Well, I reached a big milestone with my GDDDS towards the end of this week: I got it working!
Yes, I successfully used it to display an image on one of the groups prototype panels. Over the last week or so I've ironed out quite a few problems with the system. It now takes less than three seconds to download an image into the framebuffer, rather than seven minutes, and it works more reliably in general.
There's just one hitch though: I've got an op-amp that's misbehaving -- or rather, is overheating -- due to my miscalculation of the amount of current it could supply, and I think it might have finally died on Friday. This despite having fitted it with an enormous heatsink.
I've only got about a week and a half left now, so I'm going to write the user manual first and only then worry about the op-amp. I think I've got enough time to get everything working, and then I need to prepare the presentation of my project and results to the rest of the group.
In some ways, it's been very stressful for the last few weeks, but in others very enjoyable. It was really satisfying to see an image finally appear on the panel, and it makes all of the work I've done this year into something really worthwhile.