# Case 26: The Volume Indicator

## Introduction

This is a sound warning device. As we all know, noise pollution seriously affects our lives. If we are exposed to a certain decibel noise for a long time, our physical and mental state will also be harmed. Thus, we can make a noise detection device. Different decibel values light up different colors of lights to remind people to keep quiet.

![](./images/case_28_01.png)

## Quick Start 



### Materials Required


Nezha expansion board × 1

micro:bit V2 × 1

Rainbow LED ring  × 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) and [Purchase Interactive coding accessories pack here.](https://shop.elecfreaks.com/products/elecfreaks-interactive-coding-accessories-pack?_pos=1&_sid=c75dad35f&_ss=r) if you want all the above components.***



### Connection Diagram 

Inset the micro:bit, and connect the rainbow LED ring to IIC port on Nezha expansion board. 


![](./images/case_28_03.png)



### Assembly Video





Video link: [https://youtu.be/4tFv6rWx8uM](https://youtu.be/4tFv6rWx8uM)

<iframe width="560" height="315" src="https://www.youtube.com/embed/4tFv6rWx8uM" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>


### Assembly Steps

![](./images/case_step_26_01.png)

![](./images/case_step_26_02.png)

![](./images/case_step_26_03.png)

![](./images/case_step_26_04.png)

![](./images/case_step_26_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 "nezha" to download it. 

![](./images/case_03_09.png)


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

### Step 2


### Programme as the pictures indicate


![](./images/case_28_10.png)



### Reference

Link: [https://makecode.microbit.org/_5cCW2APhK263](https://makecode.microbit.org/_5cCW2APhK263)

You may download 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:_5cCW2APhK263" frameborder="0" sandbox="allow-popups allow-forms allow-scripts allow-same-origin"></iframe></div>  


### Result
After powering on, the rainbow LED ring lights up in different colors reflecting with the ambient sound level. 

![](./images/case-gif-26.gif)