HCS360T/SN Microchip Technology, HCS360T/SN Datasheet - Page 12

• Manufacturer Part Number: HCS360T/SN
• Description: IC CODE HOPP ENCODR 15FUNC 8SOIC
• Manufacturer: Microchip Technology
• Type: Code Hopping Encoderr

Specifications of HCS360T/SN

• Applications: Remote Secure Access, Keyless Entry
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

HCS360
4.0
4.1
The HCS360 code word is made up of several parts
(Figure 4-1 and Figure 4-2). Each code word contains
a 50% duty cycle preamble, a header, 32 bits of
encrypted data and 35 bits of fixed data followed by a
guard period before another code word can begin.
Refer to Table 8-3 and Table 8-5 for code word timing.
FIGURE 4-1:
FIGURE 4-2:
DS40152E-page 12
TRANSMITTED WORD
Transmission Format (PWM)
1
1 2
CODE WORD FORMAT (PWM)
CODE WORD FORMAT (MANCHESTER)
50% Duty Cycle
Preamble
Preamble
31
31
50% Duty Cycle
X
X
T
Preamble
E
T
E
Preamble
START bit
16
Header
4
X
T
E
bit 0
16
Header
10xT
bit 1
E
bit 2
Encrypted Portion
of Transmission
Encrypted Portion
of Transmission
4.2
The HCS360 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 3-1).
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 3-1). The encrypted portion alone provides up
to four billion changing code combinations.
The Fixed Code Data is made up of a V
bits, 4 function bits, and the 28-bit serial number. If the
extended serial number (32 bits) is selected, the 4 func-
tion code bits will not be transmitted. The fixed and
encrypted sections combined increase the number of
code combinations to 7.38 x 10
Code Word Organization
LOGIC "0"
LOGIC "1"
of Transmission
Fixed Portion
of Transmission
Fixed Portion
LOGIC "1"
LOGIC "0"
2002 Microchip Technology Inc.
STOP bit
19
T
E
Guard
Time
T
Guard
E
T
Time
E
LOW
T
T
E
E
bit, 2 CRC