T5557 Datasheet, PDF (15/30 Pages) ATMEL Corporation – Multifunctional 330-bit Read/Write RF-Identification IC

T5557
Sequence Start Marker
Figure 17. T5557 Sequence Start Marker in Extended Mode
Sequence Start Marker
Block-read mode ^{10 Block n 01 Block n 10 Block n 01 Block n 10 Block n 01}
Inverse Data Output
Fast Write
Regular-read mode ^{10 Block 1}
Block 2 MAXBLK 01 Block 1
Block 2 MAXBLK 10
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.
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
Intern out
data
Data clock
D
Sync
CLK
R
XOR
PSK1
PSK2
PSK3
Direct/NRZ
FSK1
FSK2
Mux
Data output
Manchester
Biphase
Inverse data output
Modulator
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
Parameters
Start gap
Write gap
Write data in
normal mode
Write data in fast
mode
Remark
–
Normal write mode
Fast write mode
‘0’ data
‘1’ data
‘0’ data
‘1’ data
Symbol
S_gap
Wn_gap
Wf_gap
d₀
d₁
d₀
d₁
Min.
10
8
8
16
48
8
24
Max.
50
30
20
31
63
15
31
Unit
FC
FC
FC
FC
FC
FC
FC
15
4517E–RFID–02/03