I believe it was late in 2012, I purchased two Raspberry Pi Model Bs. These were the first model Bs, so they only had 256MB of RAM and no mounting holes. I had no real projects in mind when I purchased them. They just sounded really cool. A working computer that ran Linux and had GPIO capabilities, for $35 plus peripherals. Sounded like a cool little toy! Especially since, at the time, I was using SBCs at work that ran Linux and had GPIO. However, they were at least an order of magnitude more expensive!
At the time I didn't have a tv with HDMI input and the RCA inputs were already used. But, I was able to find an HDMI to DVI cable to use with the monitor I had that was DVI capable. I installed Raspbian on an SD card, booted it up and poked around a bit. I didn't get to any programming on it as this wasn't too long after my second child was born. So, needless to say, not much happened with them. They got put in a box, not to see the light of day for a while.
Fast forward this spring. My brother was researching the use of solar heating water. He wanted to control some pumps and valves programmatically. My immediate thought was an Arduino. But, then, I thought of the Pis I had in a box somewhere. Overkill, but definitely would get the job done. So, I dug one out and lent it to him. This got me thinking about what I could do with the other one again.
Then, back in June, the company I currently work for did ShipIt Days. You can read more about the idea here, but basically, it's 24 hours to implement some idea. The group I was involved with put together a small roof-top garden. What the heck does that have to do with a Pi? Hang on. Technically it's a wicking garden and it was based off a garden we found on Instructables. Again, where's the Pi? Well, our idea was to have a Pi monitor the level of the water in the reservoir. We wanted something to email us when the water got low. The idea turned more into a proof of concept since getting the materials for and building a garden, building the garden, and troubleshooting the problems that arise from scaling down someone else's idea is about all you can accomplish in 24 hours. We wound up taking a sump pump float switch, some perf board and a couple of resistors (which I found out later was un-necessary) and hooked that to a couple GPIO lines on the Pi. The float switch got mounted in a bucket. When the switch is up (full of water), it is an open circuit. When the switch is down (the water is low), the switch closes. Since I have the GPIO line pulled high, this causes the GPIO line to go low.
Now, something to monitor it. Conventional wisdom says, write a python script to monitor the GPIO line and send an email when the line goes low. Well, none of us had previously worked in python. Did I mention we only had 24 hours? Well, we found a cool project called WebIO Pi. You can find more about it here. It's a pretty cool project that interfaces with the GPIO on the Pi. It has it's own little web server that will display the status of the GPIO lines. It will even let you control the inputs via a web page. Among other things, it also provides a RESTful interface to the GPIO lines. Now we're talking! It was rather quick work to make a small console application in C# that could make the appropriate REST calls to monitor the line in question and send an email when it goes low.
Since then, the B+ came out. Conveniently, it was about the same time I received a bonus at work. So, yeah, I bought one with a few accessories. A case, a breadboard and a few electronics components. Now, what to do with it? Since the kit came with 3 LEDs, I decided to simulate a traffic signal. It should be an interesting way to learn something about python. So, I plan on adding a project page for this and chronicle my progress. I have a few ideas for some iterations. Heck, I might even look for a real traffic light to put it in. I've seen them at the flea markets I've been to.