X24128
Stop Condition
The device 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 device will respond with an acknowledge
after the receipt of each subsequent 8-bit word.
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.
In the read mode the device 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 device
will continue to transmit data. If an acknowledge is not
detected, the device will terminate further data trans-
missions. The master must then issue a stop condition
to return the device 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 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.
Figure 3. Acknowledge Response From Receiver
SCL FROM
MASTER
1
8
9
DATA OUTPUT
FROM
TRANSMITTER
DATA
OUTPUT
FROM
RECEIVER
START
ACKNOWLEDGE
7027 FM 05
4
XICOR [ XICOR INC. ]
