media/led.png), drag and put ![](./media/j3.png) in "if" of block ![6-19](./media/6-19-2-2-6.png)
9. In ![variable](./media/variable.png), put ![j8](./media/j9.png) under ![](./media/j3.png)
10. Duplicate ![](./media/j3.png) and put into "else" of block ![6-19](./media/6-19-2-2-7.png), and set LED to output “LOW” and set item variable by “1”.
11. Add a delay of 0.3s below ![](./media/j16.png).

**Complete Test Code**

![6-19-2-2-8](./media/6-19-2-2-8.png)

### 3.19.2.3 Test Result

After uploading code, press the red button and the red LED lights up; press it again and the LED goes off.