I would like to have a sequence of FTWs in RAM and step through them using a somewhat asynchronous external trigger in a manner similar to how IO_UPDATE writes internal buffer memory contents to actual control registers. It appears as if the only automated sequencing through RAM is effected at a constant rate defined in the RAM profile control words. "Direct Switch" mode says (datasheet p. 16) the no sweeping occurs which I take to mean no advance through RAM between a start address and a finish address regardless of the stepping mechanism. I read the thread at AD9954 which references the example of datasheet p. 22 for the writing of a block of RAM in preparation for an automatically paced "Ramp Up" mode operation.
So is there any mechanism for "manually" advancing through a block of FTWs in RAM based on an external trigger event?