srt512 STMicroelectronics, srt512 Datasheet - Page 25

• Manufacturer Part Number: srt512
• Description: 13.56 Mhz Short-range Contactless Memory Chip With 512-bit Eeprom And Anticollision Functions
• Manufacturer: STMicroelectronics

SRT512
7.1
Description of an anticollision sequence
The anticollision sequence is initiated by the INITIATE() command which triggers all the
SRT512 devices that are present in the reader field range, and that are in INVENTORY
state. Only SRT512 devices in INVENTORY state will respond to the PCALL16() and
SLOT_MARKER(SN) anticollision commands.
A new SRT512 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
SRT512 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 SRT512 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 SRT512 devices in the field.
The anticollision sequence can stop when all SRT512 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 SRT512. 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 SRT512 one by one. After accessing each
SRT512, 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.
SRT512, deselect the tag and go to step1.
Figure 20
Anticollision
for an
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