SRI512_08 datasheet(26/47 Pages) STMICROELECTRONICS

26 / 47 page

Anticollision

SRI512

26/47

7.1

Description of an anticollision sequence

The anticollision sequence is initiated by the Initiate() command which triggers all the

SRI512 devices that are present in the reader field range, and that are in Inventory state.

Only SRI512 devices in Inventory state will respond to the Pcall16() and Slot_marker(SN)

anticollision commands.

A new SRI512 introduced in the field range during the anticollision sequence will not be

taken into account as it will not respond to the Pcall16() or Slot_marker(SN) command

(Ready state). To be considered during the anticollision sequence, it must have received the

Initiate() command and entered the Inventory state.

Table 4 shows the elements of a standard anticollision sequence. (See Figure 22 for an

example.)

After each Slot_marker() command, there may be several, one or no answers from the

SRI512 devices. The reader must handle all the cases and store all the Chip_IDs, correctly

decoded. At the end of the anticollision sequence, after Slot_marker(15), the reader can

start working with one SRI512 by issuing a Select() command containing the desired

Chip_ID. If a collision is detected during the anticollision sequence, the reader has to

generate a new sequence in order to identify all unidentified SRI512 devices in the field. The

anticollision sequence can stop when all SRI512 devices have been identified.

Table 4.

Standard anticollision sequence

Step 1

Init:

Send Initiate().

– If no answer is detected, go to step1.

– If only 1 answer is detected, select and access the SRI512. After accessing the

SRI512, deselect the tag and go to step1.

– If a collision (many answers) is detected, go to step2.

Step 2

Slot 0

Send Pcall16().

– If no answer or collision is detected, go to step3.

– If 1 answer is detected, store the Chip_ID, Send Select() and go to step3.

Step 3

Slot 1

Send Slot_marker(1).

– If no answer or collision is detected, go to step4.

– If 1 answer is detected, store the Chip_ID, Send Select() and go to step4.

Step 4

Slot 2

Send Slot_marker(2).

– If no answer or collision is detected, go to step5.

– If 1 answer is detected, store the Chip_ID, Send Select() and go to step5.

Step N

Slop N

Send Slot_marker(3 up to 14) ...

– If no answer or collision is detected, go to stepN+1.

– If 1 answer is detected, store the Chip_ID, Send Select() and go to stepN+1.

Step 17 Slot 15

Send Slot_marker(15).

– If no answer or collision is detected, go to step18.

– If 1 answer is detected, store the Chip_ID, Send Select() and go to step18.

Step 18

All the slots have been generated and the Chip_ID values should be

stored into the reader memory. Issue the Select(Chip_ID) command and

access each identified SRI512 one by one. After accessing each SRI512,

switch them into Deselected or Deactivated state, depending on the

application needs.

– If collisions were detected between Step2 and Step17, go to Step2.

– If no collision was detected between Step2 and Step17, go to Step1.

SRI512 датащи(PDF) 26 Page - STMicroelectronics

SRI512 датащи(HTML) 26 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

датащи скачать

ссылки URL