sri4k STMicroelectronics, sri4k Datasheet - Page 25

• Manufacturer Part Number: sri4k
• Description: 13.56 Mhz Short-range Contactless Memory Chip With 4096-bit Eeprom And Anticollision Functions
• Manufacturer: STMicroelectronics

SRI4K
7.1
Description of an anticollision sequence
The anticollision sequence is initiated by the INITIATE() command which triggers all the
SRI4K devices that are present in the reader field range, and that are in INVENTORY state.
Only SRI4K devices in INVENTORY state will respond to the PCALL16() and
SLOT_MARKER(SN) anticollision commands.
A new SRI4K 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
example.)
Table 4.
After each SLOT_MARKER() command, there may be several, one or no answers from the
SRI4K 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 SRI4K 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 SRI4K devices in the field. The
anticollision sequence can stop when all SRI4K devices have been identified.
Step 1
Step 2
Step 3
Step 4
Step N
Step 17 Slot 15
Step 18
shows the elements of a standard anticollision sequence. (See
Init:
Slot 0
Slot 1
Slot 2
Slop N
Standard anticollision sequence
Send INITIATE().
– If no answer is detected, go to step1.
– If only 1 answer is detected, select and access the SRI4K. After accessing the
– If a collision (many answers) is detected, go to step2.
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.
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.
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.
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.
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.
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 SRI4K one by one. After accessing each SRI4K, 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.
SRI4K, deselect the tag and go to step1.
Figure 22
Anticollision
for an
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