It is a 555 LED flashing circuit? Yep. How about a hex counter ... When [grandalf]’s friend showed them a project where a 555 timer was installed on an Arduino shield, they realized two things: ...

[ZHut] managed to bring these two worlds together by presenting how to make an Arduino blink an LED in conjunction with a 555 timer ... this idea to any number of circuits out of the 555 playbook ...