The HCS200 is a code hopping encoder designed for Remote Keyless Entry (RKE) systems. The HCS200 utilizes Microchip’s patented KEELOQ® code hopping technology, which incorporates high security, a small package outline and low cost, to make this device a perfect solution for replacement of fixed code devices in unidirectional remote keyless entry systems and access control systems. The HCS200 combines a 32-bit hopping code generated by a non-linear encryption algorithm, with a 28-bit serial number and 6 information bits to create a 66-bit transmission stream. The length of the transmission eliminates the threat of code scanning, and the code hopping mechanism makes each transmission unique, thus rendering code capture and re-send schemes useless. The encryption key, serial number, and configuration data are stored in EEPROM, which is not accessible via any external connection. This makes the HCS200 a very secure unit. The HCS200 provides an easy-to-use serial interface for programming the necessary security keys, system parameters, and configuration data.