CR14 STMicroelectronics, CR14 Datasheet - Page 21

• Manufacturer Part Number: CR14
• Description: Low Cost Iso14443 Type-b Contactless Coupler Chip With Anti-collision And Crc Management
• Manufacturer: STMicroelectronics

CR14
4.7
CR14 I²C 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 ’1’.
The CR14 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 command must first be issued, giving an address
Byte but no data Bytes, as shown in the bottom half of
to be stored in the internal address pointer, for use by the Read command that immediately
follows the dummy Write command.
In the I²C Read mode, the CR14 may read one or more data Bytes depending on the selected
register. The bus master has to generate an ACK after 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 terminates the transfer with a STOP condition, as shown in
After reading each Byte, the CR14 waits for the master to send an ACK during the 9
If the master does not return an ACK within this time, the CR14 terminates the data transfer
and switches to stand-by mode.
Figure 9.
I²C CURRENT ADDRESS READ
I²C RANDOM ADDRESS READ
CR14 I²C Read Modes Sequences
BUS Master
CR14 READ
BUS Slave
BUS Master
CR14 READ
BUS Slave
DEV SEL
DEV SEL
R/W
R/W
ACK
ACK
ADDRESS
DATA 1
ACK
ACK
DEV SEL
DATA 2
ACK
R/W
ACK
Figure
DATA 3
DATA 1
9. This causes the new address
ACK
ACK
DATA 4
4 CR14 I²C protocol description
DATA 2
Figure
ACK
ACK
9.
DATA N
DATA N
th
NoACK
NoACK
bit time.
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