Simple IR to RF translator

Hi

I have a Harmony Ultimate remote that I'm using to control my TV, amp and so on.
I also have lights in the rom that is remote controlled (Elko wireless). The light is controlled by a RF controller. But the Harmony remote only transmits IR signals.
And I really want to have only one remote, so that I for example can select "View movie" on my remote and the lights is dimmed to a predefined setting.

So I want to be able to have my Harmony send an IR signal. Have that signal recived by something, then translated to a corresponding RF signal.
To ble able to get this to work I will probably also nedd a RF receiver of some kind so that I can figure out what RF signal the existing remote sends to the lights.

My idea is to see if I can find an IR receiver, an RF receiver and a RF transmitter for Arduino and make a small program that receives the IR signals and transmits the correct RF signals.

First I would like to hear if the idea itself seems resonable. And if it does, I would really like some advice for a IR receiver, RF receiver as well as a RF transmitter.

Best regards, TEK

Research NRF24L01+.

These RF tranceivers are very good and low cost.

For everything else just protoype it one step at a time. It is doable with a medium level skillset - probably not a first project for a beginner.

There are Arduino libraries available for both IR & NRF24L01+.
See IRLib or IRremote for IR.

You will need to work out how you existing wireless lights work.

If they use AM modulation (aka OOK modulation), you may be able to use use the RCSwitch library (which I think is still hosted on GoogleCode, but its best just to search for it.)

You will need to buy an appropriate transmitter module which matches the frequency band they use, but you'd need to figure out if they use 433Mhz or 315Mhz or 915Mhz ISM bands.

If they use 2.4GHz band etc, its going to be harder and I don't think that OOK / AM is used.

Also if they use FM modulation (or any other form of modulation e.g. FSK), its unlikely that you will be able to replicate what is required to be sent (not to say its impossible, it just gets much harder)

To receive the IR signals you just need the IR receiver device (3 pin IR receiver chip thing) and you can use the IR library

Depending on what size box you want to put it in, I'd suggest you buy an Arduino Pro Mini board, as they are really small and cheap, but you'll need a usb to serial adaptor to program the board, as they don't come with on board USB.
Or you could buy a Nano.

Overall, I suspect it will be possible to do what you want, but you'd need to sort out the wireless stuff with the lights first.

Thanks for the great input.
The light system is Elko Living System. Elko is a norwegian company, and I assume that it is not well known outside norway.

The documentation for the remote says that it's sending frequence is 868 MHz. That number does not seem to be any of the ISM bands mentioned by you rogerClark. Is that going to be a problem?

This is the exact remote I have: http://proff.elko.no/annet-tilbehoer-wireless/wl-fjernkontroll-8-kanal-rf-article168-328.html

There are some english documentation here that seems to be about the same product, but I have to say that I'm not 100% sure.

I assume that this means that they do not use the 2.4GHz band.

But how can I figure out if they are using a different type of modulation than AM?

Hmm, found this page: http://proff.elko.no/produkter/elko-wireless-quick-dim-article403-323.html
This seems to be the same "stuff" that I have in my wall (that the remote sends signals to).

It says: Radiofrekvens: 868MHz, GFSK-modulasjon, data rate 2,4 kbps.

..Sorry, I totally misread your original post.

Sometimes, it is possible to tap directly onto the buttons in the existing RF remote that comes with the light. You could hook that up to an Arduino which you control via IR. The Arduino would effectively 'activate' the buttons based on the IR signals received from your Harmony.

Risk: sometimes the original remote can be damaged if the wiring hack is incorrect. Can you get a spare RF remote to play with?

If you could manage to reverse engineer the RF protocol and find a compatible transmitter - that would be the best option. There are lots of home automation sites on the net to search for, that may have already covered this protocol.

Opening the remote and tapping into the buttons is not a wonted solution. It came with the house and is very expensive - and I would like to have it available for other use...

Building a Ardino based solution would probably be both better, cheaper and more fun.
Of course, if I found an existing product that would be an option.

Unfortunately 868MHz is not a frequency band used much in the rest of the world, and consequently the modules that are for sale on eBay are vastly more expensive than the equivalent 433mhz versions.

The cheapest receiver I cold find was $35 compared to around $5 for 433mhz.

Also if the system uses some form of FSK its going to be harder to use ( I won't go into the technicalities)

At least to start with, your best option if available is to buy a another transmitter unit and take it apart.

Initially you may be able to get the Arduino just to fake the buttons being pressed, but you may also be able to work out where the data line(s) are between the processor chip and the transmitter, and if so, you can record the signal patterns on these lines with the Arduino and get the Arduino to replay them, hence you will then just be using the transmitter unit in the unit.

I don't know if they are compatible with you system, but there are "duplicator" key fobs for 868 MHz, and they may be the cheapest option if they are compatible, but it could be your system uses a strange protocol that no one has build a duplicator for.

Overall, although this is do able, its probably not a project for a novice, or someone with no other test equipment e.g an oscilloscope etc

Hmm, that's a bummer.
However, better to find out now than after getting all the parts and wasting a lot of time. I will look into other options first than.

Thanks for your help. It was very useful, even if it dit not end with the resultat that I wanted.

@TEK73

No worries.

I've had similar experiences myself . I was hoping to build something that interfaced to an existing wireless door bell, but I found it was using a complex FM based data scheme, so had to give up as it would have taken too long to reverse engineer.

Also, with a wireless garage door opener, I ended up having to take the receiver module apart and connect an Arduino inside the receiver to replace the existing board, because I found that the key fob transmitter was using a strange frequency, so it was easier to modify the existing hardware I had, than trying t build something new from scratch

But, before I throw this idea away for good.
After looking around there seems to be 868MHz modules available, like these for example: http://www.futurlec.com/Radio-868MHZ.shtml.
They are 868MHz and datarate up to 115.2 kbps (lot more than the needed 2.4 kbps.

So I assume that I will - if I look around a bit - find resonable prized receivers and transmitters.
And if we look at this blogpost: http://arduinobasics.blogspot.com/2014/07/433-mhz-rf-module-with-arduino-tutorial_30.html
He is recording the signal from the remote and playing off that same signal.

All I need to do in my case is record the signals from the existing remote and be able to repeat them at a later time.

From my point of view it should be quite easy to recording the existing signals by receiving them on a RF-receiver, find a way to store them, and then at a later time, transmit that same signal using the RF-transmitter.
Based on my understanding this eliminate all need to know the protocol, using 3rd party libraries and so on. I only need raw read/write of the RF signal.

However, from what you describe this seems to be hard to do.

Is this because we have different expectation of what the solution should be? That you expect/think more is needed than what I think?
Or is this that I'm lacking some knowledge so that there is something in the suggested design that is hard to do and that I do not understand?
Or maybe somthing else?

Would this be possible to use?

Open up your device & see if you can get a clue as to the actual transmiiter used.

From memory, these HopeRF devices are good for this, but I think there may be certain register settings you will need to know or guess. (Baudrate, freq, preambles/sync patterns/IDs etc)

I have seen a few succesful hacks using the RFM12B.

A trawl of the home automation forums may provide the answer.

There are libraries around for these Hope RF devices. AFAIK.

Just to reiterate what @AnalysIR has said.

I have used the HopeFM parts and they are very good.

The JeeNode uses them, so you may find some useful code on that site (just search JeeNode Arduino and you'll find it )

But its a fairly complex module.

If you can figure out what module is in your transmitter, you could attach the Arduino as an SPI slave and analyse the data that is being sent to the HopeFM device to set its registers etc and then it would be easy to mimic what it does on your own device, with an Arduino,

But I think you will need to take the transmitter apart and I can understand if you were reluctant to doing that as the transmitter is expensive and you many damage it

I'll see if I can get it opened, but I need some special tool to get it done. Not sure if I'm able to get my hands on one.
There is the remote, but there is also the receiver that might be easier to get open.
I'll have to check later on and get back to you about that.

Maybe this, that is for Arduino, is easier to use than the previous?

@TEK73

I've yet to come across something I could not open.

If the screw heads are a strange shape, its often possible just to find a normal flat blade screwdriver which fits into part of the screw head.

But a lot of places sell screwdriver kits, that include lots if different shaped bits. I bought another set from the ALDI the other week for $15 AU

So unless its glued shut, you should be ok

OK, today I got the tools needed and opened the remote.
(Obs, there is something wrong with this, it's not working, but that was from before I started messing around 8)

There are two chips on it.
"CC1020 TI 17G M2FO G4"
"18LF452 -IML 1128GS4"

Images of front and back is attached.

Images didn't upload, can you try attaching them again

first

second: