Datasheet

T5557

4517E–RFID–02/03

A start gap will be accepted at any time after the mode register has been loaded

(³ 3 ms). A single gap will not change the previously selected page (by former opcode

‘10’ or ‘11’).

Figure 9. Start of Reader to Tag Communication

Table 2. Write Data Decoding Scheme

Write Data Protocol The T5557 expects to receive a dual bit opcode as the first two bits of a reader com-

mand sequence. There are three valid opcodes:

• The opcodes ‘10’ and ‘11’ precede all block write and direct access operations for

page 0 and page 1

• The RESET opcode ‘00’ initiates a POR cycle

• The opcode ‘01’ precedes all test mode write operations. Any test mode access is

ignored after master key (bits 1..4) in block 0 has been set to ‘6’. Any further

modifications of the master key are prohibited by setting the lock bit of block 0 or the

OTP bit.

Writing has to follow these rules:

• Standard write needs the opcode, the lock bit, 32 data bits and the 3-bit address

(38 bits total)

• Protected write (PWD bit set) requires a valid 32-bit password between opcode and

data, address bits

• For the AOR wake-up command an opcode and a valid password are necessary to

select and activate a specific tag

Note: The data bits are read in the same order as written.

If the transmitted command sequence is invalid, the T5557 enters regular-read mode

with the previously selected page (by former opcode ‘10’ or ‘11’).

Parameters Remark Symbol Min. Max. Unit

Start gap S

gap

10 50 FC

Write gap Normal write mode W

gap

830FC

Write data in normal mode

‘0’ data d

16 31 FC

‘1’ data d

48 63 FC

Write modeRead mode

W gap

gap