HCS412I MICROCHIP [Microchip Technology], HCS412I Datasheet - Page 19

• Manufacturer Part Number: HCS412I
• Description: KEELOQ Code Hopping Encoder and Transponder
• Manufacturer: MICROCHIP [Microchip Technology]

FIGURE 4-1:
FIGURE 4-2:
Field Ack sequence repeats every 255 LF
Comms
Comms
Inductive
Inductive
(DATA)
(DATA)
Transponder reader communication to the HCS412
HCS412 response back to the reader
Comms
Comms
Communication from reader to HCS412
Filed ACK Sequence from HCS412 to reader
2002 Microchip Technology Inc.
0
RF
RF
(LC)
(LC)
previous
0
Start or
bit
previous
Start or
bit
FIELD ACKNOWLEDGE SEQUENCE
LC PIN PULSE POSITION MODULATION (PPM)
2 LF
LF
TE
TE
T
T
BITR
BITC
LF
2 LF
T
TE
PU
TE
255LF
TE
TE
3LF
Extending the high time
is acceptable but the low
time should minimally
be 1 LF
The HCS412 determines
bit values from rising edge
to rising edge times.
if no command is received.
TE
Preliminary
8LF
TE.
3LF
8LF
TE
TE
TE
3LF
TE
1
1
T
255LF
ATO
TE
2LF
TE
2 LF
Command
T
TE
BITR
4 LF
LF
TE
T
TE
BITC
HCS412
DS41099C-page 19
2 LF
TE