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Greetings,

I took a keen interest in the "video on my navi" thread. My interest is similar, though I would like to use the display/touchscreen as an interface for an on board computer. Rather than starting from a composite NTSC signal I would like to drive the LCD digitally from a PC style single board computer.

The aim of the project is to be able to switch off the navi and play MP3's or run PDA like software from the in dash console.

At this point I am still sizing up the project and trying to gather more information. Any pointers to sorting out the following subjects would be most appreciated.

1) Anyone know who makes the LCD/Touchscreen itself or what it's model number is? I found some vague indications that SHARP has been making LCDs for Alpine, but no concrete information. I took off the glove box an a few panels to get a peek at the LCD box itself, but have not gotten any more details. Would a Honda service manual be of any help here?

2) Whilst poking around in the dash I noticed a box that is likely the car's main computer. It's a silver box located near the floor just under the center of the dash. Anyone have specs on this beast? No plans to mess with it, but I am curious.

3) Has anyone found a "line in" or aux channel for the standard Honda single CD stereo? I looked under the driver's seat for the cd changer cable without luck. Any pointers on find this or does anyone have pinouts for it?

Regards,

David
 

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First off, welcome to the club David! Now on to business...

1) I'm not sure who 'really' makes the touchscreens. Before I would have said Alpine but I just realized that Alpine aftermarket systems don't even offer the touchscreen feature. At least the ones that I know of. But I do know that some Kenwoods have touchscreen capability. And possibly Pioneer's new DVD/NAVI combo unit. If you do find a way, please let us know.

2) I'm not quite sure what silver box you are refering to. Based on your description it sounds like it's the SRS (Airbag) computer unit. If it has a yellow wire harness - then it is. There are two multiplex ECU units on the front left and right side of the van. Is that what you are looking for? If you really need to know the electronical layout of the Ody I suggested investing in a Helm Electronical Troubleshooting Manual.

3) No one has found a simple way to have AUX in for the stock Honda headunit. I've heard there is a way but it involves installing an additional Clarion changer and a changer interface w/ aux inputs. But I have come across a device called a DVD Interface made by Blitzsafe. It allows you to have AUX input into your stock headunit w/o having to buy an additional changer. Only thing is they don't have one for Honda. At least not yet from what I hear. Last I heard it was in development.

-Nestor

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2000 CCS EX-NAVI
 

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Hi, and welcome!
Ambitious project here.... would love to hear if you do this mod.

BTW, what kind of computer board were you thinking of using? Are you talking about using a Palm-device like board, or something like a MIPS based architecture or even an Intel based solution? Just curious...

<font face="Verdana, Arial" size="2">Originally posted by subtlefuge:

3) Has anyone found a "line in" or aux channel for the standard Honda single CD stereo? I looked under the driver's seat for the cd changer cable without luck. Any pointers on find this or does anyone have pinouts for it?

Regards,

David
</font>
A couple of last comments on the aux in. You won't find a CD changer cable since the cable comes with the changer when you buy it. The factory radio has two connectors on the back, one which is the standard radio harness for power, speakers, etc... and another molex plug that is for an add on CD changer, tape player, etc... This is a proprietary digital bus, thus the need to buy an OEM unit or a bus adaptor that allows you to interface with an aftermarket.

One last thing, your radio has a two channel input for the navi voice, which ties into the front speakers only. There is a navi mute lead that mutes the main audio signal to make the navi voice audible.


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-Shin John
'01 DEP EX, and I'm workin' on it! (slowly)
 

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I am in the middle of a similar project. Here are my thoughts:

Screen interface:
I think you will find trying to track down manufacturer documentation a waste of time. The Ody shop manuals document the interfaces (which have mostly been well-discussed in this forum), but treat the units as black-boxes. These are OEM-specified units, and I would be very surprised if you were to dig up service manuals detailed enough to document the necessary protocols.

In any event, the situation wrt the screen video input is mostly clear: The unit accepts a standard RGB input with composite sync. This differs from VGA in that the latter has separate vertical and horizontal sync. This conversion could certainly be done (and there may even be products that do it), but IMHO you will do just as well by using a computer with NTSC outputs and doing the standard VideoNavi hack. I will probably end up using a Macintosh I-Book for this purpose, but you could certainly get a single board PC that has NTSC output.

Touch Panel:
This is a trickier issue. I have done a bit of reverse engineering on the Navi touch-screen circuit. The Video unit communicates with the Nav computer via two wires plus ground. Sniffing the transactions with a scope leads me to the following tentative hypotheses (please don't take any of this for fact):
1) The physical interface is a current loop and not a level-based interface such as RS-232.
2) There is a complex 2-way interchange going on between the two devices. There is an interchange on power up which is necessary for the screen to come up. After that, the interface is quiet until the user presses a button or touches the screen. At this point several (two, I think) transactions take place, each many bytes (something like 60 if I recall) long. It does not appear to be CAN, which would have been an obvious choice.
3) It seems to be a message/ack protocol, each message requiring a response from the computer before the next one is sent.
4) The good news is that there seems to be an easy-to-recognize bit pattern associated with each button or screen coordinate.
5) The bad news is that the button data are not sent until the second transaction. This means that one can't simply switch the current loop to a passive listener--the screen would never receive a valid ack of the first packet and would never send the event information. This leaves two alternatives (a) reverse-engineer enough of the protocol to be able to produce a valid ACK, or (b) to leave the Nav unit in the circuit and eavesdrop. Option (a) could almost certainly be done but would take more patience then I have. Option (b) is problematic because you need to prevent undesired Nav operations when you are intending to talk to the computer. This could probably by accomplished by interrupting the transaction at just the right time using a solid-state relay or some such, but this is too sleazy a solution for my taste.
Note that any such solution would involve low-level bit-hacking with something like a PIC microprocessor. This requires skills beyond those of the average Radio Shack customer, or even the average car audio installer.
Bottom line: I have more or less decided to live without the touch screen and use some other input modality. If I change my mind I will let you know.

Audio output:
As others have said, this topic has been well-explored. Unless somebody comes out with the right device to plug into the head unit's CD changer socket (this is apparently not trivial--involving issues similar to those with the touch screen), your only choices are (a) to hack into the Nav system's audio, which will only get you the front speakers (see my previous post on this). or (b) us an RF modulator.

[This message has been edited by avanti (edited 12-31-2001).]
 

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Hey avanti,

I'm just learning about this whole RGB, Horizontal, Vertical, Composite thing. I'm bascially trying to find another alternative to the decoder for the VideoNAVI mod. I was wondering if you could shed some light on a connector called a 'SCART'. Do you know if this thing can successfully extract RGB/Composite signals from things such computers, DVD players, etc.? Also I've seen on the net some connectors/adapters for PS2s that allow you too output PS2 RGB signals. Anybody think these are possible solutions? Anybodys input on the subject is more than welcomed...

BTW, I found these sites (and many others) on the SCART:

http://www.hippy.freeserve.co.uk/scart.htm
http://www.hku.nl/~pieter/HARD/MON/MON.html

-Nestor

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2000 CCS EX-NAVI
 

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Hi, Nestor,

First of all, let me make clear that although I kind of know my way around this stuff, I am no expert.

I *have* heard of SCART, and I don't think it is going to get you anywhere. It isn't a device, it is a a standard for a connector that for a number of years has been required on consumer A/V equipment in many european countries (that's why both of your references are of european websites). It was meant to avoid the complex tangle of cables we all have over here between our TVs, VCRs, and stereo systems, and to encourage TV/computer convergence. The reason you stumbled upon it is that it indeed supports RGB (so-called "component video") signals similar to that needed to drive the Navi display unit. But, as I said, it is just a standard, not a converter device. Moreover, although the connector provides for RGB, it is apparently the case that few real devices actually support this.

I also took a quick look at the PS2 stuff on the net. I'm not sure, but it looks like the PS2 outputs RGB as well as composite video, apparently with composite sync. If this is correct, it probably means that one could build a cable to directly drive the Navi from a PS2. Doesn't help with composite video sources such as VCRs etc.

The reason that this is harder is that "composite video" means that all five signals needed to produce a color picture (Red, Green, Blue, Vertical sync, and Horizontal sync) are all squeezed together into one complex signal so it can be sent on a single wire (this is what the yellow plug on your VCR uses). The "component video" signal expected by the Navi unit separates out the R G & B, but leaves vertical and horizontal sync combined (which is why we have 4 wires to switch). Computer VGA interfaces also break out the two sync signals (they also usually use higher scan rates, but that is another story). There used to be fairly simple chips to do the composite to RGB conversion, but they all seem to be discontinued (I wonder if this is why the Pioneer box is getting hard to find?).

I looked around a bit but couldn't find any other simple solution to the conversion problem. I did find the following link:
http://www.hut.fi/Misc/Electronics/circuits/vga2rgbs.html
which shows how to build a pretty simple device that will convert separate sync to composite sync, and I bet there are devices to convert NTSC composite video to RGB. Whether this would be sufficient I am not certain--it is possible that there are other issues that I am unaware of.

Finally, it is possible that the following device may work:
http://www.idk-tech.com/products/rgb/dcd03a.html
but it is hard to say, and I have no idea what it costs (it is also AC powered).

Well, I suspect I am boring everyone silly by getting this technical, but I hope it helped a little. Good luck.
 

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<font face="Verdana, Arial" size="2">Originally posted by avanti:

First of all, let me make clear that although I kind of know my way around this stuff, I am no expert.
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Avanti, welcome aboard to the club here! I really enjoy your input and technical knowledge. Very, very, welcome, and very, very informative. Maybe you're not an "expert" but it seems that you know enough to be pretty dangerous! In my book that means you're good with me, and fit in just perfectly here.
Look forward to hearing more from you!

<font face="Verdana, Arial" size="2">
I also took a quick look at the PS2 stuff on the net. I'm not sure, but it looks like the PS2 outputs RGB as well as composite video, apparently with composite sync. If this is correct, it probably means that one could build a cable to directly drive the Navi from a PS2. Doesn't help with composite video sources such as VCRs etc.
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This is a great idea for those looking to just add DVD and game capability to their Navi setup. A rear screen could be added too, driven with the composite signal. Makes for a low cost Video-navi mod! Cool idea guys!

<font face="Verdana, Arial" size="2">
Well, I suspect I am boring everyone silly by getting this technical, but I hope it helped a little. Good luck.
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Not here, that's for sure! I've learned alot from your posts, would love to continue learning from you too! Keep it up!

BTW, your sentiment is just how I feel after ranting on audio stuff.
I just figured if one or two people read my musings and get something from it, that's cool by me. This site is all about knowledge sharing, and I've definitely taken my share from this site. And this bilateral give and take is what makes this the most informative site I've ever visited!

OK, did I just rant again?


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-Shin John
'01 DEP EX, and I'm workin' on it! (slowly)
 

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Thanks avanti for you giving us your insight on the matter. Don't worry, it's been very interesting more importantly - educating. I swear...you and Shin John must of been separated at birth!

Yeah, from what I've read, so far, the PS2 is able to output RGB. But it was also discovered that people where using the RGB output to pirate DVDs to VHS. Once Sony found out about it they quickly created this thing called the 'Green Mask' to prevent further DVD piracy w/ their newer units. I'm assuming it's similar to what Macrovision does. Anyways, if this is the case then owners would probably have to either mod the PS2 or get this device: http://shop.store.yahoo.com/a-sonic/dvdregxdecfo.html . It's able to remove the Green Mask and even allows you to play DVDs from other countries. And like you said the only downside is you can't watch composited stuff like VCRs and TV tuners. Although there's absolutely nothing wrong with being stuck having DVDs or play videogames in the Odyssey.


I also read about those discontinued chips you mentioned. Yeah, those probably would have done the trick too. And I'm with you on it being a possible reason for the discontinuation of the Pioneer units. And I've seen similar decoder devices, like the one you had linked, although the one's I've found were skinner but kind of wide. The cheapest one I've found was like $160. But like you said it's AC powered. Although it wouldn't be TOO bad...you just would have to get a power converter w/ 2 sockets instead of 1.

Feel free to post anything else you find out (same goes for anyone). We are definitely starting to get somewhere.

-Nestor

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2000 CCS EX-NAVI
 
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