GP2X Does The Gp2x Run At 81.2hz?


DrStrider

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Sep 11, 2006
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I'm timing a waitvbl and here's the results I get in milliseconds:

12.315132
12.314725
12.314725
12.315132
12.314725
12.314454
12.315268

my calculations say 1000/12.315132 = 81.2 fps

Is this right? I can't find any documentation on the GP2X frame rate anywhere!
 
BradN posted on Sep 11 2006 at 09:05 PM said:
The framerate can change - don't depend on it.

Can you control it?
 
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Well, I say this because the MKI units have a more sensitive screen, and altering the framerate is one (maybe the only, I don't know a lot about it) thing used to adjust it. If you forced the usage of a particular rate, it might upset some MKI owners. It's always possible GPH could switch to another display with a fixed or more limited framerate in the future too, so take what you will from that.
 
Vimacs posted on Sep 11 2006 at 11:14 PM said:
the lcd settings screen in the system menu changes the refresh rate.


blimey :unsure:

so it does! theres no units though...!!!!

looked like it ran from about say 100fps left side to about 30fps right side or something... is this documented anywhere?


is there a magical point on the slider where i can hit 60fps and thus get DrMD running super smooth B)
 
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If Stargazer's FPS indicator is any decent test, 112 FPS at the far left, ~30 at the far right. Thing is, I don't think DrMDx vsync's to the display so I doubt you'd see any improvement. I don't notice any issues of 'tearing' like you often see in a PC emulator with a 100hz monitor or similar, though.
 
Epicenter posted on Sep 12 2006 at 08:19 AM said:
If Stargazer's FPS indicator is any decent test, 112 FPS at the far left, ~30 at the far right. Thing is, I don't think DrMDx vsync's to the display so I doubt you'd see any improvement. I don't notice any issues of 'tearing' like you often see in a PC emulator with a 100hz monitor or similar, though.

Thing you just contradicted yourself there , hehe ;)

Yeah pretty sure it has vsync. I'm gonna try and match the refresh with 60hz, see if the scrolling gets nice and smooth. Just surprised no-one else has tried this! I presume they have? There's that lcd timing program isn't there?


Any idea what happens when you plug it in a PAL/NTSC TV? I haven't got my tv out cable yet
 
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lol from the topic title I thought it would be about ultra extreme underclocking
 
A_SN posted on Sep 12 2006 at 11:26 AM said:
lol from the topic title I thought it would be about ultra extreme underclocking
Same here, but I think I tried 5Mhz once and that it didn't run :p But could be mistaken.


Anyhow, higher refresh of the LCD means more reading from the memory right? And thus more battery usesage? :unsure:
 
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Daid posted on Sep 12 2006 at 04:41 AM said:
Anyhow, higher refresh of the LCD means more reading from the memory right? And thus more battery usesage? :unsure:

This is probably right. Not sure how much it affects battery usage, but it definitely steals some memory bandwidth. About 12MB/s at 320*240*16bpp*80fps. Depending on how the memory controller works, this might be part of the reason the gp2x can't operate at very low clock speeds too.
 
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DrStrider posted on Sep 12 2006 at 08:50 AM said:
Epicenter posted on Sep 12 2006 at 08:19 AM said:
If Stargazer's FPS indicator is any decent test, 112 FPS at the far left, ~30 at the far right. Thing is, I don't think DrMDx vsync's to the display so I doubt you'd see any improvement. I don't notice any issues of 'tearing' like you often see in a PC emulator with a 100hz monitor or similar, though.

Thing you just contradicted yourself there , hehe ;)

contra in bold
 
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BradN posted on Sep 13 2006 at 12:04 AM said:
Daid posted on Sep 12 2006 at 04:41 AM said:
Anyhow, higher refresh of the LCD means more reading from the memory right? And thus more battery usesage? :unsure:

This is probably right. Not sure how much it affects battery usage, but it definitely steals some memory bandwidth. About 12MB/s at 320*240*16bpp*80fps. Depending on how the memory controller works, this might be part of the reason the gp2x can't operate at very low clock speeds too.
Mmm never thouged of that. Could 50Mhz be a problem on the highest LCD refresh settings?
 
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Daid posted on Sep 12 2006 at 05:16 PM said:
Mmm never thouged of that. Could 50Mhz be a problem on the highest LCD refresh settings?

From a pure memory bandwidth perspective, that should be easily handled, but it's possible the video subsystem needs extra clocks to do the layer compositing and other misc. things before displaying. There could be other things, like dram refresh not running fast enough at low speeds, or the clock speed tweaker program setting illegal values below some amount, etc. It's hard to tell without a hands on investigation or good technical documents. If I set the core speed on my nvidia 5200 to say, 80MHz, the display goes all screwy and it locks up, so sometimes things can expect a minimum clock rate.
 
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Daid posted on Sep 12 2006 at 11:16 PM said:
BradN posted on Sep 13 2006 at 12:04 AM said:
Daid posted on Sep 12 2006 at 04:41 AM said:
Anyhow, higher refresh of the LCD means more reading from the memory right? And thus more battery usesage? :unsure:

This is probably right. Not sure how much it affects battery usage, but it definitely steals some memory bandwidth. About 12MB/s at 320*240*16bpp*80fps. Depending on how the memory controller works, this might be part of the reason the gp2x can't operate at very low clock speeds too.
Mmm never thouged of that. Could 50Mhz be a problem on the highest LCD refresh settings?
yeah, i found that the other day
 
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