HCS300-IP Microchip Technology, HCS300-IP Datasheet - Page 5

• Manufacturer Part Number: HCS300-IP
• Description: KEE LOQ Code Hopping Encoder
• Manufacturer: Microchip Technology

FIGURE 2-2:
1996 Microchip Technology Inc.
Yes
Reset and Debounce Delay
Load Transmit Register
(A button has been pressed)
ENCODER OPERATION
Word Transmission
Update Sync Info
Encryption Key
Complete Code
Sample Inputs
Encrypt With
Power Up
Released
Transmit
Buttons
Buttons
Added
(10 ms)
Stop
All
?
?
Yes
No
No
Preliminary
3.0
The HCS300 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 encryption key is used by the transmitter to
create the encrypted message transmitted to the
receiver. This key is created and programmed at the
time of production using a key generation algorithm.
Inputs to the key generation algorithm are the serial
number for the particular transmitter being used and a
secret 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 same means of creat-
ing the key for decryption purposes. If a seed is used,
the seed will also form part of the input to the key gen-
eration algorithm.
Note:
ADDRESS
WORD
10
11
0
1
2
3
4
5
6
7
8
9
EEPROM MEMORY
ORGANIZATION
Key_0 - Key_3 (64-Bit Encryption Key)
The MSB of the serial number contains a bit
used to select the auto shutoff timer.
KEY_0
KEY_1
KEY_2
KEY_3
SYNC
RESERVED
SER_0
SER_1(Note) Device Serial Number
SEED_0
SEED_1
EN_KEY
CONFIG
MNEMONIC
EEPROM MEMORY MAP
64-bit encryption key
(word 0)
64-bit encryption key
(word 1)
64-bit encryption key
(word 2)
64-bit encryption key
(word 3)
16-bit synchronization
value
Set to 0000H
Device Serial Number
(word 0)
(word 1)
Seed Value (word 0)
Seed Value (word 1)
16-bit Envelope Key
Config Word
HCS300
DESCRIPTION
DS21137D-page 5