4

X24C01

Stop Condition

All communications must be terminated by a stop con-

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

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

X24C01 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 transfers. The transmitting device 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 X24C01 will respond with an acknowledge after

recognition of a start condition, a seven bit word address

and a R/W bit. If a write operation has been selected, the

X24C01 will respond with an acknowledge after each

byte of data is received.

In the read mode the X24C01 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 X24C01

will continue to transmit data. If an acknowledge is not

detected, the X24C01 will terminate further data trans-

missions. The master must then issue a stop condition to

return the X24C01 to the standby power mode and

place the device into a known state.

Figure 2. Definition of Start and Stop

3837 FHD F07

Figure 3. Acknowledge Response From Receiver

SCL FROM

MASTER

DATA

OUTPUT

FROM

TRANSMITTER

1

8

9

DATA

OUTPUT

FROM

RECEIVER

START

ACKNOWLEDGE

3837 FHD F08

SCL

SDA

START CONDITION

STOP CONDITION