HCS515/P Microchip Technology, HCS515/P Datasheet - Page 18

• Manufacturer Part Number: HCS515/P
• Description: IC,Remote-Control Receiver/Decoder,CMOS,DIP,14PIN
• Manufacturer: Microchip Technology
• Type: Code Hopping Decoderr

Specifications of HCS515/P

• Applications: Remote Secure Access, Keyless Entry
• Mounting Type: Through Hole
• Package / Case: 14-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

HCS515
7.0
7.1
The encoder transmission is made up of several parts
(Figure 7-1).
preamble and a header, followed by the encrypted and
then the fixed data. The actual data is 66/69 bits, which
consist of 32 bits of encrypted data and 34/37 bits of
non-encrypted data. Each transmission is followed by
a guard period before another transmission can begin.
The code hopping portion provides up to four billion
changing code combinations and includes the button
status bits (based on which buttons were activated),
along with the synchronization counter value and some
discrimination bits. The non-code hopping portion is
comprised of the status bits, the function bits, and the
28-bit serial number. The encrypted and non-encrypted
combined sections increase the number of combina-
tions to 7.38 x 10
FIGURE 7-1:
FIGURE 7-2:
DS40183D-page 18
MSb
MSb
Repeat
Repeat
(1-bit)
(1-bit)
Transmission Format (PWM)
ENCODERS
Each
(1-bit)
(1-bit)
V
V
SEED replaces Encrypted Portion when all button inputs are activated at the same time.
19
LOW
LOW
TRANSMISSION FORMAT (PWM)
.
50%
transmission
CODE WORD ORGANIZATION
34 bits of Fixed Portion
S2 S1 S0 S3
Preamble
1 1 1 1
Button
Button
Status
Status
begins
Serial Number
Serial Number
(28 bits)
(28 bits)
with
Header
10xT
E
a
Encrypted
S2 S1 S0 S3
Portion
7.2
The HCS encoder transmits a 66/69-bit code word
when a button is pressed. The 66/69-bit word is con-
structed from a code hopping portion and a non-code
hopping portion (Figure 7-2).
The Encrypted Data is generated from four button bits,
two overflow counter bits, ten discrimination bits, and
the 16-bit synchronization counter 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)
LOGIC "0"
OVR
LOGIC "1"
Fixed Code
(32 bits)
SEED
Portion
(10 bits)
DISC
2002 Microchip Technology Inc.
66 Data bits
Transmitted
LSb first.
T
Sync Counter
E
Guard
Time
(16 bits)
T
T
BP
E
T
E
LSb
LSb