2D Xmas Tree
a little christmas decoration tree made out of a PCB, all parts are within the PCB, making it only 1,6mm in height!
The trick is to arrange the components within the PCB. The contacts are made with castellation.
There a via is been milled half way, and the component gets soldered to the exposed copper.
The ATtiny25 has only 5 IO Pins when the reset should work. So to drive 20 LED´s with it, Charlieplexing is used.
That uses the tristate capability from the AVR and is using all the 5 Pins to drive the LED`s.
Downside of this is that only one LED is on at a time, at 20 LED´s that results in only 1/20 of the brightness.
The PCB itself uses the different layers to give the picture of a tree with snow.
Its made using Inkscape based on the SVG export from KiCad.
In total colors can be made using this method: Hackaday PCB Color
to generate patterns a interactive website is made: https://designer2k2.github.io/2d-xmas-tree/
The ATtiny25 is programmed over ISP, that can be done with an actual Arduino, or a ISP programmer:
the complete code, KiCad files and a instruction can be found on Github: https://github.com/designer2k2/2d-xmas-tree