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DEMOKITCRX14

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P47
Applying the I²C protocol to the CRX14 registers CRX14
22/47 Doc ID 8880 Rev 4
5 Applying the I²C protocol to the CRX14 registers
5.1 I²C parameter register protocol
Figure 10 shows how new data is written to the Parameter Register. The new value
becomes active after the I²C STOP condition.
Figure 11 shows how to read the Parameter Register contents. The CRX14 sends and re-
sends the Parameter Register contents until it receives a NoACK from the I²C Host.
The CRX14 supports the I²C Current Address and Random Address Read modes. The
Current Address Read mode can be used if the previous command was issued to the
register where the Read is to take place.
Figure 10. Host-to-CRX14 transfer: I²C write to parameter register
Figure 11. CRX14-to-host transfer: I²C random address read from parameter register
Figure 12. CRX14-to-host transfer: I²C current address read from parameter register
S
T
A
R
T
1010XXX 00h data
S
T
O
P
ACK
ACKACK
Register Byte
Value
Parameter Register
Address
Device Select
Code
Bus Master
CRX14 Write
Bus Slave
ai09240
R/W
S
T
A
R
T
1010XXX 00h data
S
T
O
P
ACK
ACK
ACK
Register Byte
Value
Parameter Register
Address
Device Select
Code
Bus Master
CRX14 Read
Bus Slave
ai09241
R
E
S
T
A
R
T
1010XXX
R/W
Device Select
Code
R/W NoACK
data
S
T
O
P
ACK
Register Byte
Value
Bus Master
CRX14 Read
Bus Slave
ai09242
S
T
A
R
T
1010XXX
Device Select
Code
R/W NoACK
CRX14 Applying the I²C protocol to the CRX14 registers
Doc ID 8880 Rev 4 23/47
5.2 I²C input/output frame register protocol
Figure 13 shows how to store a PICC request frame command of N Bytes into the
Input/Output Frame Register.
After the I²C STOP condition, the request frame is RF transmitted in the ISO14443 type-B
format. The CRX14 then waits for the PICC answer frame which will also be stored in the
Input/Output Frame Register. The request frame is over-written by the answer frame.
Figure 14 shows how to read an N-Byte PICC answer frame.
The two CRC Bytes generated by the PICC are not stored.
The CRX14 continues to output data Bytes until a NoACK has been generated by the I²C
Host, and received by the CRX14. After all 36 Bytes have been output, the CRX14 “rolls
over”, and starts outputting from the start of the Input/Output Frame Register again.
The CRX14 supports the I²C Current Address and Random Address Read modes. The
Current Address Read mode can be used if the previous command was issued to the
register where the Read is to take place.
Figure 13. Host-to-CRX14 transfer: I²C write to I/O frame register for ISO14443B
Figure 14. CRX14-to-host transfer: I²C random address read from I/O frame register for
ISO14443B
S
T
A
R
T
1 0 1 0 XX X 01h N
S
T
O
P
ACK
ACKACK
Request Frame
Length N
Input/Output
Register
Address
Device
Select
Code
Bus
Master
CRX14
Write
Bus
Slave
ai09243
R/W
Data 1 Data 2
PICC
Command
Parameter
PICC
Command
Code
Data N
PICC
Command
Parameter
PICC
Command
Parameter
ACK
ACKACKACK
S
T
A
R
T
1010XXX 01h N
S
T
O
P
ACK
ACKACK
Received
Frame
Length
Input/Output
Register
Address
Device
Select
Code
Bus
Master
CRX14
Read
Bus
Slave
ai09243
R/W
Data1 Data 2
Answer
Frame
Data
Answer
Frame
Data
Data N
Answer
Frame
Data
Answer
Frame
Data
NoACK
ACKACKACK
R
E
S
T
A
R
T
10 1 0 XXX
Device
Select
Code
R/W
ACK
Applying the I²C protocol to the CRX14 registers CRX14
24/47 Doc ID 8880 Rev 4
Figure 15. CRX14-to-host transfer: I²C current address read from I/O frame register
for ISO14443B
5.3 I²C authenticate register protocol
For information please contact your nearest STMicroelectronics sales office.
5.4 I²C slot marker register protocol
An I²C Write command to the Slot Marker Register generates an automated sixteen-
command loop (See Figure 16 for a description of the command).
All the answers from the ST short range memory devices that are detected, are written in
the Input/Output Frame Register.
Read from the I²C Slot Marker Register is not supported by the CRX14. If the I²C Host tries
to read the Slot Marker Register, the CRX14 will return the data value FFh in both Random
Address and Current Address Read modes until NoACK is generated by the I²C Host.
The result of the detection sequence is stored in the Input/Output Frame Register. This
Register can be read by the host by using I²C Random Address Read.
Figure 16. Host-to-CRX14 transfer: I²C write to slot marker register
S
T
A
R
T
1010XXX N
S
T
O
P
ACK
ACK
Answer Frame
Data
Device
Select
Code
Bus Master
CRX14 Write
Bus Slave
ai09245
R/W
Data 1 Data 2
Answer Frame
Data
Answer Frame
Data
Data N
Answer Frame
Data
Received
Frame Length
ACKACK
NoACK
ACK
03h
S
T
O
P
ACK
Slot Marker
Register
Address
Bus Master
CRX14 Write
Bus Slave
ai09246
S
T
A
R
T
1010XXX
Device Select
Code
R/W
ACK
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P47

DEMOKITCRX14

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Manufacturer:
STMicroelectronics
Description:
RFID EVALUATION KIT ISO14443-B
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