If your board is acknowledging the byte it is sent, there is no reason
for the parallel port to hold the byte that it is sending. Have you
tried not acknowledging?
If you just want to set byte on the port, you could use /dev/parport or
libieee1284 which would allow you to write the data without worrying
about the control bits.
Blaise
Quoted from filip on Fri, Apr 11, 2003 at 11:03:32PM +0200.
> I want to use /dev/lp0 (lp module) on my PC for controlling
> external devices.
> The problem is when I wtire 1 byte to /dev/lp0, paralel port
> holds this state just for a few ms - if I write to /dev/lp0 0x00
> pins change to LOW for a moment, and then some of the returns to HIGH
> and some stay LOW.
> (I made special plug - so the is no problem with handshake - details on:
> http://www.hut.fi/Misc/Electronics/circuits/nullprint.html)
>
> lsmod
> lp 8864 0 (unused)
> parport_pc 18724 1 (autoclean)
> parport 34208 1 (autoclean) [lp parport_pc]
>
> cat /proc/sys/dev/parport/parport0/modes
> PCSPP,TRISTATE
>
> In bios (Setup) I have set SPP mode.
>
> The problem is on this PC on RH7.3 and also on Slackware9.0
> but on FreeBSD everything is OK (on FreeBSD I use /dev/lpt0).
>
> It is strange because everything works corect on
> my old PC (Pentium160).
>
> Can you help?
>
> Regards,
> Filip
>
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This archive was generated by hypermail 2b29 : Fri Apr 11 2003 - 18:05:13 EDT