hacked HU for CarPC AM/FM tuner?

Vchat20 · 07-17-2005, 11:51 PM

ok. this may be a really far fetched solution, but its just something that quickly crossed my mind today.
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since there is really no "good" am/fm tuner for pc's and the homebrew tuner listed in this same forum is still a ways down the road due to finances, i figured: why not use the HU for your radio?

now before you start *****ing at me about "well, just leave the damn headunit in then!", let me explain myself.

basically the idea is to either take your curent HU or go out any buy a real cheapo one that has a fairly decent digital tuner. open it, find out where the tuner is located (if its on its own separate board, thats the best route) and just rip it out if possible. at this point it gets to the "advanced" point where pinouts need to be found and a serial/I2c/etc interface needs to be found and whatnot.

basically the idea is to interface "just" the tuner of your headunit to the carpc.

good idea? bad idea? am i a quack? what? let me know whats on your mind

0l33l · 07-18-2005, 02:10 AM

Well, maybe it would work if you ran it into your line-in

KyleYankan · 07-18-2005, 02:12 AM

Hey - be cheap. Just interface the buttons to relays or something and run it into the line-in. :-P

seanz0rz · 07-18-2005, 03:24 AM

my first attempt at a radio tuner for a pc was a parallel port controled headunit.

what would happen is the buttons on the front of the hu would be removed and repalced with relays. a button press in software would trigger the relay, causing a button press on the hu.

now that i know more about ports and software, serial would be a must.

might be worth a try if you have a crap unit sittin around. maybe ill try it.

khan1369 · 08-17-2005, 12:59 PM

This is a good idea. It is pretty much what I was planning for my car pc all together. I have an OEM AM/FM stereo from a ford and I am gonna remote mount the buttons and LCD screen. The LCD is gonna be my clock also so I can handle keeping it.

rando · 08-17-2005, 05:22 PM

This is a reasonable idea and has been discussed before. Of course each HU is different and it's not likely you'll find a clean spot to just 'rip' out the radio portion of your HU. You can usually easily remove the mechanical (tape, CD) stuff and ben left with a main board, power board, and maybe a few other parts. The big trick is reverse engineering your HU to find a suitable control interface. You could try to the human interface (buttons and display) or if you dig a bit deeper, you may find that the underlying tuner circuitry can be controlled over a standard bus (i2c, microwire, ...). If you can the data sheets for the ICs in your HU, you should be all set.

I have an old kenwood CD HU I started to do this with. It uses a custom uController to do stuff so it was going to be quite a bit a work to hack up a solid interface. In the end, the amount of time needed to make it work wasn't going to be worth it for a 'one off' project that wouldn't really benefit many other people (probably none).

GSXTurboing · 08-20-2005, 08:39 PM

I have seen some GM cars in the junkyard wit just a am/fm tuner. They have nothig else. Could you use something like this? could it be posable to use a tft touch screen to cotrol the tuner and show what channle you'r on?

bmoney03 · 08-21-2005, 04:07 PM

The older gm cars have seperate tuner boxs. All the "radio" is, is just a face that controls it all. The am/fm tuner is seperate. With an harness of some sort u can control it. Just have to fig it out.

FMode · 08-22-2005, 05:54 AM

you steal my idea

okay:
I have a VW Beta Radio 1996 (Europe Name!)
(VW Alpha without cassette, Beta with casette, Gamma with CD Changer control)

VW Beta because:
- very good tuner
- very CHEAP ! around 10 Euro at every cardump (name for it?) available in MASSES (my local cardump has around 20 units available!)

VW Beta has
Resistor network (easy to emulate for a microcontroller) as buttons.
Tune+ = 1,3V
Tune- = 1,7V
....

Display (is nescesarry for RDS and Traffic Announcements) is I2C controlled. (the internal Microcontroller controlls the Display)

I have programmed an Atmel to be a I2C slave and to replace the Display...
(still i have some I2C timing problems)

I stopped the project as i read from racemiers FM/AM Tuner...
(before i started to gain access to such a mobile Tuner IC without effort)

TheNewJimJones · 10-20-2005, 06:34 AM

This is what came stock in my car...
AM/FM Radio head unit
I dont know where i put mine after i replaced it so i thought id get a new one and modify it. Should be easy enough. I never got a chance to take it apart but im guessing that id have to disable or remove the stereo amplifier and just find where the radio output and antenna input it. This could then be easily ran to the line in on a carputer... I could also re-wite the buttons to a separate panel for easy relocation and just hide the main unit behind my LCD screen after it gets installed in the double din space. Just an idea.

Kinda like modding my x-box controllers for halo 2. Adding A and B buttons on the underside of the controller and wiring the memory card slot to USB.