Datasheet

15
T5557
4517E–RFID–02/03
Sequence Start Marker Figure 17. T5557 Sequence Start Marker in Extended Mode
The T5557 sequence start marker is a special damping pattern, which may be used to
synchronize the reader. The sequence start marker consists of two bits (‘01’ or ‘10’)
which are inserted as header before the first block to be transmitted if the bit 29 in
extended mode ist set. At the start of a new block sequence, the value of the two bits is
inverted.
Inverse Data Output The T5557 supports in its extended mode (X-mode) an inverse data output option. If
inverse data is enabled, the modulator as shown in Figure 18 works on inverted data
(see Table 4). This function is supported for all basic types of encoding.
Figure 18. Data Encoder for Inverse Data Output
Fast Write In the optional fast write mode the time between two gaps is nominally 12 field clocks for
a ‘0’ and 27 field clocks for a ‘1’. When there is no gap for more than 32 field clocks after
a previous gap, the T5557 will exit the write mode. Please refer to Table 5 and Figure 8.
Table 5. Fast Write Data Decoding Schemes
Block 1 Block 2 MAXBLK Block 1 1010 01
Block-read mode
Regular-read mode
Sequence Start Marker
Block 2 MAXBLK
10 Block n 01 Block n 10 Block n 01 Block n 10 Block n 01
Modulator
XOR
Inverse data output
D
Sync
CLK
R
Intern out
data
Data output
Data clock
PSK1
PSK2
PSK3
Direct/NRZ
FSK1
FSK2
Manchester
Biphase
Mux
Parameters Remark Symbol Min. Max. Unit
Start gap – S
gap
10 50 FC
Write gap
Normal write mode Wn
gap
830FC
Fast write mode Wf
gap
820FC
Write data in
normal mode
‘0’ data d
0
16 31 FC
‘1’ data d
1
48 63 FC
Write data in fast
mode
‘0’ data d
0
815FC
‘1’ data d
1
24 31 FC