set/reset lpt port pins - VxWorks

This is a discussion on set/reset lpt port pins - VxWorks ; Hi all, I'm using VxWorks 6.2 - Workbench 2.5 to develop a realtime automatic test equipment for a x86 board controller. I would like to profile my application using an oscilloscope, so I need to set/reset a parallel port pin ...

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Thread: set/reset lpt port pins

  1. set/reset lpt port pins

    Hi all,

    I'm using VxWorks 6.2 - Workbench 2.5 to develop a realtime automatic test
    equipment for a x86 board controller.
    I would like to profile my application using an oscilloscope, so I need to
    set/reset a parallel port pin in some points of my code (of course I'm
    thinking to connect this pin to the oscilloscope channel).

    I included the lpt support in the kernel and I called function
    lptDevCreate("/lpt/0",0) to create a device. The function correctly returned
    OK.
    Then I called function open("/lpt/0", O_RDWR, 0) and it returned a valid
    file descriptor (6).

    The problem is that function write(6, &cByte, 1) returns ERROR with errno =
    5 = "I/O error" (note: cByte is a char variable initialized to 1).
    So does function read( ).

    Where is the mistake? Note that the bios settings - address and irq - for
    parallel port match with the vxWorks kernel settings.
    Perhaps, function write( ) returns error due to the absence of some
    handshake on the parallel port control pins?
    Instead of function write( ), can I use function sysOutByte (0x378, 0x01)
    to set the pot pins?

    Thanks in advance for your help,
    Pablo



  2. Re: set/reset lpt port pins

    Of course you can use sysOutByte to control the device.
    I think it is the best way to check whether the device works properly.


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