HCS301
FIGURE 1-2:
BUILDING THE TRANSMITTED CODE WORD (ENCODER)
EEPROM Array
Crypt Key
KEELOQ
Encryption
Algorithm
Sync Counter
Serial Number
Button Press
Serial Number
Information
32 Bits
Encrypted Data
Transmitted Information
FIGURE 1-3:
BASIC OPERATION OF RECEIVER (DECODER)
1
Received Information
EEPROM Array
32 Bits of
Encrypted Data
Button Press
Information
Manufacturer Code
Serial Number
Check for
Match
Serial Number
2
Sync Counter
Crypt Key
3
KEELOQ
Decryption
Algorithm
Decrypted
Synchronization
Counter
Check for
Match
4
Perform Function
Indicated by
5
button press
NOTE: Circled numbers indicate the order of execution.
DS21143B-page 4
2001 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
