My next ‘real’ project involves implementing a web interface to control some of the things around swan tron global HQ, the half of the garage I reserved for my lab. I’ve been a huge fan of the Raspberry Pi since the mission was announced. Linux and IO…you have my attention. Add in the $35 price tag and my penchant for destroying hardware…huge fan is correct.
Before I start planning my real project, I need to figure out how this differs from the microcontrollers I’ve used in the past to deal with similar implementations. I know the CPU is going to show itself, but not to what extent. Time to start poking around.
I decided to horse around and knock out a few birds with one stone…python library, digital out, and basic pin function. Oh, and LEDs. Everyone loves LEDs.
Prior to this effort, I have mainly explored the rPi via x. I’ve spent a decent amount of time inspecting the file structure (Debian, no surprises) and the xwin UI. It is no speed demon, but it does the trick. I have the wireless adapter configured and set to auto-start, which was most of the battle. It basically performs as advertised, which on paper is very awesome for the price.
My general setup for this was very simple. I bought a cobbler set from Adafruit, which acts simply to pull the IO pins out to a breadboard. Two LEDs, two resisters. A few jumpers. Very simple.
I booted the device, and used aptitude to update and snag the rPi GPIO library.
sudo apt-get update
sudo apt-get install python-rpi.gpio
That does the heavy lifting with the python implementation…sample code is available on the main python site. The update was I used vim to create a dirty python script…unworthy of a repository, but worth a pic:
The digital outs worked as anticipated. Timing was a bit odd…I ended up playing around a bit with some pauses in order to tune the blinks as I wanted. It looks like coordinating pin outs might be tricky for more complex operations, but at least the library and hardware is up and running.
Don’t take my word for it:
The next steps will be interesting. Figuring out how to ssh into the box in order to run a script of this magnitude will be next, followed by profiling the voltage on the pinout. It should be able to throw my 5v relay with a little tweaking…if not I’ll figure out PWM and tackle the switching mechanically. Fun stuff to come…happy to be playing with the rPi finally. Stay tuned.
