fx2lib-devel

[Fx2lib-devel] Generating a clock with the GPIF

[John S. <joh...@go...>]

Hi All,

I am new to the FX2 and I want to use it to interface a CMOS imager. For
this I am wondering if it is possible to generate a clock for the image
sensor with the FX2 also. Has anybody an idea whether this might be
possible? I know I could use a programmable clock chip for this but space on
the image board is very restricted so I would be happy if I could do
without.


Thanks!

Re: [Fx2lib-devel] Generating a clock with the GPIF

[Dennis M. <de...@ub...>]

The FX2 has an interface clock pin that you can drive at either 30 or  
48mhz with the FX2.  The GPIF can drive this pin or it can listen to  
an external clock on the same pin to communicate between it and an  
external device.  If 30 or 48mhz is fine for your external imager then  
I don't see you having any problem without a separate device to  
generate a clock.

-Dennis

On Mar 21, 2009, at 4:42 AM, John Smithee wrote:

> Hi All,
>
> I am new to the FX2 and I want to use it to interface a CMOS imager.  
> For this I am wondering if it is possible to generate a clock for  
> the image sensor with the FX2 also. Has anybody an idea whether this  
> might be possible? I know I could use a programmable clock chip for  
> this but space on the image board is very restricted so I would be  
> happy if I could do without.
>
>
> Thanks!
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Re: [Fx2lib-devel] Generating a clock with the GPIF

[Eric W. <er...@wi...>]

There is no good way to make a programmable high frequency clock on the 
FX2.  You can make a low frequency clock using an internal timer driving 
a GPIO pin.  You will be limited to a resolution of 4 or 12 FX2 CPU 
clock cycle periods.  Any thing high frequency will have the CPU always 
servicing the timer interrupt.  I would not do this for any thing beyond 
audio frequencies.  Why not just use a small clock oscillator.  The size 
would likely be a fraction of the imager size.

Eric Winsor

John Smithee wrote:
> Hi All,
>
> I am new to the FX2 and I want to use it to interface a CMOS imager. 
> For this I am wondering if it is possible to generate a clock for the 
> image sensor with the FX2 also. Has anybody an idea whether this might 
> be possible? I know I could use a programmable clock chip for this but 
> space on the image board is very restricted so I would be happy if I 
> could do without.
>
>
> Thanks!
> ------------------------------------------------------------------------
>
> ------------------------------------------------------------------------------
> Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
> powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
> easily build your RIAs with Flex Builder, the Eclipse(TM)based development
> software that enables intelligent coding and step-through debugging.
> Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
> ------------------------------------------------------------------------
>
> _______________________________________________
> Fx2lib-devel mailing list
> Fx2...@li...
> https://lists.sourceforge.net/lists/listinfo/fx2lib-devel
>   

Re: [Fx2lib-devel] Generating a clock with the GPIF

[John S. <joh...@go...>]

To support different frame rates, I thought I would need a variable clock.
But probably adding blanking times to the lines will give me enough
flexibility to the frame rate so I can go with a single oscillator.

But I am curious: Wouldn't it be possible to create a waveform that
generates a high frequency clock?


On Sun, Mar 22, 2009 at 6:20 PM, Eric Winsor <er...@wi...> wrote:

> There is no good way to make a programmable high frequency clock on the
> FX2.  You can make a low frequency clock using an internal timer driving
> a GPIO pin.  You will be limited to a resolution of 4 or 12 FX2 CPU
> clock cycle periods.  Any thing high frequency will have the CPU always
> servicing the timer interrupt.  I would not do this for any thing beyond
> audio frequencies.  Why not just use a small clock oscillator.  The size
> would likely be a fraction of the imager size.
>
> Eric Winsor
>
>
>

Re: [Fx2lib-devel] Generating a clock with the GPIF

[Eric W. <er...@wi...>]

Yes I think that the GPIF could generate a high frequency clock.  You 
could even use the RDY0/1 pins to make is programmable, say 4 different 
frequencies.  This would however be limited to less than the FX2 CPU 
clock.  The single frequency clock and adjusting the blanking time seems 
like the better solution to me.

Eric Winsor

John Smithee wrote:
> To support different frame rates, I thought I would need a variable 
> clock. But probably adding blanking times to the lines will give me 
> enough flexibility to the frame rate so I can go with a single 
> oscillator.
>
> But I am curious: Wouldn't it be possible to create a waveform that 
> generates a high frequency clock?
>
>
> On Sun, Mar 22, 2009 at 6:20 PM, Eric Winsor <er...@wi... 
> <mailto:er...@wi...>> wrote:
>
>     There is no good way to make a programmable high frequency clock
>     on the
>     FX2.  You can make a low frequency clock using an internal timer
>     driving
>     a GPIO pin.  You will be limited to a resolution of 4 or 12 FX2 CPU
>     clock cycle periods.  Any thing high frequency will have the CPU
>     always
>     servicing the timer interrupt.  I would not do this for any thing
>     beyond
>     audio frequencies.  Why not just use a small clock oscillator.
>      The size
>     would likely be a fraction of the imager size.
>
>     Eric Winsor
>
>
>
> ------------------------------------------------------------------------
>
> ------------------------------------------------------------------------------
> Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
> powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
> easily build your RIAs with Flex Builder, the Eclipse(TM)based development
> software that enables intelligent coding and step-through debugging.
> Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
> ------------------------------------------------------------------------
>
> _______________________________________________
> Fx2lib-devel mailing list
> Fx2...@li...
> https://lists.sourceforge.net/lists/listinfo/fx2lib-devel
>