# Case 17: Alarm Device

## Introduction 

This is an alarm device. Press button A to make the red LED light on and flash, and the buzzer will be activated. Press button A again to cancel the alarm.



![](./images/case_17_01.png)


## Quick to Start 


### Materials

Nezha expansion board × 1

micro:bit × 1

LED-red  × 1

RJ11 wires × 1

Bricks × n

***Tips: You may need to purchase [Nezha Inventor's Kit](https://shop.elecfreaks.com/products/elecfreaks-micro-bit-nezha-48-in-1-inventors-kit-without-micro-bit-board?_pos=2&_sid=ed1b6fbd2&_ss=r) if you want all the above compoents.***


### Connection Diagram

Connect the red LED to the J1 port on Nezha expansion board. 


![](./images/case_17_03.png)


### Assembly Video


Video link:[https://youtu.be/bYN6-6PskHQ](https://youtu.be/bYN6-6PskHQ)

<iframe width="560" height="315" src="https://www.youtube.com/embed/bYN6-6PskHQ" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

### Assembly Steps


![](./images/case_step_17_01.png)

![](./images/case_step_17_02.png)

![](./images/case_step_17_03.png)

![](./images/case_step_17_04.png)

![](./images/case_step_17_05.png)




## MakeCode Programming



### Step 1


Click "Advanced" in the MakeCode drawer to see more choices. 

![](./images/case_01_10.png)

We need to add a package for programming. Click "Extensions" in the bottom of the drawer and search with "PlanetX" in the dialogue box to download it. 

![](./images/case_01_11.png)



***Note:*** If you met a tip indicating that the codebase will be deleted due to incompatibility, you may continue as the tips say or build a new project in the menu. 

### Step 2


### Programme as the picture shows: 


![](./images/case_17_15.png)

### Link
Link: [https://makecode.microbit.org/_A4CaHvTuJ7br](https://makecode.microbit.org/_A4CaHvTuJ7br)

You may also downoad it directly below: 

<div style="position:relative;height:0;padding-bottom:70%;overflow:hidden;"><iframe style="position:absolute;top:0;left:0;width:100%;height:100%;" src="https://makecode.microbit.org/#pub:_A4CaHvTuJ7br" frameborder="0" sandbox="allow-popups allow-forms allow-scripts allow-same-origin"></iframe></div>  


### Result
Press button A to alarm and the red LED flashes; press it again to stop the alarming and the LED turns off. 

![](./images/case-gif-17.gif)