HCS410 Datasheet, PDF (3/36 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
• Anticollision – 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 several
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.
*Secure Learn patent pending.
© 1997 Microchip Technology Inc.
Preliminary
DS40158C-page 3