VGA and PAL output from FPGA

I'm after a bit of advice on selecting some parts for a 'hobbyist' project which may eventually turn into a commercial product...

I'm developing a board with an FPGA which will produce RGB digital output ultimately for display on RGB (15kHz), VGA and PAL/NTSC composite video. Not necessarily simultaneously - worst case is a different FPGA image for the former two options.

I've some experience with generating monochrome CVBS and VGA output from an FPGA, so I believe I have a handle on the technical aspects. But I'd like to offload much of the work (especially the PAL) to COTS parts, and this is where I don't have much experience.

First of all, is there a single encoder chip that is capable of outputing *both* RGB (15kHz and VGA) and PAL/NTSC (again, not necessarily at the same time)? For example, an RGB->PAL encoder with a 'pass-thru' mode (which basically acts like a video DAC).

Failing that, I'm looking at the Chrontel CH7003 and Averlogic AL100/128 PAL encoders to do half the job. I'm hoping that they are capable of running in slave mode (they accept the pixel clock) in some funky resolutions approximating but not equal to 'standard' VGA (horizontal) resolutions?

I'd complement that with a simple triple video DAC (like the ADV7125 used on the Xilinx dev boards) for RGB (15kHz) and VGA outputs.

In either case/mode, I'd be doing the video timing (except for PAL output) in the FPGA and so supplying the pixel clock and syncs etc to the devices (they're slaves). Different FPGA images might run at different resolutions, some may target 15kHz monitors whilst others may target VGA, etc, hence the 'flexible' requirements.

As far as my approach to the problem is concerned, am I on the right track here? Did I choose the best/cheapest/easiest-to-get parts? Or is there a better/simpler/cheaper way to do it?

Keep in mind that it is only a spare-time project atm and although I'm willing to make some investment, obviously I'll only be ordering and manufacturing in very small quantities at this point. At best you could consider it a 'niche' product so even if I did eventually realise a commercial product, it would still be low volume.

TIA for any help/hints/suggestions!

Regards, Mark

Reply to
Mark McDougall
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"Mark McDougall" schrieb im Newsbeitrag news:434d17b6$0$16843$ snipped-for-privacy@per-qv1-newsreader-01.iinet.net.au...

CH7003 can do PAL, NTSC and VGA check out the datasheet its not clear if the VGA mode with CH7003 can accept any format but a lot of formats are supported so if you are happy with them then CH7003 can do it all.

or check ADI

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video encoders, they most do either pal/secam or pure RGB dac

sure make sure you select a component that you actually can purchase, ADI can send free samples, with Chrontel check availability in sample qty Antti

Reply to
Antti Lukats

Philips do some video encoders that may be worth a look - e.g. SAA7126 I think there are a few varients in the range - often used in set-top boxes so should be fairly cheap, and you may be able to scavenge some samples from dead boxes. For VGA, if you only need TV resolution you may be able to do some tricks, e.g. generating vga sync while feeding suitably tweaked fake ccir sync to the encoder.

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Mike Harrison

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Reply to
koko

hmm Motorola MC1377P for example, its only PAL color encoder, any will do

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Reply to
koko

Thanks, but it uses the CXA1645, which converts analogue RGB.

I have raw *digital* RGB output from an FPGA, which I want to convert to analogue RGB (15kHz), VGA, and composite (not necessarily at the same time).

I'm favouring a triple video DAC for RGB & VGA atm (ADVXXX), and encoder for composite/s-video (like the CH7003), both driven off the FPGA output. Timing is generated in the FPGA (mainly to enable time-sliced access to some SRAM, so the pixel clock will be some synchronous dividend of the main FPGA system clock), and the encoder will be a slave.

Regards, Mark

Reply to
Mark McDougall

They all seem to be YUV inputs. I haven't considered what that would require in the FPGA. I understand it's not too difficult to transform (digital) RGB to YUV? Any comments?

Regards, Mark

Reply to
Mark McDougall

sory, I hit reply after reading 2 first lines, my bad :(

all that comes to my mind is MC1377P, LM1889, TEA2000 (can you say dinosaur? 85 was a good year). I did few circuits with the first one and they worked reasonably well. But forget about simultaneous PAL/VGA with those.

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hackbox.info

or just output analog VGA from your pcb and cut development/soldering time buying this box

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pinout
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Looks unprofessional, butt ugly, bulky, but only $20 new (free/beer from a friend/ebay), tested and works great. Inside you will find MC13077P, one transistor and RF modulator.

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