LRIS2K_11 Datasheet, PDF (46/98 Pages) STMicroelectronics – 2048-bit EEPROM tag IC at 13.56 MHz, with 64-bit UID and Password, ISO15693 and ISO18000-3 Mode 1 compliant

Anticollision
17 Anticollision
LRIS2K
The purpose of the anticollision sequence is to inventory the LRIS2Ks present in the VCD
field using their unique ID (UID).
The VCD is the master of communications with one or several LRIS2Ks. It initiates LRIS2K
communication by issuing the Inventory request.
The LRIS2K sends its request in the determined slot or does not respond.
17.1
Request parameters
When issuing the Inventory command, the VCD:
● sets the Nb_slots_flag as desired
● adds the mask length and the mask value after the command field
● The mask length is the number of significant bits of the mask value.
● The mask value is contained in an integer number of bytes. The mask length indicates
the number of significant bits. LSB is transmitted first
● If the mask length is not a multiple of 8 (bits), as many 0-bits as required will be added
to the mask value MSB so that the mask value is contained in an integer number of
bytes
● The next field starts at the next byte boundary.
Table 23. Inventory request format
MSB
SOF
Request_
flags
Command
Optional
AFI
8 bits
8 bits
8 bits
Mask
length
8 bits
Mask value
0 to 8 bytes
CRC
16 bits
LSB
EOF
In the example of the Table 24 and Figure 38, the mask length is 11 bits. Five 0-bits are
added to the mask value MSB. The 11-bit Mask and the current slot number are compared
to the UID.
Table 24. Example of the addition of 0-bits to an 11-bit mask value
(b₁₅) MSB
LSB (b₀)
0000 0
100 1100 1111
0-bits added
11-bit mask value
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Doc ID 13888 Rev 9