Hi everyone !

You want to put an end to annoying intrusions of your private space? Want to be notified on your smartphone when someone is about to enter your room ? Follow this easy tutorial to create the Shark Multi-purpose Doorbell ! It has been programmed with 3 modes but you can customize as much as you like !

MODE 1: Motion recorder

This mode records how many times your door has been moved when you are away. This number is displayed when you press the buttons A and B at the same time.

MODE 2: Doorbell

When someone presses on of the two buttons, a ringtone on your smartphone notifies you that you have a visitor! Simply shake your phone to let him know through the screen that he may come in.

MODE 3: Alarm

You can use this mode to be warned on your smartphone if someone is opening your bedroom door, secret cupboard or even your fridge!

You will need:

• 1 BBC micro:bit

• 1 coin cell battery 3V + 1 coin cell holder

• 1 3D printer + filament

• Superglue

• Reusable adhesive

Step 1 : Print the shark

Simply download the STL file of the shark and the teeth on this page.

Next, you will have to slice the parts. That means to generate a code, representative of your 3D part which your printer will be able to understand. This action is called “slicing” because your printer prints layer by layer and the software needs to calculate the path that the printer's nozzle will follow. Make sure to use the appropriate slicer for your 3D printer, ask your teacher if you need help!

Here are the settings for printing the shark: speed at 70 mm/s, 0.2mm layer height, 10% infill, temperature between 200ºC and 240ºC.

Glue the teeth to the shark.

Step 2: Flash your Micro:bit

The program is interacting with your smartphone so the first thing to do is to download the Micro:bit app on the Play Store. Then you will have to pair your device following the instructions of the app. Once it is done, go on this page to download the program of the doorbell. Click on “Compile” to download the .hex file on your smartphone.

Back to the Micro:bit app, connect yout device and flash the code that you can now find in the “Flash” section. Your Micro:bit is now ready to communicate with your phone !

Step 3: Enjoy !

Power the Micro:bit with a battery (you can also use cylindrical batteries, they fit in the case !) and use reusable adhesive to set your doorbell wherever you want. Choose a mode and free your mind, the shark is here to prevent intruder from disturbing you !