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RCA (composite video) to LVDS converter design

Discussion in 'General Electronics Discussion' started by KUMARA SHP, Aug 14, 2014.

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  1. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    I have to design RCA to LVDS (round 4 pin jack) converter
    I really not good in LVDS & RCA
    how can I do that
    if I can have circuit that is very useful !
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Something is not right here. RCA is a connector type, LVDS is a signalling standard. LCDS is typically connected via flat connectors, not round ones.
    You can use RCA connectors for many types of signal, e.g. audio, video...
    You cannot convert a connector type to a signal standard.
    You can convert signals of the same type between different connector standards. Or you can convert a signal from one type to another and correspondingly change the connector type.

    You need to state more clearly what kind of signal is incoming via the RCA connectors and what kind of signal you expect to present at the output and which connector type is to be used at the output.
     
  3. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    sorry I meant composite video that come though RCA cable & convert to LVDS, can it possible?
     
  4. Gryd3

    Gryd3

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    Jun 25, 2014
    not easily. What is your end goal?

    Composite video contains two signals. Chroma, and Luma. Both are analogue.
    LVDS is a digital signalling standard. You would need to separate the Chroma/Luma signals, sample them at a high enough rate as to keep the signal intact, then transmit over LVDS.
    What you do from there is anyone's guess...
     
  5. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    I need to watch video from my car screen here is the car screen video input yellow circled
    I need to turn off the camera & see my composite input from this
    Is this LVDS input, someone told me so
     
  6. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    Tesla_screenrear.jpg
     
  7. Gryd3

    Gryd3

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    Jun 25, 2014
    Make/Model/Year of the car?
    Do you have any specs or information on the screen you with to display on?

    Are you absolutely certain that is LVDS?

    What we will be struggling with is that composite is a very detailed complete standard for video transmission. It can be delivered a large number of ways to be displayed. (RCA plugs can be used, so can BNC and many others... regardless of the cable/wires used the electrical signal is the same, or close enough.)
    LVDS is simply how to package and send information, it does not define specifics. It is almost like sending a letter to an anonymous pen pal if you don't know where they live... Everyone can use an envelope, but they may not be able to read what's inside.

    To determine what language this device uses will be an incredibly time consuming task if no one has done it before and made the findings public. You will need to reverse engineer the transmissions between an already working device so you can determine exactly how it talks.

    Edit: If you have access to an oscilloscope, you can take a reading to determine if it is a digital or analogue signal... How many conductors are in that connector? It very well could be a proprietary connector for an already existing video standard. Why reinvent the wheel?
     
  8. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    this tesla model 2013 car
    I don't know this is LVDS input or Composite video input
    this design is for my uncle however I need to watch the video from this
    I attached car camera details somtimes you can check it & give me proper details
    I really appropriate your help
    thank you

    this is car rear camera
    http://www.ovt.com/products/sensor.php?id=115
    this is image of it camera.jpg

    I need to connect this type of output from my player to car screen player

    compositeaudio1.jpg
     
  9. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Your link points to the sensor which may be within the camera. This is not, however, the camera itself. The sensor has a parallel interface whereas the camera has a serial interface of sorts. Please give the exact model of the camera, not the sensor.
     
  10. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    I am sorry I don't know the camera model , now I can't find it
    Also my knowledge is not good in that field
    how ever are there way to input RCA cable output to CAR input
    car input has 4 pins (see above image)

    I need to play video in car screen & switch between them
    if I can have my video on car screen then switching can be done

    I don't know a way to convert RCA to CAR input

    thanks
     
  11. Harald Kapp

    Harald Kapp Moderator Moderator

    10,212
    2,201
    Nov 17, 2011
    Take the R from the end of CAR away and put it in fron to get RCA ;)

    In all honesty: without knowing which signals are used on the camera connector we will not be able to help your with a scheme to connect a composite video input there. It may even be possible that the signals on the camera's 4 pin connector are composite video, but in the absence of facts we could only guess.
     
  12. Gryd3

    Gryd3

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    Jun 25, 2014
    Kumara,
    What you are asking cannot be done without the details we are asking for.

    To be safe. No, you cannot convert the composite output from the RCA connectors to the proprietary input on the screen in the car.

    If and only if, we can get the exact model of the camera and we can find the detailed specs we require on the signals from that camera can we even begin to give advice on what you can do.

    Those 4 pins could very well be:
    1 - Power (Amount unknown)
    2 - Ground
    3 - Chroma
    4 - Luma

    This would make things very very easy and would allow what you want... but as of yet, there is no way to know what the pins are actually for.
     
  13. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    thanks all
    I will try to find camera model & its output type also car input type

    Gryd3- I thought same but my uncle says car has LVDS input not composite (I can't guarantee about his knowledge)
    if your assumption is correct i can directly connect my video input to that input ,cant I? I will try that
     
  14. Gryd3

    Gryd3

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    Jun 25, 2014

    Hold up. Dont try that just yet!
    I cant vouch for which pin is which! You could cause damage without the proper tests first.
     
  15. Gryd3

    Gryd3

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    Jun 25, 2014
    If my assumption is right, they used an already existing, easy to manage composite video signal, and used a custom plug.
    Alternatively, they could be using a custom digital protocol which would make this a difficult endeavour.

    If you have a multi-meter, you could set it to voltage and probe the jack on the back of the screen to determine if one of the pins provides power to the camera (which is likely). One of the other pins should be ground. The 3rd pin may be an analogue, or digital signal pin, we do not know yet. The last pin could be a complimentary signal pin, or an additional ground. Once more, we do not know yet.

    Do you have access to an oscilloscope?
    Do you have access to a spare camera, or are you confident enough to open the camera enclosure?

    Edit: If you do decide to go probing, be sure not to accidentally short anything. If you are shy with your electronic skills, have another do it for you.
     
  16. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    According to this site, the 4 pins are power (2*) and LVFS+ and LVDS-.
    This excludes the option of just connecting the RGB or composite signals from the RCA connectors to the 4-pin connector of the car.

    The information there is still insufficient for designing a converter because LVDS here defines only the physical layer of the signalling scheme. It doesn't say anything about the logical signalling, i.e. how the video is encoded in the serial data stream.
    I'm afraid your project is doomed unless someone invests his time in analyzing the camera signals such that a mapping from composite video to the camera's LVDS signal can be defined. In a second step one will have to construct an encoder (microcontroller, FPGA or similar) that converts from composite video to this LVDS signal.
    I don''t say it can't be done, but it is definitely beyond a simple hack.
     
  17. KUMARA SHP

    KUMARA SHP

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    Aug 1, 2014
    how ever I learned lot from this
    I will come with other information

    thank you for all supports me
     
  18. Peter Ruiz

    Peter Ruiz

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    Aug 22, 2014
    I have some info on this and would like to figure this out. I need the same exact thing, to input composite video signal to the LVDS on the tesla monitor. The camera is 12v, Ground, LVDS+, and LVDS-. The 12v and ground signals are present from the back of the screen(powering the camera) and then the LVDS signal paths to the screen from the camera. I do have a scope handy to test signals. i also have a BMW module that converts composite to LVDS that is not functioning for this application. It was merely a shot but I think the resolution or scaling may be affecting it, or possibly the car needs to see the camera present(load sensing??) I have the car for one more day to test and figure out, any help would be great!
    Thanks
     
  19. Gryd3

    Gryd3

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    Jun 25, 2014
    Here's what needs to be done:
    The LVDS signal needs to be recorded.
    There needs to be test patterns presented to the camera so that there is some control over the LVDS signal.
    Once recorded, a different hand coded test pattern must be played back to the monitor in the Tesla vehicle to ensure that you understand the encoding.
    You then need to develop a custom board, or mess with an FPGA to load a frame or two from a composite video stream, convert it to whatever resolution and format is expected over the LVDS line.

    This is a very large project and will require many many hours of reverse engineering.
    There may be a shortcut if the camera can be taken apart to see if there is a particular IC in use that can be researched to determine if the LVDS stream protocol can be determined.
    Peter, you will make 0 progress in the 24-hours you have remaining unless you can break out your scope and capture all of the data on the LVDS line as you present some test patterns to it. From there, they need to be combed through to see if we can spoof the signal and inject our own color or image into the code. This will need to be played back with custom hardware.
    All red, All green, all blue, and some patterns:
    https://www.google.ca/search?q=vide...r7igK304CwBQ&ved=0CAgQ_AUoAQ&biw=1497&bih=822
     
  20. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    From Wikipedia:

    So the camera is sending a stream of bits to the screen. This is way different than composite video. To convert composite video to this format you would have to have a very complex converter. Unless such a thing exists already, making it would not be an easy project, nothing I would attempt.

    Bob
     
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