USB receiver for an RS 15-2117 RF remote?

wkearney99 · Post by **wkearney99** » Sat Dec 11, 2004 6:35 pm

Any got ideas on how to get signals sent from several RS 15-2117 8-in-1 remotes directly into a PC via the RF it sends? I'd rather avoid the lag time of having it's RF sent to the base station, retransmitted as IR and then picked up by an IRman (redhat, etc...).

Anyone hacked an RF receiver directly into one?

Post by **The Robman** » Sat Dec 11, 2004 7:51 pm

If there was a hack to be done, I would expect that the best way to approach it would be to modify the RF base unit in such a way that you could connect it directly to your PC. It might be possible to somehow join together one of those IR receivers that you can connect to a PC and the base unit itself.

wkearney99 · Post by **wkearney99** » Mon Dec 13, 2004 9:52 am

Why? Adding I/O logic to the base station would probably be a lot more complicated than adding an input to an existing USB or serial device.

While I've seen that folks have taken the RF 'puck' transmitter out of one style remote and added to another, I'm curious if anyone's done it on the receiver end.

Or might be be as trivial as linking the IR emitter output from a base station into an existing IR USB receiver?

-Bill Kearney

crust · Post by **crust** » Mon Dec 13, 2004 1:21 pm

I've run the 2117 RF receiver directly into my PC. I built a small circuit that plugs into the IR emitter in the back. It has a micro with a decode algorithm that then outputs a n-byte serial stream to the pc when it receives what it thinks is a valid IR signal.

Post by **The Robman** » Mon Dec 13, 2004 3:07 pm

Sounds interesting, have you written anything up?

crust · Post by **crust** » Mon Dec 13, 2004 11:32 pm

The Robman wrote:Sounds interesting, have you written anything up?

Not really, just a brief description. Basically, I've built a small circuit that connects to the extra IR output of the receiver. The circuit would fit in the spare space of the box. The circuit consists of a micro, a level shifter (for the serial port) and the analog interface to connect to the led output. Altogether it is 6 or so small parts. The micro has an algorithm to decode IR signals and then output a multibyte serial stream that is designed to be unique to the signal (as opposed to recreating it). That is basically all there is to it. I was planning on spinning a board for the circuit if there is enough interest to justify it, of course the 2117 has been EOL. The first one I built on a protoboard is at http://www.elkhashab.com/content/view/26//. Though I haven't updated it with any of the more recent incarnations.

The micro has much of the same firmware that I am using for an component video mux that I am building (my tv only has 2 component inputs).

Post by **The Robman** » Tue Dec 14, 2004 7:44 am

Back to my original idea, it seems to be that if you already have something like the Streamzap which lets you control your PC using an IR remote, I can't image that it would be that hard to make some sort of connector that runs from the IR blaster output into the Streamzap box.

wkearney99 · Post by **wkearney99** » Tue Dec 14, 2004 10:24 am

The Robman wrote:Back to my original idea, it seems to be that if you already have something like the Streamzap which lets you control your PC using an IR remote, I can't image that it would be that hard to make some sort of connector that runs from the IR blaster output into the Streamzap box.

Yeah, that's a good question. I'd think the latency caused by feeding the already processed IR would be slower than just having the PC interface pick up the RF directly. I know next to nothing about the various bits involved here, so that's why I'm asking.

I suppose it's worth asking if the RF signals sent by the Radio Shack stuff are in any way compatible with any existing RF-to-PC interfaces like the ATI remote? Or since it's possible to hack an RF puck into a Pronto is there a PC receiver already available for that?

classicsat · Post by **classicsat** » Tue Dec 14, 2004 12:02 pm

Chances are the remote circuits of the 2117 and the ATI unit are incompatible.

The RF path doesn't add any consequential delay anyhow, so I don't see the problem.

crust · Post by **crust** » Tue Dec 14, 2004 8:06 pm

wkearney99 wrote: I suppose it's worth asking if the RF signals sent by the Radio Shack stuff are in any way compatible with any existing RF-to-PC interfaces like the ATI remote? Or since it's possible to hack an RF puck into a Pronto is there a PC receiver already available for that?

The only PC RF receiver that I own is an old one I got from X10. It works fine with the supplied remote. That system is 310MHz and does not work with the 2117. I don't have an RF spectrum analyzer, so I dont know what frequency the 2117 uses. In addition, there are lots of different ways of encoding the signal. I am almost certain that the RS remote simply modulates an RF carrier with an IF signal that is an exact copy of the one going to the diode.

Post by **The Robman** » Tue Dec 14, 2004 8:42 pm

The RF signal is indeed an exact copy of the IR signal, and I believe the frequency is 430MHz

wkearney99 · Post by **wkearney99** » Wed Dec 15, 2004 5:29 pm

Ok, according to the FCC website it's indeed 430Mhz.

So is it as trivial as putting a 430Mhz receiver in the mr26a? Or in some other existing PC-to-USB receiver like a usb-uirt or something?

crust · Post by **crust** » Wed Dec 15, 2004 10:14 pm

Usually not, the frequency is one thing and the coding is something else. For instance, there are lots of ways to put the data into an RF carrier. The 2117 just modulates the RF with an IF that is a copy of the IR signal. One of my remotes seems to transmit a 1 byte code for the RF part of the signal while sending a regular IR stream. Alternatively, it might be transmitting more signal on the RF and the receiver is decoding to 1 byte. In either case, it would not be trivial to decode the information from the 2117. The easiest way to do it would probably be to emulate a regular IR demodulator and let the PC do the hard work. The drawback of this approach is that the PC has to constantly sample the detector.

Having said all that, i noticed that a circuit to decode RF signals has just been posted, so you could build that and use a PC w/ a generic decode algorithm ala lirc to read the RF remote.

wkearney99 · Post by **wkearney99** » Fri Dec 17, 2004 1:33 pm

What about changing the transmitter frequency? The xmitter in the 15-2117 has a tuning pot on it. I'd wonder about being able to tune it to either 418 or 433.92 MHZ, that used by Pronto or ATI remotes?

Or, alternatively, tuning the receiver to 430 instead? It'd probably be better long-term to adjust the receiver instead of cracking open a bunch of remotes.

Anyone done this?

crust · Post by **crust** » Fri Dec 17, 2004 2:01 pm

It is possible to change the frequency of the receiver (may or may not be easy), but the signal coding may still not be compatible. The 2117 just modulates the carrier with the IR signal, but the ATI may be expecting something totally different such as a phase shift keying or something else. So even changing the frequency would not make it work. Having said that I have o idea what it takes, but my other RF receiver definately uses something other than a copy of the IR signal.