Aaron Shaw from Pi-Supply sent me one of his early Gert VGA 666 adaptors for testing and comment, so I thought I’d share my findings. I followed the diagram in Gert’s manual. It’s a fairly simple build, just 20 resistors and two connectors. It took about 20 minutes, being careful to get all the resistors in the right places.
The hardest part was the stacking header. The final product will ship with a slightly shorter stacking header. This should be a bit easier to solder.
To get it working on the Pi, you need to follow the instructions to the letter. First time round I missed that I needed to copy and rename a file, but I soon found my error.
It uses a dpi interface on the BCM2835. It works quite well, although if you get really close to the screen you can see a bit of shimmering (you can see a close-up of that in the video, but it makes it look worse than it is to the naked eye).
I changed the supplied 120 Ohm resistors for HSync and VSync to 80 Ohm, to see if it got rid of the shimmering, but it made no appreciable difference on my Samsung SyncMaster 2333HD.
If you’d like to get hold of a Gert VGA 666, here’s a link to Pi-Supply