HCS412I MICROCHIP [Microchip Technology], HCS412I Datasheet - Page 33

• Manufacturer Part Number: HCS412I
• Description: KEELOQ Code Hopping Encoder and Transponder
• Manufacturer: MICROCHIP [Microchip Technology]

FIGURE 6-3:
FIGURE 6-4:
Note:
2002 Microchip Technology Inc.
5
Perform Function
Circled numbers indicate sequence of events.
Indicated by
Button Press
button press
Information
Entire Window
rotates to eliminate
use of previously
used codes
SYNCHRONIZATION WINDOW
BASIC OPERATION OF RECEIVER (DECODER)
1
2
Received Information
Serial Number
Check for
Match
(resynchronization)
Double Operation
(32K Codes)
(32K Codes)
Blocked
Window
Window
Synchronization
Encrypted Data
Decrypted
Preliminary
32 Bits of
K
Decryption
Algorithm
Counter
EE
L
3
OQ
Single Operation
(16 Codes)
Stored
Synchronization
Counter Value
Window
Manufacturer Code
4
EEPROM Array
Serial Number
Check for
Sync Counter
Match
Crypt Key
HCS412
DS41099C-page 33