Lesson 03: Unloading Alert System 卸貨提醒系統

3.1 Goal 目標

There are sensors in the unloading area. If the unloading area senses that an object has been placed in the unloading area, LED will be turned on to report the situation.


## 3.2 Background 背景 ### What is an Unloading alert system? 什麽是卸貨提醒系統?

The LED lights in the unloading area can distinguish whether the goods are received or not. When the goods are delivered and placed in the unloading area, the LED light will turn green and the person in charge will be notified immediately to confirm the receipt.


### Unloading alert system operation 卸貨提醒系統運作

The distance sensor should be able to sense the position of goods placed on the unloading area. A LED can be used to emit different colors of light (green and red light), which represent if the goods arrive.


![](picture/3/3_2.png) ![](picture/3/3_3.png) ## 3.3 Part List 材料準備

Microbit (1)
Extension board 擴展板(1)
Multi-color LED 多彩LED(1)
Distance sensor 距離傳感器 (1)
母對母杜邦綫 Female To Female Dupont Cable Jumper Wire Dupont Line (8)
M2*8mm screw (6)
M2 nut (6)
Model F (1)

## 3.4 Assembly step 組裝步驟 ### Step 1 第一步

Attach the distance sensor to F1 model with M2 * 8mm screw.


![](picture/3/3_4.png) ### Step 2 第二步

Put together all the boards (F1-F4).


![](picture/3/3_5.png) ![](picture/3/3_6.png) ![](picture/3/3_7.png) ### Step3 第三步

Attach the Multi-colour LED to F5 model with M2 * 8mm screws and nuts, and put it on F2.


![](picture/3/3_8.png) ### Step 4 第四步

Assembly completed! 組裝完成!

![](picture/3/3_9.png) ## 3.5 Hardware connect 硬件連接

Connect the Distance Sensor to P15 (trig)/ P16 (echo) port
Connect Multi-color LED to P0 P1 P2 port

將多色LED連接到P0 P1 P2端口

![](picture/3/ch3pic.png) ![](picture/3/3_10_new.jpg) ## 3.6 Programming (MakeCode) 編程 ### Step 1. Set variable and initialize multi-colour LED 設置變量並初始化多色LED + Inside on start, snap set variable distance to 0 from variables 在但啓動時裏,從變數拖入變數distance設為0 + Snap set colorLED to color pin setting.... 拖入變數colorLED設為 color pin設定...。 + Snap pause to wait 5 seconds 拖出暫停5秒 ![](picture/3/3_11.png) ![](picture/3/3_12.png) ### Step 2. Get distance value 獲取距離值 + Inside block forever. Set distance to get distance unit cm trig P15 echo P16, that’s say get the distance value by connecting the distance sensor to P15 and P16 在重複無限次的版塊裏。將變數distance設為get distance unit cm trig P15 echo P16,也就是說通過連接距離傳感器到P15和P16獲得distance值。 + Snap if statement into forever, set distance ≤ 10 into if statement 將如果語句插入重複無限次中,將如果語句設為distance≤10。 + Snap Pause to the loop to wait 1 second for next checking 把暫停拖入循環,為下一次檢查等待1秒。 ![](picture/3/3_13.png) ![](picture/3/3_14.png) ### Step 3. Show indicating colours with distance value 以距離值顯示指示色 + If distance ≤ 10, then strip show color green, else strip show color red 如果distance≤10,則顯示綠色,否則顯示紅色。 ![](picture/3/3_15.png) ![](picture/3/3_16.png)

Full Solution
MakeCode: https://makecode.microbit.org/_crvP36Fh0KUh

## 3.7 Result 總結

The distance sensor can return the distance value between the sensor and the position of goods. The LED light is used to indicate if there are goods placed at the unloading area. If there is, the LED turns green, else, the LED turns red.


## 3.8. Think 思考

Q1. How to make a sound notification if there is goods unloading (i.e. using buzzer)?