Max,

I am presently playing around with the HSP45102 also.  I can make it work
fine with my PC.  I'm using a F84 now and trying to get it to work using the
PIC.  Actually I got frustrated and ordered the Analog Devices AD9835 and
AD9832.  Those chips have built in 10-bit DAC's.  Those chips require 8-bit
x 4 loading to get the 32-bits.

My 45102 has an input buffer on it (74HC245).
The outputs are going to a Harris high speed video D/A (CA3338A),  losing
the lower 4-bits of the word.
It works perfectly all the way up to 10 MHz sine wave via the PC.

The ENPHAC just turns the DDS on/off
The TXFR line changes state when the 32-bit or 64-bit word is loaded.
The LOAD pin 18 just needs to be connected high to +5v. (not floating)

I had trouble with the bit banging on the PIC, the PC works fine.

The sequence of events are located on page 5-50, figure 3 I/O timing.

I would appreciate any info you might have on getting it to work with the
PIC

David



-----Original Message-----
From: Max Prager <mprager@CYLLENE.UWA.EDU.AU>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Wednesday, April 21, 1999 5:28 PM
Subject: HSP45102 Question


> Hi everyone,
>
> I have been playing around with the Harris HSP45102
> DDS chip and I am
> having a little trouble using it. I am assuming the
> serial data is being
> tranfered from the PIC to the DDS OK because of the
> fact that when the
> data is being transmitted, the DDS outputs 'stuff'
> (not even close to a sine wave but is is doing something) and when
> nothing is being
> transfered it outputs nothing. I do not fully
> understand the way the
> registers work in the DDS and cannot find any info on it other than the
>
> data sheet which doent  tell the sequence of events to give me an
> output. I know that the ENPHAC, TXFR and LOAD pins
> play a big part of the operation but are unsure on how to use them in a
>
> proceedure to give me an sine output.
> When I keep them all low it has the above affect and
> when I play around
> with them in my PIC program it usually outputs
> nothing. Does anyone know
> the steps to take to give a sine output on the
> HSP45102.
> Any help will be greatly appreciated
>
> Max
>