Re: [PARPORT] read data using ppdev in EPP mode

From: Tim Waugh (twaugh@redhat.com)
Date: Wed Mar 20 2002 - 09:42:07 EST

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    On Wed, Mar 20, 2002 at 02:29:26PM +0900, Myunghyun Lee wrote:

    > mode = IEEE1284_DEVICEID;
    > ioctl(fd, PPNEGOT, &mode);
    >
    > MFG:Winbond;MDL:W99200F;CLS:MEDIA;DES:WINBOND VIDEO ENCODER;

    Really you should use

    mode = IEEE1284_MODE_NIBBLE | IEEE1284_DEVICEID;

    (Device ID can be read in any reverse-capable mode.)

    > But I cannot read register value from W99200F.
    > Following is a read sequence.
    >
    > I negotiated to EPP before.
    >
    > set data direction to OUTPUT
    > set all control lines to HIGH
    > output address
    > set [Write] and [Address Strobe] to LOW
    > wait until [Wait] is HIGH ------------> Wait isn't changed to HIGH
    > set [Write] and [Address Strobe] to HIGH
    >
    > set data direction to OUTPUT
    > set [Write] and [Data Strobe] to Low
    > wait until [Wait] is HIGH ------------> Wait isn't changed to HIGH
    > read data
    > set [Write] and [Data Strobe] to HIGH

    How are you trying to do this? By hand, or with read()?

    Tim.
    */


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