HCS512-IP Microchip Technology, HCS512-IP Datasheet - Page 2

• Manufacturer Part Number: HCS512-IP
• Description: KEELOQ CODE HOPPING DECODER
• Manufacturer: Microchip Technology

HCS512
1.0
1.1
• Manufacturer’s Code – a 64-bit word, unique to
• Encoder Key – a 64-bit key, unique for each trans-
• Learn – The receiver uses information that is
The HCS encoders and decoders employ the K
code hopping technology and an encryption algorithm
to achieve a high level of security. Code hopping is a
method by which the code transmitted from the trans-
mitter to the receiver is different every time a button is
pushed. This method, coupled with a transmission
length of 66 bits, virtually eliminates the use of code
‘grabbing’ or code ‘scanning’.
FIGURE 1-1:
DS40151C-page 2
each manufacturer, used to produce a unique
encoder key in each transmitter (encoder).
mitter. The encoder key controls the decryption
algorithm and is stored in EEPROM on the
decoder device.
transmitted to derive the transmitter’s secret key,
decrypt the discrimination value and the synchro-
nization counter in learning mode. The encoder
key is a function of the Manufacturer’s Code and
the device serial number and/or seed value.
K
Key Terms
EE
Manufacturer’s
L
OQ
Code
CREATION AND STORAGE OF ENCODER KEY DURING PRODUCTION
SYSTEM OVERVIEW
Serial Number or
Transmitter
Generation
Algorithm
Seed
Key
EE
L
OQ
Encoder
1.2
The HCS encoders have a small EEPROM array which
must be loaded with several parameters before use.
The most important of these values are:
• A 28-bit serial number which is meant to be
• An encoder key that is generated at the time of
• A 16-bit synchronization value
The serial number for each encoder 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 1-1). Typically, inputs to the
key generation algorithm are the serial number of the
encoder and a 64-bit manufacturer’s code. The manu-
facturer’s code is chosen by the system manufacturer
and must be carefully controlled. The manufacturer’s
code is a pivotal part of the overall system security.
Key
unique for every encoder
production
HCS Encoder Overview
HCSXXX EEPROM Array
Serial Number
Encoder Key
Sync Counter
1997 Microchip Technology Inc.
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