LRI64-A1S STMICROELECTRONICS [STMicroelectronics], LRI64-A1S Datasheet - Page 17

• Manufacturer Part Number: LRI64-A1S
• Description: Memory TAG IC, 64-bit Unique ID with WORM User Area 13.56MHz, ISO15693 and ISO18000-3 Mode 1 Compliant
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

REQUEST PROCESSING BY THE LRI64
Upon reception of a valid Request, the LRI64 per-
forms the following algorithm, where:
–
–
–
–
–
–
SN = 0
if (Nb_slots_flag)
label1:
if LSB(UID, SN_length + Mask_length) =
wait (Slot_Frame)
if Slot_Frame = SOF
if Slot_Frame = EOF
LSB(SN,SN_length)&LSB(Mask,Mask_length)
NbS is the total number of slots (1 or 16)
SN is the current slot number (0 to 15)
The function LSB(value,n) returns the n least
significant bits of value
The function MSB(value,n) returns the n most
significant bits of value
“&” is the concatenation operator
Slot_Frame is either a SOF or an EOF
then
else
then
then
if SN < NbS-1
endif
then SN = SN + 1
goto label1
exit
endif
NbS = 1
SN_length = 0
endif
NbS = 16
SN_length = 4
endif
answer to inventory request
endif
Stop Anticollision
decode/process request
exit
endif
Explanation of the Possible Cases
Figure 22.
that can occur during an anti-collision sequence
when the number of slots is 16.
The different steps are:
–
–
–
–
–
–
–
–
–
–
Note: the decision to interrupt the anti-collision se-
quence is up to the VCD. It could have continued
to send EOFs until Slot 15 and then send the Re-
quest to LRI64 #1.
The VCD sends an Inventory Request, in a
frame, terminated by a EOF. The number of
slots is 16.
LRI64 #1 transmits its Response in Slot 0. It is
the only one to do so, therefore no collision
occurs and its UID is received and registered
by the VCD;
The VCD sends an EOF, to switch to the next
slot.
In slot 1, two LRI64 devices, #2 and #3,
transmit their Responses. This generates a
collision. The VCD records it, and remembers
that a collision was detected in Slot 1.
The VCD sends an EOF, to switch to the next
slot.
In Slot 2, no LRI64 transmits a Response.
Therefore the VCD does not detect a LRI64
SOF, and decides to switch to the next slot by
sending an EOF.
In slot 3, there is another collision caused by
Responses from LRI64 #4 and #5
The VCD then decides to send a Request (for
instance a Read Block) to LRI64 #1, whose
UID was already correctly received.
All LRI64 devices detect a SOF and exit the
anti-collision sequence. They process this
Request and since the Request is addressed
to LRI64 #1, only LRI64 #1 transmits its
Response.
All LRI64 devices are ready to receive another
Request. If it is an Inventory command, the
slot numbering sequence restarts from 0.
summarizes the main possible cases
LRI64
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