hcs320 Microchip Technology Inc., hcs320 Datasheet - Page 6

• Manufacturer Part Number: hcs320
• Description: Keeloq Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

HCS320
FIGURE 2-2:
DS41097C-page 6
No
RESET and Debounce Delay
(Button pressed) Set TX:= OFF
Load Transmit Register
Word Transmission
Increment Shift Level
Complete Code
Update Sync Info
Button Pressed?
Button Pressed?
Stop Transmit
Encrypt With
Yes
Yes
Released?
Yes
Power-Up
Crypt Key
TX=ON?
No
TX=ON?
Transmit
Transmit
Buttons
(10 ms)
Buttons
Added?
Stop
Shift
All
No
Yes
ENCODER OPERATION
Yes
No
No
No
Set TX:=ON
Yes
3.0
The HCS320 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.
ADDRESS
Note:
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
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
Not used
Not used
Configuration Word
OQ
DESCRIPTION
algorithm. Inputs to
the
key
for