This past Saturday we held our second Raspberry Jam at The Columbus Idea Foundry. We filled the tables with Raspberry Pi enthusiasts and their projects. For many of my Raspberry Pi projects, I use recent Dell LCD monitors, the ones that can take a clip-on sound bar – these monitors have a 2.5mm jack on the back that provides 12V @ 1A to power the sound bar. By attaching an automobile accessory adapter plug to that, it’s only one more step to use an automobile USB charging adapter to power the Pi. One button turns on the monitor and the Raspberry Pi both. I already had the right sort of monitor mounted as the head for my “telepresence robot” project, so it made a nice monitor and display stand. For my show-and-tell project, I was demoing how to build hybrid Raspberry Pi/Arduino projects with Firmata. It proved to be a popular display. Most of the adults who came to the Jam knew something about Arduino and were intrigued to learn how to use them together. The kids liked sliding the widget on the screen and watching the LED grow bright and dim.
Most of the presenters brought software projects, but there were a couple of hardware projects which stood out. One gentleman brought a “laptop” made from a Motorola Atrix dock attached to his Raspberry Pi. The Atrix dock was originally sold to expand a smartphone into an Android laptop with a self-powered high-def screen, keyboard, pointing device, and USB hub. Apparently these were too expensive to be popular and can now be found in the surplus channels for around $50 and sometimes much less. The trick is that the phones have a micro-HDMI and micro-USB receptacle on the side, so the dock has male micro connectors, and the adapters are not widely stocked, even from sources in Shanghai and Hong Kong. The alligator clips in the picture are what this presenter came up with as a work-in-progress method of splicing his micro-USB and full-sized USB cable ends.
The Micro-HDMI adapter for my dock hadn’t arrived in time for the Raspberry Jam (it arrived a week later, after four months in shipping). I had been hoping to show off my own Raspberry Pi laptop, but since I couldn’t, it was good to see another one on display.
One of the other projects that stood out was Vince’s furnace monitor. Vince (on the right, below) is a retired software engineer who has been wanting to track his furnace performance but couldn’t find any off-the-shelf devices or packages to do it. He and I are part of a group of computer professionals who meet often at a nearby Chinese restaurant, so over several lunches, a couple of us have been giving him advice and finding components for him to build his own furnace monitor.
Vince assembled the prototype boards in the above photo. The six-pin ICs are optoisolators to protect the GPIO pins on his Raspberry Pi (there are many ways to do this, but with optoisolators, the furnace and the Pi don’t have to share a common ground – only photons pass between them). Vince also wrote some Python scripts to read the states of the pins, log the data with timestamps, and graph his logs. Eventually, he plans to set up a web server on the Pi to let him check on the furnace in real-time.
With all these great projects coming to our quarterly Raspberry Jams, I’m looking forward to what people will bring to the Columbus Mini Maker Faire later this year.