Ridiculous TV Board venture FAIL: The Prequel

A project log for Ridiculous [LCD] Display Hacks

What more can I say?

Eric HertzEric Hertz 11/05/2015 at 04:560 Comments

Crazy ramblings written prior to the decision to take on the Ridiculous TV-Board Venture [FAIL] in the previous log...

Yesterday: pulled apart three LCD displays in an attempt to fight through brain-mush, didn't work, and ended up with a bunch of precariously-placed piles of parts that needed to be put back together before the cat got to 'em. Though, discovered that the one 15inch VGA display that had parallel signals was, in fact, dual-pixel. Which I should've remembered, since I designed an AVR circuit for it a couple/few years back that ended up being the basis for one of my longer-running and most highly-developed projects.

Thought maybe that display's housing could house the dual-pixel LVDS display's screen; since this housing has speakers, it'd be better-suited for the TV-board... But the screens' mountings were not at all the same dimensions, and the LVDS screen was actually larger than the spacing of the speakers. So, nogo.

So, now... Decided it was a sure-sign I should make use of my old Single-To-Dual-Pixel-Converter project... the one I had hanging on the wall. Traced out the display's pinouts (CCFL inverter, as well as the LVDS signals/power)... Went to grab the converter off the wall... and sure-enough two rather important wires are dangling, pins ripped from the chip. Alright, that was the prototype, I had another on a PCB that was functional at one point... couldn't remember why I went-about making the third circuit (second PCB) except that I did a better job of it and managed to squeeze out a couple more MHz for a higher refresh. So, that first PCB may be an option... And there it is dangling off the original deadbugged prototype (how'd I miss that?). And despite being soldered on a PCB, somehow it seems I managed to rip a couple pins out of the TQFP... Again, a couple *important* pins. So that one's a nogo, as well. Just art, at this point.

So, where're we at...?

Dug through all my (relatively-recently-acquired) parts supplies, don't have any more of either of those chips (though I do have a couple bare boards, I think). I do have *other* chips, which... well, no, they wouldn't work on that PCB at all... And switching from single-pixel to two single-pixel transmitters in dual-pixel mode, well, it may not really be that conceptually-difficult... What, maybe just a clock-divider and inverter? Oddly, the LVDS-display's VGA-converter circuitry uses a bunch of 74x574's (latches)... maybe that's necessary... A conceptual challenge that might be interesting, anyhow. But I don't have any... what're those chips, they're TQFP spacing, but two rows, rather'n square... SOIC? Anyways, no breakout boards for 'em, and while I might be willing to cut up one TQFP breakout board for One of these chips, I don't, currently anyhow, have the patience to do *three* of them. So, there's that.

Then... Well, it occurred to me...

That video-card I'd been fighting with, to get multimonitors... The ridiculous endeavor that was... wherein a year ago I made an adapter to make that special monitor work with a regular video card... and then this year decided to use this specialized video-card (made to work with that monitor) work with a regular-old monitor... Yeah, that video card...

Well, now that *that* video card has been hacked-apart for that monitor's adapter, there's... low-and-behold... a single-pixel-parallel-input to dual-pixel-LVDS-output daughter-board sitting 'round doing nothing... Nicely, it's made of standard parts I can easily figure out the 24-bit input pinout... So now all's I need is a single LVDS->Parallel adapter chip, preferably on a board... could use one of those cut-TQFP breakouts...

And then...

Wait, lest I forget again, part of this was leading to... Duh, there's the single-to-dual converter that I was using in my old laptop, which... well, I'll come back to that.

So, there's the old specialized video card's uber-special daughter-board that does basically what one chip on my single-to-dual-conveter did, which I could rebuild if I just had the chips (and I could probably order samples, after all). But then...

What if I want to use this specialized daughter-board with something else...? Maybe I'll put it *back* in the specialized-video-card so I can drive my old/dead laptop's screen with the wacom attached behind it, so I can finally get to some gimping...

So, spent a bit trying to figure out if this specialized video card I fought for days getting working alongside my built-in video card could handle dual-head configuration, separate images on the VGA and LVDS outputs... (and, if it does, does it support other resolutions on the LVDS-output than the one it was designed for?)...

Anyways, no dual-head. But in the process of trying to find that out, was reminded of my Matrox card which I tried to do multimonitors with first, which didn't work, but wasn't *really* tried before I remembered this one... so then had the brilliant idea of trying to put the "specialized" video-card's daughter-board into a normal-old Matrox card which just happens to have a daughter-board upgrade option (which I don't have) for DVI. Which, most-likely, takes 24bit parallel RGB, which is the input of this daughter-board.

Whew... So... At this point, we've got:

Video Card A was designed to work with Monitor A
Monitor A has been adapted to work with Video Card X (any with VGA) at the expense of Video Card A's specialized circuitry which enabled it to work with Monitor A in the first place.

Video Card A has been repurposed as a regular-ol' (VGA) video card, and is now connected to Monitor B (a regular ol VGA monitor).

Video Card B is a regular old video card (VGA) that could potentially be wired-up with Video Card A's parts to become.... a lesser version of Video Card A's original specialty.

Do I have this right?

Wait, and where's this leave us...?

Oh, so then Video Card B, which is now basically just like Video Card A was, could be used to drive my old laptop's display as a graphics-tablet. OK. Whwew.

"Why don't you just..." OMG WHY. DON'T. I. JUST.

Alright, I think I could wrap my head around readapting Video Card A back to its original purpose *IF* it can drive my graphics-tablet... BUT it might be specially-designed for 1600x1024, whereas the graphics tablet's screen is 1440x1050... MAYBE it reads the EDID, but maybe not... because, what makes it special, is that it has a BIOS-hack to allow for the screen's native resolution (1600x1024 is the only screen that ever used that connector) in various modes (e.g. text mode, or scaling for lower resolutions). So, there's that.

Where's this leaving us...

I went to tremendous effort to get that specialized 1600x1024 (ONLY) display working via a custom adapter with regular-ol'-VGA, so it'll work in text-mode, etc... and, more importantly, not be limited to just one computer (could, now, work with any computer with VGA, through a KVM, etc.). But, now, I have a regular-ol display that could do the same (only slightly smaller resolution, 1280x1024), so I guess, really, I needn't *keep* this special display generic... could put back together the specialized video card, and everything'd be back to normal, right...?

Wait, there's the graphics tablet, which still needs... bah, the VGA converter I hacked for the 1600x1024 display would probably work just great with 1440x1050, huh.

Yeah, I just can't wrap my head around taking that thing apart. But, again, I could buy a new one for not too much money... and it wouldn't even need to be hacked... but I don't have "not too much money" so there's that.

Alright. Where are we...?

I ain't changing Monitor A, nor its converter, dammit! If nothing else, it'll still be usable when Video Card A is no longer supported (which it already appears to be being phased out, judging by how much effort I had to go through to get it to work on my system). OK, that's settled.

That leaves us with:

I don't have a vid-card with DVI, so I can't use my already-built DVI->dual-pixel-LVDS converter...

(but that *does* have a single-pixel parallel to dual-pixel LVDS chip in it, and it's not *difficult* to remove... but I have this single-pixel-parallel to dual-pixel LVDS daughter-board which isn't being used... oy.)

Where are we now?

Graphics tablet...

Why don't I just fix my old friggin' laptop...? It'd be nice to sit on the couch again. Sheesh.

Graphics tablet...

If I went that route... The friggin' screen ALREADY HAS the Latest Functional Single-To-Dual LVDS converter attached to it, that was the whole reason I built the dang thing.

But, if I connect the "dang thing" to my desktop... I need to make a friggin' list, or a chart, or something... this is getting ridiculous. No, it was ridiculous when I started, it's ridiculously ridiculous. "Ridonkulous"

Alright, to connect the graphics tablet to the desktop: Either the desktop needs to output LVDS (single or dual-pixel, depending on whether I use the converter), or the display needs a VGA converter (which is currently hacked to drive Monitor A). Or I need a video card with DVI and use my DVI->LVDS converter...

The LVDS method can be accomplished with Video Card A's original daughter-board, plausibly attached to Video Card A. If not there, then in Video Card B, with a nice ol' hack-job. OK.

The VGA method I can't afford. (I ain't scrapping Monitor A's converter!)

The DVI method I can't afford.

That leaves...

Why don't I just fix up my old laptop...?

OK, the LVDS method...

If I use Video Card A's daughter-board (or take apart my DVI->LVDS converter), AND [[Video Card A works with different resolutions] OR [Video Card B can be gotten working with it and multimonitor support]]. Then, I have dual-pixel-LVDS output, which will work directly with the graphics tablet's display... no need for the single-to-dual LVDS converter I originally built for it.

THAT LEAVES the single-to-dual LVDS converter for my TV-board to drive my dual-pixel 15inch LVDS desktop monitor.


OR if I fix up my laptop, then I'll *definitely* want to keep the single-to-dual-pixel converter in it...

The graphics-tablet idea would be nogo, but I could implement that *in* the laptop, as was the original plan (and mostly accomplished), and could probably even use something like VLC, VPN, no, what was that thing... whatever, could probably use a remote-desktop type protocol to use the laptop as a graphics tablet for my desktop, if I wanted. (VNC!) So there's that.

I'd *certainly* be more comfortable writing something like this if I had my feet up on the coffee table, instead of sitting at a desk.

So, then, the "TV-board" idea still requires single-to-dual conversion...

Oh, and the graphics-tablet idea *not* being driven via the desktop with LVDS makes for no need for ... ugh.

Or I could put the graphics tablet's digitizer behind a 1024x768 display, instead... those're single-pixel LVDS, which could easily be driven by one of those cheap ol' VGA-LVDS converters. But if I'm putting money into this (which I don't have) then I might as well up it a few bucks and get another 1440x1050 display (nevermind all this ordeal would be unnecessary). But, anyways, that'd otherwise require LVDS output from my desktop, which could necessitate either single or dual-pixel depending on the display, which my DVI->LVDS converter could handle switching between...

AND HERE is where we come to one of my project-ideas of a while-back, the whole point of standardizing on a couple "IDE-Cable" pinouts for LVDS and parallel-RGB, the idea of easily-swappable and adaptable converters between various video-formats... even have half-finished PCB designs laid-out.

Anyways, my old laptop *does* have DVI, which is why I built the DVI-to-LVDS adapter... and having the graphics-tablet screen be *separate* from the main screen is kinda nice (penning on a laptop's hinge is kinda wonkey).

Wherein I'm completely exhausted, and didn't come to any conclusions about which path to take.

Kinda just want to put my feet up... but feel like I need to see *something* working, or I won't really be able to relax.

Hope it's as funny to read as it was to write, anyhow.

Oh right! I've got a fully-functional Single-to-dual LVDS converter in my dead laptop... No reason I couldn't repurpose it "temporarily"... hmm... Could even attempt laptop-repairs with an old screen that doesn't require the converter...