HCS410_01 Datasheet, PDF (2/36 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder and Transponder

HCS410
DESCRIPTION
The HCS410 is a code hopping transponder device
designed for secure entry systems. The HCS410 uti-
lizes the patented KEELOQ code hopping system and
bi-directional challenge-and-response for logical and
physical access control. High security learning mecha-
nisms make this a turnkey solution when used with the
KEELOQ decoders. The encoder keys and synchroniza-
tion information are stored in protected on-chip
EEPROM.
A low cost batteryless transponder can be imple-
mented with the addition of an inductor and two capac-
itors. A packaged module including the inductor and
capacitor will also be offered.
A single HCS410 can be used as an encoder for
Remote Keyless Entry (RKE) and a transponder for
immobilization in the same circuit and thereby dramat-
ically reducing the cost of hybrid transmitter/transpon-
der circuits.
1.0 SYSTEM OVERVIEW
1.1 Key Terms
• Anti-Collision – Allows two transponders to be in
the files simultaneously and be verified individu-
ally.
• CH Mode – Code Hopping Mode. The HCS410
transmits a 69-bit transmission each time it is acti-
vated, with at least 32-bits changing each time the
encoder is activated.
• Encoder Key – A unique 64-bit key generated and
programmed into the encoder during the manu-
facturing process. The encoder key controls the
encryption algorithm and is stored in EEPROM on
the encoder device.
• IFF – Identify friend or foe is a means of validating
a token. A decoder sends a random challenge to
the token and checks that the response of the
token is a valid response.
• KEELOQ Encryption Algorithm – The high security
level of the HCS410 is based on the patented
KEELOQ technology. A block cipher encryption
algorithm based on a block length of 32 bits and a
key length of 64 bits is used. The algorithm
obscures the information in such a way that even
if the unencrypted/challenge information differs by
only one bit from the information in the previous
transmission/challenge, the next coded transmis-
sion/response will be totally different. Statistically,
if only one bit in the 32-bit string of information
changes, approximately 50 percent of the coded
transmission will change.
• Learn – The HCS product family facilitates sev-
eral learning strategies to be implemented on the
decoder. The following are examples of what can
be done.
Normal Learn –The receiver uses the same infor-
mation that is transmitted during normal operation to
derive the transmitter’s encoder key, decrypt the dis-
crimination value and the synchronization counter.
Secure Learn* – The transmitter is activated through
a special button combination to transmit a stored
60-bit value (random seed) that can be used for key
generation or be part of the key. Transmission of the
random seed can be disabled after learning is com-
pleted.
• Manufacturer’s Code – A 64-bit word, unique to
each manufacturer, used to produce a unique
encoder key in each transmitter (encoder).
• Passive Proximity Activation – When the HCS410
is brought into in a magnetic field without a
command given by the base station, the HCS410
can be programmed to give an RF transmission.
• Transport Code – A 32-bit transport code needs to
be given before the HCS410 can be inductively
programmed. This prevents accidental
programming of the HCS410.
DS40158E-page 2
Preliminary
 2001 Microchip Technology Inc.