T5557 Datasheet, PDF (9/30 Pages) ATMEL Corporation – Multifunctional 330-bit Read/Write RF-Identification IC

Figure 10. Complete Writing Sequence
Read mode
T55571x
T555701
Opcode
T5557
Write mode
Block data
Block
address
Read mode
Programming
Block 0 loading ^{Start gap}
POR
Lock bit
Figure 11. T5557 Command Formats
Standard write
Opcode
1p * _L
1
Data 32
2 Addr 0
Protected write
1p * 1
Password 32
L
1
Data
32
2 Addr 0
AOR (wake-up command)
10
1
Password 32
Direct access (PWD = 1)
1p * 1
Password 32
0 2 Addr 0
Direct access (PWD = 0)
1p * 0 2 Addr 0
Page 0/1 regular read
1p *
Reset command
00
* p = page selector
Password
Answer-On-Request
(AOR) Mode
When password mode is active (PWD = 1), the first 32 bits after the opcode are
regarded as the password. They are compared bit by bit with the contents of block 7,
starting at bit 1. If the comparison fails, the T5557 will not program the memory, instead
it will restart in regular-read mode once the command transmission is finished.
Note: In password mode, MAXBLK should be set to a value below 7 to prevent the password
from being transmitted by the T5557.
Each transmission of the direct access command (two opcode bits, 32 bits password, ‘0’
bit plus 3 address bits = 38 bits) needs about 18 ms. Testing all possible combinations
(about 4.3 billion) takes about two years.
When the AOR bit is set, the T5557 does not start modulation in the regular-read mode
after loading configuration block 0. The tag waits for a valid AOR data stream (“wake-up
command”) from the reader before modulation is enabled. The wake-up command con-
sists of the opcode (‘10‘) followed by a valid password. The selected tag will remain
active until the RF field is turned off or a new command with a different password is
transmitted which may address another tag in the RF field.
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4517E–RFID–02/03