I also looked at the CCP module and to generate approx 1Mhz  the resolution
would be 2 bits and the PR2 value would be 0 which I am not sure if it is
allowed. The datasheets on the PWM section are as clear as mud when trying
to generate high frequencies.

Maybe someone else could shed some light on this area please.

Thanks

Peter Graham

> -----Original Message-----
> From: Sean H. Breheny [SMTP:shb7@CORNELL.EDU]
> Sent: Thursday, July 22, 1999 3:48 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: Generating clock signal
>
> Hi Peter,
>
> What about using the 16C63's CCP module to generate 50% duty cycle PWM at
> as high a frequency as possible? I am not familiar with the CCP modules,
> so
> I took a quick look at the datasheet. It wasn't obvious to me what the
> maximum frequency is because I can't see where it tells you the minimum
> allowed resolution. It would be great if you could set it to 2 bit
> resolution (and give it either 25% or 75% duty,it might work) or 3 bit
> resolution (and give it 50%). I looks to me as if you could get a few
> 100kHz that way.
>
> Sean
>
>
> At 03:31 PM 7/22/99 +1000, you wrote:
> >I am trying to modify an existing data logger that uses a 16c63 and an
> >AD7890.
> >
> >The ADC needs an external clock signal to do the conversion which at the
> >moment is generated in software on a normal output pin. My problem is
> that
> >because the signal is generated in software I can't do anything during
> that
> >time and I would also like to increase the frequency of the signal to
> reduce
> >the conversion time.
> >
> >The AD7890 has a max frequency of 2.5Mhz and the oscillator driving the
> PIC
> >is at 4.9152Mhz, so I can't use the osc. directly.
> >
> >I would like to have a freq of at least 1Mhz. Am I dreaming or is this
> >possible preferably without external components as there is no room on
> the
> >existing board design.
> >
> >Peter Graham
> >
> >
> >Attachment Converted: "c:\program files\bear
> access\winba\eudora\attach\Generating clock signal"
> >
> |
> | Sean Breheny
> | Amateur Radio Callsign: KA3YXM
> | Electrical Engineering Student
> \--------------=----------------
> Save lives, please look at http://www.all.org
> Personal page: http://www.people.cornell.edu/pages/shb7
> mailto:shb7@cornell.edu ICQ #: 3329174
> ________________________________________________________
> NetZero - We believe in a FREE Internet.  Shouldn't you?
> Get your FREE Internet Access and Email at
> http://www.netzero.net/download/index.html