PDA

View Full Version : Clear PAL50 is finally a reality



Baggers
01-11-2008, 03:58 AM
Hi All,
Full PAL50 finally achieved lol
Can't believe how simple it was after getting PAL60 sorted rofl.
Anyways, enjoy.
the archive is Parallax's graphics demo modified, oh so very slightly in tv.spin, and·I have demo/protoboard setup initially un-block-rem'd Hybrid is in there too,
I've not attached Hydra because the mouse driver is different, but it's easy enough to change.

Enjoy,
Baggers.

again, let me know if it works on all your PAL TV's ( which it should :) )

http://www.propgfx.co.uk/Baggers/Images/Pal50.jpg

Coley
01-11-2008, 04:03 AM
Nice work Baggers, I knew you'd get there in the end!

It works fine on all my PAL tv's (but you already knew that didn't you! lol)

Regards,

Coley

Baggers
01-11-2008, 04:04 AM
Somehow I had an incling it would lol :)

Cheers matey.

Jim.

Mike_GTN
01-11-2008, 05:11 AM
Wow - You've got real PAL coming out of the Propeller? This if so will be the catch of 2008 already.

Regards

Mike.

deSilva
01-11-2008, 05:20 AM
Is this the right TV.SPIN in the ZIP?

Coley
01-11-2008, 05:23 AM
Hi deSilva,

Yes that should be the right one, we have it working here nice and stable

What kind of output are you getting?

Clemens
01-11-2008, 05:31 AM
works absolutely fine on my tv. Again thank you - this should definitely replace the tv.spin in the propeller library for the next version of the propeller tool if nobody experiences any problems.

deSilva
01-11-2008, 05:50 AM
Well it behaved as the original version http://forums.parallax.com/images/smilies/smile.gif I made a lot of tests with changing "lpal" myself - monthes ago - and got more or less unsatisfactory results at all of my 2 monitors and the 600x800 beamer I checked it on. I use NTSC only from that time on.

Apart from the color a main nuissance with PAL is the non-matching number of lines of PAL and of low cost screens, which yields noticeable inferiour results by the skipping of each 5th line. This is most likely different with full blown TV sets, but those are not my output targets http://forums.parallax.com/images/smilies/smile.gif

Coley
01-11-2008, 06:03 AM
It's frustrating for you I'm sure but we are keen to get PAL 50 usable on as many different display types as we can.
I have some small LCD monitors (5 & 7 Inches) at work, I will try them tomorrow and post the results.

Regards,

Coley

Baggers
01-11-2008, 06:06 AM
Cheers guys, thanks for all your feedback so far, any more PAL users please reply also, as I'd like this test to be on as many tv's as possible, although the feedback so far is very good news all round :)

Thanks again,

Baggers.

Mike_GTN
01-11-2008, 06:21 AM
I think we need to bear in mind a few issues when talking about feeding a PAL composite signal in to the average Television set in our houses. The actual television does many compensations (depending on the internal circuits employed) each and almost every TV will provide different results. In the same sense a television is a totally forgiving object, Video Monitors as well to different levels. I've just made a somewhat non technical test and fed the output into both a Betacam SP and DVCAM video deck. The resulting output is not good, and is I still believe still a pseudo PAL output. I very much doubt you will get to total UK specs. The hardware within the chip is the real stumbling block.

Just my thoughts, certainly don't wish to take away work already done.

Regards

Mike.

Coley
01-11-2008, 07:21 AM
@ Mike_GTN

I would agree with that Mike, we aren't trying to do the defacto standard PAL display just to make it usable on as many displays as we can.

We must remember that the Propeller is only a microcontroller, a very capable one I admit, but, video generation isn't it's primary function.

I really think this has got a long way to go before we are all 100% happy, me included...

It's very helpful having someone like yourself available to test things on a professional level though! http://forums.parallax.com/images/smilies/smile.gif

One thing is for sure, if we keep working on it bit by bit, we will get there in the end!

Regards,

Coley

CardboardGuru
01-11-2008, 08:40 AM
It displays OK on the Hydra and my TV set.

I see the change was to change lpal to the nearest multiple of 16. Which the comment implies it should have been anyway.

There's still room for improvement in that single horizontal pixels aren't even, and so display colour artifacts. You can see this on the blue lines that are nearly vertical. Different sections are different shared of blue. I found this when playing with my own TV driver, and the solution is to make hx=16 rather than 10. (To compensate you also have to reduce x_tiles from 16 to 10, or it'll be too wide to display)

The resultant hack is a rather lopsided display because something isn't calculating the borders correctly, but consistently coloured single pixels. The pixels are wider than in your demo, and thus the max horizontal resolution will be lower. But still higher than an equally correct NTSC display.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Help to build the Propeller wiki - propeller.wikispaces.com (http://propeller.wikispaces.com)
Play Defender - Propeller version of the classic game (http://forums.parallax.com/showthread.php?p=685888)
Prop Room Robotics - my web store for Roomba spare parts (http://www.proproomrobotics.co.uk) in the UK

hippy
01-11-2008, 10:20 AM
Worked okay for me ( no mouse ). Some very slight left-to-right shake, not visible unless right up against
the screen but no noted strobing, same solid quality as for the PAL60 graphics demo.

PAL50 TV_Text would be the real test for me. PAL60 TV_Text had atrocious strobing.

Baggers
01-11-2008, 04:36 PM
Cheers for the feedback guys :D

Mike_GTN
01-11-2008, 09:59 PM
I don't wish to slight any attempts that are on going to make images look better for us people that see "PAL" as a pretty decent standard already. I spent 15 years as a bench engineer working for a UK TV broadcaster. I have a reasonable feeling for when a picture is just plain wrong.

Regards

Mike.

simonl
01-11-2008, 10:49 PM
So Mike, are you saying that - in your professional opinion - this driver is better or worse than the Parallax TV.spin driver? I've not tried this one (yet), but your comments have confused me [tho' that's not hard LOL].

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Cheers,

Simon
-------------------------------
www.norfolkhelicopterclub.co.uk (http://www.norfolkhelicopterclub.co.uk)
You'll always have as many take-offs as landings, the trick is to be sure you can take-off again ;-)
BTW: I type as I'm thinking, so please don't take any offense at my writing style http://forums.parallax.com/images/smilies/smile.gif

Baggers
01-11-2008, 11:00 PM
Mike, No offence taken, I've worked with broadcast HD for a good few years now, and with CG film artists, to the point where it has spoilt most films for me, as even the slightest of inaccuracies in the lighting of a real life scene and the CG overlays is easily picked up and kinda ruins the magic of the movie for me, even to the point that now even my wife can see, as she once asked me how can you tell, so I showed her too, and she now has the same problem when watching movies.
Also, this was one of the reasons we cancelled SKY because of their horrific attempt to squeeze as many channels as possible, into their bandwidth, to the point that most of the channels are appalling to watch as the picture quality due to their heavy use of overcompression made watching anything and enjoying it totally impossible. :( so yeah, I know when something is just plain wrong too, but with what we're given, it's just about the best it's gonna get, without extra hardware.

LOL Simon, This driver is better than the original Parallax TV.spin, because I've just fixed what must have been a slight oversight in their data entry, not forgetting they probably didn't have a PAL tv to test it with. maybe who knows, either way, it's about as good as it'll get, comparable to the stability of it's NTSC output.

CardboardGuru
01-11-2008, 11:22 PM
Mike, you seem to be on a different quest than the rest of us.

You're wanting a good PAL reference signal - something the Propeller is never going to give. The rest of us just want a clearer, higher resolution display on our TVs than was previously available. That it works on PAL TVs is the important thing, not whether the waveform complies to the spec. Of course given the choice it'd be nice to be absolutely on spec, but if you're playing a game, or using a propeller console, or whatever, the only thing that matters is how good the image appears, not how close to the spec it is.

If you're wanting us to agree with you that the propeller will never produce a perfectly PAL image, you've got it. We already know that.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Help to build the Propeller wiki - propeller.wikispaces.com (http://propeller.wikispaces.com)
Play Defender - Propeller version of the classic game (http://forums.parallax.com/showthread.php?p=685888)
Prop Room Robotics - my web store for Roomba spare parts (http://www.proproomrobotics.co.uk) in the UK

Baggers
01-11-2008, 11:25 PM
You got it in one CG we all know it'll never be TV Broadcast quality ( although I'd rather watch the propeller than Sky's attempt anyday lol ) but for games, it's SPOT on, as long as there's no dot crawl, or whatever you want to call it, it's perfect for retro games.
especially since the retro consoles also were never "perfect" and some even had dot crawl :)

Mike_GTN
01-12-2008, 12:01 AM
Great guys, but then catch this one Would I wish to develop a project around this chip and tell people generates PAL. Forget about it being broadcast quality for a second. No just a device that generates good honest PAL would be good enough for me. People have very different views of what is broadcast quailty anyway.

M.

CardboardGuru
01-12-2008, 12:12 AM
I think it really depends on what your field is. If you are working in TV or video related industries, then the Prop output isn't going to cut it. But where you just need some TV output for an application, then the only real need is that it works, producing a decent quality image. Baggers and Coley are mainly interested in games and the like, so high conformance to spec doesn't matter, only that it works and is visibly as good as it can be.

They've definitely improved the image quality on the standard TV driver for PAL. That's a good thing. In fact a very good thing as the standard driver was awful for PAL.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Help to build the Propeller wiki - propeller.wikispaces.com (http://propeller.wikispaces.com)
Play Defender - Propeller version of the classic game (http://forums.parallax.com/showthread.php?p=685888)
Prop Room Robotics - my web store for Roomba spare parts (http://www.proproomrobotics.co.uk) in the UK

Coley
01-12-2008, 12:20 AM
I can see where Mike is coming from here and I did say as much in my previous post.

This project still has a long way to go, we want to develop the driver to get the best possible picture, PAL or NTSC out of this great little chip.

That means we need feedback, be it good, bad or indifferent, it all helps to nudge us along the way.

Our driving force for this, is that we want to produce a commercial product and the PAL output at the moment isn't quite there - yet!

It will be, given a bit of time, effort and plenty of testing and feedback!

I now know that if I can get Mike happy with the output then it is commercially viable!

Coley

Baggers
01-12-2008, 12:38 AM
Coley, waiting for Mike to be happy with the prop's PAL output might be setting your sites a tad too high there matey :)

QuattroRS4
01-12-2008, 01:03 AM
Well IMO - shed loads better than before ..nice one !

John

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Coley
01-12-2008, 01:15 AM
http://forums.parallax.com/images/smilies/yeah.gif Thanks, John! http://forums.parallax.com/images/smilies/yeah.gif

Enthusiasm++

lol

hippy
01-12-2008, 02:15 AM
Mike makes a good point : What are the criteria for saying a Propeller-based product is
"PAL" ?

That answer can only definitively come from a measure of the video signal set against what
"the PAL specification" ( whatever/wherever that is ) states makes for PAL compatibility and
compliance.

A less rigorous answer comes from looking at it another way - If a PAL compliant TV does
not correctly display non-PAL ( shows NTSC as noise or nothing, rolls on PAL60, isn't near
rock-steady on-screen, has lines missing or things which should be there are not ) then what
it is receiving is "not PAL". Conversely, if it does work it can colloquially be called PAL or be
said to be in the right ballpark. IMO, quality of rendered image is a different issue, even if
quality is a part of the official PAL specification ( I don't know ).

On that front, I'm pleased to report that my Citizen handheld LCD TV, which didn't work with
NTSC nor PAL60 does work with the driver here, showing what I'd expect.

I'd therefore call both the Parallax 'PAL Driver' and what this driver gives "PAL", with this driver
having the edge in quality of result.

I'd therefore say either driver could be 'sold' as "PAL". Whether acceptable quality PAL to meet
a customer's statisfaction and expectations being a separate issue. For a customer who cared
more than whether something displayed on his PAL screen, I would say the Parallax driver may
not meet customer expectations whereas this driver is more likely to. But this is a very subjective
matter. I'd certainly be more happier with "PAL output" on the advertising flyer with this driver.

I'd still like to see the equivalent TV_Text to see how that fares, but appreciate there are other
things in people's lives and I'm not the sole concern.

Perhaps the best way of putting it, in my words, is, "this driver delivers something which most PAL
using end-users would have very little, if anything, to whinge about".

Baggers
01-12-2008, 02:55 AM
Thanks hippy :) nice post.

Mike_GTN
01-12-2008, 02:59 AM
Great guys, but then catch this one Would I wish to develop a project around this chip and tell people generates PAL. Forget about it being broadcast quality for a second. No just a device that generates good honest PAL would be good enough for me. People have very different views of what is broadcast quailty anyway. People also have different views on what is a good or bad picture.
@Baggers... Yeah I should have tried to Copyright the phrase "Plain Wrong" I've let this one fly.

I would be very intrerested to hear more from the designers of this Micro about the NTSC/PAL issues. I'm pleased that they are coming to the surface. I don't wish to turn this in to an all out fight between UK/Euro users of this device. Let no one be surprised
however when the Propeller does not see a big market share within the UK. Everything else is there. I'm personally not interested if it's for a retro gaming market, or as a more general device. If it tells me within the specs that the device does PAL video ouput
I'd like PAL video output (Not to some bizzare standard however), I don't want to jump through hoops to get almost there. Perhaps the Propeller II should almost do "NTSC" with weeks and months of messing around. Please Parallax see this is an issue to your European and other customers. Dot crawl.... dot crawl who on earth is shouting that http://forums.parallax.com/images/smilies/smile.gif You should use NTSC instead as
is 99% there.

Regards

Mike.

QuattroRS4
01-12-2008, 03:25 AM
Mike_GTN said...
Let no one be surprised however when the Propeller does not see a big market share within the UK.


.. Mike - I don't believe this to be entirely true -'EDIT: The more I think of it - it is simply·NOT the case.'·I for one have used the Propeller in various applications - and I firmly believe that this will not adversely affect the euro/uk market ... put simply the Propeller has a lot more to it than just Pal (albeit Quasi Pal) .. There have been a number of posts where frequencies were tweaked to get a 'satisfactory' pal image.

This IC Punches well above its weight in terms of most other uControllers ...and it has a more helpful and active forum than any other uController manufacturer .. which IMO adds to it's appeal.

You say if it says PAL then you expect PAL .. nothing less !! Similarly Look at the manufacturers of most USB to RS232(serial) converters .. they do not even come close to RS232 standards .. not just in terms of voltage ! But yet they work (at least the majority of them do)..

Lets not look at this as a failure ...

Rgds,
John Twomey

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Post Edited (QuattroRS4) : 1/14/2008 10:02:46 AM GMT

Mike_GTN
01-12-2008, 03:46 AM
Hi John,

I agree is a feature. Me very unlikely to have my multimeter sat on a couple of pins measuring some voltage that might or might not be important to me. Anything Video output is visual (yeah me also surprised I wrote this) You see the defects (or features) very clearly. I would certainly expect a device to conform to a known (ish) standard.

With

Regards

Mike.

Coley
01-12-2008, 04:00 AM
Mike,

Seeing as you have the most expertise amongst us wrt PAL video signals, perhaps you could supply us with the defacto definition and breakdown of it.
That way we could construct a more accurate driver.

Coley

Mike_GTN
01-12-2008, 04:04 AM
@Coley "I now know that if I can get Mike happy with the output then it is commercially viable!" Will purchase this as a kit from you and then push this through some serious testing for you, all for free. Serious offer on the table. Will report back via email instead of this public debating / flogging platform.

Regards

Mike.

Coley
01-12-2008, 04:35 AM
Fair enough, I will PM you an offer!

Regards,

Coley

Coley
01-12-2008, 07:14 AM
@Hippy

This one is for you my friend.

I think the strobing effect is in fact the interlace so I have created a 50 * 7 text display and turned off the interlace just to see if we can get PAL50 on your display.

It works just fine on all my tv sets and 4" LCD (Picture Attached)

Coley

Leon
01-12-2008, 07:34 PM
Baggers PAL50·works OK with my TV.

Leon
·

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Post Edited (Leon) : 1/12/2008 12:40:17 PM GMT

Baggers
01-12-2008, 07:44 PM
Cool, cheers Leon.

deSilva
01-12-2008, 08:02 PM
The "TV feature" of the propeller is something you can use - or do not. It's advantages are well known: It's cheap as it needs a cord and three transistors and a TV set which is readily available.

I think it was never a matter of "what TV monitor to buy" for the Propeller. This is a misunderstanding and total overkill!
You use a TV or similar screen because it's there!

If you have to calculate budget you:
- either buy (bundle) a true VGA monitor (with a thicker cord)
- or use an alphanumeric display (77480,...)
- or use a graphics display (OLED, KS0108,..)

What any customer expects today is the crystal clear quality of cell phon, pda, or laptop displays.
I aggree there can be special situations where to use compound video due to transmission constraints or needs of the final device... But in those cases NTSC will be fine.

I have expressed my critizism of the incompatibilty of PAL and QVGA screen so many times now, that I shall not repeat this here again http://forums.parallax.com/images/smilies/smile.gif
-------------
Edit:
I checked some hundred combinations of "lpal", "vvis", and "_xinfreq" last June - without upsetting the whole world - but with little success. I shall not use PAL with the Propeller http://forums.parallax.com/images/smilies/smile.gif

Post Edited (deSilva) : 1/12/2008 1:13:23 PM GMT

hippy
01-12-2008, 09:24 PM
Mike_GTN said...
Let no one be surprised however when the Propeller does not see a big market share within the UK.


I don't think I've been reticent in making my own views about PAL support known. The Parallax provided PAL drivers are certainly good enough to get information on screen, superb for debugging and diagnostics ( a genuine USP ), but if I were selling a Propeller-based product I would feel compelled to add a caveat that "PAL video display may not meet all your expectations".


Mike_GTN said...
If it tells me within the specs that the device does PAL video ouput I'd like PAL video output (Not to some bizzare standard however), I don't want to jump through hoops to get almost there.


The Propeller doesn't do video at all until WAITVID is wrapped up in some sort of driver so there's always some hoop jumping involved, but thankfully that's largely avoided for us developers by someone else kindly handing us a driver on a plate.

My measure of successful PAL generation would be when every potential PAL-using customer would be expected to turn round and say, "that works for me and I am happy with what I see". NTSC and PAL60 fails that test, but the latest driver is much closer and perhaps even there.

Yes, true PAL compliance as per the PAL spec is the desirable goal, but everyone happy with what they get, whether genuine PAL or not, is equally good enough for me. If everyone is happy, the market is wide-open. Even if a small minority of PAL-users are not happy with the display, it's still massively open. I feel the PAL market is much more conquerable than it was a couple of weeks ago, and the effort to get us there deserves much praise.

hippy
01-12-2008, 09:36 PM
deSilva said...
I aggree there can be special situations where to use compound video due to transmission constraints or needs of the final device... But in those cases NTSC will be fine.


I think that pre-judges what a product will be, NTSC will not be fine in all cases and PAL50 is definitely needed. If nothing else there is a marketing advantage to being PAL50. In some cases ( a few products I'm thinking of ) TV output is fundamental to its low-cost and success and being PAL is a necessity.

Not every Propeller product will need composite video output, not all will require PAL50, but some do, and that's key to those products' existence and success.

deSilva
01-12-2008, 10:41 PM
If you think so...

hippy
01-13-2008, 12:32 AM
I know so http://forums.parallax.com/images/smilies/smile.gif

The proposed commercial products I'm involved with aren't entirely a no-goer without decent PAL50 but not having that limits their attractiveness, devalues their worth, will increase criticism of the sold product, reduces potential market size aimed for and ultimately doesn't make them economically viable.

Like being fluent only in Esperanto wouldn't stop me writing credible and amazing applications for a PC, but it would limit their appeal, the market and ultimately not make a lot of money nor gain fame and fortune in a largely non-Esperanto speaking world.

JT Cook
01-13-2008, 12:56 AM
hippy said...

My measure of successful PAL generation would be when every potential PAL-using customer would be expected to turn round and say, "that works for me and I am happy with what I see". NTSC and PAL60 fails that test, but the latest driver is much closer and perhaps even there.

I can't speak for PAL, but the NTSC video is pretty solid and I have never seen a TV it hasn't worked on. Infact it provides better video then some video game devices out there where when I hook it up to my video capture card I get sold video, where some of the game devices do not provide as stable of picture.

simonl
01-14-2008, 07:45 PM
Hmm, tried both PAL60 & PAL50 drivers - used them with graphics_palette demo - and got noticeable 'crawling' (not sure how else to describe it!) of the blue background (which I don't get with the NTSC driver). Otherwise, the display is similar to NTSC, complete with some dot crawl on contrasting edges, along with some 'shadowing' too.

I suspect it's mostly down to the cheap TV tho'

My setup uses a 10MHz Xtal (_clkmode = xtal2 + pll8x, _xinfreq = 10_000_000), on a cheap Saka 5" TV.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Cheers,

Simon
-------------------------------
www.norfolkhelicopterclub.co.uk (http://www.norfolkhelicopterclub.co.uk)
You'll always have as many take-offs as landings, the trick is to be sure you can take-off again ;-)
BTW: I type as I'm thinking, so please don't take any offense at my writing style http://forums.parallax.com/images/smilies/smile.gif

Baggers
01-14-2008, 08:21 PM
ok, thanks simonl, maybe it's also the fact that 10Mhz * 16 = 160Mhz internal pll'd not overly sure, or like you say, could be the cheap Saka 5" TV :)

either way, cheers for the feedback :D

simonl
01-14-2008, 08:49 PM
Nah, it's 10MHz * 8 = 80MHz http://forums.parallax.com/images/smilies/wink.gif

I'll try again with the LCD TV in my lounge - but will have to wait 'til my better half's gone to bed LOL!

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Cheers,

Simon
-------------------------------
www.norfolkhelicopterclub.co.uk (http://www.norfolkhelicopterclub.co.uk)
You'll always have as many take-offs as landings, the trick is to be sure you can take-off again ;-)
BTW: I type as I'm thinking, so please don't take any offense at my writing style http://forums.parallax.com/images/smilies/smile.gif

Baggers
01-14-2008, 08:52 PM
Yeah, I know 10Mhz * 8 = 80Mhz operation, but I was more referencing the fact that the internal PLL goes to 16*, and that maybe that was something to do with it? but I guess we'll have to wait til your better half goes to bed :)

Gosh Mrs simonl, is that the time? lol yawn, don't you feel tired? :)

Cheers,
Jim.

Mike_GTN
01-15-2008, 06:41 AM
Hi People, I promise is really my last chime in on these PAL issues. Perhaps we should tune up the tv object and have two hundred different ones to account for every different TV screen. We could test here with a works for me... etc But then two people might have the same TV and could get different results due to internal changes within the circuits that happen through even simplistic manufacturing changes that happen.

This is really like you buy a brand new car and have to tune it up to get the performance you wish, consumption or other parameters. I'd never expect to have to do a conversion in software from Petrol to Diesel. This without also the details of how to make the conversion.

What about if the video generation hardware was a locked design that could not be tweaked to any major extent? What about if the desingers took short cuts, just to make
the PAL aspect even a possibility. May be for the next generation we should take NTSC as a second best quick fix. you can all have the fun of bit fiddling to get an even half
decent display. I wanted a reasonable display only, and not something outside of the alledged specs of the device. I've found the dot crawl and colour crawl to be really bad - Hey I must have landed in a good thread then after all.

Mike.

heater
02-22-2009, 03:07 AM
I was just trying to use the PAL50 TV driver with TV text and my newly scrounged old fashioned tube Sony TV. Very disappointing.

OK, we have nice white text on a blue background but the back ground has diagonal bands of brighter/darker blue racing sideways across the screen and horizontal bands of lighter/darker blue slowly scrolling upwards.

The text itself looks OK but is a bit flickery.

I know nothing of PAL or the TV driver but thinking that the diagonal bands might be due to some beating of not quite matched frequencies or some such I started tweaking the PAL color frequency constant in tv.spin (fpal). Surprisingly it works over a large range of values of fpal each of which changes the angle and rate of our diagonal lines. Setting it to 4_433_280 instead of the original 4_433_618 extinguishes the lines visibly. Hurray!

As for the vertical scrolling bands that seems to be something to do with my Props power supply. It injects those bands onto normal channels even when not running any TV driver. As well as a lot of audio hum. No idea how to fix that except that a friend of mine eliminated hum from his TV to computer connection by putting a transformer between the TV and the cable TV wall socket.

The last thing required to avoid epilepsy when using PAL50 is double buffering to get rid of flicker when updating/scrolling.

As a bonus though setting cols = 50 and rows = 15 (as opposed to 40,13) works and gives lots more characters on the screen.

P.S. Why do most of the animated parts of graphicsDemo not move with this package?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
For me, the past is not over yet.

whicker
02-22-2009, 04:52 AM
how much of these PAL problems just have to do with the instability of the clock oscillator?

heater
02-22-2009, 05:09 AM
That thought crossed my mind also.

So in a particularly sadistic moment I jammed my hot soldering iron tip onto my propellers crystal for about a minute. Pretty much nothing happened as it started to fry until eventually, and suddenly, the background went all multicolour stripes. The text remained OK. Poking a moist finger on the crystal pins has much the same effect.

More seriously, would it help to drive the Prop with a PAL colour frequency crystal, 4_433_618Hz? This way the fpal frequency would be spot on and everything else going on in the Prop would be in synch with it.

Or is all this to do with my home made Prop Demo Board style board built on a generic prototyping card with a DIP Prop and through hole resistors etc?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
For me, the past is not over yet.

propwell
04-11-2009, 02:42 PM
hm well, i've been testing the TV-Pal-Output. I can see the color, but it flickers a bit an, whats the main Problem for my use: The created image doesn't fill the screen completely. There's room at the top/bottom and the left/right side! How can i expand the picture?

Thanks,
Propwell

Baggers
04-11-2009, 02:48 PM
propwell, can you explain a little more?
What tile sizes are you using? does it create a res of 256x192? if so, yes, PAL image will have room on top/bottom and left and right
You can increase the HX values, to get wider pixels, to help sort out the edges.
but as for top and bottom borders, that's because PAL has more raster lines than NTSC.
Can you post pics?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
http://www.propgfx.co.uk/forum/·home of the PropGFX Lite

·

Toby Seckshund
04-11-2009, 03:36 PM
When I started to play with the prop, a couple of months ago, I went for the OBEX NTSC objects just to test things out. My monitor will autosence the incoming standard but PAL was what I wanted.
I tried the original 5MHz and got severe coarse diagonal bacground patterning, with 6MHz, with appropriate corrections, it was a nice clear pic. So I though use 4.43 (with code corrections) and hopefully gove the internals some nice easy sums to do, this did not work all I got was an unlocked mess. The same was true with 8.86 (w.c.c)
I thought it was due to a minimum "80Mhz" clock sort of thing and gave up (I suppose 17.74 would be classed as a crime against silicon)

Coley
04-11-2009, 04:42 PM
Propwell,

Look at the archive below, I have modified it to fill as much as the PAL display area as possible.
It's more of an example of what can be done just by tweaking the existing settings.

I have tested this on a Parallax demoboard and on my setup which is a 3" LCD (From Brillidea) and my Hybrid board that runs with a 6MHz crystal.
The archive attached is setup for the Parallax demoboard.
There is some dot crawl when running with a 5MHz crystal but I'm sure with a few tweaks this could be overcome.

Regards,

Coley

NOTE that the attached file will need to renamed to .zip as the forum wouldn't let me upload the zipped archive for some reason

http://forums.parallax.com/attachment.php?attachmentid=60012

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
PropGFX (http://www.propgfx.co.uk) - The home of the Hybrid Development System and PropGFX Lite

Post Edited (Coley) : 4/11/2009 9:58:48 AM GMT

Toby Seckshund
04-11-2009, 06:40 PM
There will always be some dot crawl, it is built into the whole system. The 1135/4 +25 formula that gives the 4.43 figure was always the best fudge that they could handle. On normal resolution, moving TV pic it was bearable. Start drawing fine coloured lines on CRTs with poor triad pitch and there will be greif. We have got used to 1024X768 as being normal and it hurts to go backwards. Imagine still having a 8088 feeding CGA, fantastic 20 years ago, retro now.

My original problems were the beating of the background blue.