Interfacing SAA7103 encoder with PXA255 board running windows CE

Hi all,

I have an Intel PXA255-based board running Windows CE. I have been
asked to generate NTSC TV output from this board. For this I have been
asked to use Philips SAA7103 encoder.
According to the datasheet, the SAA7103 is capable of converting
Digital RGB signals into NTSC or PAL output.
As the Windows CE BSP that I am using already has a Display driver
which is meant for LCD displays directly connected to PXA255, I would
prefer to tweak the existing driver just enough to drive the Philips
encoder. How easy would it be? What are the things I should watch out
for.
For the record, the LCLK of PXA255 is 100MHz and the display resolution
640x480 @ 8bits per pixel.

I believe the primary issue is interfacing PXA255 with SAA7103,
therefore I am asking this question here (Instead of WinCE newsgroups).

Thanks,
Vishveshwar

"vishveshwar" <vishveshwarbhat@aim.com> wrote in message 
news:1159930782.751042.74210@e3g2000cwe.googlegroups.com...
> Hi all,
>
> I have an Intel PXA255-based board running Windows CE. I have been
> asked to generate NTSC TV output from this board. For this I have been
> asked to use Philips SAA7103 encoder.
> According to the datasheet, the SAA7103 is capable of converting
> Digital RGB signals into NTSC or PAL output.
> As the Windows CE BSP that I am using already has a Display driver
> which is meant for LCD displays directly connected to PXA255, I would
> prefer to tweak the existing driver just enough to drive the Philips
> encoder. How easy would it be? What are the things I should watch out
> for.
> For the record, the LCLK of PXA255 is 100MHz and the display resolution
> 640x480 @ 8bits per pixel.
>
> I believe the primary issue is interfacing PXA255 with SAA7103,
> therefore I am asking this question here (Instead of WinCE newsgroups).
>
> Thanks,
> Vishveshwar
>

I don't think that it is that easy. That board puts out what is effectively 
VGA which is not interlaced and double the line rate of NTSC. Your pixels 
will arrive in the wrong order at the wrong rate. I doubt that you will be 
able to tweak the display drivers to change it. So you are going to need to 
grab the frame and scan convert it. For NTSC it will be hard, for PAL even 
harder. I'd just buy an external scan converter.

Peter 

Peter wrote:
> "vishveshwar" <vishveshwarbhat@aim.com> wrote in message
> news:1159930782.751042.74210@e3g2000cwe.googlegroups.com...
> > Hi all,
> >
> > I have an Intel PXA255-based board running Windows CE. I have been
> > asked to generate NTSC TV output from this board. For this I have been
> > asked to use Philips SAA7103 encoder.
> > According to the datasheet, the SAA7103 is capable of converting
> > Digital RGB signals into NTSC or PAL output.
> > As the Windows CE BSP that I am using already has a Display driver
> > which is meant for LCD displays directly connected to PXA255, I would
> > prefer to tweak the existing driver just enough to drive the Philips
> > encoder. How easy would it be? What are the things I should watch out
> > for.
> > For the record, the LCLK of PXA255 is 100MHz and the display resolution
> > 640x480 @ 8bits per pixel.
> >
> > I believe the primary issue is interfacing PXA255 with SAA7103,
> > therefore I am asking this question here (Instead of WinCE newsgroups).
> >
> > Thanks,
> > Vishveshwar
> >
>
> I don't think that it is that easy. That board puts out what is effectively
> VGA which is not interlaced and double the line rate of NTSC. Your pixels
> will arrive in the wrong order at the wrong rate. I doubt that you will be
> able to tweak the display drivers to change it. So you are going to need to
> grab the frame and scan convert it. For NTSC it will be hard, for PAL even
> harder. I'd just buy an external scan converter.
>
> Peter

The SAA7103 encoder chip is supposed to convert non-interlaced VGA
output to PAL/NTSC.
Anyway, I have been able to slap together some code to program the
encoder from within the display driver. Now I have a very unstable NTSC
video available. I can see the WinCE desktop and can move around but
the display shakes violently everytime something happens.
I have currently programmed the encoder as per the
calculations/formulae given in the SAA7103 datasheet (available at:
http://www.semiconductors.com/pip/SAA7103.html) However, since I do not
have much experience with display/video programming, I do not know how
to proceed.

Vishveshwar

vishveshwar wrote:
> Peter wrote:
> > "vishveshwar" <vishveshwarbhat@aim.com> wrote in message
> > news:1159930782.751042.74210@e3g2000cwe.googlegroups.com...
> > > Hi all,
> > >
> > > I have an Intel PXA255-based board running Windows CE. I have been
> > > asked to generate NTSC TV output from this board. For this I have been
> > > asked to use Philips SAA7103 encoder.
> > > According to the datasheet, the SAA7103 is capable of converting
> > > Digital RGB signals into NTSC or PAL output.
> > > As the Windows CE BSP that I am using already has a Display driver
> > > which is meant for LCD displays directly connected to PXA255, I would
> > > prefer to tweak the existing driver just enough to drive the Philips
> > > encoder. How easy would it be? What are the things I should watch out
> > > for.
> > > For the record, the LCLK of PXA255 is 100MHz and the display resolution
> > > 640x480 @ 8bits per pixel.
> > >
> > > I believe the primary issue is interfacing PXA255 with SAA7103,
> > > therefore I am asking this question here (Instead of WinCE newsgroups).
> > >
> > > Thanks,
> > > Vishveshwar
> > >
> >
> > I don't think that it is that easy. That board puts out what is effectively
> > VGA which is not interlaced and double the line rate of NTSC. Your pixels
> > will arrive in the wrong order at the wrong rate. I doubt that you will be
> > able to tweak the display drivers to change it. So you are going to need to
> > grab the frame and scan convert it. For NTSC it will be hard, for PAL even
> > harder. I'd just buy an external scan converter.
> >
> > Peter
>
> The SAA7103 encoder chip is supposed to convert non-interlaced VGA
> output to PAL/NTSC.
> Anyway, I have been able to slap together some code to program the
> encoder from within the display driver. Now I have a very unstable NTSC
> video available. I can see the WinCE desktop and can move around but
> the display shakes violently everytime something happens.
> I have currently programmed the encoder as per the
> calculations/formulae given in the SAA7103 datasheet (available at:
> http://www.semiconductors.com/pip/SAA7103.html) However, since I do not
> have much experience with display/video programming, I do not know how
> to proceed.
>
> Vishveshwar

I am using the following settings for the SAA7103 encoder:
Input resolution: 640x480 pixels
Input type: 8-bit indexed colour pixel. (input format 5)
pixel clock: 25MHz (since 25MHz and 12.5MHz were the only possible
valid frequencies)
Encoder Xtal: 27MHz (recommended by philips)

Vishveshwar

>
> The SAA7103 encoder chip is supposed to convert non-interlaced VGA
> output to PAL/NTSC.
> Anyway, I have been able to slap together some code to program the
> encoder from within the display driver. Now I have a very unstable NTSC
> video available. I can see the WinCE desktop and can move around but
> the display shakes violently everytime something happens.
> I have currently programmed the encoder as per the
> calculations/formulae given in the SAA7103 datasheet (available at:
> http://www.semiconductors.com/pip/SAA7103.html) However, since I do not
> have much experience with display/video programming, I do not know how
> to proceed.
>
> Vishveshwar
>

Sorry, I hadn't checked the datasheet. That chip is indeed a video scaler 
and it should do what you want. I'd start off by looking very closely at the 
waveform on a 'scope and see if it matches the ones in these images:

http://www.ntsc-tv.com/images/tv/RS-170A.gif
http://www.ntsc-tv.com/images/tv/sync-wf.gif

There are a lot of settings to check.

Peter 

>
> Sorry, I hadn't checked the datasheet. That chip is indeed a video scaler
> and it should do what you want. I'd start off by looking very closely at the
> waveform on a 'scope and see if it matches the ones in these images:
>
> http://www.ntsc-tv.com/images/tv/RS-170A.gif
> http://www.ntsc-tv.com/images/tv/sync-wf.gif
>
> There are a lot of settings to check.
>
> Peter

Thanks for the pointers. Let's see if I could arrange a 'scope!
Meanwhile, I am checking out the display on a TV tuner card on my PC,
as out here in India we use PAL system for TV. Do you think using a TV
tuner card is a good idea? Will it cover up some deficiencies of the
video output that may be exposed when a real NTSC TV is connected?

Vishveshwar

> Sorry, I hadn't checked the datasheet. That chip is indeed a video scaler
> and it should do what you want. I'd start off by looking very closely at the
> waveform on a 'scope and see if it matches the ones in these images:
>
> http://www.ntsc-tv.com/images/tv/RS-170A.gif
> http://www.ntsc-tv.com/images/tv/sync-wf.gif
>
> There are a lot of settings to check.
>
> Peter

Thanks for the pointers. Let's see if I could arrange a 'scope!

Meanwhile, I am checking out the display on a TV tuner card on my PC,
as out here in India we use PAL system for TV. Do you think using a TV
tuner card is a good idea? Will it cover up some deficiencies of the
video output that may be exposed when a real NTSC TV is connected?

Vishveshwar