HCS361_11 MICROCHIP [Microchip Technology], HCS361_11 Datasheet - Page 6

• Manufacturer Part Number: HCS361_11
• Manufacturer: MICROCHIP [Microchip Technology]

HCS361
3.0
The HCS361 contains 192 bits (12 x 16-bit words) of
EEPROM memory (Table 3-1). This EEPROM array is
used to store the encryption key information,
synchronization value, etc. Further descriptions of the
memory array is given in the following sections.
TABLE 3-1:
3.1
The 64-bit crypt key is used to create the encrypted
message transmitted to the receiver. This key is calcu-
lated and programmed during production using a key
generation algorithm. The key generation algorithm
may be different from the K
the key generation algorithm are typically the transmit-
ter’s serial number and the 64-bit manufacturer’s code.
While the key generation algorithm supplied from
Microchip is the typical method used, a user may elect
to create their own method of key generation. This may
be done providing that the decoder is programmed with
the
decryption purposes.
DS40146F-page 6
ADDRESS
WORD
10
11
0
1
2
3
4
5
6
7
8
9
same
EEPROM MEMORY
ORGANIZATION
KEY_0 - KEY_3 (64-Bit Crypt Key)
MNEMONIC
RESERVED Set to 0000H
means
SYNC_B/
SYNC_A
SEED_2
SEED_0
SEED_1
CONFIG
SER_0
SER_1
KEY_0
KEY_1
KEY_2
KEY_3
EEPROM MEMORY MAP
of
64-bit crypt key
(word 0) LSb’s
64-bit crypt key
(word 1)
64-bit crypt key
(word 2)
64-bit crypt key
(word 3) MSb’s
16-bit synch counter
16-bit synch counter B
or Seed value (word 2)
Seed Value
Seed Value
Device Serial Number
Device Serial Number
Configuration Word
EE
(word 0) LSb’s
(word 1) MSb’s
(word 0) LSb’s
(word 1) MSb’s
creating
L
OQ
DESCRIPTION
algorithm. Inputs to
the
key
for
3.2
This is the 16-bit synchronization value that is used to
create the hopping code for transmission. This value is
incremented after every transmission. Separate syn-
chronization counters can be used to stay synchro-
nized with different receivers.
3.3
The three word (48 bits) seed code will be transmitted
when seed transmission is selected. This allows the sys-
tem designer to implement the Secure Learn feature or
use this fixed code word as part of a different key genera-
tion/tracking process or purely as a fixed code transmis-
sion.
3.4
SER_0 and SER_1 are the lower and upper words of
the device serial number, respectively. There are 32
bits allocated for the Serial Number and a selectable
configuration bit determines whether 32 or 28 bits will
be transmitted. The serial number is meant to be
unique for every transmitter.
Note:
SYNC_A, SYNC_B
(Synchronization Counter)
SEED_0, SEED_1, and SEED_2
(Seed Word)
SER_0, SER_1
(Encoder Serial Number)
Since SEED2 and SYNC_B share the
same memory location, Secure Learn and
Independent mode transmission (including
IR mode) are mutually exclusive.
© 2011 Microchip Technology Inc.