HCS410-IST MICROCHIP [Microchip Technology], HCS410-IST Datasheet - Page 19

• Manufacturer Part Number: HCS410-IST
• Manufacturer: MICROCHIP [Microchip Technology]

3.4
This is the 60-bit seed code that is 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 genera-
tion/tracking process or purely as a fixed code trans-
mission. The seed is not available in IFF2-mode. A
Seed transmission can be initiated in two ways,
depending on the button inputs (Figure 3-1).
Seed transmission is available for function codes
(Table 2-2) S[2:0] = 111 and S[2:0] = 011 (delayed). The
delayed seed transmission starts with a normal code
hopping transmission being transmitted for 3 seconds,
before switching to a seed transmission. The two seed
transmissions are shown in Figure 3-1.
The least significant 32-bits of the seed are used as the
transport code. The transport code is used to write-pro-
tect the serial number, configuration word, as well as
preventing accidental programming of the HCS410
when in IFF mode.
FIGURE 3-1:
 2001 Microchip Technology Inc.
Note 1: For Seed Transmission, SEED_3 and SEED_2 are transmitted instead of SER_1 and SER_0, respectively.
Note:
All examples shown with XSER = 1 & SEED = 1
Que [1:0], CRC [1:0],
Que [1:0], CRC [1:0]
Que [1:0], CRC [1:0],
+ V
V
V
60/64-bit Seed Word/Transport Code
LOW
LOW
LOW
If both SEED and TMPSD are set, IFF2
mode is enabled.
, S [2:0]
, S[2:0]
, S [2:0]
For S[2:0] = 011 before the 3-second delay:
When S[2:0] = 111, the 3-second delay is not applicable:
For S[2:0] = 011 after the 3-second delay (Note 1):
SEED TRANSMISSION
SER_1
SEED_3 (12 bits)
SEED_3 (12 bits)
SER_0
SEED_2
SEED_2
Preliminary
3.5
There are 32 bits allocated for the serial number and a
selectable
whether 32 or 28 bits will be transmitted. The serial
number is meant to be unique for every transmitter.
3.6
The 64-bit user EEPROM can be reprogrammed and
read at any time using the IFF interface.
Encrypted Data
16-bit Data Word
SEED_1
SEED_1
Encoder Serial Number
User Data
configuration
Data transmission direction
Data transmission direction
Data transmission direction
bit
Encrypt
16-bit Counter
SEED_0
SEED_0
(XSER)
HCS410
DS40158E-page 19
determines