On Sat, Oct 19, 2013 at 11:15:38PM +0100, Wayne Stallwood wrote:
To be honest that is quite a tough one. Most of the good places tend to be a bit device/platform centric.
Yes, I was going to reply to the OP in much the same vein, but was too lazy! :-)
I have some similar projects (in particular some work for amateur astronomers and also instrumentation on my boat).
As to how to decide what to use then I'd say it really comes down to how much of an OS your project needs, all the platforms you mention would be capable (at various degrees of overkill) of doing the two projects you mention.
On the Pi/BB you have the advantage of doing it all in userland at a very high level if you want, and using pretty much any language.
Arduino you get simplicity and the fun of doing it relatively close to the metal, but you are pretty much stuck with Arduino's Pseudo C++ like language (though if this sort of development tickles your fancy and you want to expand to other projects you can of course move (and even port your existing projects to) a grown-up AVR development environment quite easily)
I actually have a Pi and an Arduino and also something called Pokeys56E, none of them is anywhere near ideal. The difficulty is mostly in the nitty gritty hardware intefacing, getting voltages into the device in such a way that it's unlikely to kill it if/when spikes and noise come along.
Currently on the boat I have an ancient 7" eeePc with a 1-wire to USB interface and sensors on the 1-wire bus. 1-wire is good for various measurements but doesn't seem to have voltage sensors. In fact *nothing* seems to offer decent voltage measuring sensors, there's lots of things with "A2D inputs" but nothing that offers an 'outside world facing' capable one.
In fact for your colleagues project there is something on arduino.cc which is already 80% of the way there.
http://arduino.cc/en/Tutorial/Datalogger.
Personally I wouldn't consider a Pi in any application where I didn't need it's Gfx/hdmi capabilities but that's because outside of those I don't believe it is a very good platform :D
It has the advantage of being really cheap though, same sort of price as many Arduino variants and *much* more accessible, especially to Linux aware people.
If you want something with a bit of both there's the Beaglebone Black, runs Linux but has lots of Arduinolike I/O capability. A little more money but not by much.