hcs360 Microchip Technology Inc., hcs360 Datasheet - Page 7

• Manufacturer Part Number: hcs360
• Description: Keeloq Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

3.5
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:
3.5.1
MOD selects between Manchester code modulation
and PWM modulation.
If MOD = 1, Manchester modulation is selected:
If MOD = 0, PWM modulation is selected.
3.5.2
BSEL 1 and BSEL 0 determine the baud rate according
to Table 3-3 when PWM modulation is selected.
TABLE 3-3:
Bit Number Symbol
2002 Microchip Technology Inc.
MOD
0
0
0
0
10
12
13
14
15
11
0
1
2
3
4
5
6
7
8
9
CONFIG
(Configuration Word)
BSEL 1 BSEL 0
MOD: MODULATION FORMAT
BSEL 1, 0
BAUD RATE SELECTION
0
0
1
1
LNGRD
BSEL 0
BSEL 1
NU
SEED
DELM
TIMO
IND
USRA0
USRA1
USRB1
USRB0
XSER
TMPSD
MOD
OVR
CONFIGURATION WORD.
BAUD RATE SELECTION
0
1
0
1
Long Guard Time
Baud Rate Selection
Baud Rate Selection
Not Used
Seed Transmission enable
Delay mode enable
Time-out enable
Independent mode enable
User bit
User bit
User bit
User bit
Extended serial number
enable
Temporary seed transmis-
sion enable
Manchester/PWM modula-
tion selection
Overflow bit
Bit Description
400
200
200
100
T
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BSEL 1 and BSEL 0 determine the baud rate according
to Table 3-4 when Manchester modulation is selected.
TABLE 3-4:
3.5.3
The overflow bit is used to extend the number of possi-
ble synchronization values. The synchronization
counter is 16 bits in length, yielding 65,536 values
before the cycle repeats. Under typical use of
10 operations a day, this will provide nearly 18 years of
use before a repeated value will be used. Should the
system designer conclude that is not adequate, then
the overflow bit can be utilized to extend the number of
unique values. This can be done by programming OVR
to 1 at the time of production. The encoder will auto-
matically clear OVR the first time that the transmitted
synchronization value wraps from 0xFFFF to 0x0000.
Once cleared, OVR cannot be set again, thereby creat-
ing a permanent record of the counter overflow. This
prevents fast cycling of 64K counter. If the decoder sys-
tem is programmed to track the overflow bits, then the
effective number of unique synchronization values can
be extended to 128K. If programmed to zero, the sys-
tem will be compatible with old encoder devices.
3.5.4
LNGRD = 1 selects the encoder to extend the guard
time between code words adding 50 ms. This can be
used to reduce the average power transmitted over a
100 ms window and thereby transmit a higher peak
power.
MOD
1
1
1
1
BSEL 1 BSEL 0
OVR: OVERFLOW
LNGRD: LONG GUARD TIME
0
0
1
1
BAUD RATE SELECTION
0
1
0
1
HCS360
800
400
400
200
T
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DS40152E-page 7
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