HCS361_11 MICROCHIP [Microchip Technology], HCS361_11 Datasheet - Page 12

• Manufacturer Part Number: HCS361_11
• Manufacturer: MICROCHIP [Microchip Technology]

HCS361
4.0
4.1
The HCS361 transmission is made up of several parts
(Figure 4-1 and Figure 4-2). Each transmission is
begun with a preamble and a header, followed by the
encrypted and then the fixed data. The actual data is
67 bits which consists of 32 bits of encrypted data and
35 bits of fixed data. Each transmission is followed by
a guard period before another transmission can begin.
Refer to Table 9-6 and Table 9-6 for transmission tim-
ing specifications. The encrypted portion provides up to
four billion changing code combinations and includes
the function bits (based on which buttons were acti-
vated) along with the synchronization counter value
and discrimination value. The non-encrypted portion is
comprised of the CRC bits, V
and the 28/32-bit serial number. The encrypted and
non-encrypted sections combined increase the number
of combinations to 1.47 x 10
FIGURE 4-1:
DS40146F-page 12
TXWAK=0
TXWAK=1
TRANSMISSION SEQUENCE:
TRANSMITTED WORD
Transmission Format (PWM)
CODE WORD:
1
T
33% Duty Cycle
18xT
BP
Preamble Header Encrypt
E
PWM Transmission Format (MOD = 0)
Preamble
20
LOW
.
6
bits, the function bits
1st CODE WORD
10xT
SPM=1
SPM=0
Pulse
E
Sync
Fixed
10
10xT
Guard
E
Header
Code Word
Duty Cycle: 1/3-2/3
(TXWAK=0)
Duty Cycle: 1/6-2/6
(TXWAK=1)
Preamble Header Encrypt
4.2
The HCS361 transmits a 67-bit code word when a but-
ton is pressed. The 67-bit word is constructed from a
Fixed Code portion and an Encrypted Code portion
(Figure 3-2).
The Encrypted Data is generated from 4 function bits,
2 user bits, overflow bit, Independent mode bit, and 8
serial number bits, and the 16-bit synchronization value
(Figure 9-4).
The Non-encrypted Code Data is made up of V
bit, 2 CRC bits, 4 function bits, and the 28-bit serial
number. If the extended serial number (32 bits) is
selected, the 4 function code bits will not be transmit-
ted.
Encrypted Portion
Code Word Organization
T
T
Fixed Code Portion
LOGIC 0
BP
LOGIC 0
BP
© 2011 Microchip Technology Inc.
=6
=3
X
X
T
T
E
E
T
T
E
E
LOGIC 1
T
T
LOGIC 1
BP
BP
Guard
Time
LOW