HCS360_11 Datasheet, PDF (7/40 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder outline and low cost,

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
BSEL 0 Baud Rate Selection
2
BSEL 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
MOD Manchester/PWM modula-
tion selection
15
OVR Overflow bit
3.5.1 MOD: MODULATION FORMAT
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, 0
BAUD RATE SELECTION
BSEL 1 and BSEL 0 determine the baud rate according
to Table 3-3 when PWM modulation is selected.
TABLE 3-3: BAUD RATE SELECTION
MOD BSEL 1 BSEL 0
TE
Unit
0
0
0
400
us
0
0
1
200
us
0
1
0
200
us
0
1
1
100
us
HCS360
BSEL 1 and BSEL 0 determine the baud rate according
to Table 3-4 when Manchester modulation is selected.
TABLE 3-4: BAUD RATE SELECTION
MOD BSEL 1 BSEL 0
TE
Unit
1
0
0
800
us
1
0
1
400
us
1
1
0
400
us
1
1
1
200
us
3.5.3 OVR: OVERFLOW
The overflow bit is used to extend the number of possi-
ble synchronization values. The synchronization coun-
ter 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 over-
flow 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 automatically
clear OVR the first time that the transmitted synchroni-
zation value wraps from 0xFFFF to 0x0000. Once
cleared, OVR cannot be set again, thereby creating a
permanent record of the counter overflow. This pre-
vents fast cycling of 64K counter. If the decoder system
is programmed to track the overflow bits, then the effec-
tive number of unique synchronization values can be
extended to 128K. If programmed to zero, the system
will be compatible with old encoder devices.
3.5.4 LNGRD: LONG GUARD TIME
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.
© 2011 Microchip Technology Inc.
DS40152F-page 7