[PARPORT] PPSETMODE and the control lines in EPP

From: Crump, Valerie (VCrump@api.com)
Date: Mon Dec 11 2000 - 20:40:38 EST

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    Hi,

    I'm using ppdev and setting (not negotiating) EPP mode. BIOS and kernel
    support for EPP mode seem ok. But doing

    epp=IEEE1284_MODE_EPP;
    ioctl(fd,PPSETMODE,&mode)

    doesn't change the control lines from compatability mode to EPP mode
    idle phase. In other words, AS# stays low instead of going high for EPP
    transfers. Subsequent read and write calls do not cause any activity on
    the control lines.

    I can do manual EPP transfers by controlling the lines appropriately
    with PPWCONTROL, PPRSTATUS, PPWDATA, and so on.

    I think it may have something to do with the direction bit, but I
    thought that was handled automatically in the hardware. If I alternate
    EPP mode writes and reads (no two or more of either in a row), the data
    lines are set and read correctly. But there's no address or data
    strobing. The second write or read does not set or read the data lines
    correctly.

    Any thoughts would be appreciated.

    Thanks,
    Valerie

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