HCS410-IP Microchip Technology, HCS410-IP Datasheet - Page 10

• Manufacturer Part Number: HCS410-IP
• Description: KEELOQ CODE HOPPING ENCODER AND TRANSPONDER
• Manufacturer: Microchip Technology

HCS410
2.2.2
The Data Modulation Format is selectable between
Pulse Width Modulation (PWM) format and Manchester
encoding. Both formats are preceded by a preamble
and synchronization header, followed by the 69-bits of
data. Manchester encoding has a leading and closing
‘1’ for each code word.
FIGURE 2-10: TRANSMISSION FORMAT—MANCH = 0
FIGURE 2-11: TRANSMISSION FORMAT—MANCH = 1
DS40158C-page 10
TOTAL TRANSMISSION:
1
CODE WORD:
TOTAL TRANSMISSION:
1 2
TRANSMISSION DATA MODULE
2
CODE WORD:
4
4 5 6
5
BPW
T
Preamble
6
E
Preamble
LOGIC "0"
LOGIC "1"
Preamble
LOGIC "0"
LOGIC "1"
Sync
Preamble Sync Encrypt
14 15 16
14 15 16
1 CODE WORD
Encrypt
1
2
1
Preliminary
3 5 7 9
Sync
2
4 6 8 10
Sync
3
Fixed
CODE WORD
Code Word
4
1 CODE WORD
Start bit
Guard
The same code word is continuously sent as long as
the input pins are kept high with a guard time separat-
ing the code words. All of the timing values are in mul-
tiples of a Basic Timing Element (T
changed using the baud rate option bits.
Encrypted
Fixed
Encrypted
Data
TX Data
Preamble
Guard
Sync
Preamble Sync Encrypt
Encrypt
BIT
Fixed Code
Fixed Code
1997 Microchip Technology Inc.
T
T
Data
E
E
Data
Stop bit
E
), which can be
Guard
Time
Guard
Time