I've been using the AD9910 with parallel port control of the frequency for over a year. It works nicely.
Now I have the need for phase control via the parallel port. Sounds like an easy change right?
Just change FUNC[1:0] from 10 to 01.
Well, whenever I try to run the AD9910 with FUNC configured for phase I get no output at all from the DDS.
Nada. Zero. Bupkiss.
Is there some register configuration that I need to do that is unique to phase control?
I have been setting the FTW and enabling the parallel port with "data assembler hold last value"=1
and using TXE as a gate.
Any suggestions as to where to start debugging this?