X9119_14 Datasheet, PDF (5/17 Pages) Intersil Corporation – Single Digitally-Controlled Potentiometer

X9119
STOP CONDITION
All communications must be terminated by a stop condition,
which is a LOW to HIGH transition of SDA while SCL is
HIGH (see Figure 3).
ACKNOWLEDGE
Acknowledge is a software convention used to provide a
positive handshake between the master and slave devices
on the bus to indicate the successful receipt of data. The
transmitting device, either the master or the slave, will
release the SDA bus after transmitting eight bits. The master
generates a ninth clock cycle and during this period the
receiver pulls the SDA line LOW to acknowledge that it
successfully received the eight bits of data.
The X9119 will respond with an acknowledge after
recognition of a start condition and its slave address and
once again after successful receipt of the command byte. If
the command is followed by a data byte the X9119 will
respond with a final acknowledge (see Figure 2).
SCL FROM
MASTER
1
8
9
DATA OUTPUT
FROM TRANSMITTER
DATA OUTPUT
FROM RECEIVER
ST AR T
FIGURE 2. ACKNOWLEDGE RESPONSE FROM RECEIVER
ACKNO WLEDGE
ACKNOWLEDGE POLLING
The disabling of the inputs, during the internal nonvolatile
write operation, can be used to take advantage of the typical
5ms EEPROM write cycle time. Once the stop condition is
issued to indicate the end of the nonvolatile write command
the X9119 initiates the internal write cycle. ACK polling,
Flow 1, can be initiated immediately. This involves issuing
the start condition followed by the device slave address. If
the X9119 is still busy with the write operation, no ACK will
be returned. If the X9119 has completed the write operation,
an ACK will be returned and the master can then proceed
with the next operation.
FLOW 1. ACK Polling Sequence
NONVOLATILE WRITE
COMMAND COMPLETED
ENTERACK POLLING
ISSUE
START
ISSUE SLAVE
ADDRESS
ISSUE STOP
ACK
NO
RETURNED?
YES
FURTHER
NO
OPERATION?
YES
ISSUE
INSTRUCTION
ISSUE STOP
PROCEED
PROCEED
5
FN8162.4
July 9, 2008