Electronic butterfly jewel

I decided to make a cool gift for my wife anniversary so I designed a PCB jewel. She loves butterflies so I tried to make her one.

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I decided to make a cool gift for my wife anniversary so I designed a PCB jewel. She loves butterflies so I tried to make it in the form of a butterfly. I googled a butterfly and found one I like. I used Inkscape to generate a “.png” file at 96 x 96 DPI resolution for the border of my board, here is the result:

It uses a standard 3V CR1220 battery in order to blink 12 LEDs. The micro-controller is an ATTiny85-20MU that drives directly the LED’s. The first iteration used 3 AG1 batteries but I  switched to the more covenant CR1220.

I need a voltage over 2.2V in order to light the LED’s but I don’t power on all LED’s at once, so I don’t need a driver for them. I can easily get 20mA from the digital pins of the ATTiny85.

Check the working video:

  • 1 × KEYSTONE 3000 Batery holder
  • 12 × LED SMD 1206
  • 4 × 150ohm SMD 1206
  • 1 × KMR211G Switch
  • 1 × ATtiny85-20MU Microprocessors, Microcontrollers, DSPs / ARM, RISC-Based Microcontrollers

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  • Updated software

    strofo06/18/2020 at 11:48 1 comment

    After looking through the projects of Gerben I learned that I can use the tristate input of the uC to mask the unwanted LEDs. Basically it divides the 3.3V voltage in two sub 2.2V that I need to light a LED. It was too much code to use the pinMode function of the Arduino so I put the needed DDRB register values in an array. Now I can do some nice rotating and bouncing effects - wrote some helper functions for them. 

    So I've updated the Github project files accordingly.

    Thanks Gerben!

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  • 1
    Get the KiCad project from github:
  • 2
    Get the Arduino sketch from github:

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strofo wrote 06/10/2020 at 22:38 point

Thanks! Yes it's been running for several days now. I don't think I need the caps because I don't have any communication going on. It's just internal processing and I don't care about timing too much.

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Gerben wrote 06/10/2020 at 19:10 point

Very pretty.

Interesting way of placing the resistors in your schematic. I always have both the anodes and cathodes go through a resistor (and use halve the calculated resistor value).

Is it running stable without any capacitors?

  Are you sure? yes | no

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