HCS301

DS21143A-page 8

Preliminary

© 1996 Microchip Technology Inc.

FIGURE 4-1:

CODE WORD TRANSMISSION FORMAT

FIGURE 4-2:

CODE WORD ORGANIZATION

FIGURE 4-3:

SYNCHRONOUS TRANSMISSION MODE

FIGURE 4-4:

TRANSMISSION WORD FORMAT DURING SYNCHRONOUS TRANSMISSION MODE

LOGIC ‘0’

LOGIC ‘1’

Bit

Period

Preamble

Header

Encrypted Portion

of Transmission

Fixed Portion of

Transmission

Guard

Time

Repeat

(1 bit)

(1 bit)

Button

Status

(4 bits)

28-bit

Serial Number

Button

Status

(4 bits)

Discrimina-

tion bits

(12 bits)

16-bit

Sync Value

1 bit of Status

1 bit Fixed

+

Serial Number and

Button Status (32 bits)

+

32 bits of Encrypted Data

Fixed Code Data

Encrypted Code Data

66 bits

of Data

Transmitted

t = 50 ms

“01,10,11”

PWM

S2(S3)

S[1:0]

16

2

4

28

16

16

Transmission Direction

Reserved

Padding

Button

Code

Serial Number

Data Word

Sync Counter