X24645

4

Figure 3. Acknowledge Response From Receiver

Stop Condition

All communications must be terminated by a stop

condition, which is a LOW to HIGH transition of SDA

when SCL is HIGH. The stop condition is also used to

place the device into the standby power mode after a

read sequence. A stop condition can only be issued

after the transmitting device has released the bus.

Acknowledge

Acknowledge is a software convention used to indicate

successful data transfer. The transmitting device,

either master or slave, will release the bus after trans-

mitting eight bits. During the ninth clock cycle the

receiver will pull the SDA line LOW to acknowledge

that it received the eight bits of data. Refer to Figure 3.

The X24645 will respond with an acknowledge after

recognition of a start condition and its slave address. If

both the device and a write operation have been

selected, the X24645 will respond with an acknowl-

edge after the receipt of each subsequent 8-bit word.

In the read mode the X24645 will transmit eight bits of

data, release the SDA line and monitor the line for an

acknowledge. If an acknowledge is detected and no

stop condition is generated by the master, the X24645

will continue to transmit data. If an acknowledge is not

detected, the X24645 will terminate further data trans-

missions. The master must then issue a stop condition

to return the X24645 to the standby power mode and

place the device into a known state.

2783 ILL F06

SCL FROM

MASTER

DATA OUTPUT

FROM

TRANSMITTER

1

8

9

DATA

OUTPUT

FROM

RECEIVER

START

ACKNOWLEDGE