[Guide] ili9341 SPI TFT Screen on Retropie

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abrugsch
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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by abrugsch » Wed Feb 01, 2017 9:13 am

Mischief wrote:Can PWM audio still be used with these screens? I do like the screen/Pi Zero combo PCB so much space saved :D
if you specifically don't want to mess with the PWM from the Pi for backlight, you *COULD* use a 555 timer circuit to control the backlight as an external PWM. bonus is you can use a pot to adjust the resistance which controls the mark/space ratio (the thing that would actually make it brighter or dimmer) meaning you can put it on the old contrast knob :)

well this is what I intend to do with my display (but I'll probably use it in DPI mode unless I can get some performance out of it...)

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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by moosepr » Wed Feb 01, 2017 9:34 am

abrugsch wrote: if you specifically don't want to mess with the PWM from the Pi for backlight, you *COULD* use a 555 timer circuit to control the backlight as an external PWM. bonus is you can use a pot to adjust the resistance which controls the mark/space ratio (the thing that would actually make it brighter or dimmer) meaning you can put it on the old contrast knob :)

well this is what I intend to do with my display (but I'll probably use it in DPI mode unless I can get some performance out of it...)
If you want to get really simple, just use the pot as a potential divider to adjust the voltage that goes to the backlight.

I personally dont see why people say the SPI screens are so bad, the only problem i have noticed is tearing, and that only happens when large chunks of screen estate change rapidly
Get a small cheep LCD in your project https://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery https://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small https://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! https://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by abrugsch » Wed Feb 01, 2017 10:33 am

The problem with a voltage divider is it doesn't really suit LED's all that well. just needs trying out tbh.
moosepr wrote:I personally dont see why people say the SPI screens are so bad, the only problem i have noticed is tearing, and that only happens when large chunks of screen estate change rapidly
well to be fair, I haven't really tried to get my PiTFT to perform. I quickly set it up to test it out and haven't gone back to it (hence my qualified statement above) but the lag on it when i did was noticable and made games borderline unplayable. Now as I said, I didn't spend any time tuning it so I'm going to have another stab at it soon, but I just think if I CAN do direct drive RGB 565, why shouldn't I ;)

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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by moosepr » Wed Feb 01, 2017 12:07 pm

abrugsch wrote: but I just think if I CAN do direct drive RGB 565, why shouldn't I ;)
That's as good a reason as any! ;)

I think some SPI screens suffer at higher resolutions. a 320x480 screens have many more pixels than a 240x320 screen, and so of course will be slower.

I will have to get some video recorded on my 'minimal pi' so everyone can see
Get a small cheep LCD in your project https://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery https://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small https://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! https://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by moosepr » Thu Feb 02, 2017 2:36 am

I was having a bit of a play with speeds last night, managed to get it all the way up to 90000000 (7 zeros) and a stable screen. Turning on the FPS indicator in the emulationstation UI settings gave me a nice surprise (if you can read that!)

Image

so i had a bit more of a play, up to 100000000 (8 zeros) and that was a bit too fast!!

Image

although the actual screen does flicker up, so maybe with shorter cables, it might work
Get a small cheep LCD in your project https://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery https://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small https://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! https://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by abrugsch » Thu Feb 02, 2017 2:44 am

cool! I'll be definitely interested in whatever final settings you settle on.
my adafruit one is an ILI9341 under the hood so if your settings make it fly I'll be happy :) then I'll get the rest of my GPIO's back for other more important things... like working cartridge port and controller buttons :)

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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by moosepr » Thu Feb 02, 2017 2:53 am

abrugsch wrote:cool! I'll be definitely interested in whatever final settings you settle on.
my adafruit one is an ILI9341 under the hood so if your settings make it fly I'll be happy :) then I'll get the rest of my GPIO's back for other more important things... like working cartridge port and controller buttons :)
I was running the sega genesis version of sonic last night and the screen could more than keep up. Bought my camera in to work so i could try and get some good video in daylight at lunch, but then i forgot my pi :roll:

There is still a bit of tearing, but i only really notice it in the menu
Get a small cheep LCD in your project https://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery https://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small https://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! https://www.sudomod.com/forum/viewtopic.php?f=13&t=2919

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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by moosepr » Fri Feb 03, 2017 1:39 am

here we go, as promised

https://youtu.be/nE0DtXGXHAw

you can see the tearing on the emulationstation menu, and on the sega logo, but once your in the game, there is no sign of it. I even did a little wiggle to show how responsive it all is :P
Get a small cheep LCD in your project https://www.sudomod.com/forum/viewtopic.php?f=22&t=2312
Wrap it all round a battery https://www.sudomod.com/forum/viewtopic.php?f=13&t=2292
Or use a custom PCB to make it really small https://www.sudomod.com/forum/viewtopic.php?f=13&t=2512
or make it really really really really tiny!! https://www.sudomod.com/forum/viewtopic.php?f=13&t=2919


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Re: [Guide] ili9341 SPI TFT Screen on Retropie

Post by moosepr » Fri Feb 03, 2017 5:03 am

abrugsch wrote:that *DOES* look good :)

I love the harness BTW!

Its not too shabby!!especially when the screen is just a few quid and doesnt need any hardware mods

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

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