DaveUK
Posts: 1
Joined: Tue Jan 10, 2012 1:58 pm

Re: IR Remote Controller

Tue Jan 10, 2012 2:08 pm

I tried a Gear4 UnityRemote, but unfortunatly it didn't work too well for me.

http://www.gear4.com/showcase-unity/

I'd like to create my own version of the device using the R. PI. with iPhone/iPad sending commands which would get translated into IR output.

Not sure how I'd do the IR bits (will need to read a book I guess) - but should be ok with the software side.

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meltwater
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Joined: Tue Oct 18, 2011 11:38 am

Re: IR Remote Controller

Tue Jan 10, 2012 2:21 pm

I had a very simple IR device (single LED I think, EDIT: correction it used two…which was the neat trick it needed to work) working from an audio output, did the job very well in fact (just needed to do some processing once you"d recorded the IR signal for it to be used).

I can dig up some details on it if you are interested (hopefully the wiki pages are still around).

As for doing it properly, there are a number of ways since the siginal is modulated, you can try to modulate it yourself using the I/O pins (which may depend on the speeds you can switch) or you can feed it into a hardware modulator.  Of course there are a few off-the-shelf IR-Blaster type solutions available too.
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rajn
Posts: 8
Joined: Fri Jan 06, 2012 9:38 pm

Re: IR Remote Controller

Wed Jan 11, 2012 4:15 am

What about the wifi qwerty key board style remotes available these days from the chinese suppliers , can pick them up anywhere from 15 - 18$/pc

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Gert van Loo
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Re: IR Remote Controller

Wed Jan 11, 2012 8:11 am

Recently on the Microchip website I came across chips which do IR to UART conversion. Including, they claim, with handling some of the IR protocol. Just connect between an IR transceiver and the Raspi UART. That will make your interface and programming dead simple. The Raspberry-Pi has the capability to output a clock (with programmable frequency) on one of its GPIO pins so you can use that for the baud rate input. I have no idea what baud rate is required.

Wooloomooloo
Posts: 92
Joined: Fri Nov 25, 2011 10:52 am

Re: IR Remote Controller

Wed Jan 11, 2012 9:00 am

I suppose it depends on how exactly you want to go about it: do you want to use an infrared communication channel (like IrDA) between two devices or a consumer infrared protocol (like RC5) between a transmitter and receiver (like traditional remote controls)?

The thing is that a) IrDA always had a bad reputation for anything other than immediate vicinity transfers (as in within 1m, face-to-face) and b) the Microchip circuits are specifically IrDA ICs as far as I know, some even going as far as having an entire autonomous serial-over-infrared (IrCOMM) stack on-chip. I have my doubts about how well can one use a dedicated MIR/FIR (IrDA) device for CIR (remote control) operations and vice versa, if at all - the signalling is quite different as I remember it.

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meltwater
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Re: IR Remote Controller

Wed Jan 11, 2012 11:29 am

Yep last time I looked at it, IrDA wasn"t usable, which at the time with a laptop and phone which had it was annoying.  The two are not interchangeable.

Will dig up those links if I can, but if I recall correctly, the infrared remote control signals were low rate bits, with a very high modulation frequency (twice the frequency the sound card could produce, but by using two LEDs with one reversed you could produce it on the -ve side of the soundwave).

Ok, here"s some details I"ve dug up off my HD from 2 years ago, I recall the signal I used were similar to the ones on this site (although the protocol may have differed – certainly start burst applied):

http://www.sbprojects.com/know.....r/sirc.php





Based on this blog [http://jumpjack.wordpress.com/2008/05/], it was possible to record and play back the signals.

By using very basic circuits I was able to directly record the IR signal through the soundcard via a IR LED, directly from the remote.  The waveform is the kind of signal you get to start with.



In that form, it then needed some extra work to be usable to transmit the signal out again in the correct form…

To this end, I ended up creating a script within Audacity to do this, see the following section of the Audacity wiki (http://wiki.audacityteam.org/i.....t_Commands).

You end up with something similar to:



I did also experiment with attempting to capture signals via the serial port and sending out again, but it seemed like the signals weren't very reliable.

As it happened, the soundcard method was enough to remote control my freeview box, by using a video capture card to see it and logmein to view the connected PC.  Also (since the box was prone to freezing-up when transferring files from it) I could use an IR signal to reset the power too (using a IR power switch).
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