CRX14_05 Datasheet, PDF (9/40 Pages) STMicroelectronics – Low Cost ISO14443 type-B Contactless Coupler Chip with Anti-Collision, CRC Management and Anti-Clone Function

CRX14
CRX14 REGISTERS
The CRX14 chip coupler contains six volatile reg-
isters. It is entirely controlled, at both digital and
analog level, using the four registers listed below
and shown in Table 2.:
■ Parameter Register
■ Input/Output Frame Register
■ Authentication Register
■ Slot Marker Register
The other 2 registers are located at addresses 04h
and 05h. They are “ST Reserved”, and must not
be used in end-user applications.
In the I²C protocol, all data Bytes are transmitted
Most Significant Byte first, with each Byte transmit-
ted Most significant bit first.
Table 2. CRX14 Control Registers
Address
00h
Parameter Register
01h
Input/output Frame Register
02h
Authenticate Register
03h
Slot Marker Register
04h
ST Reserved
05h
ST Reserved
Length
1 Byte
36 Bytes
NA
1 Byte
NA
NA
Access
Purpose
W
Set parameter register
R
Read parameter register
W
Store and send request frame to the PICC.
Wait for PICC answer frame
R
Transfer PICC answered frame data to Host
W
Start the Authentication process
R
Get the Authentication status
W
Launch the automated anti-collision process
from Slot_0 to Slot_15
R
Return data FFh
R and W ST Reserved. Must not be used
R and W ST Reserved. Must not be used
Parameter Register (00h)
The Parameter Register is an 8-bit volatile register
used to configure the CRX14, and thus, to custom-
ize the circuit behavior. The Parameter Register is
located at the I²C address 00h and it is accessible
in I²C Read and Write modes. Its default value,
00h, puts the CRX14 in standard ISO14443 type-
B configuration.
Table 3. Parameter Register Bits Description
Bit
Control
Value
Description
b₀ Frame Standard
0
ISO14443 type-B frame management
1
RFU
b₁ RFU
0
Not used
0
Answer PICC Frames are delimited by SOF and EOF
b₂ Answer Frame Format
1
Answer PICC Frames do not provide SOF and EOF delimiters
0
b₃ ASK Modulation Depth
1
10% ASK modulation depth mode
RFU
b₄ Carrier Frequency
0
13.56MHz carrier on RF OUT is OFF
1
13.56MHz carrier on RF OUT is ON
b₅
t_WDG
b₆ ^{Answer delay watchdog}
b5=0, b6=0: Watchdog time-out = 500µs to be used for read
b5=0, b6=1: Watchdog time-out = 5ms to be used for authentication
b5=1, b6=0: Watchdog time-out = 10ms to be used for write
b5=1, b6=1: Watchdog time-out = 309ms to be used for MCU timings
b₇ RFU
0
Not used
Note: RFU = Reserved for Future Use.
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