Build a model railroad traffic light controller
Programming a traffic light controller on a microcontroller is not too complicated, and an easy job for Arduino. But, wait a minute… it can be done even simpler if you could program it as a PLC with a ladder diagram. There are more people out there that know how to program a PLC than who know how to program an Arduino. Besides, a nice open source compiler for doing ladder diagrams on PIC and AVR micros is available for free, so let’s give it a try.