To use a LapLink cable, you must have "parport", "parport_pc" and "ppdev"
already compiled into the kernel or insert via 'insmod' into the kernel.
#insmod parport
#insmod parport_pc
#insmod ppdev
Then in the c program....
//////////////////////////////////////////////////////////////
unsigned char ucData;
int nPort;
nPort = open("/dev/parport0", O_RDWR);
ioctl(nPort, PPCLAIM, 0);
// ... do stuff
// to write 5 bits
ioctl(nPort, PPWDATA, &ucData);
// ... do stuff
// to read 8 bits
ioctl(m_nPort, PPRSTATUS, ucData);
// ... do stuff
close(nPort);
//////////////////////////////////////////////////////////////
The pin out the LapLink cable is very important... This is why you can read
8 (although they are really 5 bits and shifted) and why you can only write 5
bits at a time.
D7 - xx
D6 - xx
D5 - xx
D4 - ~S7 Remember the "active low verses active high" thing
D3 - S6
D2 - S5
D1 - S4
D0 - S3
xx - S2
xx - S1
xx - S0
Good picture of pins to bits
http://www.doc.ic.ac.uk/~ih/doc/par/
If you can claim the port after opening it, then you can write anything to
D4-D0 you want the other end to see in S7-S3 and vice-versa...
Nate
----- Original Message -----
From: "Bob Tanner" <tanner@real-time.com>
To: "Nate Jenkins" <nate@uniwest.com>
Cc: <linux-parport@torque.net>
Sent: Monday, February 10, 2003 2:10 PM
Subject: Re: [PARPORT] Simple EPP PPNEGOT?
> Quoting Nate Jenkins (nate@uniwest.com):
> > I have had success with using ppdev with a LapLink cable between two PCs
but
> > not with the negotiation code you referenced. I ended up having to
control
> > it myself on the pin by pin basis.
> >
> > So are you trying to talk "to a PC from a PC" or "to Peripheral from
PC"? I
> > thought your email said both. Maybe just practicing with PC for now?
>
> Can you control the port pin-by-pin in user-space using parport?
>
> I can't seem to figure that out.
> --
> Bob Tanner <tanner@real-time.com> | Phone : (952)943-8700
> http://www.mn-linux.org, Minnesota, Linux | Fax : (952)943-8500
> http://www.tcwug.org, Minnesota, Wireless | Coding isn't a crime.
> Fingerprint: 02E0 2734 A1A1 DBA1 0E15 623D 0036 7327 93D9 7DA3
>
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