24AA01H Datasheet, PDF (7/30 Pages) Microchip Technology – 1K I2C™ Serial EEPROM with Half-Array Write-Protect

4.6 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 24XX01H,
this is set as ‘1010’ binary for read and write opera-
tions. The next three bits of the control byte are “don’t
cares” for the 24XX01H.
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 24XX01H monitors
the SDA bus, checking the device type identifier being
transmitted. Upon receiving a ‘1010’ code, the slave
device outputs an Acknowledge signal on the SDA line.
Depending on the state of the R/W bit, the 24XX01H
will select a read or write operation.
Operation
Read
Write
Control
Code
1010
1010
Block Select R/W
Block Address 1
Block Address 0
24AA01H/24LC01BH
FIGURE 4-2:
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
© 2008 Microchip Technology Inc.
DS22104A-page 7