Arduino Based Split-Flap Game





Introduction: Arduino Based Split-Flap Game

Holiday Gifts Contest

Second Prize in the
Holiday Gifts Contest

We have a great Dutch Holiday tradition called sinterklaas (5th of december, this is what the US Santa is based on). For the older "non-believers" we make surprises. The purpose is to buy a small present but make a really cool "surprise" around it. Here my arduino based Split-flap game I made as surprise.

I made this for my 15-year old niece that was asking for very expensive presents only, so I thought I would make her a bit more price conscious :-)

The wooden box and all the components for the Split-flap display were made on my CNC machine. I used 2mm thick plastic to mill out the 36 cards in the display. The wheels holding the cards and the pulleys for the cardwheel and stepper motor were milled from left over thick plastic blocks. I milled a 10 teeth pulley (XL037) for the stepper motor and a 40 teeth pulley for the cardwheel, giving me a ration of 4:1 and with my 1.8 degree per step motor, this gives me plenty of accuracy to make sure I display the right cards. I did build into my arduino code I can easily change the offset for each card to fine calibrate. I had to do this, as not all my cards where equal in size.

The arduino (uno) used to run this all was tested to its limit 15 I/O ports :-)
- 5 pins for the score LEDs
- 4 pins for the stepper motor control, via ULN2003a
- 1 PWM pin for Servo to lock or unlock the side door
- 1 PWM pin for piezo speaker so we can make some sounds
- 1 pin for micro switch to align start of cards
- 2 pins for the lower and higher button

Here a video of the game in action:

if you happen to be Dutch (or at least understand that language), you can also watch the Dutch version of the video :-)

UPDATE:Wow, thank you all for the very nice comments! Clearly I am not the only one enjoying the sound and sight of the split-flap display :-) So I thought I would share you a video I made a few weeks back on my initial testing of the display. At some point I want to create 100 units, so I can have a wall in my living room of 25 characters by 4 lines to display "stuff" :-)



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Which size belt do you used?

A-mazing project!

Absolutely great!! But hard to duplicate based on your instructions. Would like to modify as a learning tool for my class room. Are there schematics and more diagrams available? I don't have CNC machine.

I totally agree with you!

Hi, nice thing...

How do you calibrate the starting position of the stepper motor? Is there some sort of feedback loop from the split flap display back to the arduino?

yes, check out the 40 toot pulley and card holder file. The is a "big bump" in the pulley that passes a micro switch every rotation. I use this for calibration.

This is awesome! Such a creative and fun gift. Can you explain more how the micro switch works to align the cards? Does this help to calibrate the start point for the stepper motor?


Hey this is great! Brilliant idea. Can I ask how you attached the cards to the card-wheel?

The cards have on each side a bit sticking out, see the "card 8cmx5cm.dxf" file. These bits go into the wholes in the wheel.

the coolest thing on instructables.... by far.