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MFD serial connector?

Discussion in 'Gen 2 Prius Accessories & Modifications' started by xtopher, Jan 10, 2007.

  1. xtopher

    xtopher New Member

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    I decided to make a new topic after posting at the end of a dormant thread. Sorry for the double post. :rolleyes:

    I have been planning to put a mac mini in my car even before I saw jkusnetz page, on digg and make.
    http://www.kusnetz.net/prius/
    I even bought the mac mini before the prius with this in mind.

    A couple of questions for the group. I have an`06 and plan on using the costaletech lockopick3 to get my video up to the screen. I really want the touch screen function (Awesome hack by the way). What I do not want to do is buy a can-view just for the serial interface. I know it can do a lot more but I am not interested in that right now ( maybe when I have some $$$$$ kicking around for PHEV).

    So here is what I would like to know.

    1) Is there any way to Tap/sniff the actual screen connection, I am assuming it is serial, and use that signal with jkusnetz hack/software to go directly to the Kespan.
    2) Does anyone one know if it the signal is simple serial like what the Can-View gives out?
    3) Which wire/connector this is on the MFD?

    Here is what I see in my mind:
    -A small connector board with one or two Vampire taps and a female serial connector.
    -Maybe a diode for signal blockage.
    -We might be able to use one tap with common ground(?).
    -All we would need to do is read the Tx signal and pass it on to the mini via jkusnetz programs.

    I have access to lots of electrical components, and am very comfortable with electronics in general ( I teach basic Electronics in a local high school). I have some basic microcontroller skills, and might be able to work up some sort of intermediary interpreter if necessary. I just don’t know where to start or if I am wasting my time with false assumptions.

    I sent this to CoastalETech a week ago as a project idea, no response. I wasn’t sure if I were alone in this desire. So if you are drop them a note.
     
  2. eflier

    eflier Silver Business Sponsor

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    <div class='quotetop'>QUOTE(topher @ Jan 10 2007, 08:04 PM) [snapback]373955[/snapback]</div>
    given your electronics background, here is a rough description of the Prius touch screen protocol, in the interest of giving you an idea of what is involved, so you can make your own decision on which route to go.
    The Prius AVC (audio/video) bus connects the MFD, radio/cd and optional NAV and amps by means of a 2 wire differential bus centred on +2.5v with a 250mv differential signal at 41uS per bit. It has the format: long start bit (172uS), 2 byte sender address, 2 byte receiver address, control, length, variable length data field, all with parity. Each message must be acknowledged by the device it is sent to.

    When a device which needs to know touch-screen data is active on the bus, the MFD sends out a serial message to that device with X and Y bytes at the end of the message.
    The important part is: "a device which needs to know touch screen data must be active". For example, when the NAV is on screen, the NAV needs to know touch screen data and so that data is put out on the AVC bus for the NAV to pick up. If you select any screen other than NAV, those other screens do not need to know touch screen data because they are all internal to the MFD and so get it direct. Consequently, if you look on the bus when these other screens are active, you will find no touch screen data. If you think about it, you wouldn't want the NAV to be accepting touch input when you are actually selecting a CD track. For the 2004/5 Prius CAN-view registers on the bus as a new device that requires touch screen data and thats how I can then convert it to standard PV format serial for jkusnetz & co to feed their car PCs.

    The problem here is that even assuming you have NAV when you put video in via a hacked 2006/7 camera input, you are selecting that camera input and not the NAV, so the NAV is not active and the touch screen data is not broadcast. That's rather a fundamental problem. In view of that, my advice (however unpalatable) is that you instead consider buying a motorized LCD like the Lilliput 701 (look under V4 mounting options) where the LCD disappears from view when not in use.) That way you can feed the much better resolution Lilliput directly from your MACmini and also get the touch screen data from it via USB with standard MAC drivers.

    I'm clearly not suggesting CAN-view; for this 2006/7 application; it's simply not appropriate, I'm just trying to save you some potential frustration.
    good luck!
     
  3. xtopher

    xtopher New Member

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    thank you for this indepth explanation. after i posted i read another post (dealing with video in on the 06 modles) that talked about the the fact that even with the screen showing something else you might still be sending data to the original device.

    so i kinda thought that this would be an issue, i wasnt sure what the lockpick did to the MFD to make it work. I see the short side of it is if the lockpick is not requesting data, then the MFD will not send it.

    i looked at the second screen threads that you mention, and while i do like the idea of higher res, i dont want the second screen. i think i am going to go with an RF remote (Kespan, Front Row), and put off the touch screen untill the CAN-Views find a work around AND i have more of a reason than just a media center.

    can i ask where you got this wonderful chunk of data and stats??? So if i am feeling froggy over the summer or something and want to play i can find out more.

    thanks again.
     
  4. madzarevic

    madzarevic New Member

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    <div class='quotetop'>QUOTE(eflier @ Jan 13 2007, 12:51 PM) [snapback]375231[/snapback]</div>
    Did you manage to find some kind of design spec or something?? If so would it be possible to get a link to it?

    <div class='quotetop'>QUOTE(eflier @ Jan 13 2007, 12:51 PM) [snapback]375231[/snapback]</div>
    Would a XM radio or a factory DVD player count as an external device? I have an ultimate lockpick from coastaletech and the AUX video and audio show up in the MFD as coming from a DVD player.
     
  5. mee081224

    mee081224 New Member

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    This is a hard under taking, I have been waiting for someone to crack the video. Remember there are 3 parts to this, video, then touch screen, then audio. This was done on the 05 which had an analog screen we have a digital screen much different ball park. We have to figure out all the things for it, there are some ppl getting close but nothing has popped up in recent weeks
    here are the forums
    http://priuschat.com/My-In-Dash-Car-PC-project-t28275.html
    http://priuschat.com/2006-Prius-MFD-GVIF-V...put-t27375.html

    There is some code out there from the mac mini using perl to get the touch screens, but remember we would need a way to connect to the screen and get the touches to go to the computer
     
  6. madzarevic

    madzarevic New Member

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    <div class='quotetop'>QUOTE(massimo @ Jul 27 2007, 06:11 PM) [snapback]486484[/snapback]</div>
    Well I have a 2005 prius, so already have working analog video and audio.

    <div class='quotetop'>QUOTE(massimo @ Jul 27 2007, 06:11 PM) [snapback]486484[/snapback]</div>
    It was my understanding that this perl script is just for reading the data coming from a can-view device (which costs $hundreds and does a bunch of stuff I am not really interested in. I don't have a problem writing a touchscreen driver for an xserver, but I just have to figure out a way to get the touchscreen data out of the MFD in the first place.

    Actually one of the senior electrical engineers where I work sort of explained how the CAN bus works, and he's saying it would be pretty easy to tap into this stuff, but it might take longer for me to figure it all out since I am a software person.

    Basically for at least the touchscreen part of this problem here is what I have gathered needs to happen. We need to have a device on the bus that registers the fact that it requires touchscreen data to be transmitted on the bus. (from eflier) Then we need some kind of can-bus to rs-232 bridge that will allow a normal PC to communicate over the bus (read the touchscreen data), and from that point on it's all just software.

    Who knows though, I haven't even started yet, and this could all be way harder than I am envisioning.
     
  7. emailcurt

    emailcurt New Member

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    Just registering myself as another very interested party here. Unfortunately like others I can write software and do the basic hardware stuff but it's a level more advanced than me.

    My goals would be to get something that can actually interface to the canview for 2006/7 models, along with other devices like a carputer. It seems to me that coastal or someone else could sell a bunch of 'prius MFD adapter' boxes that would accept incoming video in a couple different forms (RGB and RCA composite for example) and output touchscreen data via serial and/or USB. It seems clear this is possible to build, just a bit beyond most hobbyists. But alas no one has created such a device...