Re: AD9914: profile mode vs single-tone vs parallel port modulation

sittie aisha magayo-ong wrote:

 

Hi,

After the basic steps, have you then tried changing:

1. F[3:0]=0100
2. define POW and AMP accordingly to the 32-bit parallel port.
3. IOUPDATE = 3.3V

 

and see if that changes the phase offset and amplitude of the 1.75GHz signal.

Sittie -

Yes I have tried this procedure.  It does not work.  There is no output after the F[] pins change - the frequency (or amplitude) is zero.

However, if I first set F[3:0] = 2; Set PD=frequency tuning word; Set IOUPDATE=high; THEN the procedure you described works.  In other words, in the parallel port modulation mode, it seems that the source of FTW is different than in the single-tone mode. 

Carl