CRX14_10 Datasheet, PDF (32/47 Pages) STMicroelectronics – ISO14443 type-B contactless coupler chip with anti-collision, CRC management and anti-clone function

Tag access using the CRX14 coupler
CRX14
Figure 29. Standard TAG command: answer frame reception
TAG
SOF
I²C
TAG
Data
TAG
Data
TAG
Data
TAG
Data
TAG
CRC
TAG
CRC
TAG
EOF
S
T
A
R
T
Device
Select
Code
Input/
Output
Register
Address
01h
Answer
Frame
Length
P
TAG
Data
TAG
Data
TAG
Data
Data 1 Data 2 Data
S
TAG T
Data O
P
Data P
RF
SOF
Data 1 Data 2
Data
Data P
CRC
CRC
EOF
Figure 30. Standard TAG command: complete TAG access description
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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
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7.2
Anti-collision TAG sequence
The CRX14 can identify an ST short range memory using a proprietary anti-collision
system.
Issuing an I²C Write command to the Slot Marker Register (Figure 16) causes the CRX14
TO automatically generate a 16-slot anti-collision sequence, and to store the identified
Chip_ID in the Input/Output Frame Register, as specified in Table 4.
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 correctly 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 Input/Output Frame Register to retrieve all
the identified Chip_IDs.
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Doc ID 8880 Rev 4