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Hardware > GBA Micro Video Signals: let's try again

#60734 - jgarneau - Mon Nov 14, 2005 6:05 am

For some reason in addition to my post being edited in the other thread, which I understand because I linked a bad URL, the topic was locked. Let's try to answer my question again here:

I was hoping to send the GBA Micro video signal to a large monitor. I know it's perhaps more easily (or at least more documentedly) doable with somewhat legit-looking Chinese equipment, but I was hoping to be able to do something that was a little less bulky, (I'm talking about a Micro here, and these were built for the original/SP) a little bit cheaper, and hopefully a little more DIY.

I figured that the gameboy LCD screens work off an RGB signal which is then converted by those chinese boxes into S-Video/Composit signal. I'm hoping to grab the original signal.

#60979 - FluBBa - Wed Nov 16, 2005 12:38 pm

The only one I have heard of doing homebrew style is Brian Provinsiano.
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#61007 - Joat - Wed Nov 16, 2005 6:40 pm

While it's certainly possible to tap into the micro video signals (should be 15 color pins, one or two syncs or blanks and a pixel clock), the resulting device will almost certainly not go back into a micro housing or anything resembling one.

Why not get a GB player, use your cube on a TV with a nice s-video cable, a micro link cable adaptor, and a gba link cable to cube controller port adaptor. The GB player allows you to use a GBA connected to the controller port as a controller, it has a built in joyboot program to read the buttons. Granted, if you were planning on just stepping up the display to something bigger but still portable, this wouldn't work, although I can't really imagine why you would do this (but I'm sure there is a good reason if it's what you are after), and in the same vein, a micro as a controller stinks, it's too small; original GBA works best as a GB player remote IMO.

If you don't already have the equipment (soldering iron and scope or LA at the bare minimum), buying a cube and a gb player (if you don't already own them) is going to be far cheaper anyways.

Having said all that, if you do decide to build it, here is some useful info:
the pixel clock on the GBA is 1/4 system clock = 4194304 Hz, each scanline is 1232/4 = 308 pixels, with 240 visible, 228 scanlines to a frame (59.727 frames/sec), 5 bits / pixel color *out* of the GBA, but I think most screens used are 6 bpp now, so they may actually have 6 lines per channel. Dunno if pixel data is clocked on rising or falling edge of the pixel clock, or the polarity of the sync/blank signals, never messed with he signals electrically.

CCFL man is doing a similar thing for the DS (well, in theory at least, he's been talking about doing it for ages), might get together and compare notes. The DS has a number of advantages (they built it to exactly NTSC timing specs, wonderful!) over the GBA for converting to TV, and one major disadvantage (two screens, so you have to either display only one screen at a time, or use two DACs with a pair of latches in front of them).
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