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#303886 - 07/11/2007 13:38 Controlling the empeg tuner
osito
new poster

Registered: 17/09/2004
Posts: 21
Loc: Ludwigshafen, Germany
Hello @all,

building up a car pc in my car and due to a lack of good USB tuners i remembered my empeg not being used for a certain time ...

This leads directly into my question:
Is there any project or attempt to control the original empeg or PCATS tuner with a normal PC (like e.g. a hp e-pc 42 that i'm willing to use in my car) via USB or serial interface, ideally under Windows XP?

I'd be glad to get some information, documentation and source code to, at least, built up this project on my own.
It would be great too if this programm or fractions of code can decode RDS and TMC information too.

I'd appreciate every little snippet you can provide me.

Thanks in advance and best regards from germany,
Andres

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#303887 - 07/11/2007 14:22 Re: Controlling the empeg tuner [Re: osito]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 30555
Loc: Seattle, WA
The tuner module is not a completely independent unit. From what I understand, it doesn't just receive serial commands. Some of the work is done by the DSP on the empeg itself. So you can't just connect it up to a PC without an empeg in there somewhere.

You can perfectly well control the tuner from a PC as long as you're installing both the Empeg and the tuner as a matched pair. Then there are serial commands you can send to the empeg (although now that I think about it, I'm not sure how many of those serial commands can apply to the tuner).
_________________________
Tony Fabris

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#303888 - 07/11/2007 14:30 Re: Controlling the empeg tuner [Re: osito]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 13494
Loc: Canada
Quote:
Hello @all,

building up a car pc in my car and due to a lack of good USB tuners i remembered my empeg not being used for a certain time ...

This leads directly into my question:
Is there any project or attempt to control the original empeg or PCATS tuner with a normal PC (like e.g. a hp e-pc 42 that i'm willing to use in my car) via USB or serial interface, ideally under Windows XP?


It would be relatively straightforward to connect the FM tuner (or even just the embedded RF module that's inside the tuner box) directly to a PC serial port + sound card input. This would give mono FM reception very easily.

For stereo reception, and RDS etc.., demultiplexing of the signal is required. The DSP audio processor chip does this in the empeg. I don't know if it can be done in software on a PC or not.. I suppose it depends on the available sampling rates of the sound card.

Cheers

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#303889 - 07/11/2007 14:34 Re: Controlling the empeg tuner [Re: mlord]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 13494
Loc: Canada
Quote:

For stereo reception, and RDS etc.., demultiplexing of the signal is required. The DSP audio processor chip does this in the empeg. I don't know if it can be done in software on a PC or not.. I suppose it depends on the available sampling rates of the sound card.


See the Wikipedia description of FM Stereo for more of an idea of what might be involved to get stereo, RDS, etc..

It looks as if a sound card sample rate >= 106KHz is necessary to do the MPX decoding in software.

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#303890 - 09/11/2007 08:28 Re: Controlling the empeg tuner [Re: mlord]
osito
new poster

Registered: 17/09/2004
Posts: 21
Loc: Ludwigshafen, Germany
Hello Tony, hello Mark,

thanks for your quick replies.

@Mark: Modern soundcards have sample rates up to 192 kHz

Anyway i have decided now to install the empeg too after i have replaced its VFD display.
After that the empeg controls the tuner as designed and the sound of the car pc can be heard across the aux input of the empeg.
The car pc could be used to do navigation and video only.
In that case i have to read the RDS/TMC stream in real time with the PC from the empegs serial or USB interface.

@Tony: Is this possible and is there a list of the available serial commands?

Further i could use the car pc to easily put new songs, which i have copied to it via WLAN, on the empeg (btw. is this possible at all if the empeg is in its sled?)

Thanks and best regards,
Andres

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#303891 - 09/11/2007 15:19 Re: Controlling the empeg tuner [Re: osito]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 30555
Loc: Seattle, WA
Quote:
Anyway i have decided now to install the empeg too after i have replaced its VFD display.

I assume you mean doing the display extender? Hopefully you'll be able to get your hands on one. Or, you could just install the empeg in the dash? (I'm assuming you don't have room for it?)

Another thing you could do is use ethernet to remotely control the empeg from the CarPC screen if you like.

Quote:
is there a list of the available serial commands?


http://www.riocar.org/modules.php?op=mod...g+Player+App#25

Quote:
Further i could use the car pc to easily put new songs, which i have copied to it via WLAN, on the empeg (btw. is this possible at all if the empeg is in its sled?)


http://www.riocar.org/modules.php?op=mod...mp;faqent=64#64
but read the note here:
http://www.riocar.org/modules.php?op=mod...mp;faqent=65#65
_________________________
Tony Fabris

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#303892 - 09/11/2007 19:30 Re: Controlling the empeg tuner [Re: osito]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 13494
Loc: Canada
Quote:
Anyway i have decided now to install the empeg too after i have replaced its VFD display.

Was the old one broken?

Quote:
In that case i have to read the RDS/TMC stream in real time with the PC from the empegs serial or USB interface.

You may have to write a little bit of empeg software to get it to send the RDS stream out over the serial port. It doesn't do that by default right now.

On the bright side, somebody else has already saved you some work there, by making the RDS stream easily available for such programs.

Cheers

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#303893 - 11/11/2007 20:08 Re: Controlling the empeg tuner [Re: mlord]
osito
new poster

Registered: 17/09/2004
Posts: 21
Loc: Ludwigshafen, Germany
Hello Mark and Tony,

thank you for your replies and the valuable links to the FAQ.

Good to know that networking is available even if the empeg is in the sled.
And thank you for your cool program empegface.
I will play around with it when my empeg is assembled again.

The VFD of my empeg broke and i managed already to buy a replacement VFD and solder out the old one
but until now i didn´t have time to complete the repair.
The empeg is sleeping partly disassembled in its bag now until i have exchanged the display.
After that it will be installed in the dash like in the good old days.

I knew about the listed serial commands but i thought there were more commands i can get the RDS stream with.
With the search function i found the link of a member called alex25 concerning his TMC script but the link to http://www.empeg.homelinux.com/TMC.zip is dead.
It was posted around July 2004 and alex25 did his last post in March 2006.

Do you know where i can get his script or some other code?
Or is there some kind of service manual or other documentation about the deepest internals available?
As a Linux Admin i'm very advanced in shell scripting but i'm a rookie as far as C++ is concerned.
But with as much information as possible i could give it a try.

Thanks for your help so far, i appreciate it very much.

Best regards,
Andrés

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#303894 - 11/11/2007 22:32 Re: Controlling the empeg tuner [Re: osito]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 13494
Loc: Canada
Quote:
..
I knew about the listed serial commands but i thought there were more commands i can get the RDS stream with.


All that I know about the RDS data, is that somebody sent me a hack to create /dev/rds1, from which one can read a copy of the RDS data (while the main player app reads the same stuff from /dev/rds0, I think).

That code went into Hijack as of v83. If you search the BBS for v83, you *might* find out who contributed it, and then search for their threads on similar topics.

EDIT: The person's name was René Vogt

Good luck!


Edited by mlord (11/11/2007 22:34)

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