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Auto clear sweep and phase accumulators

Question asked by Vladib on Apr 6, 2011
Latest reply on May 9, 2011 by DSB



I'm a little confused in the use of  the auto clear phase accumulator 
and auto clear sweep accumulator bits.


A have few questions about this:


1.What is difference in the use of bits  FR[12..15] and CRF[0..3]

and how  to  set these bits in the  frequency sweep mode for one channel.


2. From the data sheet of AD9958/59 it follows that:  "The automatic clearing function is
repeated for every subsequent I/O update or change in profile pins until the clear and release bits are reset
I/O update or change in profile pins  via the serial port" (page 27).


It is not clear what kind of change in a profile pin have in mind.
For example consider "LINEAR SWEEP MODE ENABLE—NO-DWELL BIT SET" (Fig 38).

The signal P2 on profile pin changed twice during the sweep interval -  (at point A, he rises and between points A and B, it falls).
It is logical to assume that clearing takes place only on the rising edge, but I would like to know exactly.


3. In the  frequency sweep mode I use I/O update within sweep interval to change signal amplitude.

   Does this mean that the phase accumulator (or sweep accumulator) will be immediately cleared?


Many thanks for your advice.