paralel port - doesn't keep pins states

paralel port - doesn't keep pins states

[filip]

Hello,

I hope it is the right place to ask about my problem...

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
keeps this state just for few ms...
(I made special plug - so the is no problem with handshake - details on:
http://www.hut.fi/Misc/Electronics/circuits/nullprint.html)

It is strange because everything works corect on my old PC (Pentium160).

Regards,
Filip

Re: paralel port - doesn't keep pins states

[Alexandru Damian]

filip wrote:

>Hello,
>
>I hope it is the right place to ask about my problem...
>
>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
>keeps this state just for few ms...
>(I made special plug - so the is no problem with handshake - details on:
>http://www.hut.fi/Misc/Electronics/circuits/nullprint.html)
>  
>
It's normal, since the parallel -port specification clearly states that 
the port doesn't maintain
the pins voltage more than a minimum mandatory delay, and while setting, 
the
state is undefined.

>It is strange because everything works corect on my old PC (Pentium160).
>
That was broken hardware, it didn't meet the specifications :))

>
>Regards,
>Filip
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