Magic 8 of Hearts

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WARNING LiPo battery in this project was underrated and got hot and puffed up. Use a higher rated battery.

This write up is about a project merging the Magic 8-Ball with Valentine candies. The basic premise is that the heart is shaken like a Magic 8-Ball and message reminiscent of the candy heart sayings appear in the window.

The Magic 8 of Hearts, as we call it, has several features:

1. Inductively charged.

2. Shake to activate.

3. Digital LCD display of message.

4. Magnetic reed switch to reset nano arduino

5. Magnetic reed switch to disable power to arduino while charging.

Ridiculous Backstory

LVL1 Director of Legal Evil Emeritus was acting oddly human the last few days. When asked about his behavior, he said he was preoccupied with hacking a heart. Immediately people stepped aside and a few members checked to see if they had any new chest scars. But the scare was short lived as he revealed what the heart hacking was: The Magic 8 of Hearts


This project consists of the following parts.

M8H Guts.jpg

M8H Shell.jpg

Arduino Nano PowerBoost 500 Charger - Rechargeable 5V Lipo USB Boost @ 500mA+
White LEDs Inductive Charging Set - 5V @ 500mA max
1.44" 128*128 TFT LCD SPI 3.7v 650mah Li-po Battery
MMA7361LC 3-Axis Accelerometer ±1.5/6g FQP30N06L MOSFET
Perf Board Split Heart
Not Shown
49 ohms resister (LED) 150 ohms resister (LCD Backlight)
Reed Switch 12k ohms resister (MOSFET Limiter)

Prepare The Heart

Make a hole in the heart.

M8H Heart Hole.jpg

Make a insertable Perf Board

M8H Heart Board Empty.jpg

Layout the Board

After several tries, the components are placed on the board.

M8H Board Layout Final.jpg

Wiring of Boards

Arduino Nano Pin Accelerometer Pin
A1 X-Axis
A2 Y-Axis
A3 Z-Axis
A4 Free Fall 0g
3.3v Sensitivity
3.3v Vdd

A reed switch (N.O.) connects Arduino Reset to GND.

Arduino Nano Pin 128*128 TFT LCD SPI Pin
D5 LED Backlight w/ 150 ohm resistor
D8 A0
D9 Reset
D10 CS
3.3v Vdd
Adafruit Boost Charger Pin Other Component Pin
USB Vdd Adafruit Inductive Charger
BAT V+ 3.7V LiPo Battery
5V Arduino Nano 5V
GND Adafruit Inductive Charger
GND GND Arduino Nano

A reed switch (N.O.) connects Charger EN to GND.

Five white LEDs with a 49 ohm resistors in series are wired in parallel. The positive rail is attached to the 3.7v line of the LiPo battery. The GND rail is attached to the MOSFET Drain lead. The MOSFET Source lead is attached to Battery GND. A 12k ohm resistor is attached across the MOSFET Gate and Source leads. The Gate lead is also attached to the Arduino D6 pin.

M8H Pictogram.jpg

The coil in the picture above is a simplified representation of the inductive charging coil and associated circuitry.

Prepare the Screen

Classical wirewrap will connect the screen to the controller.

M8H LCD Wire Wrap.jpg

The screen is then glued into the front shell.

M8H LCD Shell.jpg

Solder up all the parts.

M8H Board Wired.jpg

Power Plant

Place inductive charger receiver in back half of heart shell and glue in place.

Yes, I forgot to take a photo!

Place a rubber flap over unit to prevent shorts.

M8H Inductive Cover.jpg

Arrange remaining power supply components.

M8H Heart Power Supply.jpg

Prepare another flap to insulate the power supply from the rest of the project.

M8H Power Isolation.jpg

Merge the Halves

M8H Board Halves.jpg

M8H Board Merged.jpg

M8H Whole.jpg

The Code


Magic 8 of Hearts Video 1

Magic 8 of Hearts Video 2

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