X9470 Datasheet, PDF (23/24 Pages) Xicor Inc. – RF Power Amplifier (PA) Bias Controller

Figure 15. Acknowledge Polling Sequence
Byte load completed
by issuing STOP.
Enter ACK Polling
Issue START
Issue Slave
Address Byte
(Read or Write)
ACK
returned?
YES
nonvolatile write
Cycle complete.
Continue command
sequence?
YES
Continue normal
Read or Write
command
sequence
Issue STOP
NO
NO
Issue STOP
X9470
Random Read
Random read operations allows the master to access
any location in the X9470. Prior to issuing the Slave
Address Byte with the R/W bit set to zero, the master
must first perform a “dummy” write operation.
The master issues the start condition and the slave
address byte, receives an acknowledge, then issues
the word address bytes. After acknowledging receipt
of each word address byte, the master immediately
issues another start condition and the slave address
byte with the R/W bit set to one. This is followed by an
acknowledge from the device and then by the eight bit
data word. The master terminates the read operation
by not responding with an acknowledge and then issu-
ing a stop condition. Refer to Figure 13 for the
address, acknowledge, and data transfer sequence.
In a similar operation called “Set Current Address,” the
device sets the address if a stop is issued instead of
the second start shown in Figure 14. The X9470 then
goes into standby mode after the stop and all bus
activity will be ignored until a start is detected. This
operation loads the new address into the address
counter. The next Current Address Read operation will
read from the newly loaded address. This operation
could be useful if the master knows the next address it
needs to read, but is not ready for the data.
PROCEED
It should be noted that the ninth clock cycle of the read
operation is not a “don’t care.” To terminate a read
operation, the master must either issue a stop condi-
tion during the ninth cycle or hold SDA HIGH during
the ninth clock cycle and then issue a stop condition.
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FN8204.0
March 8, 2005