CR14 datasheet(18/46 Pages) STMICROELECTRONICS

Part #	CR14

Description	Low Cost ISO14443 type-B Contactless Coupler Chip with Anti-Collision and CRC Management

PDF	46 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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4 CR14 I²C protocol description

CR14

18/46

Figure 6.

I²C Bus Protocol

4.5

I²C Memory Addressing

To start up communication with the CR14, the bus master must initiate a START condition.

Then, the bus master sends 8 bits (with the most significant bit first) on the Serial Data line,

SDA. These bits consist of the Device Select Code (7 bits) plus a RW bit.

According to the I²C bus definition, the seven most significant bits of the Device Select Code

are the Device Type Identifier. For the CR14, these bits are defined as shown in Table 6.

The 8th bit is the Read/Write bit (RW). It is set to ‘1’ for I²C Read, and to ‘0’ for I²C Write

operations.

If the data sent by the bus master matches the Device Select Code of a CR14 device, the

corresponding device returns an acknowledgment on the SDA bus during the 9th bit time.

The CR14 devices whose Device Select Codes do not correspond to the data sent, generate a

No-ACK. They deselect themselves from the bus and go into stand-by mode.

SCL

SDA

SCL

SDA

START

CONDITION

SDA

INPUT

SDA

CHANGE

AI00792

STOP

CONDITION

MSB

ACK

START

CONDITION

SCL

MSB

ACK

STOP

CONDITION

CR14 Datasheet(PDF) 18 Page - STMicroelectronics