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LCD Screen
#1
Hey Ed,

So after getting everything built and setup I had a question in regards to the LCD. This isn't a complaint but more informational, The included LCD has pretty low resolution and is pretty choppy with the Retro PI GUI, I was wondering if there was an LCD out there with a better Resolution that has the same output as well as Size as an alternative?

Trust me I am more than happy with the bundle you put together and not asking you to change it in anyway, I just figured since you source all these parts you might know of something out there Smile

Thanks!
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#2
Yeah, I have done a lot of research on LCDs for this project. Here are some key points.

It is a very intentional choice not to use a higher resolution LCD. That might sound odd at first, but it's very important for the way the screen is used in this handheld. If we used a higher resolution screen, the processor would not be able to keep up. Consider that if we doubled the X resolution and the Y resolution, that would actually be 4x more pixels to process per frame. The Pi Zero would not be able to push that data quick enough, and it would result in a way worse user experience.

I'm going to talk about a "problem" here that I think is mainly cosmetic. What I mean by that is the issue is mostly noticeable in menus and other such places that don't actually impact the gaming experience. Of course this is not absolutely true, as we don't control what the games do. A game could exhibit this in a noticeable way, but I have not seen it impact playability.

From your quick mention of "choppy," I assume that you are talking about the diagonal tearing you see when the GUI menus fade in and out during transitions. There are 2 reasons for this. First, the LCD is actually meant to be used in a portrait mode. Most small LCDs are made like this now, because most of the small devices we use are portrait (as opposed to landscape) format. The second problem that combines with the portrait issue is that we, currently, have no way to get feedback from the LCD about where in a refresh cycle it is. That means we can only push data to the LCD at the desired rate even if the LCD is mid-refresh. Ideally, we would get information from the LCD that would allow us to sync our writes with the refresh cycle. So, the refresh problem leads to tearing, and the portrait mode leads to that tearing showing up as diagonal artifacts.

I have not yet been able to find an LCD that is suitable that would seem to fix these problems (without adding worse ones). I will say, though, that this is an ongoing effort for me. I have very recently looked pretty closely at a couple other LCDs that I thought might work. So far, I've not found anything better.
Card Fighters' Clash 2 English Translation ( http://cfc2english.blogspot.com/ )
Neo Geo Pocket Flash Cart and Linker Project ( http://www.flashmasta.com/ )
Avatar art thanks to Trev-Mun ( http://trevmun.deviantart.com/ )
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#3
As a side note, I will mention that I did some software development to try to fix the diagonal issue. The result was that the tearing was still apparent, but it was vertical instead. The code added some processing overhead, which could maybe be tolerated if it "fixed" the problem. I actually thought that the diagonal was less obvious than the vertical. I think the vertical caught the eye's attention more than the diagonal does.
Card Fighters' Clash 2 English Translation ( http://cfc2english.blogspot.com/ )
Neo Geo Pocket Flash Cart and Linker Project ( http://www.flashmasta.com/ )
Avatar art thanks to Trev-Mun ( http://trevmun.deviantart.com/ )
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#4
Thanks Ed for that explanation on the current LCD screens, very thorough and informational Smile

Much Appreciated, Keep up the awesome work!
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#5
Hey Ed,

I figure this may be the best thread to add this comment to.

I really like the product but the only drawback I see is that the LCD screen is meant for portrait and is being forced into the landscape mode. I notice this since the left of the screen tends to be brighter than the right. For me, this creates an uneven lighting effect on the eyes. I have to tilt the system to the left or the right a bit to even it out. If I turn the screen 90 degrees, the lighting evens out for my eyes and makes for a more pleasing visual experience.

I know you must have done loads of research for this project, but if you find any landscape LCD screen that can fit this project I would recommend it for future iterations.

Thoughts?

Overall though, this project kicks butt. I like playing all kinds of systems on the go with responsive GBA controls.
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#6
I know what you mean, Nollier. We have not found any other suitable LCD. Believe me, I have tried! There is one other LCD that works well, but it's 3.5" and therefore doesn't fit into the GBA-style shell.
Card Fighters' Clash 2 English Translation ( http://cfc2english.blogspot.com/ )
Neo Geo Pocket Flash Cart and Linker Project ( http://www.flashmasta.com/ )
Avatar art thanks to Trev-Mun ( http://trevmun.deviantart.com/ )
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#7
Gotcha. I know sourcing specific electronics can be tough. Digikey and Mouser just dont have enough sometimes. Thanks for the response! Im gonna play some Zelda.
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