CRX14_10 Datasheet, PDF (24/47 Pages) STMicroelectronics – ISO14443 type-B contactless coupler chip with anti-collision, CRC management and anti-clone function

Applying the I²C protocol to the CRX14 registers
CRX14
Figure 15. CRX14-to-host transfer: I²C current address read from I/O frame register
for ISO14443B
Bus Master
S
T
A
R
T
Device
Select
Code
R/W
ACK
ACK
ACK
ACK
NoACK
S
T
O
P
CRX14 Write
Bus Slave
1 0 1 0 XX X
N
Data 1
Data 2
Data N
Received Answer Frame Answer Frame Answer Frame Answer Frame
Frame Length
ACK
Data
Data
Data
Data
ai09245
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
Bus Master
CRX14 Write
Bus Slave
S
R/W
T
S
A _{Device Select}
Slot Marker
T
R
Code
Register
O
T
Address
P
1 0 1 0X X X
03h
ACK
ACK
ai09246
24/47
Doc ID 8880 Rev 4