CRX14_05 Datasheet, PDF(16/40 Page) STMicroelectronics – Low Cost ISO14443 type-B Contactless Coupler Chip with Anti-Collision, CRC Management and Anti-Clone Function

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CRX14_05 Datasheet, PDF (16/40 Pages) STMicroelectronics – Low Cost ISO14443 type-B Contactless Coupler Chip with Anti-Collision, CRC Management and Anti-Clone Function

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CRX14

CRX14 IÂ²C Read Operations

To send a Read command, the bus master sends

a START condition, followed by a Device Select

Code and the R/W bit set to â1â.

The CRX14 that corresponds to the Device Select

Code acknowledges and outputs the first data

Byte of the addressed register.

To select a specific register, a dummy Write com-

mand must first be issued, giving an address Byte

but no data Bytes, as shown in the bottom half of

Figure 10. This causes the new address to be

stored in the internal address pointer, for use by

the Read command that immediately follows the

dummy Write command.

Figure 10. CRX14 IÂ²C Read Modes Sequences

In the IÂ²C Read mode, the CRX14 may read one

or more data Bytes depending on the selected reg-

ister. The bus master has to generate an ACK af-

ter each data Byte to read all the register data in a

continuous stream. Only the last data Byte should

not be followed by an ACK. The master then termi-

nates the transfer with a STOP condition, as

shown in Figure 10.

After reading each Byte, the CRX14 waits for the

master to send an ACK during the 9th bit time. If

the master does not return an ACK within this time,

the CRX14 terminates the data transfer and

switches to stand-by mode.

IÂ²C CURRENT ADDRESS READ

R/W

ACK

BUS Master

DEV SEL

CRX14 READ

BUS Slave

DATA 1

ACK

IÂ²C RANDOM ADDRESS READ

R/W

DATA 2

DATA 3

DATA 4

R/W

ACK

BUS Master

CRX14 READ

DEV SEL

ADDRESS

DEV SEL

BUS Slave

ACK

DATA 1

ACK

DATA 2

ACK

NoACK

DATA N

ACK

NoACK

DATA N

AI09266

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