Standalone Gameboy Player

It's been a while, so it's time for an update! Previously I started to integrate a different HDMI encoder; I made some progress with this but didn't get it fully working and I ran out of steam. After coming back to this project a while later, it transpires that Zwenergy had swapped out the HDMI encoder used by gbaHD to an external one and by the looks of it, the one I was trying to use!

I'm really happy with this at it saves me the effort, although unfortunately it still isn't fully compatible with my TV - again the horizontal positioning doesn't sync and there is no sound. As better compatibility is claimed, I tried something that didn't work before - hooking it up to a HDMI converter.

I recently got a CRT TV and I'm using a basic HDMI to composite converter with it, so I tried it with that. Et voila - we have video and sound! The aspect ratio is wrong as gbaHD output is 16:9 and the TV is 4:3; I'm planning to re-fork gbaHD and synthesise a version with a 4:3 ratio.

Of course, this kind of defeats the point of having HDMI output when there are other options. It still gives me the ability to use other adaptors - I have a HDMI to VGA adapter to test too - and if gbaHD is developed further then compatibility with my awkward TV may still happen!

After the issues with the vertical alignment and sound output with the HDMI encoder used by gbaHD, I went in search of an alternative encoder. I've been working to integrate hdl-util's HDMI 1.4b encoder; when I tested their demo I got sound and although the vertical alignment issue persisted, the much smaller vertical sync size means that it's far more likely that the GBA video would appear fully on my TV.

One idea for the vertical sync is to hold the output on the GBA clock on startup for a few cycles. It'd be a bit of a blunt workaround but may help for my particular build and setup.

I haven't yet got a workable output, which I think is down to getting the timings just right. The GBA video needs to lead the HDMI video, but if it's too fast either the line buffer will overfill or the GBA will do a frame refresh before the HDMI video has been drawn. I need to work on a model of the video timings so I can find the right balance.

Updates from here on will probably be a bit slow as I take it a bit easier on this project. And if new Analogue Pocket pre-orders come up before I've completed this, I'll probably mothball the project. Hopefully I can get it working before that!

Progress has been a bit slow but I've finally got some form of video output thanks to Zwenergy's gbaHD project. It's not correctly vertically aligned, which I think might be due to a poor SPS (vsync) connection. I also don't have audio output; it seems hit or miss if your TV is compatible with the audio output format. I'm using a SNES Classic Mini controller as opposed to the original SNES controller and that seems to be working fine. Finally I noticed I'm not getting GameBoy Player features (okay, just rumble really) in games which I have some thoughts on why that's happening, although actually having working rumble is beyond the scope of what I'm planning. I'll be updating the project details slowly with more details on the above developments!

I designed and ordered some flex PCBs from Oshpark to make it easier to tap into the test points on the Gameboy Player.

My designs are simple - I found a couple of minor issues where I got the alignment of a couple of pads out and I could have taken a bit more time to include a few more test points, routing the PCB(s) around other components.

I found it fairly easy to solder the boards in and they'll make it much easier to solder wires to the test points, as well as providing some much needed mechanical strength to the soldered connections to the test points. I can also tap into some of the test points with pigtail clips before committing to soldering wires.

I started this project after coming across InsideGadgets AdvanceVGA board, which adds VGA out to the original Gameboy Advance. I ordered one last December and I can't wait to get it working with the Gameboy Player. Since then I'd also come across the GBAHD project, which uses a SeeedStudio Spartan Edge Accelerator board with an FPGA to add HDMI out. So I thought, why not try both VGA and HDMI out?! I'm excited as this will be my first FPGA project. It'll be a while before I have time to get it working, but I'm looking forward to it and with the help of Codemasterv who has also been investigating the use of GBAHD with the Gameboy Player hopefully we'll crack it sooner rather than later!