Model rail CDU autosiding controller with optical trigger
Usage: Unit boots in auto mode with siding 1 active. sidings advance automatically when sensors are triggered in sequence. A short button push in auto-mode will also advance the siding. A long button push (3 sec) will lock a particular siding open. Another long push will take you back to auto mode on that siding. A short push in lock-mode will advance to the next siding, keeping that locked open.
Version 4 ported to PIC16F88, the 84 version used an external crystal. The 88 verison frees up the ports for use.