24LC256-ISLASHMS datasheet(11/42 Pages) MICROCHIP

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DS21930B-page 11

24AAXX/24LCXX/24FCXX

5.0

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 5-1).

5.1

Bus Not Busy (A)

Both data and clock lines remain high.

5.2

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.

5.3

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.

5.4

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 clock pulse per

bit of data.

Each data transfer is initiated with a Start condition and

terminated with a Stop condition. The number of data

bytes transferred between Start and Stop conditions is

determined by the master device.

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