hcs360 Microchip Technology Inc., hcs360 Datasheet - Page 9

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

3.5.8
If SEED = 0, seed transmission is disabled. The Inde-
pendent Counter mode can only be used with seed
transmission disabled since SEED_2 is shared with the
second synchronization counter.
With SEED = 1, seed transmission is enabled. The
appropriate button code(s) must be activated to trans-
mit the seed information. In this mode, the seed infor-
FIGURE 3-2:
3.5.9
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 3-5.
2002 Microchip Technology Inc.
All examples shown with XSER = 1, SEED = 1
Note 1: For Seed Transmission, SEED_2 is transmitted instead of SER_0.
CRC+V
CRC+V
CRC+V
SEED: ENABLE SEED
TRANSMISSION
TMPSD: TEMPORARY SEED
TRANSMISSION
When S[3:0] = 1001, delay is not acceptable.
For S[3:0] = 0x3 before delay:
For S[3:0] = 0011 after delay (Note 1, Note 2):
2: For Seed Transmission, the setting of DELM has no effect.
LOW
LOW
LOW
Seed Transmission
SER_1
SER_1
SER_1
SER_0
SEED_2
SEED_2
mation (SEED_0, SEED_1, and SEED_2) and the
upper 12 or 16 bits of the serial number (SER_1) are
transmitted instead of the hop code.
Seed transmission is available for function codes
(Table 3-9) S[3:0] = 1001 and S[3:0] = 0011(delayed).
This takes place regardless of the setting of the IND bit.
The two seed transmissions are shown in Figure 3-2.
TABLE 3-5:
Synchronous Counter
Encrypted Data
SEED_1
16-bit Data Word
SEED_1
Values
0000H
0060H
0050H
0048H
SYNCHRONOUS COUNTER
INITIALIZATION VALUES
Data transmission direction
Data transmission direction
Data transmission direction
Encrypt
SEED_0
16-bit Counter
SEED_0
Transmissions
HCS360
Number of
DS40152E-page 9
128
64
32
16