HCS512_11 MICROCHIP [Microchip Technology], HCS512_11 Datasheet - Page 14

• Manufacturer Part Number: HCS512_11
• Manufacturer: MICROCHIP [Microchip Technology]

HCS512
8.0
8.1
The K
eral parts (Figure 8-1). Each transmission begins with
a preamble and a header, followed by the encrypted
and then the fixed data. The actual data is 66/69 bits
which consists of 32 bits of encrypted data and 34/37
bits of non-encrypted data. Each transmission is fol-
lowed by a guard period before another transmission
can begin. The encrypted portion provides up to four
billion changing code combinations and includes the
button status bits (based on which buttons were acti-
vated) along with the synchronization counter value
and some discrimination bits. The non-encrypted por-
tion is comprised of the status bits, the function bits,
FIGURE 8-1:
FIGURE 8-2:
DS40151E-page 14
MSb
MSb
EE
Repeat
Repeat
(1-bit)
(1-bit)
L
K
Transmission Format (PWM)
OQ
EE
encoder transmission is made up of sev-
L
(1-bit)
(1-bit)
V
V
OQ
SEED replaces Encrypted Portion when all button inputs are activated at the same time.
LOW
LOW
TRANSMISSION FORMAT (PWM)
50%
ENCODERS
CODE WORD ORGANIZATION
34 bits of Fixed Portion
S2 S1 S0 S3
Preamble
1 1 1 1
Button
Button
Status
Status
Serial Number
Serial Number
(28 bits)
(28 bits)
Header
10xT
E
Encrypted
S2 S1 S0 S3
Portion
and the 28-bit serial number. The encrypted and non-
encrypted combined sections increase the number of
combinations to 7.38 x 10
8.2
The HCSXXX encoder transmits a 66/69-bit code word
when a button is pressed. The 66/69-bit word is con-
structed from an encryption portion and a non-
encrypted code portion (Figure 8-2).
The Encrypted Data is generated from four button bits,
two overflow counter bits, ten discrimination bits, and
the 16-bit synchronization value.
The Non-encrypted Data is made up from 2 status
bits, 4 function bits, and the 28/32-bit serial number.
Button
Status
32 bits of Encrypted Portion
Code Word Organization
(2 bits)
OVR
LOGIC "0"
LOGIC "1"
Fixed Code
(32 bits)
SEED
Portion
(10 bits)
© 2011 Microchip Technology Inc.
DISC
19
.
66 Data bits
Transmitted
LSb first.
T
Sync Counter
E
Guard
Time
(16 bits)
T
T
BP
E
T
E
LSb
LSb