Watch Your Kid Using Radio of Micro:bit

We sometimes hear of the accidents involving kids, causing injury and deaths. These are some possible reasons I can think of:

1. the parents have other things to attend to and cannot keep an eye on the kids;
2. the parents are thinking about other things and have forgotten about the kids;
3. the parents are careless.

If there is something to remind the parents to watch over their kids, these accidents might could be avoided.

Watch Your Kid consists of 2 sets of wearable worn by the kid and the parent respectively

The Micro:bits are coded so that it can function as alarm when the kid is too far from the parent.

The radio of Micro:bit allows wireless communication between the two wearables.

Note: It works most of the time but may still fail too due to certain conditions. So, it is strongly advisable to be used for learning and entertainment purpose only.

2 Sets of Circuits

• Micro:bit x 2
• Battery holder x 2
• Batteries x 4
• Crocodile wire x 4
• Buzzer x 2

Kid's Wearable (A Pouch)

• Needle x1
• Safety pin x 2
• Used cloth
• Thread

Kid's Wearable (A Velcro Strap)

• Used cloth
• Velcro
• Double-sided tape

Make a pouch as the wearable for the kid. Cut out a cloth of 17cm x 14 cm.

Fold the cloth upward to the size of 17 cm x 9 cm.

Fold the both right and left sides of the cloth inward to the size of 10 cm x 9 cm (to keep the battery holder with wires).

Sew both the right and left sides of the cloth into a pouch. The pouch is done.

Complete the circuit. Make 2 sets of it.

Put the battery holder below Micro:bit. Arrange wires and put them below battery holder.

Put the circuit into the pouch. Pinned it at both sides on the kid's clothes. Arrange the buzzer so that it faces outward. The wearable for the kid is done.

Cut out 5 cm x 22 cm of double-sided tape. Cut out some cloth to be pasted at the front and the back of it. Cut a set of Velcro (5 cm x 5cm). Paste them at the ends of the front and the back of the cloth.

Fix the circuit on the strap.

Code in Makecode Editor.

• It shows the icon of a baby trolley on start so that the user knows it is working.
• Set radio group to 1 so that both micro:bits are connected to the same channel.
• Radio send number 0 to transfer data consistently(forever).
• Signal strength: the value ranges from -128 to -42 (-128 means a weak signal and -42 means a strong one.)
• When the kid is next to the parent, it shows the icon "✔".
• When the kid starts to walk away from the parent, the signal of -42 will drop. When the distance is about 1 meter, the signal would fall below -65. This will trigger the buzzer and show the icon of "X".
• Download the code to both the Micro:bits.

Click here for the sample code.

In the video, the rabbit acts as the kid, whereas the frog acts as the parent.