HCS360_01 Datasheet, PDF (9/28 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder

HCS360
3.5.6 IND: INDEPENDENT MODE
The independent mode can be used where one
encoder is used to control two receivers. Two counters
(SYNC_A and SYNC_B) are used in independent
mode. As indicated in Table 3-7, function codes 1 to 7
use SYNC_A and 8 to 15 SYNC_B. The independent
mode also selects IR mode. In IR mode function codes
12 to 15 will use SYNC_B. The PWM output signal is
modulated with a 40 kHz carrier. It must be pointed out
the 40 kHz is derived from the internal clock and will
therefore vary with the same percentage as the baud
rate. If IND = 0, SYNC_A is used for all function codes.
If IND = 1, independent mode is enabled and counters
for functions are used according to Table 3-7.
For IND = 1 and S[3:0] ≡ 0xC, 0xD, 0xE, 0xF, Basic
Pulse Width modulation becomes:
3.5.7 USRA,B: USER BITS
User bits form part of the discrimination value. The user
bits together with the IND bit can be used to identify the
counter that is used in independent mode.
3.5.8 XSER: EXTENDED SERIAL NUMBER
If XSER = 1, the full 32-bit serial number [SER_1,
SER_0] is transmitted. If XSER = 0, the four most sig-
nificant bits of the serial number are substituted by
S[3:0] and is compatible with the HCS200/300/301.
3.5.9 TMPSD: TEMPORARY SEED
TRANSMISSION
The temporary seed transmission can be used to dis-
able learning after the transmitter has been used for a
programmable number of operations. This feature can
be used to implement very secure systems. After learn-
ing is disabled, the seed information cannot be
accessed even if physical access to the transmitter is
possible. If TMPSD = 1 the seed transmission will be
disabled after a number of code hopping transmis-
sions. The number of transmissions before seed trans-
mission is disabled, can be programmed by setting the
synchronization counter (SYNC_A, SYNC_B) to a
value as shown in Table .
TABLE 3-6: SYNCHRONOUS COUNTER
INITIALIZATION VALUES
Synchronous Counter
Values
0000H
0060H
0050H
0048H
Number of
Transmissions
128
64
32
16
TABLE 3-7: FUNCTION CODES
S3
S2
S1
S0
1
0
0
0
1
2
0
0
1
0
3
0
0
1
1
4
0
1
0
0
5
0
1
0
1
6
0
1
1
0
7
0
1
1
1
8
1
0
0
0
9
1
0
0
1
10
1
0
1
0
11
1
0
1
1
12
1
1
0
0
13
1
1
0
1
14
1
1
1
0
15
1
1
1
1
IND = 0 IND = 1
Comments
Counter
A
A
A
A
A
A
If SEED = 1, transmit seed after delay.
A
A
A
A
A
A
A
A
A
B
A
B
If SEED = 1, transmit seed immediately.
A
B
A
B
A
B IR mode
A
B IR mode
A
B IR mode
A
B IR mode
 2001 Microchip Technology Inc.
DS40152D-page 9