Composite vs DPI

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moosepr
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Re: Composite vs DPI

Post by moosepr » Mon Jul 24, 2017 1:57 am

the crappy composite screens are actually probably using DPI to talk to the screen, but the driver board (the bit you have to convert to 5v) is taking the composite signal and converting that to DPI (hence it not being brilliant). Composite screens dont use any GPIO, and dont need any special setup.

DPI is probably the best you can get as far as speed and quality goes. the only downside is that it uses pretty much all the GPIO pins, so they are not available to use elsewhere. DPI also needs some setting up, although i think its just some code in config.txt

SPI gets a bad writeup. It is not as fast as DPI, but you can still get a good quality screen as there is no 'conversion' going on. If you keep screen resolution to 240x320 or lower, things can actually run pretty well. There are some poor quality 3.5" screen that need 320x480 resolution, and have super slow connections that are worthy of the bad reputation.

my personal favourite is SPI because you get the crispness of DPI without using lots of GPIO, so you can use it for buttons. It was good enough for wermy to use in the MintyPi!! Have a look and see what you think

https://youtu.be/nE0DtXGXHAw
Get a small cheep LCD in your project http://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery http://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small http://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! http://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: Composite vs DPI

Post by tinkerBOY » Mon Jul 24, 2017 2:15 am

moosepr wrote:
Mon Jul 24, 2017 1:57 am
the crappy composite screens are actually probably using DPI to talk to the screen, but the driver board (the bit you have to convert to 5v) is taking the composite signal and converting that to DPI (hence it not being brilliant). Composite screens dont use any GPIO, and dont need any special setup.

DPI is probably the best you can get as far as speed and quality goes. the only downside is that it uses pretty much all the GPIO pins, so they are not available to use elsewhere. DPI also needs some setting up, although i think its just some code in config.txt

SPI gets a bad writeup. It is not as fast as DPI, but you can still get a good quality screen as there is no 'conversion' going on. If you keep screen resolution to 240x320 or lower, things can actually run pretty well. There are some poor quality 3.5" screen that need 320x480 resolution, and have super slow connections that are worthy of the bad reputation.

my personal favourite is SPI because you get the crispness of DPI without using lots of GPIO, so you can use it for buttons. It was good enough for wermy to use in the MintyPi!! Have a look and see what you think

https://youtu.be/nE0DtXGXHAw
Wow very nice video. Image quality on that screen looks great. Do you have a link to that screen you used? Is that 2.4"? I actualy have read some of your posts before on spi screens and been wanting to really try that. I guess im on a search for that perfect screen for gbz related projects.

I will definitely going to try the spi screen. Also will try DPI as well, so do you know any small screen that i can experiment with? I guess i can start with the crappy 3.5" screen that i already have?

Great insight, thank you!

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Re: Composite vs DPI

Post by moosepr » Mon Jul 24, 2017 3:43 am

thanks! the screen is only 2.2", it is a bog standard ili9341 http://www.ebay.co.uk/itm/301884935685

they do them in 2.2, 2.4, and 2.8. I have seen some 3.2 inch ones now and then, just make sure its 240x320
Get a small cheep LCD in your project http://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery http://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small http://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! http://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: Composite vs DPI

Post by Helder » Mon Jul 24, 2017 6:50 am

I actually have a very good contact in China and they have 1.8 inch all the way to 3.2inch SPI 240x320 so there are ways to obtain these sizes if you look hard enough and that GBA project GamePie Advance uses such a screen in 3.2 inch size (2.8inch is almost a perfect fit from my testing) so it's a decent screen to use for on the cheap.
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Re: Composite vs DPI

Post by tinkerBOY » Mon Jul 24, 2017 7:06 am

Helder wrote:
Mon Jul 24, 2017 6:50 am
I actually have a very good contact in China and they have 1.8 inch all the way to 3.2inch SPI 240x320 so there are ways to obtain these sizes if you look hard enough and that GBA project GamePie Advance uses such a screen in 3.2 inch size (2.8inch is almost a perfect fit from my testing) so it's a decent screen to use for on the cheap.
I've seen 2.2", 2.4", and 2.8" ili9341 screens on Aliexpress. Are these the spi screens to look for?

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Re: Composite vs DPI

Post by abrugsch » Mon Jul 24, 2017 7:12 am

zeroboy wrote:
Mon Jul 24, 2017 7:06 am
I've seen 2.2", 2.4", and 2.8" ili9341 screens on Aliexpress. Are these the spi screens to look for?
sounds like it ;)
got a link, there are a few variations


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Re: Composite vs DPI

Post by abrugsch » Mon Jul 24, 2017 7:23 am

yeah, they all look good, but you don't necessarily "NEED" them to be PCB mounted, and the memory card reader will almost certainly be a waste of time on the Pi (though I think a few people have gotten them working?)

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Re: Composite vs DPI

Post by moosepr » Mon Jul 24, 2017 7:25 am

Helder wrote:
Mon Jul 24, 2017 6:50 am
I actually have a very good contact in China and they have 1.8 inch all the way to 3.2inch SPI 240x320
oooh 1.8" @ 240x320 sounds interesting!
Get a small cheep LCD in your project http://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery http://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small http://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! http://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: Composite vs DPI

Post by abrugsch » Mon Jul 24, 2017 7:26 am

haven't you seen them?

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