hcs410 Microchip Technology Inc., hcs410 Datasheet - Page 22

• Manufacturer Part Number: hcs410
• Description: Keeloq Code Hopping Encoder And Transponder Keeloq Code Hopping Encoder And Transponder
• Manufacturer: Microchip Technology Inc.

HCS410
4.0
Use of the HCS410 in a system requires a compatible
decoder. This decoder is typically a microcontroller with
compatible firmware. Firmware routines that accept
transmissions from the HCS410, decrypt the code hop-
ping portion of the data stream and perform IFF func-
tions are available. These routines provide system
designers the means to develop their own decoding
system.
FIGURE 4-1:
DS40158E-page 22
INTEGRATING THE HCS410
INTO A SYSTEM
Manufacturer’s
Code
CREATION AND STORAGE OF ENCODER KEY DURING PRODUCTION
Serial Number or
Transmitter
Generation
Algorithm
Seed
Key
Preliminary
Encoder
4.1
The serial number for each transmitter is programmed
by the manufacturer at the time of production. The
generation of the encoder key is done using a key gen-
eration algorithm (Figure 4-1). Typically, inputs to the
key generation algorithm are the serial number of the
transmitter or seed value, and a 64-bit manufacturer’s
code. The manufacturer’s code is chosen by the sys-
tem manufacturer and must be carefully controlled. The
manufacturer’s code is a pivotal part of the overall
system security.
Key
Key Generation
HCS410 EEPROM Array
 2001 Microchip Technology Inc.
Serial Number
Encoder Key
Sync Counter
.
.
.