PIC12C508 Datasheet PDF - Microchip

INTRODUCTION

●The purpose of this application note is to demonstrate how KEELOQ® code hopping technology can be conveniently employed to implement an automatic code hopping password generator/keypad.

●Using a PIC12C508, the hopping code produced by an HCS300 is converted to a string of 16 hex digits. This  string is then transferred to the PC via the keyboard line, thereby emulating the actual pressure of a sequence of keys on a standard PC/AT® keyboard. Since this conversion process is transparent to any application, it appears as if the user is simply typing on a PC/AT-type keyboard.