This post is off topic but I'll answer it anyway.

Since you only get 8-12 outputs on that port, you aren't going to be
able to drive your DDS without some interface logic. Consider using a
shift register, either bit, or nibble wide, to prepare your inputs
before strobing the data into chip. You can ignore the phase
registers, I've never had a use for them. You need both freq
registers to set the phase progression with the full resolution of the
part.

Keep in mind you're also probably going to need an anti-alias filter
on the output to get rid of all those harmonics depending on your
application of course. Mini-Circuits has some canned solutions that
will save you a lot of time as far as the filter is concered.

Please post your electronics related questions to an electronics
group.

Regards


wrote in message . com...
hi
i have read ad9830 dds ic datasheet, but i have steel problem how i
should program it, for example i want to use pararel port for
interfacing , and for example want 3.1MHZ on out put, how i should
use D0 to D15 and A0,A1,A2? should i use both freq reg ( 0,1) and
all 4 phase reg ? or one is enouth?
any help would be most appreciated
thanks
payam