Lpc2000

----- Original Message ----- 
From: "microbit" <microbit@...>
To: <lpc2100@yahoogroups.com>
Sent: Wednesday, December 03, 2003 4:00 PM
Subject: Re: [lpc2100] DDS working


> Hi Leon,
>
> > apart from glitches - spurs on the waveforms. I think I had the ~ in the
> > wrong place.
> >
> > I didn't get those glitches with the AVR, using the same DAC. I've got
> some
> > LEDs on some of the lines to the DAC, so I'll try disconnecting them -
> they
>
> I figured it had to do something with the IOCLR write of complemented
> values.
> I think you'll find that the glitches represent the time it takes between
> the IOSET and the IOCLR
> operation to update the I/O (ie. there are a few instructions involved).
>
> The only way probably will be to use a latch, unless your DAC has a
strobe.

The DAC has got a latch, so I can try that.

>
> Tip : Try declaring a long* for IOCLR and one for IOSET, and write to the
> port that way.
> Register move instructions are then generated instead of the LDR, which
> takes less cycles/time.
> If you find the glitches get "narrower", then it's definitely the update
> time between IOSET, and
> writing the complement to IOCLR.

I'll try that.

Thanks,
Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
http://www.geocities.com/leon_heller