Infrared over Headphones
 

I've recently been researching how to access the infrared hardware on the newest crop of Android phones, and stumbled across something interesting -- there have already been several attempts to port the LIRC server to Android. This surprised me, because up to now most Android devices lacked IR; however, all these ports were using LIRC's audio interface.

"Audio interface? What audio interface?", I asked.

As it turns out, there's a surprisingly simple way to generate IR signals via a sound card. Not being a hardware person, I've been ignoring the various hardware hacks described on the LIRC website; however, it seems that this particular hack is usable on cell phone devices. In fact, at least one group has put together a battery-boosted version of the audio-jack IR transmitter.

Also interesting to me is that there is an infrared receiver device also able to be connected to a sound card.

The possibilities are intriguing; this could be an easy way to bring IR to phones like the N9 or the upcoming Jolla phone. Also, having an IR receiver could allow the N900 to be turned into a "learning remote".

However, as I may have mentioned, I'm clueless when it comes to hardware. A question for those who are not: just how tricky do these LIRC hardware hacks look to you? What sort of risks do you think they pose when used with a cell phone? And, about how expensive would you expect the final product to be? :) The "Irdroid" device appears to be selling for $36, and I'm thinking of picking one up asap to get my own app (Pierogi) working with it, but it'd be nice to be able to offer these audio IR ports at a somewhat lower price...

Re: Infrared over Headphones
 

you mean something like this?

http://www.mactech.com/content_image...9848426816.jpg

check out:
http://www.mactech.com/2004/08/06/ip...remote-control
and
http://www.instructables.com/id/DIY-...r-iPhone-iPod/

Re: Infrared over Headphones
 

Hold your breath man i told you keep up the devlopment when asking a java one.
Coz there is to be a wave of ir devices by chineese oems followed by brands:)
i personally saw 2 tabs and a phone with ir port.
Also i saw a andro or java?? Might be propetiary tab with kick stand having a seperate media remote insted.
Cant comment on the ext ir as when i asked today they said it a scam but saw a guy using one they asked him he said it works limited possiblites::

your universe just got a byte better:)

p.s. Dn ask about those devices. They are chineese gadgets who always come with something intresting to sell there products some are good enough even saw a device much earlier with ir gesture sensor..

Re: Infrared over Headphones
 

It is very simple to make and there is no way to justify the $38 tag. DIY production would be about $5 if you buy all the components, although most hobbyists will be able to bash it together for free from random bits they've found in the drawer. And it's cool because sending an IR signal is as simple as playing a prerecorded audio.

There are no risks to the phone that I can think of. The load the LEDs represent is about a quarter of a load presented by your average headset, so they won't damage your audio output. The LEDs do, however, require a bit higher voltage (even though less current) than the headphones. Which means there might be the risk of the phone not producing a high enough output to light them up. Does anyne know what the max audio power is? Anyway, if it turns out not enough then a boosted version would do the trick. And while we are playing with the boost, we can as well double the IR frequency with no changes to the phone, at the cost of using 4 LEDs instead of 2.

The input might be a challenge though. How I wish there was an external mic or line in on my phone!

Re: Infrared over Headphones
 

Er, the earphones that come with the N900 have a microphone (for use in talking on the phone) -- wouldn't that mechanism work just as well for general audio input?

Re: Infrared over Headphones
 

This covers my thoughts on IR power I guess you haven't read it?
http://talk.maemo.org/showthread.php?t=25998

Personally I would look at investigating Bluetooth Infrared transceivers.
After my attempts at making a IR repeater failed due to too much IR noise, bluetooth would solve this and the range issue in one.

Re: Infrared over Headphones
 

Nope, I missed that one. :) I guess that's why the Irdroid dongle has includes a battery...

Yeah, I suppose I should look into that as well. I've been trying to avoid Bluetooth for a while, it seems like a lot more hassle to work with than IR. :)

Re: Infrared over Headphones
 

Hey, it's great idea! If you manage to come up with writing/porting some software to control it, I'll gladly patch-up a receiver and transmitter and send it to you, of course as a donation.

As you've said, it might be nice idea to boost N900 Ir output power:
http://cache.gizmodo.com/assets/reso...er_tvbgone.jpg

...while still keeping "brain" processed by N900 (like with Pierogi), allowing much better functions, than any "learning remote" in universe (like stateful AC control).

Keeping my thumbs for it!

/Estel

Re: Infrared over Headphones
 

I wonder what the frequency response of that mic input is. I would not expect it to go far beyond 15kHz, and even that is very optimistic. It is probably limited to something like 4kHz, just enough for speech. The carrier frequency on many remotes go to tens of kHz.

Re: Infrared over Headphones
 

Actually, I'm kind of late to the game with this. The LIRC server has apparently had support for this particular gadget for some years. (Of course, this also means that Irreco & co. have as well, as they are all using the LIRC server.)

So, in short, your N900 can already control it. :)

Let me see if I can't get the same support into Pierogi. I can probably get the software to you faster than you can get the hardware to me... :) :) (Of course, adding "learning" functionality to Pierogi is another question, that'll take a lot more effort.)