CharliePlex by Tim Pelling – Zero Ohm Electronics

CharliePlex by Tim Pelling

Posted by Momen Odeh on

 Tim Pelling was kind enough to provide us with the information on this post. Thank you Tim ^^



  1.       What am I trying to do:

An 'experimental' 4 pin, 3x4, 12 led addressable charlieplex display using POV to display alphabetic characters, controlled by another ATTiny85.  It's showing the number 4 in the picture, whilst it can display the whole alphabet given the poor resolution it's pretty difficult to read.


  1. Technical description:


Notes (if any)



LEDs, Cardboard, Patience




Next step:


To do list:


Change the loop code to maximize LED brightness.

Interesting interactions between brightness and speed occur depending on how many LEDs each character requires lit … with my current code.

Frame-buffer for scrolling led messages from serial input (have working fixed message scrolling code, but want variable messages)


build a 5 pin (4x5=20led) display on perfboard with mounted input button and ATTiny i.e. use all the ATTiny's available pins for use as a self-contained scrolling LED message board, using morse code via the single button as message input


Fail! Bought two types of perfboard from ZeroOhm to try them out, didn’t work!

Now to go back and purchase some ‘standard’ perfboard and try again.

Anyway – Fail it might be, but everything you do wrong teaches you something.


If you have any questions, feel free to leave a comment below.

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