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24AA00_11 Datasheet, PDF (5/34 Pages) Microchip Technology – 128-Bit I2C™ Bus Serial EEPROM
24AA00/24LC00/24C00
3.0 FUNCTIONAL DESCRIPTION
The 24XX00 supports a bidirectional 2-wire bus and
data transmission protocol. A device that sends data
onto the bus is defined as a transmitter, and a device
receiving data as a receiver. The bus has to be
controlled by a master device which generates the
Serial Clock (SCL), controls the bus access, and
generates the Start and Stop conditions, while the
24XX00 works as slave. Both master and slave can
operate as transmitter or receiver, but the master
device determines which mode is activated.
4.0 BUS CHARACTERISTICS
The following bus protocol has been defined:
• Data transfer may be initiated only when the bus
is not busy.
• During data transfer, the data line must remain
stable whenever the clock line is high. Changes in
the data line while the clock line is high will be
interpreted as a Start or Stop condition.
Accordingly, the following bus conditions have been
defined (Figure 4-1).
4.1 Bus Not Busy (A)
Both data and clock lines remain high.
4.2 Start Data Transfer (B)
A high-to-low transition of the SDA line while the clock
(SCL) is high determines a Start condition. All
commands must be preceded by a Start condition.
4.3 Stop Data Transfer (C)
A low-to-high transition of the SDA line while the clock
(SCL) is high determines a Stop condition. All
operations must be ended with a Stop condition.
4.4 Data Valid (D)
The state of the data line represents valid data when,
after a Start condition, the data line is stable for the
duration of the high period of the clock signal.
The data on the line must be changed during the low
period of the clock signal. There is one bit of data per
clock pulse.
Each data transfer is initiated with a Start condition and
terminated with a Stop condition. The number of the
data bytes transferred between the Start and Stop
conditions is determined by the master device and is
theoretically unlimited.
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DS21178H-page 5