HCS370SL MICROCHIP [Microchip Technology], HCS370SL Datasheet - Page 15

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

FIGURE 4-3:
FIGURE 4-4:
In addition to the Modulation Format, Guard Time, and
Baud Rate, the following options are also available to
change the transmission format:
• If the START/STOP Pulse Enable (STEN) config-
• A wake-up sequence can be transmitted before
• The WAKE option is the same for both Encoder 1
2002 Microchip Technology Inc.
uration option is enabled, the HCS370 will place a
leading and trailing ‘1’ on each code word. This is
necessary for modulation formats such as
Manchester and PPM to interpret the first and last
data bit.
the transmission starts. The wake-up sequence is
configured with the Wake-up (WAKE) configura-
tion option and can be disabled or set to 50 ms,
75 ms, or 100 ms of pulses as indicated in
Figure 4-5.
and Encoder 2.
1 2
1 2
31xT
VPWM BIT ENCODING:
VARIABLE PULSE WIDTH MODULATION (VPWM)
PULSE POSITION MODULATION (PPM)
31xT
E
50% Preamble
E
50% Preamble
16
16
10xT
10xT
on Transition Low to High
on Transition High to Low
E
E
Preliminary
Header
Header
START bit
Encrypted Portion
T
FIGURE 4-5:
BP
Encrypted Portion
WAKE-UP = 75 ms
WAKE-UP = 50 ms
WAKE-UP = 100 ms
LOGIC "0"
LOGIC "1"
LOGIC “0”
LOGIC “0”
Guard Time = 6.4 ms, 51.2 ms, or 102.4 ms
T
T
WAKE-UP
T
T
2
E
E
BP
BP
X
T
E
WAKE-UP ENABLE
Fixed Code Portion
T
Fixed Code Portion
E
3
CODE
T
T
X TE
T
T
T
E
BP
LOGIC “1”
E
E
E
LOGIC “1”
T
E
T
T
T
T
2T
E
E
BP
E
2
T
E
T
X
BP
G
5T
T
T
E
E
E
CODE
HCS370
DS41111D-page 15
STOP bit
Guard
Time
T
Guard
G
Time