- From: Peter Gawthrop <P.Gawthrop_at_eng.gla.ac.uk>
- Date: Sat, 18 Oct 2003 19:10:44 +0100 (BST)
Hi Frank,
that seems ok now, many thanks for your help,
Peter.
--------------------------------------------------------------------
| Prof. Peter J Gawthrop | Tel: +44 141 330 4960/2528 |
| Centre for Systems and Control & | Fax: +44 141 330 4343 |
| Dept. of Mechanical Engineering | Room: James Watt 653 |
| University of Glasgow | Email: P.Gawthrop_at_eng.gla.ac.uk |
| GLASGOW G12 8QQ, Scotland, UK | URL: www.mech.gla.ac.uk/~peterg |
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From: Frank Mori Hess <fmhess_at_users.sourceforge.net>
Subject: Re: multiq3 driver: wrong value returned
Date: Mon, 13 Oct 2003 15:20:16 -0500
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> On Monday 13 October 2003 03:02 pm, Frank Mori Hess wrote:
> > On Monday 13 October 2003 01:57 pm, Peter Gawthrop wrote:
> > > Hi,
> > >
> > > I am using comedi-0.7.67 with the multiq3 driver modified to avoid the
> > > "Fix incorrect return value of AI insn function" (see most recent cvs
> > > mod.)
> > >
> > > The analogue input (Quanser Consulting MultiQ-3) seems to return the
> > > correct voltage V when V is negative. But when V is positive, it
> > > returns V-5 volts. This seems to happen on all channels.
> >
> > Are you sure it doesn't return -5-V for negative V? That's what I get
> > it should be when looking at the docs and driver.
>
> Hmm, actually the docs contradict themselves. Anyways, here is a patch
> against 0.7.67 that will probably work.
>
>
> fmhess_at_morizuma:~/cvs/comedi/comedi/drivers> cvs diff -ubB -r r0_7_67x -r
> 1.19 multiq3.c
> Index: multiq3.c
> ===================================================================
> RCS file: /var/cvs/comedi/comedi/drivers/multiq3.c,v
> retrieving revision 1.17
> retrieving revision 1.19
> diff -u -b -B -r1.17 -r1.19
> - --- multiq3.c 15 Feb 2003 18:35:46 -0000 1.17
> +++ multiq3.c 13 Oct 2003 20:12:34 -0000 1.19
> _at__at_ -103,7 +103,8 _at__at_
> {
> int i,n;
> int chan;
> unsigned int hi, lo;
> + int16_t raw_data;
>
> chan = CR_CHAN(insn->chanspec);
> outw(MULTIQ3_CONTROL_MUST | MULTIQ3_AD_MUX_EN | (chan<<3),
> _at__at_ -125,10 +126,12 _at__at_
>
> hi = inb(dev->iobase + MULTIQ3_AD_CS);
> lo = inb(dev->iobase + MULTIQ3_AD_CS);
> - - data[n] = ((hi << 8) | lo) & 0xfff;
> + raw_data = ((hi << 8) & 0xff00) | (lo & 0xff);
> + raw_data += 0x1000;
> + data[n] = raw_data & 0x1fff;
> }
>
> - - return i;
> + return n;
> }
>
> static int multiq3_ao_insn_read(comedi_device *dev, comedi_subdevice *s,
>
>
> - --
> Frank
>
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Received on 2003-10-18Z17:10:44