CR14 STMicroelectronics, CR14 Datasheet - Page 32

• Manufacturer Part Number: CR14
• Description: Low Cost Iso14443 Type-b Contactless Coupler Chip With Anti-collision And Crc Management
• Manufacturer: STMicroelectronics

7 Tag access using the CR14 coupler
Figure 29. Standard TAG Command: Answer Frame Reception
Figure 30. Standard TAG Command: Complete TAG Access Description
7.2
32/46
I²C
RF
I²C
RF
START
TAG
SOF
SOF
Device
Select
Code
Write
Anti-Collision TAG Sequence
The CR14 can identify an ST short range memory using a proprietary anti-collision system.
Issuing an I²C Write command to the Slot Marker Register
automatically generate a 16-slot anti-collision sequence, and to store the identified Chip_ID in
the Input/Output Frame Register, as specified in
After receiving the Slot Marker Register I²C Write command, the CR14 generates an RF
PCALL16 command followed by fifteen SLOT_MARKER commands, from SLOT_MARKER(1)
to SLOT_MARKER(15). After each command, the CR14 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 CR14 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.
Register
Address
Data 1
TAG
Data
I/O
Request
Data 2
Length
Frame
TAG
Data
Request
Data
TAG
Data
Frame
Bytes
Data P
STOP
TAG
Data
SOF
Characters
Request
CRC
Frame
TAG
CRC
CRC
TAG
CRC
CRC
EOF
<-->
T 0
EOF
TAG
EOF
<-->
T 1
Table
SOF
S
T
A
R
T
Device
Select
Code
Answer Frame
Characters
5.
TAG
Register
Address
Output
Input/
01h
(Figure
Answer
Length
Frame
CRC
P
EOF
16) causes the CR14 TO
START
Data 1
TAG
Data
Device
Select
Code
Read
TAG
Data
Data 2
Answer
Length
Frame
TAG
Data
Data
Request
Frame
Bytes
Data P
ai09262
TAG
Data
CR14
ai09261
STOP
S
T
O
P