The HCS301 is a code hopping encoder designed for secure Remote Keyless Entry (RKE) systems. The HCS301 utilizes Microchip’s patented KEELOQ® hopping technology, which incorporates high security, a small package outline, and low cost, to make this device a perfect solution for unidirectional remote keyless entry systems and access control systems. The HCS301 combines a 32-bit hopping code generated by a non-linear encryption algorithm, with a 28-bit serial number and six status 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 (code grabbing) 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 HCS301 a very secure unit. The HCS301 provides an easy-to-use serial interface for programming the necessary security keys, system parameters, and configuration data. Additional features include an LED Drive, Overflow bits, Time-out, and Battery low indicator. The HCS301 operates in a voltage range of 3.5V to 13.0V.