HCS412_11 Datasheet, PDF (28/52 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder and Transponder Burglar alarm systems

HCS412
4.4.2 ANTICOLLISION AND RF ECHO
(LFSP = 11)
In addition to enabling anticollision, this mode adds that
all HCS412 responses and Acknowledges are echoed
on the DATA output line. Responses are first transmit-
ted on the DATA line, followed by the equivalent data
transmitted on the LF LC lines (Figure 4-16,
Figure 4-17).
LF communication from the token to the transponder
reader has much less range than LF communication
from the reader to the token. Transmitting the informa-
tion on the DATA line increases communication range
by enabling longer range RF talk back.
The information is sent on the DATA line first to benefit
longer range passive-entry authentication times.
FIGURE 4-16: RF ECHO OPTION AND READ COMMAND
TPU
TATO
Inductive
(LF)
DATA (RF)
ACK
TOTH
32-Bit Response
16-Bit
16-Bit
Response Response
LF Communication from reader to HCS412
LF Communication from HCS412 to reader
FIGURE 4-17: RF ECHO OPTION AND IFF COMMAND
Inductive (LF)
DATA (RF)
LF Communication from reader to HCS412
LF Communication from HCS412 to reader
FIGURE 4-18: RF ECHO OPTION AND REQUEST HOPPING CODE COMMAND
TATO
TOTH
Field
ACK
Request Hopping
Code Opcode
Inductive
(LF)
32-Bit PPM
Response
Next
Field
Ack
DATA (RF)
LF Communication from reader to HCS412
LF Communication from HCS412 to reader
DS41099D-page 28
© 2011 Microchip Technology Inc.