CRX14_05 Datasheet, PDF (27/40 Pages) STMicroelectronics – Low Cost ISO14443 type-B Contactless Coupler Chip with Anti-Collision, CRC Management and Anti-Clone Function

Figure 31. Standard TAG Command: Complete TAG Access Description
CRX14
Device
Select I/O Request Request
I²C
Code Register Frame Frame
Write Address Length Bytes
Device
Select
Code
Read
Answer
Frame
Length
Request
Frame
Bytes
START
STOP
START
STOP
SOF
EOF
SOF
EOF
Request
TAG
RF
Frame CRC ^{T0 T1} Answer Frame CRC
Characters
<--> <--> Characters
ai09262
Anti-Collision TAG Sequence
The CRX14 can identify an ST short range memo-
ry using a proprietary anti-collision system.
Issuing an I²C Write command to the Slot Marker
Register ( Figure 17.) causes the CRX14 TO auto-
matically generate a 16-slot anti-collision se-
quence, and to store the identified Chip_ID in the
Input/Output Frame Register, as specified in Table
5.
After receiving the Slot Marker Register I²C Write
command, the CRX14 generates an RF PCALL16
command followed by fifteen SLOT_MARKER
commands, from SLOT_MARKER(1) to
SLOT_MARKER(15). After each command, the
CRX14 waits for a tag answer. If the answer is cor-
rectly decoded, the corresponding Chip_ID is
stored in the Input/Output Frame Register. If there
is no answer, or if the answer is wrong (with a CRC
error, for example), the CRX14 stores an error
code in the Input/Output Frame Register. At the
end of the sequence, the host has to read the In-
put/Output Frame Register to retrieve all the iden-
tified Chip_IDs.
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