hcs301 Microchip Technology Inc., hcs301 Datasheet - Page 6

• Manufacturer Part Number: hcs301
• Description: Keeloq Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

HCS301
FIGURE 2-2:
DS21143B-page 6
Yes
RESET and Debounce Delay
Load Transmit Register
(A button has been pressed)
Word Transmission
Update Sync Info
Complete Code
Sample Inputs
Encrypt With
ENCODER OPERATION
Power-Up
Crypt Key
Released
Transmit
Buttons
(10 ms)
Buttons
Stop
Added
All
?
?
Yes
No
No
3.0
The HCS301 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.
Note:
ADDRESS
WORD
10
same
11
0
1
2
3
4
5
6
7
8
9
EEPROM MEMORY
ORGANIZATION
KEY_0 - KEY_3 (64-Bit Crypt Key)
The MSB of the serial number contains a bit
used to select the Auto-shutoff timer.
means
SER_1(Note) Device Serial Number
MNEMONIC
RESERVED Set to 0000H
RESERVED Set to 0000H
SEED_0
SEED_1
CONFIG
EEPROM MEMORY MAP
KEY_0
KEY_1
KEY_2
KEY_3
SER_0
SYNC
of
2001 Microchip Technology Inc.
EE
creating
L
64-bit encryption key
(word 0) LSb’s
64-bit encryption key
(word 1)
64-bit encryption key
(word 2)
64-bit encryption key
(word 3) MSb’s
16-bit synchronization
value
Device Serial Number
(word 0) LSb’s
(word 1) MSb’s
Seed Value (word 0)
Seed Value (word 1)
Config Word
OQ
DESCRIPTION
algorithm. Inputs to
the
key
for