IR to IR translator project.

[bvwelch]

Edit: I've recently done a 2nd revision of this project, which uses a more convenient chip. See the web site listed below for updated information.

First, let me say, I never would have attempted this project without this great new tool-- IRCapture / DecodeIR , combined with Tommy's sensor hardware. Of equal importance to me was the extensive expertise and documentation concerning "remote" protocols here at the JP1 group.

Let me describe the "problem" I wanted to solve: I have a Panasonic DMR-E85 "pvr" and a Humax HFA-100 HDTV tuner. The "pvr" has provisions for controlling a "cable box", via its IR Blaster. Once you set this up, then you can use the pvr's "timer record" feature to set up schedules to record TV shows in the future, and the "pvr" will use the "blaster" to make sure that the "cable box" is set to the correct channel when the recording starts.

The on-screen "setup menu" for the pvr has a long, long list of supported cable boxes. Unfortunately, my Humax HFA-100 HDTV tuner is not on the list.

I could have tried to modify the DMR-E85's firmware, and perhaps add real support for the Humax. But instead, my approach to solving the problem was to choose one of the "set top boxes" that the DMR-E85 *does* support, and build an IR-to-IR "translator" circuit. I built a little picmicro board, and wrote a C program for it, that translates the "pvr's" IR blaster output into the equivalent command for the Humax HFA-100.

From the "pvr's" on-screen menu, I chose a "philips" set top box, simply because it was easy to decipher using the new CaptureIR / DecodeIR application. As it turns out, this set top box uses a NEC1 code with device 109, and seems to have the typical channel numbers like 02, 03, 48, etc.

In contrast, the Humax has channels like: 19-1, 19-2, 48-1, 48-2, etc. That is to say, each TV station has multiple "over the air" digital channels, so they use the "minus" to distinguish which digital channel you would like to view.

Obviously, some method of mapping input channel numbers to output channel numbers had to be invented. But since the "philips" set top box doesn't really exist, I was able to "make up my own" input channels. The mapping I chose was to map 19 to 19-1, and 20 to 19-2, etc.

So, the picmicro decodes the entire "philips" channel number string, and "looks up" the appropriate "humax" channel number string and then sends it to the Humax. By coincidence, the Humax is NEC1, device 0, sub-device 48.

I am satisfied with the results of the project. I have some ideas of other little "gadgets" that I would like to build, using this project as a starting point. For example, IR to RS232 would be easy, but there are lots of other gadgets out there already that do that. IR to X10 might be interesting, but the IR543 is probably good enough for most situations. However, IR to X10's CM11a or "firecracker" wouldn't be too hard. IR to X10 RF would be a challenge. I'd probably hack into a X10 keychain remote or something like that. In general, I don't recommend re-inventing the wheel, but since I enjoy building little picmicro projects anyway, it is neat to combine IR with other functions.

As soon as I scan in the schematic, and write up some documentation, I will put the source code and schematic on-line, and will put a link to it on my web page: http://bvwelch.com

Perhaps it will be of use to others here, at least as "food for thought" or maybe even a starting point.

Thanks much JP1 group!

William