24LC02B-I-SN Datasheet, PDF (7/32 Pages) Microchip Technology – 2K I2C™ Serial EEPROM

24AA02/24LC02B
5.0 DEVICE ADDRESSING
A control byte is the first byte received following the
Start condition from the master device. The control byte
consists of a four-bit control code. For the 24XX02, this
is set as ‘1010’ binary for read and write operations.
The next three bits of the control byte are “don’t cares”
for the 24XX02.
The last bit of the control byte defines the operation to
be performed. When set to ‘1’, a read operation is
selected. When set to ‘0’, a write operation is selected.
Following the Start condition, the 24XX02 monitors the
SDA bus, checking the device type identifier being
transmitted and, upon a ‘1010’ code, the slave device
outputs an Acknowledge signal on the SDA line.
Depending on the state of the R/W bit, the 24XX02 will
select a read or write operation.
FIGURE 5-1:
CONTROL BYTE
ALLOCATION
Control Code
Read/Write Bit
Block
Select
Bits
S 1 0 1 0 x x x R/W ACK
Slave Address
Start Bit
x = “don’t care”
Acknowledge Bit
Operation
Read
Write
Control
Code
1010
1010
Block Select R/W
Block Address 1
Block Address 0
FIGURE 5-2:
ADDRESS SEQUENCE BIT ASSIGNMENTS
Control Byte
Address Low Byte
1 0 1 0 x x x R/W
Control
Code
x = “don’t care”
Block
Select
bits
A
7
•
•
•
•
•
•
A
0
© 2009 Microchip Technology Inc.
DS21709J-page 7