24aa014-i-st Microchip Technology Inc., 24aa014-i-st Datasheet - Page 6

• Manufacturer Part Number: 24aa014-i-st
• Description: 1k I2c Serial Eeprom
• Manufacturer: Microchip Technology Inc.

24AA014/24LC014
5.0
A control byte is the first byte received following the
Start condition from the master device (Figure 5-1).
The control byte consists of a four-bit control code; for
the 24AA014/24LC014 this is set as ‘1010’ binary for
read and write operations. The next three bits of the
control byte are the Chip Select bits (A2, A1, A0). The
Chip Select bits allow the use of up to eight 24AA014/
24LC014 devices on the same bus and are used to
select which device is accessed. The Chip Select bits
in the control byte must correspond to the logic levels
on the corresponding A2, A1 and A0 pins for the device
to respond. These bits are in effect the three Most
Significant bits of the word address.
The last bit of the control byte defines the operation to
be performed. When set to a ‘1’, a read operation is
selected. When set to a ‘0’, a write operation is
selected. Following the Start condition, the 24AA014/
24LC014 monitors the SDA bus, checking the control
byte being transmitted. Upon receiving a ‘1010’ code
and appropriate Chip Select bits, the slave device out-
puts an Acknowledge signal on the SDA line. Depend-
ing on the state of the R/W bit, the 24AA014/24LC014
will select a read or write operation.
DS21809D-page 6
DEVICE ADDRESSING
FIGURE 5-1:
5.1
The Chip Select bits A2, A1 and A0 can be used to
expand the contiguous address space for up to 8K bits
by adding up to eight 24AA014/24LC014 devices on
the same bus. In this case, software can use A0 of the
control byte as address bit A8, A1 as address bit A9,
and A2 as address bit A10. It is not possible to
sequentially read across device boundaries.
Start Bit
S
Contiguous Addressing Across
Multiple Devices
1
Control Code
0
Slave Address
1
CONTROL BYTE FORMAT
© 2007 Microchip Technology Inc.
0
Read/Write Bit
Chip Select
A2
Acknowledge Bit
Bits
A1
A0
R/W
ACK