X24026

4

Stop Condition

All communications must be terminated by a stop condi-

tion, which is a LOW to HIGH transition of SDA when

SCL is HIGH. The stop condition is also used by the

X24026 to place the device in 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 transmitting

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 X24026 will respond with an acknowledge after rec-

ognition of a start condition and its slave address. If both

the device and a write operation have been selected, the

X24026 will respond with an acknowledge after the

receipt of each subsequent eight bit word.

In the read mode the X24026 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 X24026 will

continue to transmit data. If an acknowledge is not

detected, the X24026 will terminate further data trans-

missions. The master must then issue a stop condition to

return the X24026 to the standby power mode and place

the device into a known state.

Figure 2. Definition of Start and Stop

Figure 3. Acknowledge Response from Receiver

SCL

SDA

START BIT

STOP BIT

7020 FRM 04

7020 FRM 05

SCL FROM

MASTER

DATA

OUTPUT

FROM

TRANSMITTER

1

8

9

DATA

OUTPUT

FROM

RECEIVER

START

ACKNOWLEDGE