T5557 Datasheet, PDF (6/30 Pages) ATMEL Corporation – Multifunctional 330-bit Read/Write RF-Identification IC

Tag to Reader
Communication
Regular-read Mode
Block-read Mode
e5550 Sequence
Terminator
6 T5557
Any field gap occurring during this initialization phase will restart the complete
sequence. After this initialization time the T5557 enters regular-read mode and modula-
tion starts automatically using the parameters defined in the configuration register.
During normal operation, the data stored within the EEPROM is cycled and the Coil 1,
Coil 2 terminals are load modulated. This resistive load modulation can be detected at
the reader module.
In regular-read mode data from the memory is transmitted serially, starting with block 1,
bit 1, up to the last block (e.g., 7), bit 32. The last block which will be read is defined by
the mode parameter field MAXBLK in EEPROM block 0. When the data block
addressed by MAXBLK has been read, data transmission restarts with block 1, bit 1.
The user may limit the cyclic datastream in regular-read mode by setting the MAXBLK
between 0 and 7 (representing each of the 8 data blocks). If set to 7, blocks 1 through 7
can be read. If set to 1, only block 1 is transmitted continously. If set to 0, the contents of
the configuration block (normally not transmitted) can be read. In the case of MAXBLK =
0 or 1, regular-read mode can not be distinguished from block-read mode.
Figure 6. Examples for Different MAXBLK Settings
MAXBLK = 5
0
Block 1
Loading block 0
Block 4
Block 5
MAXBLK = 2
0
Block 1
Loading block 0
Block 2
Block 1
Block 1
Block 2
Block 2
Block 1
MAXBLK = 0
0
Block 0
Loading block 0
Block 0
Block 0
Block 0
Block 0
Every time the T5557 enters regular- or block-read mode, the first bit transmitted is a
logical ‘0’. The data stream starts with block 1, bit 1, continues through MAXBLK, bit 32,
and cycles continuously if in regular-read mode .
Note: This behavior is different from the original e555x and helps to decode PSK-modulated
data.
With the direct access command, the addressed block is repetitively read only. This
mode is called block-read mode. Direct access is entered by transmitting the page
access opcode (‘10’ or ‘11’), a single ‘0’ bit and the requested 3-bit block address when
the tag is in normal mode.
In password mode (PWD bit set), the direct access to a single block needs the valid
32-bit password to be transmitted after the page access opcode whereas a ‘0’ bit and
the 3-bit block address follow afterwards. In case the transmitted password does not
match with the contents of block 7, the T5557 tag returns to the regular-read mode.
Note: A direct access to block 0 of page 1 will read the configuration data of block 0, page 0.
A direct access to bock 3 .. 7 of page 1 reads all data bits as zero.
The sequence terminator ST is a special damping pattern which is inserted before the
first block and may be used to synchronize the reader. This e5550-compatible sequence
terminator consists of 4 bit periods with underlaying data values of ‘1’. During the sec-
ond and the fourth bit period, modulation is switched off (Manchester encoding –
switched on). Biphase modulated data blocks need fixed leading and trailing bits in com-
bination with the sequence terminator to be identified reliable.
4517E–RFID–02/03