I am not perfectly sure if this is the right forum here to ask this, but I started to think if I could control my arduino from my N9 (via USB). Searching here or in the internet did not give that much results.

So, in my understanding there are a few separate issues:

-could n9 USB be used for serial communication?

-I guess there would be no problems in installing/compiling avr compiling tools into N9?

-could N9 usb be used to power arduino? (I'd guess no, but
this is not critical)

-And how about the arduino IDE? As it is java based, in practice easy debian would be only even theoretical possibility? (Again this is not that critical)

I know that probably this would be easier if I just went and bought bluetooth capable arduino, but I'd like to try this first.

So before I start to bang my head against wall while trying to learn new things, I'd like to hear if this is even theoretically doable

Well, plugged arduino and n9 together via usb, and as I thought, n9 won't give power to arduino. At least without any tricks that currently are beyond my knowledge. So I guess I have to shop something that lets me power arduino up without usb...

It'd require USB host mode. Which isn't totally impossible on the N9 so it seems. Still, even if that hurdle is taken, I don't know if the N9 supports the USB comm profile out of the box. Then there's the thingy with power. I guess the N9 can provide enough juice to get an Arduino running, but that might not be enough to power the various extras you hook up to it.

It might be possible to get the other tools running. And even the Arduino IDE might just run, as there is a working J2SE runtime for ARM which can run on the N9.

So yeah, my guess is it would be possible, given enough effort. But if it's only for the "just because I can!"-factor, it seems to me this would be way too much effort.

Bluetooth might be a better option - and indeed I'd like to know if that's going to work easily. It would allow for very easy communication without other requirements, once that communication channel is established. But if you're planning on using it on your home network, an ethernetshield is probably by far the easiest solution. You can communicate using HTTP, which makes it possible to use it directly from QML.

Do you mean host mode is needed for power or power and serial communication? I was thinking to give a try and see if I could use pyserial, but I need first to power the arduino up with something else than usb.

For both. But it's perfectly possible to use an external power source and USB at the same time. Older Arduinos have a jumper, newer Arduinos switch automatically.

Okay, I had hoped that serial communications might work without host mode, but if that is not the case, then that makes it a bit too complicated for my taste at least for now.