I went to the Cambridge Jam yesterday and displayed HDMIPi production model #1, met lots of people, including Eben, Liz, and a multitude of Pi enthusiasts and bloggers (quite normal for a #CamJam). There was also a CNBC news crew there to film some Pi action. They shot a brief clip of me doing something like this…

Matt Hawkins @RPiSpy kindly took this one for me using my camera. Good job he’s not a monkey, or we might have a copyright dispute. It was really nice to spend some time chatting to Matt. (Thanks for taking the photo Matt.)

Gert Brought a VGA Adaptor

Demonstrating on the table next to me was Gert van Loo, one of the chip architects of the Raspberry Pi’s BCM2835, most of whom seem to be working as RPF Engineers and moonlighting as Ninjas these days (Gordon & James, I’m looking at you). Gert designed the original BCM2835-based Raspberry Pi prototype, the Gertboard, GertDuino and the camera board. He’s also got some other stuff in the pipeline that’s not ready for prime-time blogging.

Gert was displaying a VGA adaptor he’d made for the B+. He said that there was a parallel interface on the BCM2835 that could be used to drive VGA natively in hardware (with no CPU load) But only on the B+ are there enough ports (and the right ports) brought out to pins to be able to use it.

It Uses Nearly All The Ports

It uses all but four of the B+ GPIO ports. It basically consists of a 40-way header, and a resistor ladder digital to analog converter (DAC) and a VGA port. He’s designed it so that it can use surface mount (SMT) or through-hole resistors and he’s open sourcing the whole thing some time next week. SMT resistors are more easily available in exactly the right values. He won’t be manufacturing and marketing it as he feels it’s not worth the hassle, and also it’s likely to have issues with EMC. It’s highly likely that it would cause radio frequency emissions, which, for a manufactured product is a big ‘no-no’. But that doesn’t mean we can’t make our own from the plans.

Update 10/9/2014 Gert has now Open Sourced this at https://github.com/fenlogic/vga666

It’s capable of displaying 1080p60 VGA video with no CPU load. Here’s Gert displaying a 1080p VGA signal using his adaptor.



VGA & HDMI Simultaneously

It’s also capable of running VGA and HDMI independently and simultaneously (or will be in a few days, when Dom has modified the appropriate files). So you’ll be able to plug in an HDMI screen, like HDMIPi, AND a VGA screen and have them both working independently at the same time.

I asked Gert if it would later be possible to run VGA, HDMI and DSI all at the same time. He said that might be pushing it.

I will likely get a few PCBs made for fun, but I don’t think it’s one I’ll be kitting into a product. If a lot of people want the PCB I might arrange a group buy for that, but you’d have to sort out your own components. Leave a comment if that sounds interesting to you.

It was an excellent Jam as always. Hearty congratulations to Mike @recantha and Tim @Geeky_Tim and make sure you check out Piwars, which is going to be the December CamJam’s subject matter.

Other CamJam blog posts…