LRI2K datasheet(74/89 Pages) STMICROELECTRONICS

74 / 89 page

Commands codes

LRI2K

74/89

20.22

Inventory Initiated

Before receiving the Inventory Initiated command, the LRI2K must have received an Initiate

or a Fast Initiate command in order to set the Initiate_ flag. If not, the LRI2K does not answer

to the Inventory Initiated command.

On receiving the Inventory Initiated request, the LRI2K runs the anticollision sequence. The

Inventory_flag must be set to 1. The Meaning of Flags 5 to 8 is given in Table 13: Request

flags 5 to 8 when bit 3 = 1.

The request contains:

●

the flags,

●

the Inventory command code

●

the AFI if the AFI flag is set

●

the mask length

●

the mask value

●

the CRC

The LRI2K does not generate any answer if an error occurs.

The response contains:

●

the flags

●

the Unique ID

During an Inventory process, if the VCD does not receive an RF LRI2K response, it waits a

time t3 before sending an EOF to switch to the next slot. t3 starts from the rising edge of the

request EOF sent by the VCD.

●

If the VCD sends a 100% modulated EOF, the minimum value of t3 is:

t3min = 4384/fC (323.3 µs) + tSOF

●

If the VCD sends a 10% modulated EOF, the minimum value of t3 is:

t3min = 4384/fC (323.3 µs) + tNRT

where:

●

tSOF is the time required by the LRI2K to transmit an SOF to the VCD

●

tNRT is the nominal response time of the LRI2K

tNRT and tSOF are dependent on the LRI2K-to-VCD data rate and subcarrier modulation

mode.

Table 84.

Inventory Initiated request format

Request

SOF

Request

Flags

Inventory

Initiated

IC Mfg

code

Optiona

l AFI

Mask

length

Mask value

CRC16

Request

EOF

8 bits

D1h

02h

8 bits

0 - 64 bits

16 bits

Table 85.

Inventory Initiated response format

Response

SOF

Response

Flags

DSFID

UID

CRC16

Response

EOF

8 bits

00h

64 bits

16 bits

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