sudomod

Mischief wrote:Can PWM audio still be used with these screens? I do like the screen/Pi Zero combo PCB so much space saved

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...)

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

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

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

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!)



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



although the actual screen does flicker up, so maybe with shorter cables, it might work

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

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

There is still a bit of tearing, but i only really notice it in the menu

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

that *DOES* look good

I love the harness BTW!

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?