24lc04b Microchip Technology Inc., 24lc04b Datasheet - Page 6

• Manufacturer Part Number: 24lc04b
• Description: 2 4k I C Serial Eeprom
• Manufacturer: Microchip Technology Inc.

24AA04/24LC04B
3.6
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 24XX04, this
is set as ‘
The next two bits of the control byte are “don’t cares” for
the 24XX04. The last bit, B0, is used by the master
device to select which of the two 256-word blocks of
memory are to be accessed. This bit is, in effect, the
Most Significant bit of the word address.
The last bit of the control byte defines the operation to
be performed. When set to ‘
selected. When set to ‘
Following the Start condition, the 24XX04 monitors the
SDA bus checking the device type identifier being
transmitted and, upon receiving a ‘
slave device outputs an Acknowledge signal on the
SDA line. Depending on the state of the R/W bit, the
24XX04 will select a read or write operation.
DS21708G-page 6
Operation
Read
Write
Device Addressing
1010
’ binary for read and write operations.
Control
1010
1010
Code
0
’, a write operation is selected.
Block Address
Block Address
Block Select
1
’, a read operation is
1010
’ code, the
R/W
1
0
FIGURE 3-2:
Start Bit
x = “don’t care”
S
1
Control Code
0
Slave Address
1
CONTROL BYTE
ALLOCATION
© 2007 Microchip Technology Inc.
0
x
Select
Block
Bits
x
Acknowledge Bit
Read/Write Bit
B0 R/W ACK