HCS360 Datasheet, PDF (6/24 Pages) Microchip Technology – KEELOQ CODE HOPPING ENCODER

HCS360
3.2 SYNC_A, SYNC_B
(Synchronization Counter)
This is the 16-bit synchronization value that is used to
create the hopping code for transmission. This value
will be changed after every transmission. A second syn-
chronization value can be used to stay synchronized
with a second receiver.
3.3 SEED_0, SEED_1, and SEED_2
(Seed Word)
This is the three word (48 bits) seed code that will be
transmitted when seed transmission is selected. This
allows the system designer to implement the secure learn
feature or use this fixed code word as part of a different
key generation/tracking process or purely as a fixed code
transmission.
3.4 SER_0, SER_1
(Encoder Serial Number)
SER_0 and SER_1 are the lower and upper words of
the device serial number, respectively. There are 32 bits
allocated for the serial number and a selectable config-
uration bit determines whether 32 or 28 bits will be
transmitted. The serial number is meant to be unique
for every transmitter.
3.5 CONFIG
(Configuration Word)
The configuration word is a 16-bit word stored in
EEPROM array that is used by the device to store
information used during the encryption process, as well
as the status of option configurations. Further
explanations of each of the bits are described in the
following sections.
TABLE 3-2 CONFIGURATION WORD
Bit Number Symbol
Bit Description
0
LNGRD Long Guard Time
1
FAST 0 Baud Rate Selection
2
FAST 1 Baud Rate Selection
3
NU
Not Used
4
SEED Seed Transmission enable
5
DELM Delay mode enable
6
TIMO Time out enable
7
IND
Independent mode enable
8
USRA0 User bit
9
USRA1 User bit
10
USRB0 User bit
11
USRB1 User bit
12
XSER Extended serial number
enable
13
TMPSD Temporary seed transmis-
sion enable
14
MANCH Manchester/PWM modula-
tion selection
15
OVR Overflow bit
3.5.1 LNGRD: LONG GUARD TIME
LNGRD = 1 selects the encoder to extend the guard
time between code words. This can be used to reduce
the average power transmitted over a 100ms window
and thereby transmit a higher peak power.
3.5.2 FAST 1, FAST 0 BAUD RATE SELECTION
FAST 1 and FAST 0 selects the baud rate according to
Table 3-3.
TABLE 3-3 BAUD RATE SELECTION
TE
FAST 1
FAST 0
400
0
0
200
0
1
200
1
0
100
1
1
DS40152C-page 6
Preliminary
© 1996 Microchip Technology Inc.