Nov 262014
Gert VGA666 from Pi-Supply

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.

Gert VGA666 from Pi-Supply

Gert VGA666 from Pi-Supply

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.

Gert VGA666 underside

Gert VGA666 underside

If you’d like to get hold of a Gert VGA 666, here’s a link to Pi-Supply

  12 Responses to “Gert VGA 666 review and video”

  1. […] Pi Supply are currently taking pre-orders for the VGA adapter board that they launched using a Kickstarter campaign. Alex Eames from RasPi.TV has got hold of an early one to have a play with and has blogged a quick video review here. […]

  2. Looks good, should hopefully receive my KS reward soon :)

    How well does it work with the VGA input on the HDMIPi? Did you manage to track down a ‘recommended’ VGA connector for soldering onto the HDMIPi board? I just think it’ll be fun to have all 3 inputs of an HDMIPi connected up at once to different Raspberry Pis.

    • Oh, and is the “shimmering” any less noticeable if you use a lower output resolution on the VGA? (as you might typically find on an older monitor)

      • I tried 1280 x 800 and it didn’t seem to be any better. It may just be the Samsung SyncMaster 2333HD? WJDK

        • Or it may be a side-effect of using a cheap resistor-ladder DAC? WJDK!

          Reading between the lines it seems like the DPI peripheral in the BCM2835 was originally designed for output to mobile-phone type LCD screens, and the VGA output is just another very clever Gert-hack :)

    • I haven’t tried it with HDMIPi. None of the units I have assembled have got a VGA port on. I’ll have to dig out one of the prototypes to try that.

      Not tracked down a standard part, since hardly anyone seems to want it.

  3. HDMI to VGA + audio out active converters are really cheap nowdays. They are about 10 USD from china. But only with Gert 666 VGA can you connect two displays in the same time to the Pi. With Pi2 maybe the performace will be fine also.

    • I haven’t tried GertVGA on my Pi1 or Pi2 yet, as it’s been sitting on the shelf since before Christmas, waiting for me to have a free evening to solder it together! :-/

      AFAIK the performance of Gert 666 VGA is entirely dependent on the GPU (i.e. the ARM doesn’t even know it’s there), and thus will probably perform identically on the Pi1 and Pi2 ? (although there might be a slight boost from the faster RAM speed?)

  4. Hello I am Samir I have used the above particular circuit for connecting a vga monitor to raspberry Pi. But whenever I connect another size display I have to change the dpi_mode number in the config.txt file for setting the best resolution. Is there any way to auto detect the best possible resolution if i change the display every time. I also had a observation that whenever we connect normal HDMI to VGA converter cable the I2C communication is ON so we can request the resolutions modes by certain commands mentioned in the Raspberry pi documentation but if we use the Gert VGA 666 adapter and when we do changes to the config file the i2c port is disable and we can’t request these required optimum display resolution. I was the end result as auto detection of the resolution and set it when a change of display happens. Please support me regarding this issue. Thank you.

    • I think the simple answer is probably no. This Gert VGA adaptor is meant as a clever hack, rather than a sophisticated solution. For one thing, Gert said it will spray RF all over the place so would never get CE/FCC approval. That’s one of the reasons he gave it to the world instead of making it a product.

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