# case 23 micro:bit Crawlers

## Introduction

Let the children use the building blocks and micro:bit to make a crawling caterpillar. In this process, children could experience the fun of building blocks and get a preliminary understanding of the ratchet structure.

![](./images/case_23_01.png)

## Quick Start


### Materials Required

Nezha expansion board × 1

micro:bit V2 × 1

360°servo × 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 servo to S1 and the micro:bit to Nezha expansion board. 


![](./images/case_23_03.png)



### Assembly Video

<iframe width="560" height="315" src="https://www.youtube.com/embed/iJO1XlIaWwE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

### Assembly Steps

![](./images/case_step_23_01.png)

![](./images/case_step_23_02.png)

![](./images/case_step_23_03.png)

![](./images/case_step_23_04.png)

![](./images/case_step_23_05.png)

![](./images/case_step_23_06.png)

![](./images/case_step_23_07.png)

![](./images/case_step_23_08.png)

![](./images/case_step_23_09.png)

![](./images/case_step_23_10.png)

![](./images/case_step_23_11.png)

![](./images/case_step_23_12.png)

![](./images/case_step_23_13.png)

![](./images/case_step_23_14.png)

![](./images/case_step_23_15.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” in the dialogue box to download it.

![](./images/case_03_09.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.






### Programme as the picture shows:


![](./images/case_23_10.png)



### Link
Link：[https://makecode.microbit.org/_HwoEvqEku9jX](https://makecode.microbit.org/_HwoEvqEku9jX)

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:_HwoEvqEku9jX" frameborder="0" sandbox="allow-popups allow-forms allow-scripts allow-same-origin"></iframe></div>  


### Result
The crawlers move forward after powering on. 

![](./images/case-gif-23.gif)