ATA5551M-PPMY_14 Datasheet, PDF (14/28 Pages) ATMEL Corporation – Standard Read/Write ID Transponder with Anti-collision

4.3.15 STOP OP-Code
The STOP OP-code (‘11’) is used to stop modulation until a power-on reset occurs. This feature can be used to have a
steady RF field where single transponders are collected one by one. Each IC is read and than disabled, so that it does not
interfere with the next IC.
Note:
The STOP OP-code should contain only the two OP-code bits to disable the IC. Any additional data sent will
not be ignored, and the IC will not stop modulation.
Figure 4-19. OP-code Transmission
Standard OP-code
1
0 more data ...
Start gap
Stop OP-code
1
1
> 64 clocks
Read mode
Write mode
4.3.16 Password
When password mode is on (usePWD = 1), the first 32 bits after the OP-Code 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 IC will not program the memory,
but restart in read mode at block 1 once writing has completed.
Notes:
● If PWD is not set, but the IC receives a write datastream containing any 32 bits in place of a password, the IC will
enter programming mode.
● In password mode, MAXBLK should be set to a value below 7 to prevent the password from being transmitted by the
Atmel^® e5551.
● Every transmission of 2 OP-code bits, 32 password bits, one lock bit, 32 data bits and 3 address bits (= 70 bits) needs
about 35 ms. Testing all 2³² possible combinations (about 4.3 billion) takes about 40,000 h, or over four years. This is
a sufficient password protection for a general-purpose IDIC.
Figure 4-20. Programming
Write mode
Check V_PP
HV on
Modulation
Writing done (> 64 clocks since last gap)
0.12ms
16ms
Programming starts
(HV at EEPROMs
HV on for testing if V_PP is ok
Programming ends
Reading starts
Operation
Write
V_PP/Lock ok?
Program EEPROM
Read
14 ATA5551M-PPMY [DATASHEET]
9334B–RFID–05/14