Gameboy Player PCB

I'll state for the record (and a free thread bump for those hoping for more attention/insights) that my only goal was to make the GBP look decent on a CRT without having to buy component cables, so the only thing I bugged the developers about was 240p forcing. Changing timing further will be a much more difficult endeavor, so I might suggest asking those on the software side of things if it would be plausible, specifically the Swiss video patch developer Extrems. This could at least get you one step closer to a proof-of-concept.

 

When he said it was difficult on that thread I think he meant matching the refresh exactly would be difficult.

Getting close (to halfline resolution at least) looks very plausible from what I've gleaned from the yagcd. That link shows all the video registers along with the values corresponding to pal/ntsc/pal60 modes. Unfortunately it doesn't have values for 240p or information on how to calculate things.

If we could get the 240p values it would help figure out a way to calculate a screen mode closer to GBA. One possibility would be dumping the video registers using Dolphin emu with a 240p game like MMX colly. I don't see any way to do that using debug mode though. Maybe there are special debug builds. The register values must be contained in the save states so that's another possibility for extracting the numbers.

 

Any progress on this? I'm perfectly fine with the framerate in 240p, but I didn't want to discourage anyone looking for more accurate results.

Question- I've heard the Super Gameboy (even the Super Gameboy 2) is much worse regarding mismatched framerate, is that right?

 

I have stripped a GB-Player pcb yesterday and uploaded the hires scans here:
https://www.dropbox.com/sh/w8fv38h2xrett7x/AABkX7Z1ZcIsq6W8taO3I_Qma?lst

Also I made a list of all components:
https://dl.dropboxusercontent.com/u/27485470/gbplayer_components.pdf

I want to rebuilt the GB-Player and basically exchange the GBS-DOL for an FPGA to get 240p/15kHz RGB from the CPU.
(Not doing the fpga-part but I have someone workin on it who's really capable of doing it).
Since there are no schematics available for any of the GBAs I'll do that on my own.
Right now I'm having a hard time identifying the ICs, if anybody here has an idea what these are (in the list, labeled P1, A7, N1 etc) please help me out with that info.
Also if someone would like to confirm my readings for resistors and caps that would be very much appreciated. Thanks!

 

? The GBA always puts out 240p RGB

To fix the under/overflow glitch you can synthesize the GBA's clock to synchronize the two systems.
First you need a deterministic GC control signal that can be divided into a 50% duty cycle reference signal using a flip-flop and/or multivibrator.

Then using a fractional PLL:
Reference signal -> ~54000000, ~54000000/4/858/[263 or 262]*280896 = ~16.8 MHz synchronized GBA clock

 

Yes, the GBA's native resolution falls into the 240p specs, but you don't have many options for a flawless presentation on a TV in 240p. The GBP outputs 480i or 480p, the TV-adapters do the same and what I wanna do is turn the gba into a stationary dedicated console system.
I added scans and strips of the AGB. I'm already working on the schematic for pcb layouting in eagle. I could use some help because I'm having trouble finding datasheets for all the SOT ICs (5 Leads/3Leads and diodes).
Here are the scans:
https://www.dropbox.com/sh/w8fv38h2xrett7x/AABkX7Z1ZcIsq6W8taO3I_Qma?lst

 

I see what you mean, so it's a consolized GBA with nothing to do with the GC (which handles the video scaling and output entirely).

If you're going to make your own console, you need to change the GBA's clock for ~59.94 Hz vertical timing, but then also derive another synchronous clock frequency with approximately square pixels @ 4:3 for the re-timed video output (4.6 MHz). Without clock gating the GBA to synchronize the two or deviating from the standard video frame timing, this will be difficult.

 

Yes! It seems doable with an fpga and intelligent frame buffer, I don't do the fpga-part. I need help identifying components on the GBA mainboard, those transistors and diodes have codes like M.C, 6E, N1 R SC...
Please have a look at the scans of the GBA (AGB) that I've made here http://goo.gl/RBYHv5
If you have any info about these parts that'd be awesome! Thanks!

 

You could try posting on the forum at http://www.eevblog.com/ there are guys there who know a LOT about electronics and may be able to identify some of the strange parts.

 

Never thought of that.. but actually that's a great idea. THANKS!

 

The exact transistors and diodes can't be identified, but it doesn't matter, they're small signal transistors and switching diodes. You can measure if the diodes are Schottkys and their arrangement, which is what's important.

 

The GB Player is a strange device. Very simplistic. I don't really know what the GBS-DOL (I think by NEC) chip is. I assume its a communication chip of some kind. Any thoughts?

 

Most likely converts the LCD data that the AGB chip outputs into a format that can be read by the port on the GC.