DEMOKITCRX14 STMicroelectronics, DEMOKITCRX14 Datasheet - Page 20

• Manufacturer Part Number: DEMOKITCRX14
• Description: RFID EVALUATION KIT ISO14443-B
• Manufacturer: STMicroelectronics
• Type: Development kitr

Specifications of DEMOKITCRX14

• Contents: CD-ROM, CRX14 Board, USB Transceiver, Samples and Documentation
• Processor To Be Evaluated: CRX14
• Interface Type: I2C
• Operating Supply Voltage: 5 V
• For Use With/related Products: CRX14
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-3704

CRX14 I²C protocol description
Figure 8.
4.7
20/47
decoded by the CRX14
First byte of instruction
with R/W = 1 already
I²C polling flowchart using ACK
CRX14 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 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 command must first be issued, giving an
address Byte but no data Bytes, as shown in the bottom half of
new address 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 CRX14 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
Figure
9.
ReSTART
STOP
NO
NO
CODE with R/W=1
START Condition
DEVICE SELECT
Radio Frequency
data exchange
Doc ID 8880 Rev 4
operation is
in progress
addressing
the CRX14
returned
ACK
Next
YES
YES
Proceed to READ
Operation
STOP
Figure
9. This causes the
ai09234
CRX14