hcs410 Microchip Technology Inc., hcs410 Datasheet - Page 8

• Manufacturer Part Number: hcs410
• Description: Keeloq Code Hopping Encoder And Transponder Keeloq Code Hopping Encoder And Transponder
• Manufacturer: Microchip Technology Inc.

HCS410
2.2.1
The HCS410 transmission (CH Mode) is made up of
several parts (Figure 2-10 and Figure 2-11). Each
transmission is begun with a preamble and a header,
followed by the encrypted and then the fixed data. The
actual data is 69 bits which consists of 32 bits of
encrypted data and 37 bits of fixed data. Each trans-
mission is followed by a guard period before another
transmission
and Table 5-5 for transmission timing specifications.
The combined encrypted and nonencrypted sections
increase the number of combinations to 1.47 x 10
FIGURE 2-8:
FIGURE 2-9:
DS40158E-page 8
* Optional.
* Optional.
(Q1, Q0
(Q1, Q0
QUE0
QUE
bit)
bit)
TRANSMISSION DATA FORMAT
(2 bits)
(2 bits)
QUE
QUE
CRC
(2 bit)
CRC
(2 bit)
can
(2 bits)
CRC
(2 bits)
HOP CODE WORD ORGANIZATION (RIGHT-MOST BIT IS CLOCKED OUT FIRST)
SEED CODE WORD ORGANIZATION
CRC
V
(1 bit)
V
(1 bit)
LOW
LOW
begin.
V
(1 bit)
V
(1 bit)
Fixed Code Data
S2 S1 S0 0
S2 S1 S0 0
LOW
LOW
Button
Status*
(4 bits)
Button*
Status
(4 bits)
Refer
(4 bits)
Button
+
+
to
Serial Number
Button Status (32 bits)
Table 5-4
+
Serial Number and
28-bit
20
Fixed Code Data
Preliminary
.
S2 S1 S0 0
The HCS410 transmits a 69-bit code word when a but-
ton is pressed. The 69-bit word is constructed from a
Fixed Code portion and Code Hopping portion
(Figure 2-8).
The Encrypted Data is generated from 4 function bits,
2 overflow bits, and 10 discrimination bits, and the 16-
bit synchronization counter value (Figure 2-8).
The Nonencrypted Code Data is made up of 2 QUE
bits, 2 CRC bits, a V
28-bit serial number. If the extended serial number
(32 bits) is selected, the 4 function code bits will not be
transmitted (Figure 2-8).
Button
Status
(4 bits)
Unencrypted
+
SEED
Overflow (2 bits)
Encrypted Code Data
(60 bits)
Discrimination
SEED
MSB
bits (10 bits)
32 bits of Encrypted Data
and
LOW
 2001 Microchip Technology Inc.
bit, 4 function bits, and the
Synchronization
Counter Value
16-bit
LSB
69 bits
of Data
Transmitted
69 bits
of Data
Transmitted