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Solved: AD9910 Parallel Port: FM works, PM gives no output

Question asked by DavidLee on Sep 11, 2016
Latest reply on May 10, 2018 by KennyG


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?