Once I have finished my N64/GBA project, I thought this would be a good project:
I have a GP2x, nice little system, especially for emulation, however the screen is small, buttons not in good places, and bad control system (you can easily replace the joystick with a D-pad, not difficult, but that doesn't solve the other issues with the system).
TV output from the GP2x is bad, it gives 320x240 output via RGB to its own LCD, but outputs in a different resolution, something like 320x228 or whatever, so lines are missed and it looks a bit wierd: also tv out quality is bad. You can output via S-video, but there isn't a lot of point as the system skips lines on the output. Also, as if this isn't bad enough, the colours are washed out (at least with PAL, NTSC isn't so bad apparently).
Here is the question: how would I be able to trace the lines from the chip or traces to find out which points to solder wires to for the RGB, C-sync and ground? I don't believe anyone has found these before (or maybe tried), so I am on new territory here for the GP2x. If the answer is "with a multimeter", what readings so I look for, and what do I get my multimeter to look for please?
My thoughts are that if I can get this RGB, then one of two things will happen: either the PSone screen will take the 320x240 and make it fullscreen (640x480) or just show a quarter sized screen (320x240), I won't know until I try it. If it is fullscreen, proper RGB, this system will be worth making a proper case project for!!
Any ideas guys? - I know there has to be a way to do this investigation, after all, it will be the same type of probing I would have thought as other people have used when locating the RGB connections on other games systems.
Finding RGB on a mobo, not in this forum (technique?)...
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Best bet would be to find the datasheet for the chip outputting the composite video, and seeing if it outputs RGB to certain pins. I bet a decent wiki on the hardware of the GP2X should have what chip does composite video, and would likely link to the datasheet for it.
Barring that, you'll need an oscilloscope, and you'll be looking for analog signals. Take C-Sync from composite using a LM1881 or similar. Then plug the analog signal you find to either R,G, or B lines and see if a display is rendered. Just trial and error to find the right color lines.
Unfortunately, it is entirely possible the GP2X doesn't have analog RGB, only forms of digital RGB.
Barring that, you'll need an oscilloscope, and you'll be looking for analog signals. Take C-Sync from composite using a LM1881 or similar. Then plug the analog signal you find to either R,G, or B lines and see if a display is rendered. Just trial and error to find the right color lines.
Unfortunately, it is entirely possible the GP2X doesn't have analog RGB, only forms of digital RGB.