Hooking an STE up to a TV: Options?

[ijor]

I had access to a small video generator, where I could set the frequencies to almost any value. I set values per a "simple ST scan doubler". Meaning the original ST settings (both at 50Hz and 60Hz), but doubling the dot clock and horizontal frequency. I tested two CRTs and two LCDs.

 

Both CRTs displayed a perfect picture in both 50Hz and 60Hz.

 

Both LCDs "synced" correctly at 60Hz, but one of them didn't accept the 50Hz signal at all. The display was acceptable but definition was rather poor in all cases. It was obvious that they didn't correctly detect and/or support the ~32 MHz dot clock. For some reason, the best picture was at 50 Hz (on the only LCD monitor that supported it).

[+poobah]

that's some interesting information.

It'd be nice to know more on how the LCD controllers interpret conflicting information in a given signal.

Do you know what controllers are in the LCDs you used? there may be some clues in the datasheets.

 

I'm fairly certain that LCDs (at least here in the states) operate at 60 Hz regardless of the input signal. How they deal with the timing flaws is another matter altogether, though I would guess any modern LCD incorporates some sort of frame buffer to accommodate a wide range of signals.

 

If you get access again, there are some timing sets I'd like you to try (Haven't had time to build up something myself, had the opportunity to go work on an EE master's degree, so I went for it)

Edited February 1, 2009 by poobah

[ijor]

Sorry, no idea about which controllers they used. Btw, doesn't seem to be easy to find datasheets for this type of controllers. I've found a few by NXP and some other major brands, but the technical comprehensive datasheet doesn't seem to be available in their web site. All they have is more a marketing doc with only a brief technical description.

 

Yes, of course that they all have a frame buffer. And yes, I understand that most (if not all) refresh at 60 Hz. That's exactly one of the reasons that they need frame buffers, the other is, of course, for scaling.

 

If you get access again, there are some timing sets I'd like you to try ...

 

Sure. Can't "play" with it every day. But I'll probably have other chances to run additional tests.

[Thorsten Günther]

I had access to a small video generator, where I could set the frequencies to almost any value. I set values per a "simple ST scan doubler". Meaning the original ST settings (both at 50Hz and 60Hz), but doubling the dot clock and horizontal frequency. I tested two CRTs and two LCDs.

 

I don't have the means to do this, but I bought a Toshiba 15V300 LCD TV with VGA input to try it on my ST. This TV set does display all ST modes (ST high through the VGA input only, the other modes as RGB through the SCART connector), but it doesn't like a PAL VCS with NTSC cartridge through RF - the resulting picture is black and white only. My large CRT TV has no problem coping with the strange timing of this combination, though.

 

The only drawback of the Toshiba is that the background pattern of the ST desktop - especially in ST high mode - results in obvious scaling artifacts (vertical black and white lines).

 

Thorsten

[Foster]

Hi poobah.

 

I'm just curious if you've been able to spend any more time with your s-video board. If you have success would you consider making some available for purchase? I know I'd take a few I especially like the idea of having s-video output on 1040's lacking fm.

 

Thanks,

... Steve

[+poobah]

Hi poobah.

 

I'm just curious if you've been able to spend any more time with your s-video board. If you have success would you consider making some available for purchase? I know I'd take a few I especially like the idea of having s-video output on 1040's lacking fm.

 

Thanks,

... Steve

 

Hey Steve,

 

I did a quick layout on protoboard, got it up and running on my 1040STf.

I need to do a proper layout and get some boards made.

I will post here when I have something ready to go.

It may be a few weeks, taking some (more) college classes at the moment, and the homework is really cutting into my atari-time.

[Foster]

That's awesome news! Count me in for a few. Good luck with school.