24AA02/24LC02B
FIGURE 5-1:
CONTROL BYTE
ALLOCATION
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.
Read/Write Bit
Block
Select
Bits
Control Code
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.
S
1
0
1
0
x
x
x
R/W ACK
Slave Address
Acknowledge Bit
Start Bit
x = “don’t care”
Control
Code
Operation
Block Select
R/W
Read
Write
Block Address
Block Address
1010
1010
1
0
FIGURE 5-2:
ADDRESS SEQUENCE BIT ASSIGNMENTS
Control Byte
Address Low Byte
A
7
A
0
x
x
1
0
1
0
x R/W
•
•
•
•
•
•
Control
Code
Block
Select
bits
x = “don’t care”
© 2009 Microchip Technology Inc.
DS21709J-page 7
MICROCHIP [ MICROCHIP ]
