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Electronic Engineer needed to design circuit for switching front and rear cameras

Discussion in 'Model S: User Interface' started by artsci, Aug 26, 2013.

  1. artsci

    artsci Sponsor

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    If you haven't seen this thread we've tentatively determined that a Tesla rear camera mounted in the front of the car can be integrated with the touch screen to provide parking and front bumper protection likely to be far superior to parking sensors for protection of the front end of the car when parking. Problem is designing a circuit that can switch the signal to the touch screen from the rear and front cameras. As the thread indicates, ICs do exist for switching LVDS signals and for inverting the image. But we need a circuit design that will make this possible and we need an EE or other IC design expert to do it. Any volunteers? I'll cover any costs for parts and the like.

    Once we have a circuit design, we can have these made and available to owners who want this mod.
     
  2. anthony

    anthony Member

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    I know a few, will ask around to see if anyone is interested.
     
  3. artsci

    artsci Sponsor

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    Thanks Anthony.
     
  4. dpodoll

    dpodoll Member

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    artsci - Please add me to what I am sure will be a long list of owners who will impliment this once it is a reality.
     
  5. deonb

    deonb Active Member

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    I can probably do this and send to you as an EAGLE file. What do you have in mind? (i.e. What is your control signal to decide between front and rear input?)
     
  6. artsci

    artsci Sponsor

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    If I understand the question correctly the control could be a rocker or toggle switch.
     
  7. deonb

    deonb Active Member

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    Why not switch it based on the reverse lights? Do you need more control than what that would provide?


    Anyway, did a bit of research. This is not a difficult circuit to build. First thing though:

    That FIN1022 zax123 suggested is 800 Mpbs only. Do you know what the data rate is of the Tesla rear view camera?

    If those cameras are 3.125 Gbps, you may need something like a DS25CP104A instead. The sucky thing about the DS25CP104A is that it is a QFN package, so I can't just send you a EAGLE file for you to make the board yourself - you'll need a reflow oven or at least a rework station, which I assume you don't have access to or want to invest in. Unfortunately it doesn't look like there is a pre-made eval board available for that chip either.

    Anyway, I can assemble the board for you, but I don't have access to LVDS cameras to test. In your endeavors did you come up with a cheap source for LVDS cameras that match the Tesla as well as a test screen? I would like to avoid opening up my car.

    You realize of course this would only work with the Tech package, right? Without the tech package, the rear-view camera is an analogue camera.


    PS: This project will give me a great excuse to install a new 6-50 for my reflow oven. My previous one somehow magically transformed itself into a 14-50. Wonder why :D.
     
  8. artsci

    artsci Sponsor

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    I can send you the Tesla camera for testing if that would help.

    I don't understand the reverse lights as a switch. The front camera would be on the touch screen when we put the car in reverse? Am I missing something?
     
  9. SUPRKAR

    SUPRKAR Member

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    perhaps what deonb is thinking is at rest or when reverse lights off the default would be front camera output to the screen then when in reverse rear camera output to screen. This automates the operation however it restricts the switching between cameras should the driver wish to select which camera is shown when turning on camera mode from the main screen icon. I would prefer being able to select what camera is shown manually with a switch.
     
  10. deonb

    deonb Active Member

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    #10 deonb, Aug 26, 2013
    Last edited: Aug 26, 2013
    Right. I think for 90% of the operations, basing it on when the car is in reverse is fine. In fact, currently the rear view camera comes on when you put the car in reverse and goes off when you move to something else. I bet this is good enough for the majority of scenarios and you use the 'Camera' button probably fairly infrequent.

    Similarly, if the camera is viewing behind when in reverse and forward otherwise (of course still driven from the touch screen button), it should probably take care of the majority of scenarios, especially if someone doesn't want to add an unsightly switch to the car.

    Of course, you can add a 3-way switch in addition, forward, backward, and automatic, where automatic is based on the current gear.


    I would also need a screen, or something to convert the LVDS signal to something else. Would this work?
    http://www.nextwarehouse.com/item/?1132179_g10e

    I don't mind buying equipment - just need to know what to get that matches. If you manage to start selling your camera system, you can maybe buy the test cameras back from me at cost to resell again.
     
  11. SUPRKAR

    SUPRKAR Member

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    #11 SUPRKAR, Aug 27, 2013
    Last edited: Aug 27, 2013
    Deonb
    The camera has four wires two wires are for power and two wires are for the LVDS+ and LVDS- the wires are shielded. The rear of the main screen of the Tesla has a connector the same as on the camera. When switched the connector from the screen puts out voltage to the reverse camera then looks for the LVDS signal back from the camera on the two wires LVDS+ and LVDS-

    It would be nice if we could locate a LVDS camera which is used for front view. I know Lexus and Infinity use front facing cameras in some of their cars but I am not sure if they are LVDS output. If they are we could possibly use one of those to experiment with.
     
  12. zax123

    zax123 CDN Model S P308

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    Is it completely unrealistic to think that we could in fact source a *different* camera for the front? That way we wouldn't have to worry about inverting the signal. Will whatever circuit that ends up getting designed be able to accept other LVDS camera signals and convert them to one the touchscreen circuitry will accept? That might even make for a less expensive implementation overall as there are perhaps less-expensive LVDS cameras out there that could do the job.
     
  13. dpodoll

    dpodoll Member

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    My guess is that the "inverting" of the image is done by the software driving the monitor as opposed to the camera itself.
     
  14. wycolo

    wycolo Active Member

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    For the front camera is it all that important to bother with inverting? You are only interested in nearness to curb or railroad tie, so being upside down or left/right should not matter.
    --
     
  15. wcalvin

    wcalvin Member

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    You don't want to switch between front camera and the usual rear camera. You want both displays at the same time.

    Just pipe the front camera into the web browser, positioned in the bottom half of the 17"..
     
  16. SUPRKAR

    SUPRKAR Member

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    How to get the camera to the web browser? If possible that sounds interesting....
     
  17. HansK

    HansK Member

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    I'd rather keep things simple and just show the front camera unless in reverse, avoid external switches, and use Tesla's camera if it's a simple jumper or resistor on the pcb to unreverse the image. The reason I'd want to reuse Tesla's camera is to ensure 100% compatibility with the camera system in the firmware (until or unless we know for sure that there's nothing to worry about).

    By minimizing the requirements at the get go, we're more likely to be successful. Then, we can revise the switcher and other components later...
     
  18. santana338

    santana338 Member

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    deonb,

    I found an evaluation board for $200. It looks like this will this do what you want. The connectors are not compatible though.

    SUPRKAR, can you put an oscope on the LVDS signals to get an idea of what the data rate is?
     
  19. zax123

    zax123 CDN Model S P308

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    Unless there's a curb close to the right bumper and not the left and you're turning in that direction -- if you know what I mean...
     
  20. santana338

    santana338 Member

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    Checking the curb via camera while parallel parking will be a mental challenge if the image is flipped L-R.
     

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