HCS473 Datasheet, PDF (33/68 Pages) Microchip Technology – Code Hopping Encoder and Transponder

HCS473
Table 7-5 timing values are compensated only for
HCS473 internal filter delays. The transponder reader
designer must compensate communication timing
accordingly for the cumulative antenna delays.
Use LF Demodulator mode to see the effects of the
internal filters and the LC antennae, Section 3.2.1.2.
It must be clearly understood that the HCS473 core
does not see the LF field immediately upon the base
station turning it on, nor does it immediately detect its
removal. If the internal analog delay and cumulative
antenna delays are greater than a given low time, the
HCS473 will obviously never “see” the low.
FIGURE 3-19:
LF ACK RESPONSE ADJUSTMENTS (LFRSP=1)
Transponder Select Sequence
Command
12-Bit
VID
TID=0 TID=1 TID=2
Simultaneous
LF ACK
Next
Command
Inductive
(LC Pins)
RF Response
(DATA Pin)
TCMD
6 LFTE
TTSACK
TTSCMD
5 LFTE
Transponder Select ACK
Present Transport Code Sequence
32-Bit
Command _Transport
CRC
Simultaneous
LF ACK
Next
Command
Inductive
(LC Pins)
RF Response
(DATA Pin)
TCMD
TTPACK
TFINH
TCMD
TCMD
5 LFTE
Transport ACK
Write Sequence
Command Address
16-Bit
Write Data
CRC
Simultaneous
LF ACK
Next
Command
Inductive
(LC Pins)
RF Response
(DATA Pin)
TCMD
TWRT
Anticollision Off Sequence
Command CRC
Simultaneous
LF ACK
Next
Command
Inductive
(LC Pins)
RF Response
(DATA Pin)
TCMD
TAOACK
TFINH
TCMD
5 LFTE
ACOL Off ACK
TCMD
TFINH
TCMD
TCMD
5 LFTE
Write ACK
 2002 Microchip Technology Inc.
Preliminary
DS40035C-page 31