U3280M_07 Datasheet, PDF (9/21 Pages) ATMEL Corporation – Transponder Interface for Microcontroller

Figure 4-4. Serial Protocol
SCL
U3280M
SDA
Stand- _START
by condition
Data
valid
Data Data/
change acknowledge
valid
STOP Stand-
condition by
Control Byte Format
START A4
EEPROM address
A3
A2
A1
Mode control
bits
Read/
NWrite
A0
C1
C0
R/NW Ackn
The control byte follows the START condition and consists of the 5-bit row address, 2 mode con-
trol bits and the read/not-write bit.
Data Transfer Sequence
START Control byte Ackn
Data byte
Ackn
Data byte
Ackn
STOP
• After the STOP condition and before the START condition the device is in standby mode and
the SDA line is switched to an input with the pull-up resistor.
• The START condition follows a control byte that determines the following operation. Bit 0 of
the control byte is used to control the following transfer direction. A “0” defines a write access
and a “1” defines a read access.
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4688D–RFID–03/07