Need Propeller programmer to change VGA Output to PAL

AG_Milcots

My company wishes to create a device identical to the Hobbytronics serial to VGA converter (http://www.hobbytronics.co.uk/serial-vga) except output PAL instead of VGA to integrate into our products (only). Hobbytronics indicated their design and code are open and we can use it for this purpose. It looks like this change can be done by modifying the VGA High-Res Text Driver by Chip Gracey to output PAL. Its likely not easy as Chip is clearly a genius. Please contact me if you are qualified and interested in this (paid) work or just have some good advice.

Mike Green

PAL (and NTSC) is not capable of handling the same resolution as VGA and the way the timing is handled is very different. I would suggest first looking at the various video text drivers in the Propeller Object Exchange for ideas of what's doable. What sort of line width and number of lines do you need? What sort of color control do you need? Remember that video is partially limited in bandwidth by the color subcarrier. You'll get higher resolution if you use black & white.

Coley

I would contact @Baggers, he is more than qualified and works as a contract programmer.
IMO he is probably the best qualified person to handle this particular task.

AG_Milcots

Mike, PAL Output needed for Composite and S-Video for the video controller we are using is 720 × 576, 50 Hz interlaced, 15.6KHz Hor. The VGA unit works at 800x600 output (75Hz) so we won't be loosing too much resolution. Black and White or Green like a BIOS screen is what we are after.

Coley I'll try to contact Baggers, thanks.

Brian Fairchild

Using PAL you will not be able to display 720 pixels horizontally. There are three problems...

1) PAL, at that resolution, uses a 13.5MHz pixel clock. The active line width of PAL is 52us which limits you to 704 pixels wide.

2) The bandwidth of a PAL signal is limited to 6MHz which will severely affect your horizontal resolution. Also, sitting at 4.43361875MHz you have the colour subcarrier which, if you are unlucky, will alias quite nicely with your pixel data.

3) The Propeller is not able to generate PAL. It can manage something which is like PAL, but it isn't PAL. Many displays will render it OK but with some artifacts. The problem is that it can't generate the 4.43361875MHz subcarrier accurately.

Brian Fairchild

(pressed POST too soon)

720 pixel wide text implies around 90 characters per line. Such text would be unreadable on any TV fed with composite video.

Coley

I'm fairly certain we did a PAL version of this at 720x576 resolution but here is the NTSC version for your amusement

AG_Milcots

We manufacture displays with built in video controller's that are very much like an off the shelf computer display but for rugged applications. In addition to HDMI, DVI and VGA they also have (typically) S-Video and composite inputs capable of receiving 720 × 576, 50 Hz interlaced, 15.6KHz Hor. which are rarely used by the customer. We want to provide a BIOS like screen so our customers can see the status of their display (internal temperatures, etc.) using the (free) PAL S-Video input. Since our customers typically use the VGA input we can't use the Hobbytronics unit. I was hoping to do the same thing using the PAL input.

I'm encouraged by a post by bagger (which I can't find, but have the location of the file: http://forums.parallax.com/uploads/attachments/49190/97803.zip) which looks like he got PAL images perfect.

Coley

That was for P2 HOT FPGA image on the DE2-115 board, sadly not for Propeller V1

Baggers

Yeah, that was P2 HOT, for the Propeller V2, What exactly is it you're wanting?
PS, I've not seen an email or anything from you as of yet.

AG_Milcots

Sorry, I'm not sure why the message didn't get to you.
We manufacture displays with built in video controller's that are very much like an off the shelf computer display but for rugged applications. In addition to HDMI, DVI and VGA they also have (typically) PAL S-Video and composite inputs capable of receiving 720 × 576, 50 Hz interlaced, 15.6KHz Hor. which are rarely used by the customer. We want to provide a BIOS like screen (see attached) so our customers can see the status of their display (internal temperatures, etc.) using the (unused) PAL S-Video input. Since our customers typically use the VGA input we can't use the really nice Hobbytronics unit (http://www.hobbytronics.co.uk/serial-vga). To me it looked like the best way to do this was to use the (open) Hobbytronics firmware and "just" modify the VGA driver its uses written by Chip Gracey to a PAL driver. It seems this isn't so simple after all, but thought it would be better than creating a FPGA. There are some older single chip solutions, but they are end of life. We need something that will be available for 5-7 years. If you are interested in this (paid) work, please let me know. Thanks.

Cluso99

PM sent

ericball

Or just use: http://forums.parallax.com/discussion/114343/one-pin-tv-text-driver

Eric

Bean

Black and white PAL is pretty easy. It is the color that is hard (I think PAL has the colorburst 180 degrees out for each line or something like that).

Bean