HCS370SL MICROCHIP [Microchip Technology], HCS370SL Datasheet - Page 14

• Manufacturer Part Number: HCS370SL
• Description: KEELOQ Code Hopping Encoder
• Manufacturer: MICROCHIP [Microchip Technology]

HCS370
4.0
4.1
The HCS370 transmission is made up of several code
words. Each code word contains a preamble, header,
and data. A code word is separated from another code
word by guard time. The Guard Time Select (GSEL)
configuration option can be set to 0 ms, 6.4 ms, 51.2
ms, or 102.4 ms.
All other timing specifications for the modulation for-
mats are based on a basic timing element (T
Timing Element can be set to 100 s, 200 s, 400 s or
FIGURE 4-1:
FIGURE 4-2:
DS41111D-page 14
1 2
TRANSMITTED WORD
Transmission Modulation Format
1
31xT
PULSE WIDTH MODULATION (PWM)
MANCHESTER (MAN)
31xT
E
50% Preamble
E
50% Preamble
16
Header
START bit
E
4xT
). This
16
E
Header
Preliminary
4-10
xT
bit 0 bit 1 bit 2
E
Encrypted Portion
Encrypted Portion
800 s with the Baud Rate Select (BSEL) configuration
option. The Header time can be set to 4T
the Header Select (HSEL) configuration option. These
options can all be set individually for Encoder 1 and
Encoder 2.
There are four different modulation formats available,
the Modulation Select (MSEL) Configuration Option is
used to select between:
• Pulse Width Modulation (PWM)
• Manchester (MAN)
• Variable Pulse Width Modulation (VPWM)
• Pulse Position Modulation (PPM)
LOGIC "0"
LOGIC "1"
Fixed Code Portion
Fixed Code Portion
LOGIC "0"
LOGIC "1"
2002 Microchip Technology Inc.
T
E
Guard
Time
T
T
T
BP
E
E
T
BP
E
STOP bit
T
T
or 10T
E
E
Guard
Time
E
with