Switching channels with the Fusion 878A Chip

Discussion in 'Amateur Video Production' started by ftw667, Aug 9, 2007.

  1. ftw667

    ftw667 Guest

    Hi all!

    I am an electrical & computer engineering student and I am working on
    a design project for school. It is a multiple camera security
    monitoring system. I am using the Fusion 878a chip on the capture
    card along with Matlab to process the images. The problem I am having
    is switching the channels.

    I am only going to be using 1 card so I will only need to worry about
    4 channels. I know that 'muxsel' is the variable that controls the
    mux between the 4 channels, however, I can not find any sample code to
    get me started. I am not sure how to communicate with the PCI card
    using c code. I have done similar projects with a 6811, however I was
    burning the code into EEPROM.

    I am going to try to develop a c program that takes a one variable
    input and uses that value to determine the muxsel value for which
    camera I want to use.

    Any help or guidance that anyone could provide would be appreciated.

    Thanks in advance!

    ftw667, Aug 9, 2007
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  2. Researching that question is a perfect job for an "electrical &
    computer engineering student" :)
    Gene E. Bloch, Aug 9, 2007
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  3. ftw667

    Paul Guest

    There is some source for a driver here, but I cannot make sense of it all.
    At least, by using this stuff, you might manage to capture a picture or


    The BT848 and BT878 have been around long enough, that there should be more
    than one Linux package with drivers in it. It shouldn't take much searching
    to dig up other examples.

    Paul, Aug 9, 2007
  4. ftw667

    ftw667 Guest

    Thanks for the link. I can capture images no problem, but the 4x1 mux
    on the chip that selects which channel is being processed is what I am
    having trouble with. The entire project is complete sans the
    switching. My advisor suggested that I post a message here about
    using the MUXSEL line.

    Thanks again,

    ftw667, Aug 9, 2007
  5. ftw667

    Paul Guest

    The question I would ask, is what are you using for code at the moment ?
    Look at the registers being accessed. They may be coded as an offset to
    a PCI BAR (base address register). If you have source, and can see in the
    source, some other registers being used in an obvious way, then going to
    the MUXSEL byte, changing bits 6:5 to a new value, should be no problem at

    Conexant BT878 (1.78MB) datasheet - MUXSEL on PDF page 119 (page # 107 in doc)

    Note that, with any hardware, sometimes there are restrictions on changing
    register contents on the fly. I don't remember enough details of that
    chip right at the moment, to tell you whether capture should be stopped,
    between attempts to change MUXSEL. If you are operating in a snapshot mode,
    and only recording a single frame, chances are that most of the time it would
    be safe to muck about.

    In video capture mode, the BT878 makes a dandy PCI tester, and if your
    implementation is not a good one, the thing will stall in no time at all.
    I had that problem with one motherboard here - it couldn't handle a BT878
    for very long, without freezing. The computer I'm typing on at the moment,
    has no troubles with PCI.

    Paul, Aug 9, 2007
  6. ftw667

    Ken Maltby Guest

    Has your class gotten to SMB and I2C, yet?

    Ken Maltby, Aug 10, 2007
  7. ftw667

    Ken Maltby Guest

    I²C might be more exact.
    Ken Maltby, Aug 10, 2007
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