This is a charlieplexing PCB. The figure is a black cat sitting on an unicorn ([on reddit](https://www.reddit.com/r/blackcats/comments/7opy9u/and_lo_i_saw_a_rider_on_a_pale_horse_and_the/)). The artwork was made by inkscape and EasyEDA. A Tinkercad simulation with arduino compatible spaghetti code: [https://www.tinkercad.com/things/0iIPoKPwN5V-unicat-charlieplexing](https://www.tinkercad.com/things/0iIPoKPwN5V-unicat-charlieplexing) Video from the working PCB: [https://youtu.be/Z9F6bd1mocM](https://youtu.be/Z9F6bd1mocM) The ordering of the LEDs are not the same in the schematic sheet and the PCB layout. However their numbering are equal. Moreover 100 Ohm resistors at 3V are not the most suitable for different type of LEDs (in use red, yellow, green, blue at the same time). (for example: the voltage drop of blue leds is regularly over 3V.) **Charlieplexing tables** (order of leds according the schematic) ```language LED HIGH LOW ------------------- 01 PB3 PB2 02 PB2 PB3 03 PB3 PB1 04 PB1 PB3 08 PB2 PB1 07 PB1 PB2 06 PB2 PB0 05 PB0 PB2 12 PB3 PB0 11 PB0 PB3 10 PB1 PB0 09 PB0 PB1 ``` ** If you want to write a sketch the following should be considered.** (the below is order of leds according the layout) ```language LED PB0 PB1 PB2 PB3 ----------------------------------- 01 - - L H 02 - - H L 03 - L - H 04 - H - L 05 H - L - 06 L - H - 07 - H L - 08 - L H - 09 H L - - 10 L H - - 11 H - - L 12 L - - H ```