NEED IR CODES FOR ZENITH VCR

D-ROC · Post by **D-ROC** » Tue Feb 24, 2004 7:55 pm

Can any one please help me find the IR codes and protocol used for a zenith VCR model# VCM321. I tried to call zenith, but they would not help me. I am doing a project for school and I need to communicate with the VCR by generating and transmitting the proper codes for play, stop, rec., etc to the VCR. Any help would be greatly appreciated

Thank you.

johnsfine · Post by **johnsfine** » Wed Feb 25, 2004 7:22 am

What form do you need those signals in? (What device will you be using to generate the signals?)

You asked in a JP1 forum, so maybe you actually have a JP1 cable and JP1 remote. If it's a learning JP1 remote and you also have the original Zenith remote, you can learn a few signals and decode with IR.EXE and see what they are.

I took a quick look for Zenith VCRs in several online sources of IR codes. In each such place someone had commented that most or all Zenith VCRs use the same commands (I didn't check the commands myself to see if that's true).

All the model numbers listed began "VR". There was nothing similar to "VCM321". But if the VCM321 does use the same signals as the others, I can tell you how to get the IR codes (if you tell me what form you want them in).

D-ROC · Post by **D-ROC** » Wed Feb 25, 2004 10:31 am

I’m going to build an IR transmitter with a 555 timer and connect it to a microcontroller to send the codes to the VCR. Once I find the frequency for the modulation used by zenith (I think it will be like 40k Hz) and the way they form the pulses used for each function like play, stop, etc. I will try and program the microcontroller to output the correct code though the transmitter. I do not have a JP1 cable and JP1 remote. I was directed by someone else to ask here and see if some one could help me. The whole project that I am trying do is to make a phone operated remote.

Thanks

johnsfine · Post by **johnsfine** » Wed Feb 25, 2004 12:10 pm

The Zenith devices I know about use Zenith's own IR protocol, but you might want to try verifying that your device does before building hardware that assumes it.

The exact modulation frequency isn't that important. The UEI remote we use in this forum use 40.2Khz for Zenith. Most of the CCF file samples I have for Zenith are 40.24, but some are 40.64 and work just as well. I'm sure 40kHz (as you mentioned) would be fine. (probably anything from 38kHz to 42kHz would also work).

The Zenith protocol uses modulated pulses around 500 uS long. Again the exact length is not important. Those are used to mark what I call "half bits".

A half bit is about 5500 uS long with either one or two 500 uS pulses at the beginning, so either
500 uS modulated, 5000 uS quite
or
500 uS modulated, 500 uS quite, 500 uS modulated, 4000 uS quite

A "frame" of the signal is some number of "half bits" encoding the command (for VCR's I think it is 15 half bits) then a long gap.

I believe most commands repeat the (same) whole frame several times.

If that basically makes sense (and doesn't make you decide the task is too complicated), ask for whatever details you can't deduce from the above.

D-ROC · Post by **D-ROC** » Wed Feb 25, 2004 1:32 pm

Do you know the code for play, stop, menu, etc

Like the code transmitter for play is 1001001
Rec is 1000100
Stop is 1001000

Something like that so I can store each command. I'm going to try and store the unmodulated signal.

thanks

johnsfine · Post by **johnsfine** » Wed Feb 25, 2004 6:44 pm

Get the decodeCCF program from
http://groups.yahoo.com/group/jp1/files/Programs/
and the DecodeIR DLL from
http://groups.yahoo.com/group/jp1/files/2.%20Tools/
and one or both CCF files for Zenith VCR's from
RemoteCentral Zenith VCR's

In the readme for DecodeCCF it gives an advanced form of the command line
decodeCCF 24 x foo.ccf
The 'x' tells it to give timing details in addition to the usual decode.

For each command the output file will include a long string of "burst pairs" starting like this one:
496-5118 496-5118 496-472 496-4124 496-472 496-4124 496-5118

That says 496uS modulated followed by 5118uS quite, then another 496 modulated etc.

The decodes also give the 7-bit value of each command, but I think you need to see the timing detail to understand.

(It's 7 bits because there is an initial '0' half bit and then every logical bit is sent as two inverse half bits, for a total of 15 half bits).

D-ROC · Post by **D-ROC** » Sat Feb 28, 2004 10:15 am

I put the decodeIR.dll in the same folder with decodeccf.exe. Then droped the zenith vcr ccf file on top of the decodeccf.exe file and made the txt file. I'm not sure how to read this file to get the code.

johnsfine · Post by **johnsfine** » Sat Feb 28, 2004 10:28 am

I had suggested using the command line interface for DecodeCCC (from Windows Command Prompt) rather than the drag an drop interface, because I thought you needed to see the timing details of the signals, rather than just the decodes.

Either way, the txt file is tab delimited with many fields that exceed typical tab widths, so it is possible to read in any text editor (such as NotePad), but it is much easier to read in some program (such as Excel) that can import tab delimited text and display it with correct column allignment.

These Zenith signals will have "Zenith" in the first tab column, the number of logical bits (7) in the second, the value of the leading half bit in the third, and the funtion number (which combines the 7 logical bits into one number) in the fourth.

(Each logical bit is actually transmitted as a half bit with the value of that logical bit, followed by a half bit with the opposite value).

If you use the command line interface (or define a right click menu command as documented in the ReadMe) you can also get the timing detail I described above, so you can compare your understanding of how the bits are encoded with that timing detail.