Microchip Technology HCS300 - Page 4

HCS300
DS21137G-page 4 © 2011 Microchip Technology Inc.
FIGURE 1-2: BUILDING THE TRANSMITTED CODE WORD (ENCODER)
FIGURE 1-3: BASIC OPERATION OF RECEIVER (DECODER)
NOTE: Circled numbers indicate the order of execution.
Button Press
Information
EEPROM Array
32 Bits
Encrypted Data
Serial Number
Transmitted Information
Crypt Key
Sync Counter
Serial Number
KEELOQ
®
Encryption
Algorithm
Button Press
Information
EEPROM Array
Manufacturer Code
32 Bits of
Encrypted Data
Serial Number
Received Information
Decrypted
Synchronization
Counter
Check for
Match
Sync Counter
Serial Number
KEELOQ
®
Decryption
Algorithm
1
3
4
Check for
Match
2
Perform Function
Indicated by
button press
5
Crypt Key