X24026
Stop Condition
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.
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.
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.
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.
Figure 2. Definition of Start and Stop
SCL
SDA
STARTBIT
STOP BIT
7020 FRM 04
Figure 3. Acknowledge Response from Receiver
SCL FROM
MASTER
1
8
9
DATA
OUTPUT
FROM
TRANSMITTER
DATA
OUTPUT
FROM
RECEIVER
START
ACKNOWLEDGE
7020 FRM 05
4
XICOR [ XICOR INC. ]
