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LPC or PCI design?

Discussion in 'Electronic Design' started by John Bordynuik, Mar 2, 2007.

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  1. Hello All,

    In the past I have used Ethernet and USB to capture data from various
    devices to a PC. I am having to connect a fair number of devices that
    require some substantial buffering and processing first (i.e.: 500+ MB).

    To simplify the project I am looking at connecting my technology to the
    LPC buses found inside P4 (modern) computers. This appears to be an
    excellent interface to transfer data quickly to a PC. The other option is to
    use a PCI DAQ card and capture all data that way.

    Has anyone here successfully interfaced their projects to the LPC bus
    inside a P4 system (like a HP Evo)?

    I would appreciate any feedback.

    I have been able to determine that I would need some kind of strobe line
    to control when my device communicates on the LPC bus. I believe this is
    done now via a GPIO line on the Intel chipset. Again, any info or experience
    you may have with this would be helpful.

    Regards,

    John Bordynuik
    JBI
     
  2. John Barrett

    John Barrett Guest

    Not that I have an answer for you -- my background is PCI -- but is that
    500mb a single block of data to move, or are you trying to move that much
    per second ?? (i.e. are you streaming the data and if so, what is your peak
    data rate ??)
     
  3. John Bordynuik selects "Not that I have an answer for you -- my background
    is PCI -- but is that 500mb a single block of data to move, or are you
    trying to move that much per second ?? (i.e. are you streaming the data and
    if so, what is your peak data rate ??)"

    Hi John,

    Some background... I have designed many data recovery systems in the past
    and what I am finding is that I need a consistent high-speed interface in a
    PC to transfer pre-processed data from a custom drive . I am now having to
    recover 3490E tapes (36-track) and slow the drives down to get a really good
    read on really bad tapes.

    I am streaming data at 5MB to 20MB/sec. I would like to interface directly
    to a PC and use it to capture and process the info. It would be nice to have
    an interface fast enough to allow for future designs (faster streaming).

    Most P4 PCs are selling for $260-300 off lease and cost less than a DAQ
    board. Cost is an issue because I usually have large numbers of tapes to
    read (thousands) and need to use many drives.

    John Bordynuik
     
  4. John Barrett

    John Barrett Guest

    USB and FireWire both meet those specifications with rates up to or above
    50MB/S (480mb/s for usb 2.0, 400mb/s or 800mb/s for FireWire)

    Wide-SCSI should also be able to keep up with those kinds of rates, if your
    drives are SCSI interfaced, or you build a SCSI translator

    Otherwise you are looking at an atmega 32 bit microcontroller with on-chip
    USB to do the grunt work of talking to the drive and pumping the data
    upstream

    or a similar FPGA/CPLD solution if the faster atmega chips cant keep up with
    the data rate from the drive (the primary difference is that the FPGA/CPLD
    solution can internally use what amounts to DMA to transfer data from the
    drive to memory and memroy to USB without the microcontroller portion of the
    core having to handle the data on a byte by byte basis)
     
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