20. IoT Case 11: Roof garden clothes rack

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20.1. Goal

Make a smart roof garden clothes rack, once the weather condition is changed, the rack can be opened/ closed automatically.

20.2. Background

What is Roof garden clothes rack?

People no long need to rush up to the roof when raining as the clothes rack can be closed automatically even when house owner is not at home.

Roof garden clothes rack operation

Micro:bit can receive WAN commands from WAN (eg. IFTTT), the the micro:bit will get the command name. If the command name is “Rain”, the servo will turn to 90ᵒ and the rack will be opened. If the command name is “Clear”, the servo will turn to 180ᵒ and the rack will be closed.

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20.3. Part List

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20.4. Assembly step

Step 1

Step 1. Attach the raindrop sensor to the model H2

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Step 2

Step 2. Attach the long stand (H3) to the model H1

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Step 3

Step 3. Put together all the cardboard parts.

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Step 4

Step 4. Screw the cloth rack (H5) onto the 180ᵒ servo using M2 screws

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Step 5

Step 5. Put together the models H4-H5 and H6-H7.

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Step 6

Step 6. Assembly completed!

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20.5. Hardware connect

Connect the 180ᵒ Servo to P1 port of IoT:bit

Micro:bit P1 Servo
S (yellow) S (orange)
V (red) V (red)
G (black) G (brown)

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20.6. Programming (MakeCode)

Step 1. Initialize OLED, IoT:bit and connect to WiFi

  • Snap Initialize OLED with width:128, height: 64 to on start

  • Snap Initialize IoT:bit TX P16 RX P8 from IoT:bit to on start

  • Snap Set Wi-Fi to ssid pwd from IoT:bit

  • Enter your Wi-Fi name and password. Here we set smarthon as SSID and 12345678 as password pic_60

Step 2. Show icon “tick” after WiFi connection

  • Snap show icon from basic to On WiFi connected and select icon tick

  • Draw the Device ID variable from On WiFi connected to the show string block placeholder pic_50

Step 3. Receive WAN command

  • Go to OLED

  • Snap the clear OLED display to On WiFi received to avoid overlap

  • Snap the show string to On WiFi received

  • Draw the WAN_Command variable to show string placeholder pic_70

Step 4. Control rack open/close by WAN command

  • Snap if-condition

  • Set variable WAN_Command = Rain into if-condition

  • Snap Turn Servo to … degree from SmartCity > Output

  • Set Servo degree to 90 at P1 (control the servo to open the rack)

  • Set variable WAN_Command = Clear into else-if-condition

  • Snap Turn Servo to … degree from SmartCity > Output

  • Set Servo degree to 180 at P1 (control the servo to close the rack) auto_fit

Step 5. Press A to open clothes rack

  • Snap on button … pressed from Input, set button A

  • Snap Turn Servo to… from SmartCity > Output

  • Set servo to 90 degree at P1 (open clothes rack) pic_50

Step 6. Press B to close clothes rack

  • Snap on button … pressed from Input, set button B

  • Snap Turn Servo to… from SmartCity > Output

  • Set servo to 180 degree at P1 (close clothes rack) pic_50

Full Solution

MakeCode: https://makecode.microbit.org/_6KyfVPJEd10A

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20.7. IoT (IFTTT)

* For the setting of IFTTT, please refer to “Chapter 4: Cloud Control micro:bit by IFTTT”

Step 1. Create applet in IFTTT

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20.8. Result

The micro:bit is controlled by IFTTT (trigger by weather open data). When the weather condition change to “Rain”, the cloth rack will be opened. When the weather condition change to “Clear”, the cloth rack will be closed.

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20.9. Think

Q1. Can you control the clothes rack by other weather conditions? (e.g. sunlight)