Summary:
Creating an Infrared Emitter (and Receiver) Other Half + Software to use your Jolla as Universal Remote (like e.g. Logitech Harmony).


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The idea seems pretty obvious, at least to me, but I did not found anything about this. Therefore I'm going forward and start collecting ideas on how this can be done.

Hardware (The Other Half):
Since IR is a bit time-critical, especially sending, I think the timing should be done on a µC rather than on the Jolla itself.
The emitter/receiver circuit should be fairly simple, there are lots of examples in the net (see the link below in Interface).


Interface Hardware - Software:
The receiver should only be active when requested to safe power. (I'm not trying to make the Jolla be controllable by an remote)

For interfacing the Hardware with the OS we could use LIRC (http://www.lirc.org):
Pros:

• Network support for free
• Existing device database

Cons:

• Kernel driver needed (I'm not sure how to do this. Also the move of LIRC (or parts of it) into the kernel made this not easier)

I also found a nice project that can send and decode many IR protocols on an avr (it's in german: https://www.mikrocontroller.net/articles/IRMP):
Pros:

• Think it supports more protocols than LIRC
• Software just needs to read the decoded message and save it to be later send.

Cons:

• sending and reading libraries need 8kB on the avr with all protocols activated

Software:
What it should support:

• Profiles (living room, kitchen, friends living room). Unlike a Universal Remote, I have my mobile with me most of the time, so it's not stationary.
• Activities (chaining together signals, like e.g. Logitech Harmony does)
• User defined Layout for activities and devices. I never done QML before, but from a quick look at the reference and tutorials this should be doable.

So, what do you think? Useful, possible? Feedback and help welcome.