Need Some Testing Again

[notaz]

I've got a new idea to use in our emus. If the LCD slider in GP2X firmware affects LCD refresh rate, why can't we set the GP2X LCD refresh rate to exactly 50Hz (PAL) or 60Hz (NTSC)? This would mean perfect sync of emulated video with the actual display, and the emulator could sync it's timing with the _real_ 50/60Hz vsync signal from GP2X.

So I have written this little test. It can set various internal GP2X registers, which I found to be affecting the LCD refresh rate. It also draws some moving lines to see if the bottom right pixel problem shows up.

If I set DISPCLKDIV to at least 17, the bottom-right pixel problem goes away. Setting it to 5 also seems to fix it, but a white column appears on the left.

These settings set the refresh rate to 50 for me without the pixel problem:
CODE

DISPCLKDIV: 17
HSWID: 26
HSSSTR: 9
HSEND: 9
VSEND: 22
DESTR: 37



These put it really near 60Hz, but not perfect (will try to do something about that later):
CODE

DISPCLKDIV: 17
HSWID: 1
HSSSTR: 0
HSEND: 0
VSEND: 7
DESTR: 34




What I want to know is if it is the same on other people's units. What about mk1? Can YOU help me to find out by some testing?

 

[TelcoLou]

I've got a MK I ... I'll test this out in a short while and report back

 

[geo12]

Works exactly the same for me, DISPCLKDIV between 5 and 17 makes the bottom right pixel go away.
I'm using a MKII with firmware 3.0

I don't really understand what this means, but I hope it helps

 

[TelcoLou]

OK,

I have a MK I, FW 2.1.1

The bottom right pixel-thing gets fixed the closer I move DISPCLKDIV to 17, but then I notice a slight flickering on the screen. Also it makes the 2 lines move slower.

 

[slaanesh]

This might also be useful for MAME.

How configurable is the LCD slider? MAME emulates hardware that usually has a refresh of 60hz though 30, 40 and 57hz exist.

 

[notaz]

OK,

I have a MK I, FW 2.1.1

The bottom right pixel-thing gets fixed the closer I move DISPCLKDIV to 17, but then I notice a slight flickering on the screen. Also it makes the 2 lines move slower.

Can you try setting these settings and see if you get 50fps?
CODE

DISPCLKDIV: 17
HSWID: 26
HSSSTR: 9
HSEND: 9
VSEND: 22
DESTR: 37

How configurable is the LCD slider? MAME emulates hardware that usually has a refresh of 60hz though 30, 40 and 57hz exist.

Well I don't think you can get perfect 60/50Hz (or whatever) with the gp2xmenu's LCD slider, I am just trying to find MP2520F register values which would work for everyone without flicker, etc. Once the values are known, then I will be be able to write a guide "how to set LCD refresh to perfect 60Hz", or add a lib or something.

 

[notaz]

I have updated my test to this. It now can adjust UPLL clock and the divider. It should be possible to eliminate that pixel problem by adjusting 4 first parameters, I have found some, but the problem still comes up when I change the bpp count.

 

[grahf]

I'll test this tonight on my 1st edition MK1 notaz.

 

[grahf]

Using the first settings, i get a rate of 50. No messed up pixels.
Using the second settings, i get a rate of 60. no messed up pixels.

What do you want me to check for?

 

[notaz]

Using the first settings, i get a rate of 50. No messed up pixels.
Using the second settings, i get a rate of 60. no messed up pixels.

What do you want me to check for?

Thanks. I just wanted to see if other people are getting similar results to mine with those settings.

 

[rememberthe8bit]

I have updated my test to this. It now can adjust UPLL clock and the divider. It should be possible to eliminate that pixel problem by adjusting 4 first parameters, I have found some, but the problem still comes up when I change the bpp count.


If you run this, will the settings remain in the registers after you've exited?

 

[notaz]

If you run this, will the settings remain in the registers after you've exited?

Yes, they will remain until you restart your GP2X.