CRX14_10 Datasheet, PDF (25/47 Pages) STMicroelectronics – ISO14443 type-B contactless coupler chip with anti-collision, CRC management and anti-clone function

CRX14
Applying the I²C protocol to the CRX14 registers
Figure 17. CRX14-to-host transfer: I²C random address read from slot marker register
S
T
Bus Master ^A
R
T
R/W
Device Select
Code
CRX14 Read
1 0 1 0X X X
Slot Marker
Register
Address
00h
R
E
S
T
R/W
A _{Device Select}
R
Code
T
1 0 1 0X X X
NoACK
S
T
O
P
FFh
Bus Slave
ACK
ACK
ACK
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Figure 18. CRX14-to-host transfer: I²C current address read from slot marker register
Bus Master
CRX14 Read
Bus Slave
S
R/W
T
A _{Device Select}
R
Code
T
1 0 1 0X X X
ACK
NoACK
S
T
O
P
FFh
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5.5
Addresses above location 06h
In I²C Write mode, when the CRX14 receives the 8-bit register address, and the address is
above location 06h, the device does not acknowledge (NoACK) and deselects itself from the
bus. The Serial Data line, SDA, stays at logic ‘1’ (pull-up resistor), and the I²C Host receives
a NoACK during the 9th bit time. The SDA line stays High until the STOP condition is issued.
In the I²C Current and Random Address Read modes, when the CRX14 receives the 8-bit
register address, and the address is above location 06h, the device does not acknowledge
the Device Select Code after the START condition, and deselects itself from the bus.
Doc ID 8880 Rev 4
25/47