I tried many different schematic editors, and EasyEDA turned out to be the best. At least for me. It can even be used as a web-based application.

The thing I like the most is that it's equipped with a comprehensive component library, from which I chose the AtTiny2313 microcontroller in QFN packaging. This controller has enough pins for all my matrixes. Yes, it's equipped with just 2 KiB of flash and 100 bytes of RAM but that's okay. It should be a good exercise for my skills: to fit my applications in its limitations.

I won't show how to use EasyEDA because:

• it's simple,
• there are lots of tutorials,
• and mainly because I don't feel experienced enough to teach anyone electronics.

This is how my final schematics looks like.

Advice #1: Always add resistors to any LEDs. If you're unaware of nominal, use this online calculator. I didn't know it, that's why my LEDs will have very bright but very short life, so shame on me.