DEMOKITCRX14 STMicroelectronics, DEMOKITCRX14 Datasheet - Page 18

• 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
4.5
18/47
Figure 6.
I²C memory addressing
To start up communication with the CRX14, 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 CRX14, these bits are defined as shown in
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 CRX14 device, the
corresponding device returns an acknowledgment on the SDA bus during the 9
The CRX14 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
SCL
SDA
I²C bus protocol
CONDITION
START
CONDITION
START
MSB
1
MSB
1
2
Doc ID 8880 Rev 4
2
INPUT
SDA
3
3
CHANGE
SDA
7
7
8
8
ACK
9
ACK
CONDITION
9
STOP
CONDITION
STOP
AI00792
th
bit time.
Table
CRX14
6.