i will try using my old 386 for this hoping that you are right BUT there
are some items that remain:
- why can't EXCLUSIVE mode (both in open() and ioctl() ) can't get the
port to remain 'aquired' ?
- why under another OS, the port behaves nicely :) ??
> I too am getting some sort of interference out of the parallel port
> pins. During my early testing I had installed a test connector to the
> parallel port with an LED tied to D4 (pin 5). My code should have
> pulsed the LED on/off at 1Hz (50% duty cycle). Instead, the LED would
> get short pulses off pulses at 1 Hz.
>
> To make matters worse, when I printed to my USB printer, the LED would
> start blinking oddly even though nothing should have been talking to it.
>
> I ran my test in single user mode, uninstalled the printer, tried lots
> of other things which didn't work. I also ran a test which bypasses the
> paraport driver and uses ioperm to drive the parallel port. Still no
> luck.
>
> Finally, I ran on an older HP Vectra instead of my e-machine. The HP
> Vectra did behave nicely, the data pins stayed driven at whatever level
> I left them for many seconds.
>
> I'm guessing that the e-machine i/o chip does something odd when nobody
> is talking to it. Like after 50ms, it goes back to some default mode.
> The parallel port does work properly at speed, it just misbehaves
> inbetween cycles.
>
> I'm also new to the parport stuff and could be suffering from excessive
> user ignorance.
>
> --mark
----------------------------
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ataraxis@disponibil.net
lucian@psdtimis.ro
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This archive was generated by hypermail 2b29 : Thu Mar 06 2003 - 03:06:48 EST