Vertical Scanlines

[Li Wang]

After going through two FLU model GP32s, I came to the conclusion that the low build quality just isn't worth the trouble of monkeying with them. So I finally exchanged the second for a regular unit. I have noticed vertical scanlines on multiple programs. I know this has been mentioned before as a sign of a faulty unit, but nothing else has happened with the unit that always goes along with it. No overheating or strange reboots, etc. The scanlines are there regardless of the brand or type of batteries. Is it normal for scanlines to show up in some programs?

A list of programs where scanlines/minor flicker shows up:

Mill - left side of the screen during gameplay. Barely noticeable in darker areas.

NesterGP - right side of the menu screen. Gone during actual gameplay.

SNES9XGP - flickering scanlines all over screen during gameplay. Hard to notice with darker graphics. It's actually more like just flickering than flickering with scanlines.

GP Cinema - more noticeable than with any other program. Scan lines all over the entire menu interface. Haven't tried any movies yet, so I dunno if it goes away then.

Stuff I DID use the old units for doesn't have any noticeable scan lines on the new one, so I haven't been able to prove that the unit is faulty through that.

Someone please tell me scanlines are normal for these programs and I won't have to exchange this thing for a third time.

 

[Chip]

They're normal for me. I get them a lot, but I don't really think of them as being obtrusive (I only really see them when I'm looking for them).

I don't think you have a faulty unit, I think they're all just a bit shoddy.

 

[JDUK]

After having read about problems with shitty FLU iinstalls i did recormend we kept track of the supplier they cam from, but no one bothered. I got mine form GBAX and it was spotless. as for the verticle line problem i noticed this twic but only as the last 2 lots of batteries where dyeing on me. It seems there is a pretty big difference in Performance, Battery Consumption and Build quality on the GP32 which is realy a great shame, im lucky to have a great build unit with long battery life but OC'ing over 133 will cuase mine to crash in under minuite. Others are not so lucky though thats probably the risk we take with such a cheap unit ??

 

[Tobriand]

I tend to get them when my batteries are running low. Especially on rechargeables (I assume due to a substantially lower voltage - they're 2.2volts as opposed to the supposedly required 3).

 

[Li Wang]

What I was kind of wanting to know is whether everyone gets them in one of those specific programs in the same places.

BTW, my crap FLUs came from Entware, though I don't see what the difference would be.

 

[sgbfree]

I got them on Mill in the same place

 

[Li Wang]

Thanks. I had guessed I could probably chalk it up to some programs just inherently having scanlines but wanted to be sure just in case. I actually haven't even noticed scanlines for low batteries on anything except (I think) SMS32.

 

[Toris]

It's actually a GP32 hardware bug. It's the same one that causes the sound clicking, and distortion.

If you write too much to memory too quickly, the writeback buffer gets blocked up, and makes dma transfers for sound and video unable to work, and so strange things happen, such as scanlines, display flickering, and audio clicking.

So, don't worry, nothing wrong with your GP32, it happens to them all... (and it's more noticeable with a FLU, or in bright sunlight btw...)

 

[mr.spiv]

Now this is where a vertical/horizontal blanking period would be handy as during that time it would be sure that memory transfers would not affect anything. Anyways, talking from experience with small preparations etc those flickerings etc can be avoided completely (my "raster demo" is an example of that). All that is required is (software & developer wise) to align buffers correctly and turn off both cache & writeback from those buffers that are written extensively or used by any DMA. That of course has a slight performance hit... :blink: