The Microchip Technology Inc. HCS515 is a code hopping decoder designed for secure Remote Keyless Entry (RKE) systems. The HCS515 utilizes the patented KEELOQ code hopping system and high security learning mechanisms to make this a canned solution when used with the HCS encoders to implement a unidirectional remote and access control systems. The HCS515 can be used as a stand-alone decoder or in conjunction with a microcontroller.