HCS410/WM Microchip Technology, HCS410/WM Datasheet - Page 8

• Manufacturer Part Number: HCS410/WM
• Description: IC CODE HOPPING ENCODER SMD
• Manufacturer: Microchip Technology
• Series: KEELOQ®r
• Type: Code Hopping Encoder and Transponderr

Specifications of HCS410/WM

• Applications: Access Control Systems
• Package / Case: *
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Mounting Type: -

HCS410/WM
5.0
Use of the HCS410/WM in a system requires a compat-
ible decoder. This decoder is typically a microcontroller
with compatible firmware. Firmware routines that
accept transmissions from the HCS410/WM, decrypt
the code hopping portion of the data stream and per-
form IFF functions are available. These routines pro-
vide system designers the means to develop their own
decoding system.
FIGURE 5-1:
5.2
In order for a transmitter to be used with a decoder, the
transmitter must first be ‘learned’. Several learning
strategies can be followed in the decoder implementa-
tion. When a transmitter is learned by a decoder, it is
suggested that the decoder stores the serial number in
EEPROM. The decoder must keep track of these
values for every transmitter that is learned.
The maximum number of transmitters that can be
learned is a function of how much EEPROM memory
storage is available. The decoder must also store the
manufacturer’s code in order to learn an HCS410/WM,
since this value will not change in a typical system, it is
usually stored as part of the microcontroller ROM code.
Storing the manufacturer’s code as part of the ROM
code is also better for security reasons.
DS41116B-page 8
INTEGRATING THE
HCS410/WM INTO A SYSTEM
Receiver Learning an HCS410/WM
Manufacturer’s
Code
CREATION AND STORAGE OF ENCODER KEY DURING PRODUCTION
Serial Number or
Transmitter
Generation
Algorithm
Seed
Key
Preliminary
Encoder
5.1
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 5-1). 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/WM EEPROM Array
Serial Number
Encoder Key
Sync Counter
2001 Microchip Technology Inc.
.
.
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