added comedilib_reference and comedilib updates
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7 changed files with 2482 additions and 26 deletions
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@ -270,16 +270,13 @@ int main(int argc,char *argv[])
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Should be understandable. Open the device, get the data,
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print it out. This is basically the guts of <tt>demo/inp.c</tt>,
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without error checking or fancy options. Including all
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the appropriate headers is sometimes a little tricky.
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without error checking or fancy options.
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Compile it using
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<tscreen><verb>
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cc tut1.c -lcomedi -o tut1
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</verb></tscreen>
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Hopefully it works.
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A few notes: The range variable tells comedi which gain
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to use when measuring an analog voltage. Since we don't
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know (yet) which numbers are valid, or what each means,
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@ -303,20 +300,29 @@ a voltage. Naturally, as a good programmer, your first
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question is: "How do I do this in a device-independent
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manner?"
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For each subdevice, the comedi kernel module keeps a
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'range_type' variable. This variable contains the number
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of available ranges (i.e., gains) that you can select,
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along with an offset in a list of range information
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structures. If you know the range_type variable, you
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can use these macros:
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Most devices give you a choice of gain and unipolar/bipolar
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input, and Comedi allows you to select which of these to
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use. This parameter is called the "range parameter", since
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it specifies the "input range" for analog input (or "output range"
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analog output.) The range parameter represents both the gain
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and the unipolar/bipolar aspects.
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RANGE_OFFSET(range_type)
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RANGE_LENGTH(range_type)
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Comedi keeps the number of available ranges and the largest
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sample value for each subdevice/channel combination. (Some
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devices allow different input/output ranges for different
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channels in a subdevice.)
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to extract such information. However, you want the
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actual voltage information, not some integer offset
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in a table. Rather than messing with the library
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internals, use the function
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The largest sample value can be found using the function:
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comedi_get_maxdata()
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The number of available ranges can be found using the function:
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comedi_get_n_ranges()
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For each value of the range parameter for a particular
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subdevice/channel, you can get range information using the
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function:
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ptr=comedi_get_range(comedi_file,subdevice,channel,
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range)
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@ -333,8 +339,7 @@ typedef struct{
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}comedi_range;
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</verb></tscreen>
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As you might expect, ptr[range] is for range 'range',
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which you provided to comedi_data_read() above. 'min' represents
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The structure element 'min' represents
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the voltage corresponding to comedi_data_read() returning 0,
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and 'max' represents comedi_data_read() returning 'maxdata',
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(i.e., 4095 for 12 bit A/C converters, 65535 for 16 bit,
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@ -356,13 +361,6 @@ and the opposite
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data=comedi_from_phys(it,volts,range,maxdata);
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</verb></tscreen>
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You probably noticed (and were worried) that we haven't
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discussed how to determine maxdata and range_type. Well,
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you could ask the kernel this information each time you need
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it, but since there are other variables, special cases,
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and several subdevices to worry about, it would be nice
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if the library could take care of this... (read on...)
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<p>
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<sect1>Another section
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@ -385,7 +383,7 @@ where file is of type <tt>(comedi_t *)</tt>. This function
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calls <tt>open()</tt>, like we did explicitly in a previous
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section, but also fills the <tt>comedi_t</tt> structure with
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lots of goodies -- information that we will need to use
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soon.
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soon.
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Specifically, we needed to know maxdata for a specific
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subdevice/channel. How about:
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792
doc/comedilib_reference-1.html
Normal file
792
doc/comedilib_reference-1.html
Normal file
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@ -0,0 +1,792 @@
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>Comedi Documentation: Libcomedi Reference</TITLE>
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<LINK HREF="comedilib_reference.html#toc1" REL=contents>
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</HEAD>
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<BODY>
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Next
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Previous
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<A HREF="comedilib_reference.html#toc1">Contents</A>
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<HR>
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<H2><A NAME="s1">1. Libcomedi Reference</A></H2>
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<P>
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<P>
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<H2><A NAME="ss1.1">1.1 Constants and Macros</A>
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</H2>
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<P>
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<P>
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<P>
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<H3>RANGE_LENGTH() <I>(deprecated)</I></H3>
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<P>
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<A NAME="RANGE_LENGTH"></A> <P><CODE>RANGE_LENGTH(rangetype)</CODE>
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<P>
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<P>Rangetype values are library-internal tokens that represent an
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array of range information structures. These numbers are primarily
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used for communication between the kernel and library.
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<P>
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<P>The RANGE_LENGTH() macro returns the length of the array that is
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specified by the rangetype token.
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<P>
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<P>The RANGE_LENGTH() macro is deprecated, and should not be used in
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new applications. It is scheduled to be removed from the header
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file at version 1.0. Binary compatibility may be broken for version
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1.1.
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<P>
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<P>
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<P>
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<H2><A NAME="ss1.2">1.2 Data Types and Structures</A>
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</H2>
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<P>
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<H3><A NAME="comedi_t"></A> comedi_t</H3>
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<P>The data type <CODE>comedi_t</CODE> is used to represent an open Comedi
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device. A valid <CODE>comedi_t</CODE> pointer is returned by a successful
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call to <CODE>comedi_open()</CODE>, and should be used for subsequent
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access to the device.
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It is a transparent type, and pointers to type <CODE>comedi_t</CODE>
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should not be dereferenced.
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<P>
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<P>
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<P>
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<H3><A NAME="sampl_t"></A> sampl_t</H3>
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<P>The data type <CODE>sampl_t</CODE> is one of the generic types used to represent
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data values in libcomedi. It is used in a few places where a shorter
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data type is useful, but is limited to 16 bits on the i386 architecture.
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<P>
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<P>
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<P>
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<H3><A NAME="lsampl_t"></A> lsampl_t</H3>
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<P>The data type <CODE>lsampl_t</CODE> is one of the generic types used to represent
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data values in libcomedi. It is currently defined to be <CODE>unsigned int</CODE>.
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<P>
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<P>
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<P>
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<P>
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<P>
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<H3><A NAME="comedi_trig_struct"></A> comedi_trig_struct <I>(deprecated)</I></H3>
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<P>
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<P>The <CODE>comedi_trig</CODE> structure
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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struct comedi_trig_struct{
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unsigned int subdev; /* subdevice */
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unsigned int mode; /* mode */
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unsigned int flags;
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unsigned int n_chan; /* number of channels */
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unsigned int *chanlist; /* channel/range list */
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sampl_t *data; /* data list, size depends on subd flags */
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unsigned int n; /* number of scans */
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unsigned int trigsrc;
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unsigned int trigvar;
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unsigned int trigvar1;
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unsigned int data_len;
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unsigned int unused[3];
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}
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</PRE>
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</CODE></BLOCKQUOTE>
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<P>The <CODE>comedi_trig</CODE> structure is a control structure used by the
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COMEDI_TRIG ioctl, an older method of communicating
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instructions to the driver and hardware. Use of Comedi triggers is
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deprecated, and should not be used in new applications.
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<P>
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<P>
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<P>
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<H3><A NAME="comedi_sv_t"></A> comedi_sv_t</H3>
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<P>
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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struct comedi_sv_struct{
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comedi_t *dev;
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unsigned int subdevice;
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unsigned int chan;
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/* range policy */
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int range;
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int aref;
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/* number of measurements to average (for ai) */
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int n;
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lsampl_t maxdata;
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}
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</PRE>
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</CODE></BLOCKQUOTE>
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<P>The <CODE>comedi_sv_t</CODE> structure is used by the <CODE>comedi_sv_*()</CODE>
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functions to provide a simple method of accurately measuring
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slowly varying inputs. See the relevant section for more
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details.
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<P>
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<P>
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<P>
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<H2><A NAME="ss1.3">1.3 Functions</A>
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</H2>
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<P>
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<P>
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<H3><A NAME="comedi_close"></A> comedi_close()</H3>
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<P>
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<P><CODE>void comedi_close(comedi_t *it);</CODE>
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<P>
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<P>Closes a device previously opened by comedi_open().
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<P>
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<P>The return type of this function will change to <CODE>int</CODE>, in
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order to match <CODE>fclose</CODE>.
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<P>
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<P>Source: <CODE>/lib/comedi.c</CODE>
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<P>
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<P>
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<H3><A NAME="comedi_data_read"></A> comedi_data_read()</H3>
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<P>
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<P><CODE>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
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unsigned int range,unsigned int aref,lsampl_t *data);</CODE>
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<P>
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<P>Reads a single sample on the channel that
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is specified by the comedi device <CODE>it</CODE>, the
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subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
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For the A/D conversion (if appropriate),
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the device is configured to use range specification
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<CODE>range</CODE> and (if appropriate) analog reference type
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<CODE>aref</CODE>. Analog reference types that are not supported
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by the device are silently ignored.
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<P>
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<P><CODE>comedi_data_read()</CODE> reads one data value from
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the specified channel and places the
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data value that is read in the location pointed to by
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<CODE>data</CODE>.
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<P>
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<P>On sucess, <CODE>comedi_data_read()</CODE> returns 0. If there is an
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error, -1 is returned.
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<P>
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<P>Valid analog reference numbers are:
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<P>
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<UL>
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<LI>AREF_GROUND Reference to analog ground</LI>
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<LI>AREF_COMMON Reference to analog common</LI>
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<LI>AREF_DIFF Differential reference</LI>
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<LI>AREF_OTHER Board-specific meaning</LI>
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</UL>
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<P>Valid data values returned by these function is an unsigned integer
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less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
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Conversion of these data value to physical units can be performed
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by <CODE>
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<A HREF="#comedi_to_phys">comedi_to_phys()</A></CODE>.
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<P>Source: <CODE>/lib/data.c</CODE>
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<P>
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<P>
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<H3>comedi_data_write()</H3>
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<P>
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<P><CODE>int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
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unsigned int range,unsigned int aref,lsampl_t data);</CODE>
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<P>
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<P>Writes a single sample on the channel that
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is specified by the comedi device <CODE>it</CODE>, the
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subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
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For the D/A conversion (if appropriate), the device is
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configured to use range specification
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<CODE>range</CODE> and (if appropriate) analog reference type
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<CODE>aref</CODE>. Analog reference types that are not supported
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by the device are silently ignored.
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<P><CODE>comedi_data_write()</CODE> writes the data value
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specified by the argument <CODE>data</CODE> to
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the specified channel.
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<P>On sucess, <CODE>comedi_data_write()</CODE> returns 0. If there is an error, -1 is
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returned.
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<P>Valid analog reference numbers are:
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<P>
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<UL>
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<LI>AREF_GROUND Reference to analog ground</LI>
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<LI>AREF_COMMON Reference to analog common</LI>
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<LI>AREF_DIFF Differential reference</LI>
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<LI>AREF_OTHER Board-specific meaning</LI>
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</UL>
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<P>Valid data values used by these functions is an unsigned integer
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less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
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Conversion of physical units to these data value can be performed
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by <CODE>
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<A HREF="#comedi_from_phys">comedi_from_phys()</A></CODE>.
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<P>Source: <CODE>/lib/data.c</CODE>
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<P>
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<P>
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<P>
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<H3>comedi_dio_bitfield();</H3>
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<P><CODE>int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned
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int write_mask,unsigned int *bits);</CODE>
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<P>
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<P>The function <CODE>comedi_dio_bitfield()</CODE> allows multiple channels to
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be read simultaneously from a digital input or digital I/O device.
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The parameter <CODE>write_mask</CODE> and the value pointed to by <CODE>bits</CODE>
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are interpreted as bit fields, with the least significant bit
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representing channel 0. For each bit in <CODE>write_mask</CODE> that is
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set, the cooresponding bit in <CODE>*bits</CODE> is written to the digital
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output channel. Each digital input channel is read, and the result
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placed in the approprate bits in <CODE>*bits</CODE>.
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<P>
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<P>The current implementation reads and writes bits using separate
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system calls, which is not ideal. When the kernel driver supports
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simultaneous reading/writing, this will be fixed in the library.
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<P>
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<P>It should be noted that it is not possible to access channels
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greater than 31 using this function.
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<P>
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<P>Source: <CODE>/lib/dio.c</CODE>
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<P>
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<P>
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<P>
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<H3>comedi_dio_config()</H3>
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<P><CODE>int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned
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int chan,unsigned int dir);</CODE>
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<P>
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<P>The function <CODE>comedi_dio_config</CODE> configures individual channels
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in a digital I/O subdevice to be either input or output, depending
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on the value of parameter <CODE>dir</CODE>. Depending on the capabilities
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of the hardware device, multiple channels may be affected by
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a single call to <CODE>comedi_dio_config</CODE>.
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<P>
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<P>Valid directions are:
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<UL>
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<LI> COMEDI_INPUT</LI>
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<LI> COMEDI_OUTPUT</LI>
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</UL>
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<P>Source: <CODE>/lib/dio.c</CODE>
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<P>
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<P>
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<P>
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<H3>comedi_dio_read()</H3>
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<P><CODE>int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int
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chan,unsigned int *bit);</CODE>
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<P>
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<P>The function reads the status of channel <CODE>chan</CODE> belonging to the digital
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input subdevice <CODE>subd</CODE> of device <CODE>it</CODE>. The result, 0 or 1, is stored
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in bit. Returns -1 on failure.
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<P>
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<P>This function is equivalent to <CODE>comedi_data_read(it,subd,chan,0,0,bit)</CODE>.
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<P>
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<P>Source: <CODE>/lib/dio.c</CODE>
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<P>
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<P>
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<H3>comedi_dio_write()</H3>
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<P><CODE>int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned
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int chan,unsigned int bit);</CODE>
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<P>
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<P>The function writes the value of <CODE>bit</CODE>, 0 or 1, to channel <CODE>chan</CODE>,
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belonging to the digital output device <CODE>subd</CODE> of device <CODE>it</CODE>. Returns
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-1 on failure.
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<P>
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<P>Source: <CODE>/lib/dio.c</CODE>
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<P>
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<P>
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<H3>comedi_fileno()</H3>
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<P>
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<P><CODE>int comedi_fileno(comedi_t *it);</CODE>
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<P>
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<P>The function <CODE>comedi_fileno</CODE>
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returns the integer descriptor for the handle <CODE>it</CODE>. It
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is equivalent to the standard function <CODE>fileno</CODE>. If
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<CODE>it</CODE> is an invalid <CODE>comedi_t</CODE> pointer, the function
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returns -1 and sets the appropriate libcomedi error value.
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<P>Source: <CODE>/lib/comedi.c</CODE>
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<P>
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<P>
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<P>
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<H3>comedi_find_range()</H3>
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<P>
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<P><CODE>int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
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int chan, unsigned int unit, double min, double max);</CODE>
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<P>
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<P>The function <CODE>comedi_find_range</CODE> tries to
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locate the optimal (smallest) range for the channel <CODE>chan</CODE>
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belonging to a <CODE>subdevice</CODE> of the comedi device <CODE>it</CODE>,
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that includes both <CODE>min</CODE> and <CODE>max</CODE> in <CODE>units</CODE>.
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If it finds a matching range, it returns its index. If no
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matching range is available, it returns -1.
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<P>
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<P>Valid units are:
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<P>
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<UL>
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<LI>UNIT_volt </LI>
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<LI>UNIT_mA</LI>
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<LI>UNIT_none</LI>
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</UL>
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<P>Source: <CODE>/lib/range.c</CODE>
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<P>
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<P>
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<P>
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<H3><A NAME="comedi_errno"></A> comedi_errno()</H3>
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<P><CODE>int comedi_errno(void);</CODE>
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<P>
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<P>The function <CODE>comedi_errno()</CODE>
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returns an integer describing the most recent comedilib error. This
|
||||
integer may be used as the <CODE>errnum</CODE> parameter for
|
||||
<CODE>
|
||||
<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
|
||||
<P>When a libcomedi function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<CODE>comedi_errno()</CODE>. This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<CODE>
|
||||
<A HREF="#comedi_perror">comedi_perror()</A></CODE>
|
||||
and <CODE>
|
||||
<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
|
||||
<P>These functions are intended to mimic the behavior of the
|
||||
standard C library functions <CODE>perror()</CODE>,
|
||||
<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
|
||||
libcomedi functions sometimes return an error that is generated
|
||||
by the C library; the Comedi error message in this case
|
||||
is the same as the C library.
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_find_subdevice_by_type()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
|
||||
start_subdevice);</CODE>
|
||||
<P>
|
||||
<P>The function <CODE>comedi_find_subdevice_by_type</CODE> tries to
|
||||
locate a subdevice belonging to comedi device <CODE>it</CODE>,
|
||||
having type <CODE>type</CODE>, starting with the subdevice
|
||||
<CODE>start_subdevice</CODE>. If it finds the requested subdevice,
|
||||
it returns its index. If it does not locate the requested
|
||||
subdevice, it returns -1 and sets the comedi error number to
|
||||
"subdevice not found". If there is an error, the function
|
||||
returns -1 and sets the appropriate error.
|
||||
<P>
|
||||
<P>For subdevice types, see the manual page for the function
|
||||
<CODE>
|
||||
<A HREF="#comedi_get_subdevice_type">comedi_get_subdevice_type()</A></CODE>.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3><A NAME="comedi_from_phys"></A> comedi_from_phys()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>lsampl_t comedi_from_phys(double data, comedi_range *rng,
|
||||
lsampl_t maxdata);</CODE>
|
||||
<P>Converts data given in physical units (<CODE>data</CODE>) into sample values
|
||||
(lsampl_t, between 0 and maxdata). The parameter <CODE>rng</CODE>
|
||||
represents the conversion information to use, and the parameter
|
||||
<CODE>maxdata</CODE> represents the maximum possible data value for the
|
||||
channel that the data will be written to.
|
||||
<P>
|
||||
<P>Source: <CODE>/lib/range.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_board_name()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>char *comedi_get_board_name(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_get_board_name</CODE> returns a pointer
|
||||
to a string containing the name of the device. This pointer is
|
||||
valid until the comedi descriptor <CODE>it</CODE> is closed. This
|
||||
function returns <CODE>NULL</CODE> if there is an error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_driver_name()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>char *comedi_get_driver_name(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_get_driver_name</CODE> returns a pointer
|
||||
to a string containing the name of the driver being used by comedi
|
||||
for the comedi device represented by <CODE>it</CODE>. This pointer is
|
||||
valid until the comedi descriptor <CODE>it</CODE> is closed. This
|
||||
function returns <CODE>NULL</CODE> if there is an error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_maxdata()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int
|
||||
subdevice,unsigned int chan);</CODE>
|
||||
<P>
|
||||
<P>The function <CODE>comedi_get_maxdata()</CODE> returns the maximum
|
||||
valid data value for channel <CODE>chan</CODE> of subdevice
|
||||
<CODE>subdevice</CODE> belonging to the comedi device <CODE>it</CODE>
|
||||
This function returns 0 on error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_n_channels()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);</CODE>
|
||||
<P>The function <CODE>comedi_get_n_channels()</CODE> returns the number
|
||||
of channels of the subdevice belonging to the comedi device <CODE>it</CODE>
|
||||
and having index <CODE>subdevice</CODE>. This function returns -1 on error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_n_ranges()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
|
||||
chan);</CODE>
|
||||
<P>The function <CODE>comedi_get_n_ranges()</CODE> returns the number
|
||||
of ranges of the channel <CODE>chan</CODE> belonging to the <CODE>subdevice</CODE>
|
||||
of the comedi device <CODE>it</CODE>. This function returns -1 on error.
|
||||
<P>Source: <CODE>/lib/range.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_n_subdevices()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_n_subdevices(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_get_n_subdevices</CODE> returns the
|
||||
number of subdevices associated with the comedi descriptor
|
||||
<CODE>it</CODE>, or -1 if there is an error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_range()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
|
||||
range);</CODE>
|
||||
<P>The function <CODE>comedi_get_range</CODE> returns a pointer to a
|
||||
comedi_range structure that contains information that can be used to
|
||||
convert sample values to or from physical units. The pointer is valid
|
||||
until the comedi device <CODE>it</CODE> is closed. If there is an
|
||||
error, NULL is returned.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_rangetype()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
|
||||
chan);</CODE>
|
||||
<P>The function <CODE>comedi_get_rangetype()</CODE> returns an integer
|
||||
that represents the number of range specifications available for a
|
||||
particular channel <CODE>chan</CODE> of the subdevice <CODE>subdevice</CODE>, as well as a conversion table to convert sample
|
||||
values to/from physical units.
|
||||
<P>The macro
|
||||
<CODE>RANGE_LENGTH(rangetype)</CODE>
|
||||
can be used to determine the number of range specifications for a given
|
||||
range type.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H3><A NAME="comedi_get_subdevice_type"></A> comedi_get_subdevice_type()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</CODE>
|
||||
<P>The function <CODE>comedi_get_subdevice_type()</CODE> returns an
|
||||
integer describing the type of subdevice that belongs to the comedi
|
||||
device <CODE>it</CODE> and has the index <CODE>subdevice</CODE>. The
|
||||
function returns -1 is there is an error.
|
||||
<P>Valid subdevice types are:
|
||||
<P>
|
||||
<UL>
|
||||
<LI><CODE>COMEDI_SUBD_UNUSED</CODE>
|
||||
Subdevice has no functionality, i.e., a place-holder.</LI>
|
||||
<LI><CODE>COMEDI_SUBD_AI</CODE> Analog input</LI>
|
||||
<LI><CODE>COMEDI_SUBD_AO</CODE> Analog output</LI>
|
||||
<LI><CODE>COMEDI_SUBD_DI</CODE> Digital input</LI>
|
||||
<LI><CODE>COMEDI_SUBD_DO</CODE> Digital output</LI>
|
||||
<LI><CODE>COMEDI_SUBD_DIO</CODE>
|
||||
Digital input/output. Channels are configurable as to whether they
|
||||
are inputs or outputs.</LI>
|
||||
<LI><CODE>COMEDI_SUBD_COUNTER</CODE> Counter</LI>
|
||||
<LI><CODE>COMEDI_SUBD_TIMER</CODE> Timer</LI>
|
||||
<LI><CODE>COMEDI_SUBD_MEMORY</CODE>
|
||||
Memory, e.g., EEPROM or dual-ported RAM</LI>
|
||||
<LI><CODE>COMEDI_SUBD_CALIB</CODE>
|
||||
Calibration DACs</LI>
|
||||
<LI><CODE>COMEDI_SUBD_PROC</CODE>
|
||||
Processor or DSP</LI>
|
||||
</UL>
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_timer() <I>(deprecated)</I></H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_timer(comedi_t *it,unsigned int subdev, double
|
||||
freq,unsigned int *trigvar, double *actual_freq);</CODE>
|
||||
<P>
|
||||
<P>The function <CODE>comedi_get_timer</CODE> converts the frequency <CODE>freq</CODE>
|
||||
to a number suitable to send to the driver in a <CODE>comedi_trig</CODE>
|
||||
structure. This function remains for compatibility with very
|
||||
old versions of Comedi, that converted sampling rates to timer
|
||||
values in the libary. This conversion is now done in the kernel,
|
||||
and every device has the timer type <CODE>nanosec_timer</CODE>, indicating
|
||||
that timer values are simply a time specified in nanoseconds.
|
||||
<P>
|
||||
<P>This function is deprecated and should not be used in new applications.
|
||||
<P>
|
||||
<P>Source: <CODE>/lib/timer.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_version_code()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_version_code(comedi_t *it);</CODE>
|
||||
<P>
|
||||
<P>The function <CODE>comedi_get_version_code()</CODE> returns the
|
||||
version code of the currently running comedi module. The version
|
||||
code is of the form 0x01072b, which is the version code for
|
||||
version 1.7.43.
|
||||
<P>
|
||||
<P>This function is of limited usefulness. A typical mis-application
|
||||
of this function is to use it to determine if a certain feature is
|
||||
supported. If the application needs
|
||||
to know of the existence of a particular feature, an existence
|
||||
test function should be written and put in the libcomedi source.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_loglevel()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_loglevel(int loglevel);</CODE>
|
||||
<P>
|
||||
<P>This function affects the output of debugging and error messages
|
||||
from libcomedi. By increasing the loglevel, additional debugging
|
||||
information will be printed. This function returns the previous
|
||||
loglevel. Error messages and debugging are printed to the
|
||||
stream <CODE>stderr</CODE>. The loglevel can also be affected by the
|
||||
environment variable COMEDI_LOGLEVEL.
|
||||
<P>
|
||||
<P>In order to conserve resources, some debugging information is
|
||||
disabled when libcomedi is compiled.
|
||||
<P>
|
||||
<P>The meaning of the loglevels is as follows:
|
||||
<P>
|
||||
<UL>
|
||||
<LI><CODE>COMEDILIB_LOGLEVEL=0</CODE>
|
||||
|
||||
Comedilib prints nothing.
|
||||
</LI>
|
||||
<LI><CODE>COMEDILIB_LOGLEVEL=1</CODE> (default)
|
||||
|
||||
Comedilib only prints error messages when there is a
|
||||
self-consistency error (i.e., internal bug).
|
||||
</LI>
|
||||
<LI><CODE>COMEDILIB_LOGLEVEL=2</CODE>
|
||||
|
||||
Comedilib prints an error message when an invalid
|
||||
parameter is passed to comedilib.
|
||||
</LI>
|
||||
<LI><CODE>COMEDILIB_LOGLEVEL=3</CODE>
|
||||
|
||||
Comedilib prints an error message whenever an error is generated
|
||||
in the comedilib library or is generated in the C library when
|
||||
called by comedilib.
|
||||
</LI>
|
||||
<LI><CODE>COMEDILIB_LOGLEVEL=4</CODE>
|
||||
|
||||
Comedilib prints a lot of debugging messages.
|
||||
</LI>
|
||||
</UL>
|
||||
<P>Bugs: Libcomedi doesn't currently have much debugging information.
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_open()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>comedi_t *comedi_open(char *filename);</CODE>
|
||||
<P>Opens a comedi device specified by the filename <CODE>filename</CODE>.
|
||||
Returns NULL on error. On sucess, it returns a handle that is
|
||||
given as a parameter to other libcomedi functions.
|
||||
<P>
|
||||
<P>You are not supposed to have access to the internals of the
|
||||
<CODE>comedi_t</CODE> structure.
|
||||
<P>Bugs: Not strictly identical to <CODE>fopen</CODE>
|
||||
<P>Source: <CODE>/lib/comedi.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3><A NAME="comedi_perror"></A> comedi_perror()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>void comedi_perror(const char *s);</CODE>
|
||||
<P>When a comedilib function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<CODE>
|
||||
<A HREF="#comedi_errno">comedi_errno()</A></CODE>.
|
||||
This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<CODE>comedi_perror()</CODE>
|
||||
and <CODE>
|
||||
<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
|
||||
<P>These functions are intended to mimic the behavior of the
|
||||
standard C library functions <CODE>perror()</CODE>,
|
||||
<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
|
||||
comedilib functions sometimes return an error that is generated
|
||||
inside the C library; the comedi error message in this case
|
||||
is the same as the C library.
|
||||
<P>The function <CODE>comedi_perror()</CODE> prints an error
|
||||
message to stderr. The error message consists of the
|
||||
argument string, a colon, a space, a description of the error
|
||||
condition, and a new line.
|
||||
<P>Bugs: Does not support internationalization.
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3><A NAME="comedi_strerror"></A> comedi_strerror()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>*comedi_strerror(int errnum);</CODE>
|
||||
<P>When a comedilib function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<CODE>
|
||||
<A HREF="#comedi_errno">comedi_errno()</A></CODE>. This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<CODE>
|
||||
<A HREF="#comedi_perror">comedi_perror()</A></CODE>
|
||||
and <CODE>comedi_strerror()</CODE>.
|
||||
<P>These functions are intended to mimic the behavior of the
|
||||
standard C library functions <CODE>perror()</CODE>,
|
||||
<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
|
||||
comedilib functions sometimes return an error that is generated
|
||||
inside the C library; the comedi error message in this case
|
||||
is the same as the C library.
|
||||
<P>The function <CODE>comedi_strerror()</CODE> returns a pointer to a
|
||||
character string
|
||||
describing the comedilib error <CODE>errnum</CODE>. The persistence
|
||||
of the returned pointer is undefined, and should not be trusted
|
||||
after the next libcomedi call. An unrecognized error number will
|
||||
return a pointer to the string "undefined error", or similar.
|
||||
<P>Bugs: Does not support internationalization.
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_sv_init()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd,
|
||||
unsigned int chan);</CODE>
|
||||
<P>
|
||||
<P><CODE>comedi_sv_init</CODE> initializes the slow varying comedi structure
|
||||
<CODE>sv</CODE> of the device <CODE>dev</CODE>, the subdevice <CODE>subd</CODE> (analog input) and
|
||||
the channel <CODE>chan</CODE>.
|
||||
The slow varying comedi structure <CODE>sv</CODE> of type <CODE>
|
||||
<A HREF="#comedi_sv_t">comedi_sv_t</A></CODE>
|
||||
specifies the signal measurement. The default number of averaged
|
||||
samples is 100. Returns zero on success, -1 on error.
|
||||
<P>Bugs: comedi_sv_* was very poorly designed.
|
||||
<P>Source: <CODE>/lib/sv.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_sv_update()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_sv_update(comedi_sv_t *sv);</CODE>
|
||||
<P>The function <CODE>comedi_sv_update</CODE> updates the slow varying comedi structure
|
||||
<CODE>sv</CODE>.
|
||||
Returns zero on success, -1 on error.
|
||||
<P>Source: <CODE>/lib/sv.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>int comedi_sv_measure()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_sv_measure(comedi_sv_t *it,double *data);</CODE>
|
||||
<P><CODE>comedi_sv_measure</CODE> measures the slow variing signal. The measurement
|
||||
is specified by the slow varying comedi structure <CODE>sv</CODE>, the result is
|
||||
stored in <CODE>data</CODE>.
|
||||
On success returns the number of samples, -1 on error.
|
||||
<P>Source: <CODE>/lib/sv.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3><A NAME="comedi_to_phys"></A> comedi_to_phys()</H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>double comedi_to_phys(lsampl_t data, comedi_range *rng,
|
||||
lsampl_t maxdata);</CODE>
|
||||
<P>Converts data given in sample values (lsampl_t, between 0 and
|
||||
maxdata) into physical units (double). The parameter <CODE>rng</CODE>
|
||||
represents the conversion information to use, and the parameter
|
||||
<CODE>maxdata</CODE> represents the maximum possible data value for the
|
||||
channel that the data was read.
|
||||
<P>Source: <CODE>/lib/range.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_trigger() <I>(deprecated)</I></H3>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_trigger(comedi_t *it,comedi_trig *trig);</CODE>
|
||||
<P>The function <CODE>comedi_trigger</CODE> instructs comedi to
|
||||
perform the command specified by the
|
||||
<A HREF="#comedi_trig_struct">trigger structure</A> <CODE>trig</CODE>. Results depend on
|
||||
the particular command being issued. If there is an
|
||||
error, -1 is returned.
|
||||
<P>Lifetime: removal at 1.0.
|
||||
<P>Source: <CODE>/lib/comedi.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H3>comedi_get_timer()</H3>
|
||||
|
||||
<P>
|
||||
<P>
|
||||
<BLOCKQUOTE><CODE>
|
||||
<PRE>
|
||||
int comedi_get_timer(comedi_t *it,unsigned int subdev,double freq,unsigned int *trigvar,
|
||||
double *actual_freq);
|
||||
</PRE>
|
||||
</CODE></BLOCKQUOTE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<HR>
|
||||
Next
|
||||
Previous
|
||||
<A HREF="comedilib_reference.html#toc1">Contents</A>
|
||||
</BODY>
|
||||
</HTML>
|
39
doc/comedilib_reference-2.html
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39
doc/comedilib_reference-2.html
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|
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|
|||
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
||||
<HTML>
|
||||
<HEAD>
|
||||
<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
|
||||
<TITLE>Comedi Documentation: Reference Comedilib-0.7.9: types</TITLE>
|
||||
<LINK HREF="comedilib_reference-3.html" REL=next>
|
||||
<LINK HREF="comedilib_reference-1.html" REL=previous>
|
||||
<LINK HREF="comedilib_reference.html#toc2" REL=contents>
|
||||
</HEAD>
|
||||
<BODY>
|
||||
<A HREF="comedilib_reference-3.html">Next</A>
|
||||
<A HREF="comedilib_reference-1.html">Previous</A>
|
||||
<A HREF="comedilib_reference.html#toc2">Contents</A>
|
||||
<HR>
|
||||
<H2><A NAME="s2">2. Reference Comedilib-0.7.9: types</A></H2>
|
||||
|
||||
<P>
|
||||
<H2><A NAME="ss2.1">2.1 sampl_t</A>
|
||||
</H2>
|
||||
|
||||
<P>defined in <CODE>comedi.h</CODE>
|
||||
correspond to <CODE>unsigned int</CODE>
|
||||
type of the sample data
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_sv_t"></A> <A NAME="ss2.2">2.2 comedi_sv_t</A>
|
||||
</H2>
|
||||
|
||||
<P>defined in <CODE>comedilib.h</CODE>
|
||||
correspond to <CODE>
|
||||
<A HREF="comedilib_reference-3.html#comedi_sv_struct">comedi_sv_struct</A></CODE>
|
||||
<P>
|
||||
<P>
|
||||
<HR>
|
||||
<A HREF="comedilib_reference-3.html">Next</A>
|
||||
<A HREF="comedilib_reference-1.html">Previous</A>
|
||||
<A HREF="comedilib_reference.html#toc2">Contents</A>
|
||||
</BODY>
|
||||
</HTML>
|
72
doc/comedilib_reference-3.html
Normal file
72
doc/comedilib_reference-3.html
Normal file
|
@ -0,0 +1,72 @@
|
|||
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
||||
<HTML>
|
||||
<HEAD>
|
||||
<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
|
||||
<TITLE>Comedi Documentation: Reference Comedilib-0.7.9: structures</TITLE>
|
||||
<LINK HREF="comedilib_reference-4.html" REL=next>
|
||||
<LINK HREF="comedilib_reference-2.html" REL=previous>
|
||||
<LINK HREF="comedilib_reference.html#toc3" REL=contents>
|
||||
</HEAD>
|
||||
<BODY>
|
||||
<A HREF="comedilib_reference-4.html">Next</A>
|
||||
<A HREF="comedilib_reference-2.html">Previous</A>
|
||||
<A HREF="comedilib_reference.html#toc3">Contents</A>
|
||||
<HR>
|
||||
<H2><A NAME="s3">3. Reference Comedilib-0.7.9: structures</A></H2>
|
||||
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_trig_struct"></A> <A NAME="ss3.1">3.1 comedi_trig_struct</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P>
|
||||
<BLOCKQUOTE><CODE>
|
||||
<PRE>
|
||||
struct comedi_trig_struct{
|
||||
unsigned int subdev; /* subdevice */
|
||||
unsigned int mode; /* mode */
|
||||
unsigned int flags;
|
||||
unsigned int n_chan; /* number of channels */
|
||||
unsigned int *chanlist; /* channel/range list */
|
||||
sampl_t *data; /* data list, size depends on subd flags */
|
||||
unsigned int n; /* number of scans */
|
||||
unsigned int trigsrc;
|
||||
unsigned int trigvar;
|
||||
unsigned int trigvar1;
|
||||
unsigned int data_len;
|
||||
unsigned int unused[3];
|
||||
}
|
||||
</PRE>
|
||||
</CODE></BLOCKQUOTE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_sv_struct"></A> <A NAME="ss3.2">3.2 comedi_sv_struct</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<BLOCKQUOTE><CODE>
|
||||
<PRE>
|
||||
struct comedi_sv_struct{
|
||||
comedi_t *dev;
|
||||
unsigned int subdevice;
|
||||
unsigned int chan;
|
||||
|
||||
/* range policy */
|
||||
int range;
|
||||
int aref;
|
||||
|
||||
/* number of measurements to average (for ai) */
|
||||
int n;
|
||||
|
||||
lsampl_t maxdata;
|
||||
}
|
||||
</PRE>
|
||||
</CODE></BLOCKQUOTE>
|
||||
<P>
|
||||
<HR>
|
||||
<A HREF="comedilib_reference-4.html">Next</A>
|
||||
<A HREF="comedilib_reference-2.html">Previous</A>
|
||||
<A HREF="comedilib_reference.html#toc3">Contents</A>
|
||||
</BODY>
|
||||
</HTML>
|
646
doc/comedilib_reference-4.html
Normal file
646
doc/comedilib_reference-4.html
Normal file
|
@ -0,0 +1,646 @@
|
|||
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
||||
<HTML>
|
||||
<HEAD>
|
||||
<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
|
||||
<TITLE>Comedi Documentation: Reference Comedilib-0.7.9: functions</TITLE>
|
||||
<LINK HREF="comedilib_reference-3.html" REL=previous>
|
||||
<LINK HREF="comedilib_reference.html#toc4" REL=contents>
|
||||
</HEAD>
|
||||
<BODY>
|
||||
Next
|
||||
<A HREF="comedilib_reference-3.html">Previous</A>
|
||||
<A HREF="comedilib_reference.html#toc4">Contents</A>
|
||||
<HR>
|
||||
<H2><A NAME="s4">4. Reference Comedilib-0.7.9: functions</A></H2>
|
||||
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.1">4.1 comedi_close()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>void comedi_close(comedi_t *it);</CODE>
|
||||
<P>Closes a device previously opened by comedi_open().
|
||||
<P>Source: <CODE>/lib/comedi.c</CODE>
|
||||
<P>
|
||||
<H2><A NAME="ss4.2">4.2 comedi_data_read()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
|
||||
unsigned int range,unsigned int aref,lsampl_t *data);</CODE>
|
||||
<P>Reads a single sample on the channel that
|
||||
is specified by the comedi device <CODE>it</CODE>, the
|
||||
subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
|
||||
For the operation,
|
||||
the device is configured to use range specification
|
||||
<CODE>range</CODE> and (if appropriate) analog reference type
|
||||
<CODE>aref</CODE>. Analog reference types that are not supported
|
||||
by the device are silently ignored.
|
||||
<P><CODE>comedi_data_read()</CODE> reads one data value from
|
||||
the specified channel and places the
|
||||
data value that is read in the location pointed to by
|
||||
<CODE>data</CODE>.
|
||||
<P>On sucess, <CODE>comedi_data_read()</CODE> returns 0. If there is an error, -1 is
|
||||
returned.
|
||||
<P>Valid analog reference numbers are:
|
||||
<P>
|
||||
<UL>
|
||||
<LI>AREF_GROUND Reference to analog ground</LI>
|
||||
<LI>AREF_COMMON Reference to analog common</LI>
|
||||
<LI>AREF_DIFF Differential reference</LI>
|
||||
<LI>AREF_OTHER Board-specific meaning</LI>
|
||||
</UL>
|
||||
<P>Valid data values used by these function is an unsigned integer
|
||||
less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
|
||||
Conversion of these data value to physical units can be performed
|
||||
by <CODE>
|
||||
<A HREF="#comedi_to_phys">comedi_to_phys()</A></CODE>.
|
||||
<P>Source: <CODE>/lib/data.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.3">4.3 comedi_data_write()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
|
||||
unsigned int range,unsigned int aref,lsampl_t data);</CODE>
|
||||
<P>Writes a single sample on the channel that
|
||||
is specified by the comedi device <CODE>it</CODE>, the
|
||||
subdevice <CODE>subd</CODE>, and the channel <CODE>chan</CODE>.
|
||||
For the operation,
|
||||
the device is configured to use range specification
|
||||
<CODE>range</CODE> and (if appropriate) analog reference type
|
||||
<CODE>aref</CODE>. Analog reference types that are not supported
|
||||
by the device are silently ignored.
|
||||
<P><CODE>comedi_data_write()</CODE> writes the data value
|
||||
specified by the argument <CODE>data</CODE> to
|
||||
the specified channel.
|
||||
<P>On sucess, <CODE>comedi_data_write()</CODE> returns 0. If there is an error, -1 is
|
||||
returned.
|
||||
<P>Valid analog reference numbers are:
|
||||
<P>
|
||||
<UL>
|
||||
<LI>AREF_GROUND Reference to analog ground</LI>
|
||||
<LI>AREF_COMMON Reference to analog common</LI>
|
||||
<LI>AREF_DIFF Differential reference</LI>
|
||||
<LI>AREF_OTHER Board-specific meaning</LI>
|
||||
</UL>
|
||||
<P>Valid data values used by these functions is an unsigned integer
|
||||
less than or equal to <CODE>maxdata</CODE>, which is channel-dependent.
|
||||
Conversion of physical units to these data value can be performed
|
||||
by <CODE>
|
||||
<A HREF="#comedi_from_phys">comedi_from_phys()</A></CODE>.
|
||||
<P>Source: <CODE>/lib/data.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.4">4.4 comedi_dio_bitfield();</A>
|
||||
</H2>
|
||||
|
||||
<P>int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned int write_mask,
|
||||
unsigned int *bits);
|
||||
<P>Source: <CODE>/lib/dio.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.5">4.5 comedi_dio_config()</A>
|
||||
</H2>
|
||||
|
||||
<P><CODE>int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned int chan,unsigned int dir);</CODE>
|
||||
<P>The function <CODE>comedi_dio_config</CODE> configures the direction <CODE>dir</CODE> of
|
||||
channel <CODE>chan</CODE> belonging to the configurable digital input/output subdevice
|
||||
<CODE>subd</CODE> of the device <CODE>it</CODE>. Returns -1 on failure.
|
||||
<P>
|
||||
<P>Valid directions are:
|
||||
<UL>
|
||||
<LI> COMEDI_INPUT</LI>
|
||||
<LI> COMEDI_OUTPUT</LI>
|
||||
</UL>
|
||||
<P>Source: <CODE>/lib/dio.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.6">4.6 comedi_dio_read()</A>
|
||||
</H2>
|
||||
|
||||
<P><CODE>int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int chan,unsigned int *bit);</CODE>
|
||||
<P>The function reads the status of channel <CODE>chan</CODE> belonging to the digital
|
||||
input subdevice <CODE>subd</CODE> of device <CODE>it</CODE>. The result, 0 or 1, is stored
|
||||
in bit. Returns -1 on failure.
|
||||
<P>Source: <CODE>/lib/dio.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.7">4.7 comedi_dio_write()</A>
|
||||
</H2>
|
||||
|
||||
<P><CODE>int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned int chan,unsigned int bit);</CODE>
|
||||
<P>The function writes the value of <CODE>bit</CODE>, 0 or 1, in channel <CODE>chan</CODE>,
|
||||
belonging to the digital output device <CODE>subd</CODE> of device <CODE>it</CODE>. Returns
|
||||
-1 on failure.
|
||||
<P>Source: <CODE>/lib/dio.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.8">4.8 comedi_fileno()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_fileno(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_fileno</CODE>
|
||||
returns the integer descriptor for the handle <CODE>it</CODE>. If
|
||||
<CODE>it</CODE> is an invalid <CODE>comedi_t</CODE> pointer, the function
|
||||
returns -1 and sets the appropriate comedilib error value.
|
||||
<P>Source: <CODE>/lib/comedi.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.9">4.9 comedi_find_range()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
|
||||
int chan, unsigned int unit, double min, double max);</CODE>
|
||||
<P>The function <CODE>comedi_find_range</CODE> tries to
|
||||
locate the optimal (smallest) range of a channel <CODE>chan</CODE> belonging to a
|
||||
<CODE>subdevice</CODE> of the comedi device <CODE>it</CODE>, which includes the data
|
||||
range between <CODE>min</CODE> and <CODE>max</CODE> in <CODE>units</CODE> with highest
|
||||
precision. If it finds a matching range,
|
||||
it returns its index. If no matching range is available, it returns -1.
|
||||
<P>Valid units are:
|
||||
<P>
|
||||
<UL>
|
||||
<LI>UNIT_volt </LI>
|
||||
<LI>UNIT_mA</LI>
|
||||
<LI>UNIT_none</LI>
|
||||
</UL>
|
||||
<P>Source: <CODE>/lib/range.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_errno"></A> <A NAME="ss4.10">4.10 comedi_errno()</A>
|
||||
</H2>
|
||||
|
||||
<P><CODE>int comedi_errno(void);</CODE>
|
||||
<P>
|
||||
<P>When a comedilib function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<CODE>comedi_errno()</CODE>. This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<CODE>
|
||||
<A HREF="#comedi_perror">comedi_perror()</A></CODE>
|
||||
and <CODE>
|
||||
<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
|
||||
<P>These functions are intended to mimic the behavior of the
|
||||
standard C library functions <CODE>perror()</CODE>,
|
||||
<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
|
||||
comedilib functions sometimes return an error that is generated
|
||||
inside the C library; the comedi error message in this case
|
||||
is the same as the C library.
|
||||
<P>The function <CODE>comedi_errno()</CODE>
|
||||
returns an integer describing the most recent comedilib error. This
|
||||
integer may be used as the <CODE>errnum</CODE> parameter for
|
||||
<CODE>
|
||||
<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.11">4.11 comedi_find_subdevice_by_type()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
|
||||
start_subdevice);</CODE>
|
||||
<P>The function <CODE>comedi_find_subdevice_by_type</CODE> tries to
|
||||
locate a subdevice belonging to comedi device <CODE>it</CODE>,
|
||||
having type <CODE>type</CODE>, starting with the subdevice
|
||||
<CODE>start_subdevice</CODE>. If it finds the requested subdevice,
|
||||
it returns its index. If it does not locate the requested
|
||||
subdevice, it returns -1 and sets the comedi error number to
|
||||
"subdevice not found". If there is an error, the function
|
||||
returns -1 and sets the appropriate error.
|
||||
<P>For subdevice types, see the manual page for the function
|
||||
<CODE>
|
||||
<A HREF="#comedi_get_subdevice_type">comedi_get_subdevice_type()</A></CODE>.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_from_phys"></A> <A NAME="ss4.12">4.12 comedi_from_phys()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>lsampl_t comedi_from_phys(double data, comedi_range *rng, lsampl_t maxdata);</CODE>
|
||||
<P>Converts data given in physical units (double) into sample values (lsampl_t, between 0 and maxdata).
|
||||
The parameter <CODE>rng</CODE> represents the conversion information to use, and the parameter <CODE>maxdata</CODE> represents
|
||||
the maximum possible data value for the channel that the data will be written to.
|
||||
<P>Source: <CODE>/lib/range.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.13">4.13 comedi_get_board_name()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>char *comedi_get_board_name(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_get_board_name</CODE> returns a pointer
|
||||
to a string containing the name of the device. This pointer is
|
||||
valid until the comedi descriptor <CODE>it</CODE> is closed. This
|
||||
function returns NULL if there is an error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.14">4.14 comedi_get_driver_name()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>char *comedi_get_driver_name(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_get_driver_name</CODE> returns a pointer
|
||||
to a string containing the name of the driver being used by comedi
|
||||
for the comedi device represented by <CODE>it</CODE>. This pointer is
|
||||
valid until the comedi descriptor <CODE>it</CODE> is closed. This
|
||||
function returns NULL if there is an error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.15">4.15 comedi_get_maxdata()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int subdevice,unsigned int
|
||||
chan);</CODE>
|
||||
<P>The function <CODE>comedi_get_maxdata()</CODE> returns the maximum
|
||||
valid data value for channel <CODE>chan</CODE> of subdevice
|
||||
<CODE>subdevice</CODE> belonging to the comedi device <CODE>it</CODE>
|
||||
This function returns 0 on error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.16">4.16 comedi_get_n_channels()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);</CODE>
|
||||
<P>The function <CODE>comedi_get_n_channels()</CODE> returns the number
|
||||
of channels of the subdevice belonging to the comedi device <CODE>it</CODE>
|
||||
and having index <CODE>subdevice</CODE>. This function returns -1 on error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.17">4.17 comedi_get_n_ranges()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
|
||||
chan);</CODE>
|
||||
<P>The function <CODE>comedi_get_n_ranges()</CODE> returns the number
|
||||
of ranges of the channel <CODE>chan</CODE> belonging to the <CODE>subdevice</CODE>
|
||||
of the comedi device <CODE>it</CODE>. This function returns -1 on error.
|
||||
<P>Source: <CODE>/lib/range.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.18">4.18 comedi_get_n_subdevices()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_n_subdevices(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_get_n_subdevices</CODE> returns the
|
||||
number of subdevices associated with the comedi descriptor
|
||||
<CODE>it</CODE>, or -1 if there is an error.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.19">4.19 comedi_get_range()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
|
||||
range);</CODE>
|
||||
<P>The function <CODE>comedi_get_range</CODE> returns a pointer to a
|
||||
comedi_range structure that contains information that can be used to
|
||||
convert sample values to or from physical units. The pointer is valid
|
||||
until the comedi device <CODE>it</CODE> is closed. If there is an
|
||||
error, NULL is returned.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.20">4.20 comedi_get_rangetype()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
|
||||
chan);</CODE>
|
||||
<P>The function <CODE>comedi_get_rangetype()</CODE> returns an integer
|
||||
that represents the number of range specifications available for a
|
||||
particular channel <CODE>chan</CODE> of the subdevice <CODE>subdevice</CODE>, as well as a conversion table to convert sample
|
||||
values to/from physical units.
|
||||
<P>The macro
|
||||
<CODE>RANGE_LENGTH(rangetype)</CODE>
|
||||
can be used to determine the number of range specifications for a given
|
||||
range type.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_get_subdevice_type"></A> <A NAME="ss4.21">4.21 comedi_get_subdevice_type()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</CODE>
|
||||
<P>The function <CODE>comedi_get_subdevice_type()</CODE> returns an
|
||||
integer describing the type of subdevice that belongs to the comedi
|
||||
device <CODE>it</CODE> and has the index <CODE>subdevice</CODE>. The
|
||||
function returns -1 is there is an error.
|
||||
<P>Valid subdevice types are:
|
||||
<P>
|
||||
<UL>
|
||||
<LI><CODE>COMEDI_SUBD_UNUSED</CODE>
|
||||
Subdevice has no functionality, i.e., a place-holder.</LI>
|
||||
<LI><CODE>COMEDI_SUBD_AI</CODE> Analog input</LI>
|
||||
<LI><CODE>COMEDI_SUBD_AO</CODE> Analog output</LI>
|
||||
<LI><CODE>COMEDI_SUBD_DI</CODE> Digital input</LI>
|
||||
<LI><CODE>COMEDI_SUBD_DO</CODE> Digital output</LI>
|
||||
<LI><CODE>COMEDI_SUBD_DIO</CODE>
|
||||
Digital input/output. Channels are configurable as to whether they
|
||||
are inputs or outputs.</LI>
|
||||
<LI><CODE>COMEDI_SUBD_COUNTER</CODE> Counter</LI>
|
||||
<LI><CODE>COMEDI_SUBD_TIMER</CODE> Timer</LI>
|
||||
<LI><CODE>COMEDI_SUBD_MEMORY</CODE>
|
||||
Memory, e.g., EEPROM or dual-ported RAM</LI>
|
||||
<LI><CODE>COMEDI_SUBD_CALIB</CODE>
|
||||
Calibration DACs</LI>
|
||||
<LI><CODE>COMEDI_SUBD_PROC</CODE>
|
||||
Processor or DSP</LI>
|
||||
</UL>
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.22">4.22 comedi_get_timer()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P>
|
||||
<BLOCKQUOTE><CODE>
|
||||
<PRE>
|
||||
int comedi_get_timer(comedi_t *it,unsigned int subdev, double freq,unsigned int *trigvar,
|
||||
double *actual_freq);
|
||||
</PRE>
|
||||
</CODE></BLOCKQUOTE>
|
||||
<P><CODE>comedi_get_timer</CODE> returns the type of the timer of the subdevice
|
||||
<CODE>subdev</CODE> of the device <CODE>it</CODE> ,
|
||||
<P>Supported timers are:
|
||||
<P>
|
||||
<UL>
|
||||
<LI>NULL</LI>
|
||||
<LI>dt282x_timer</LI>
|
||||
<LI>dt2814_timer</LI>
|
||||
<LI>atmio_timer</LI>
|
||||
<LI>acl8112_timer</LI>
|
||||
<LI>nanosec_timer</LI>
|
||||
</UL>
|
||||
<P>Source: <CODE>/lib/timer.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.23">4.23 comedi_get_version_code()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_get_version_code(comedi_t *it);</CODE>
|
||||
<P>The function <CODE>comedi_get_version_code()</CODE> returns the
|
||||
version code of the currently running comedi module. The version
|
||||
code is of the form 0x01072b, which is the version code for
|
||||
version 1.7.43.
|
||||
<P>Source: <CODE>/lib/get.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.24">4.24 comedi_loglevel()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_loglevel(int loglevel);</CODE>
|
||||
<P>This function affects the output of debugging and error messages
|
||||
from comedlib. By increasing the loglevel, additional debugging
|
||||
information will be printed. This function returns the previous
|
||||
loglevel. Some debugging information will only be printed if
|
||||
comedilib was compiled with this debugging information included.
|
||||
The loglevel can also be affected by the environment
|
||||
variable COMEDI_LOGLEVEL. The meaning of the loglevels is as
|
||||
follows:
|
||||
<P>COMEDILIB_LOGLEVEL=0
|
||||
<P>Comedilib prints nothing.
|
||||
<P>COMEDILIB_LOGLEVEL=1 (default)
|
||||
<P>Comedilib only prints error messages when there is a
|
||||
self-consistency error.
|
||||
<P>COMEDILIB_LOGLEVEL=2
|
||||
<P>Comedilib prints an error message whenever an invalid
|
||||
parameter is passed to comedilib.
|
||||
<P>COMEDILIB_LOGLEVEL=3
|
||||
<P>Comedilib prints an error message whenever an error is generated
|
||||
in the comedilib library or is generated in the C library when
|
||||
called by comedilib.
|
||||
<P>COMEDILIB_LOGLEVEL=4
|
||||
<P>Comedilib prints a lot of debugging messages.
|
||||
<P>
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.25">4.25 comedi_open()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>comedi_t *comedi_open(char *fn);</CODE>
|
||||
<P>Opens a comedi device specified by the filename fn. Returns NULL
|
||||
on error. Returns a handle that is given as a parameter to other
|
||||
comedilib functions.
|
||||
<P>You are not supposed to have access to the structure comedi_t.
|
||||
<P>Source: <CODE>/lib/comedi.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_perror"></A> <A NAME="ss4.26">4.26 comedi_perror()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>void comedi_perror(const char *s);</CODE>
|
||||
<P>When a comedilib function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<CODE>
|
||||
<A HREF="#comedi_errno">comedi_errno()</A></CODE>.
|
||||
This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<CODE>comedi_perror()</CODE>
|
||||
and <CODE>
|
||||
<A HREF="#comedi_strerror">comedi_strerror()</A></CODE>.
|
||||
<P>These functions are intended to mimic the behavior of the
|
||||
standard C library functions <CODE>perror()</CODE>,
|
||||
<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
|
||||
comedilib functions sometimes return an error that is generated
|
||||
inside the C library; the comedi error message in this case
|
||||
is the same as the C library.
|
||||
<P>The function <CODE>comedi_perror()</CODE> prints an error
|
||||
message to stderr. The error message consists of the
|
||||
argument string, a colon, a space, a description of the error
|
||||
condition, and a new line.
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_strerror"></A> <A NAME="ss4.27">4.27 comedi_strerror()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>*comedi_strerror(int errnum);</CODE>
|
||||
<P>When a comedilib function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<CODE>
|
||||
<A HREF="#comedi_errno">comedi_errno()</A></CODE>. This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<CODE>
|
||||
<A HREF="#comedi_perror">comedi_perror()</A></CODE>
|
||||
and <CODE>comedi_strerror()</CODE>.
|
||||
<P>These functions are intended to mimic the behavior of the
|
||||
standard C library functions <CODE>perror()</CODE>,
|
||||
<CODE>strerror</CODE>, and <CODE>errno()</CODE>. In particular,
|
||||
comedilib functions sometimes return an error that is generated
|
||||
inside the C library; the comedi error message in this case
|
||||
is the same as the C library.
|
||||
<P>The function <CODE>comedi_strerror()</CODE> returns a pointer to a
|
||||
character string
|
||||
describing the comedilib error <CODE>errnum</CODE>. The persistence
|
||||
of the returned pointer is undefined, and should not be trusted
|
||||
after the next comedilib call. An unrecognized error number will
|
||||
return a pointer to the string "undefined error", or similar.
|
||||
<P>Valid error strings are:
|
||||
<P>
|
||||
<UL>
|
||||
<LI><CODE>"No error"</CODE></LI>
|
||||
<LI><CODE>"Unknown error</CODE></LI>
|
||||
<LI><CODE>"Bad comedi_t structure"</CODE></LI>
|
||||
<LI><CODE>"Invalid subdevice"</CODE></LI>
|
||||
<LI><CODE>"Invalid channel"</CODE></LI>
|
||||
</UL>
|
||||
<P>Source: <CODE>/lib/error.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.28">4.28 comedi_sv_init()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd,
|
||||
unsigned int chan);</CODE>
|
||||
<P>The special functions <CODE>comedi_sv_*()</CODE> are designed to
|
||||
make it easy to accurately measure slowly varying analog inputs.
|
||||
A slowly varying input is one that is effectively constant over the course
|
||||
of approximately 100 A/D conversions. However, since these
|
||||
conversions can sometimes be pre-empted by scheduling, for most
|
||||
purposes, a slowly varying signal should be effectively constant
|
||||
for greater than 20 ms (the default Linux timeslice).
|
||||
<P>By averaging many A/D conversions of a relatively constant
|
||||
signal, it is possible to get a better measurement of the signal
|
||||
than a single A/D conversion. In general, the uncertainty of the
|
||||
measurement decreases as the square root of the number of samples.
|
||||
This is limited by the rate that which the signal varies, and
|
||||
ultimately by the spurious free dynamic range of the A/D converter.
|
||||
<P><CODE>comedi_sv_init</CODE> initializes the slow varying comedi structure
|
||||
<CODE>sv</CODE> of the device <CODE>dev</CODE>, the subdevice <CODE>subd</CODE> (analog input) and
|
||||
the channel <CODE>chan</CODE>.
|
||||
The slow varying comedi structure <CODE>sv</CODE> of type <CODE>
|
||||
<A HREF="comedilib_reference-2.html#comedi_sv_t">comedi_sv_t</A></CODE>
|
||||
specifies the signal measurement. Default number of averaged samples is 100.
|
||||
Returns zero on success, -1 on error.
|
||||
<P>Source: <CODE>/lib/sv.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.29">4.29 comedi_sv_update()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_sv_update(comedi_sv_t *sv);</CODE>
|
||||
<P><CODE>comedi_sv_update</CODE> updates the slow varying comedi structure
|
||||
<CODE>sv</CODE>.
|
||||
Returns zero on success, -1 on error.
|
||||
<P>Source: <CODE>/lib/sv.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.30">4.30 int comedi_sv_measure()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_sv_measure(comedi_sv_t *it,double *data);</CODE>
|
||||
<P><CODE>comedi_sv_measure</CODE> measures the slow variing signal. The measurement
|
||||
is specified by the slow varying comedi structure <CODE>sv</CODE>, the result is
|
||||
stored in <CODE>data</CODE>.
|
||||
On success returns the number of samples, -1 on error.
|
||||
<P>Source: <CODE>/lib/sv.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="comedi_to_phys"></A> <A NAME="ss4.31">4.31 comedi_to_phys()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>double comedi_to_phys(lsampl_t data, comedi_range *rng, lsampl_t maxdata);</CODE>
|
||||
<P>Converts data given in sample values (lsampl_t, between 0 and maxdata) into physical units (double).
|
||||
The parameter <CODE>rng</CODE> represents the conversion information to use, and the parameter <CODE>maxdata</CODE> represents
|
||||
the maximum possible data value for the channel that the data was read.
|
||||
<P>Source: <CODE>/lib/range.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.32">4.32 comedi_trigger()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P><CODE>int comedi_trigger(comedi_t *it,comedi_trig *trig);</CODE>
|
||||
<P>The function <CODE>comedi_trigger()</CODE> instructs comedi to
|
||||
perform the command specified by the
|
||||
<A HREF="comedilib_reference-3.html#comedi_trig_struct">trigger structure</A>
|
||||
<CODE>trig</CODE>. Results depend on the particular command
|
||||
being issued. If there is an error, -1 is returned.
|
||||
<P>Complete information about comedi commands is given in the
|
||||
manual page comedi(8).
|
||||
<P>Source: <CODE>/lib/comedi.c</CODE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<H2><A NAME="ss4.33">4.33 comedi_get_timer()</A>
|
||||
</H2>
|
||||
|
||||
<P>
|
||||
<P>
|
||||
<BLOCKQUOTE><CODE>
|
||||
<PRE>
|
||||
int comedi_get_timer(comedi_t *it,unsigned int subdev,double freq,unsigned int *trigvar,
|
||||
double *actual_freq);
|
||||
</PRE>
|
||||
</CODE></BLOCKQUOTE>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<P>
|
||||
<HR>
|
||||
Next
|
||||
<A HREF="comedilib_reference-3.html">Previous</A>
|
||||
<A HREF="comedilib_reference.html#toc4">Contents</A>
|
||||
</BODY>
|
||||
</HTML>
|
31
doc/comedilib_reference.html
Normal file
31
doc/comedilib_reference.html
Normal file
|
@ -0,0 +1,31 @@
|
|||
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
||||
<HTML>
|
||||
<HEAD>
|
||||
<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
|
||||
<TITLE>Comedi Documentation</TITLE>
|
||||
<LINK HREF="comedilib_reference-1.html" REL=next>
|
||||
|
||||
|
||||
</HEAD>
|
||||
<BODY>
|
||||
<A HREF="comedilib_reference-1.html">Next</A>
|
||||
Previous
|
||||
Contents
|
||||
<HR>
|
||||
<H1>Comedi Documentation</H1>
|
||||
|
||||
<H2>David Schleef, <CODE>ds@stm.lbl.gov</CODE> </H2>
|
||||
<P>
|
||||
<H2><A NAME="toc1">1.</A> <A HREF="comedilib_reference-1.html">Libcomedi Reference</A></H2>
|
||||
|
||||
<UL>
|
||||
<LI><A HREF="comedilib_reference-1.html#ss1.1">1.1 Constants and Macros</A>
|
||||
<LI><A HREF="comedilib_reference-1.html#ss1.2">1.2 Data Types and Structures</A>
|
||||
<LI><A HREF="comedilib_reference-1.html#ss1.3">1.3 Functions</A>
|
||||
</UL>
|
||||
<HR>
|
||||
<A HREF="comedilib_reference-1.html">Next</A>
|
||||
Previous
|
||||
Contents
|
||||
</BODY>
|
||||
</HTML>
|
878
doc/comedilib_reference.sgml
Normal file
878
doc/comedilib_reference.sgml
Normal file
|
@ -0,0 +1,878 @@
|
|||
<!doctype linuxdoc public "-//LinuxDoc//DTD LinuxDoc 96//EN">
|
||||
|
||||
<article>
|
||||
<title>Comedi Documentation
|
||||
<author>David Schleef, <tt/ds@stm.lbl.gov/
|
||||
|
||||
|
||||
|
||||
|
||||
<sect>Libcomedi Reference
|
||||
<p>
|
||||
|
||||
<sect1>Constants and Macros
|
||||
<p>
|
||||
|
||||
|
||||
<sect2>RANGE_LENGTH() <it/(deprecated)/
|
||||
<p>
|
||||
<label id="RANGE_LENGTH">
|
||||
|
||||
<tt/RANGE_LENGTH(rangetype)/
|
||||
|
||||
<p>
|
||||
Rangetype values are library-internal tokens that represent an
|
||||
array of range information structures. These numbers are primarily
|
||||
used for communication between the kernel and library.
|
||||
|
||||
<p>
|
||||
The RANGE_LENGTH() macro returns the length of the array that is
|
||||
specified by the rangetype token.
|
||||
|
||||
<p>
|
||||
The RANGE_LENGTH() macro is deprecated, and should not be used in
|
||||
new applications. It is scheduled to be removed from the header
|
||||
file at version 1.0. Binary compatibility may be broken for version
|
||||
1.1.
|
||||
|
||||
|
||||
<p>
|
||||
<sect1>Data Types and Structures
|
||||
|
||||
<p>
|
||||
<sect2>comedi_t
|
||||
<label id="comedi_t">
|
||||
|
||||
<p>
|
||||
The data type <tt/comedi_t/ is used to represent an open Comedi
|
||||
device. A valid <tt/comedi_t/ pointer is returned by a successful
|
||||
call to <tt/comedi_open()/, and should be used for subsequent
|
||||
access to the device.
|
||||
It is a transparent type, and pointers to type <tt/comedi_t/
|
||||
should not be dereferenced.
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>sampl_t
|
||||
<label id="sampl_t">
|
||||
|
||||
<p>
|
||||
The data type <tt/sampl_t/ is one of the generic types used to represent
|
||||
data values in libcomedi. It is used in a few places where a shorter
|
||||
data type is useful, but is limited to 16 bits on the i386 architecture.
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>lsampl_t
|
||||
<label id="lsampl_t">
|
||||
|
||||
<p>
|
||||
The data type <tt/lsampl_t/ is one of the generic types used to represent
|
||||
data values in libcomedi. It is currently defined to be <tt/unsigned int/.
|
||||
|
||||
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_trig_struct <it/(deprecated)/
|
||||
<label id="comedi_trig_struct">
|
||||
<p>
|
||||
|
||||
The <tt/comedi_trig/ structure
|
||||
|
||||
<tscreen><verb>
|
||||
struct comedi_trig_struct{
|
||||
unsigned int subdev; /* subdevice */
|
||||
unsigned int mode; /* mode */
|
||||
unsigned int flags;
|
||||
unsigned int n_chan; /* number of channels */
|
||||
unsigned int *chanlist; /* channel/range list */
|
||||
sampl_t *data; /* data list, size depends on subd flags */
|
||||
unsigned int n; /* number of scans */
|
||||
unsigned int trigsrc;
|
||||
unsigned int trigvar;
|
||||
unsigned int trigvar1;
|
||||
unsigned int data_len;
|
||||
unsigned int unused[3];
|
||||
}
|
||||
</verb></tscreen>
|
||||
|
||||
The <tt/comedi_trig/ structure is a control structure used by the
|
||||
COMEDI_TRIG ioctl, an older method of communicating
|
||||
instructions to the driver and hardware. Use of Comedi triggers is
|
||||
deprecated, and should not be used in new applications.
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_sv_t
|
||||
<label id="comedi_sv_t">
|
||||
<p>
|
||||
|
||||
<tscreen><verb>
|
||||
struct comedi_sv_struct{
|
||||
comedi_t *dev;
|
||||
unsigned int subdevice;
|
||||
unsigned int chan;
|
||||
|
||||
/* range policy */
|
||||
int range;
|
||||
int aref;
|
||||
|
||||
/* number of measurements to average (for ai) */
|
||||
int n;
|
||||
|
||||
lsampl_t maxdata;
|
||||
}
|
||||
</verb></tscreen>
|
||||
|
||||
The <tt/comedi_sv_t/ structure is used by the <tt/comedi_sv_*()/
|
||||
functions to provide a simple method of accurately measuring
|
||||
slowly varying inputs. See the relevant section for more
|
||||
details.
|
||||
|
||||
|
||||
|
||||
<sect1>Functions
|
||||
<p>
|
||||
|
||||
<sect2>comedi_close()
|
||||
<label id="comedi_close">
|
||||
<p>
|
||||
|
||||
<tt>void comedi_close(comedi_t *it);</tt>
|
||||
|
||||
<p>
|
||||
Closes a device previously opened by comedi_open().
|
||||
|
||||
<p>
|
||||
The return type of this function will change to <tt/int/, in
|
||||
order to match <tt/fclose/.
|
||||
|
||||
<p>
|
||||
Source: <tt>/lib/comedi.c</tt>
|
||||
|
||||
|
||||
<sect2>comedi_data_read()
|
||||
<label id="comedi_data_read">
|
||||
<p>
|
||||
|
||||
<tt>int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan,
|
||||
unsigned int range,unsigned int aref,lsampl_t *data);</tt>
|
||||
|
||||
<p>
|
||||
Reads a single sample on the channel that
|
||||
is specified by the comedi device <tt>it</tt>, the
|
||||
subdevice <tt>subd</tt>, and the channel <tt>chan</tt>.
|
||||
For the A/D conversion (if appropriate),
|
||||
the device is configured to use range specification
|
||||
<tt>range</tt> and (if appropriate) analog reference type
|
||||
<tt>aref</tt>. Analog reference types that are not supported
|
||||
by the device are silently ignored.
|
||||
|
||||
<p>
|
||||
<tt>comedi_data_read()</tt> reads one data value from
|
||||
the specified channel and places the
|
||||
data value that is read in the location pointed to by
|
||||
<tt>data</tt>.
|
||||
|
||||
<p>
|
||||
On sucess, <tt>comedi_data_read()</tt> returns 0. If there is an
|
||||
error, -1 is returned.
|
||||
|
||||
<p>
|
||||
Valid analog reference numbers are:
|
||||
|
||||
<itemize>
|
||||
<item>AREF_GROUND Reference to analog ground
|
||||
<item>AREF_COMMON Reference to analog common
|
||||
<item>AREF_DIFF Differential reference
|
||||
<item>AREF_OTHER Board-specific meaning
|
||||
</itemize>
|
||||
|
||||
Valid data values returned by these function is an unsigned integer
|
||||
less than or equal to <tt>maxdata</tt>, which is channel-dependent.
|
||||
Conversion of these data value to physical units can be performed
|
||||
by <tt><ref id="comedi_to_phys" name =
|
||||
"comedi_to_phys()"></tt>.
|
||||
|
||||
Source: <tt>/lib/data.c</tt>
|
||||
|
||||
|
||||
<sect2>comedi_data_write()
|
||||
<p>
|
||||
|
||||
<tt>int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan,
|
||||
unsigned int range,unsigned int aref,lsampl_t data);</tt>
|
||||
|
||||
<p>
|
||||
Writes a single sample on the channel that
|
||||
is specified by the comedi device <tt/it/, the
|
||||
subdevice <tt/subd/, and the channel <tt/chan/.
|
||||
For the D/A conversion (if appropriate), the device is
|
||||
configured to use range specification
|
||||
<tt/range/ and (if appropriate) analog reference type
|
||||
<tt/aref/. Analog reference types that are not supported
|
||||
by the device are silently ignored.
|
||||
|
||||
<tt/comedi_data_write()/ writes the data value
|
||||
specified by the argument <tt/data/ to
|
||||
the specified channel.
|
||||
|
||||
On sucess, <tt>comedi_data_write()</tt> returns 0. If there is an error, -1 is
|
||||
returned.
|
||||
|
||||
Valid analog reference numbers are:
|
||||
|
||||
<itemize>
|
||||
<item>AREF_GROUND Reference to analog ground
|
||||
<item>AREF_COMMON Reference to analog common
|
||||
<item>AREF_DIFF Differential reference
|
||||
<item>AREF_OTHER Board-specific meaning
|
||||
</itemize>
|
||||
|
||||
Valid data values used by these functions is an unsigned integer
|
||||
less than or equal to <tt>maxdata</tt>, which is channel-dependent.
|
||||
Conversion of physical units to these data value can be performed
|
||||
by <tt><ref id="comedi_from_phys" name =
|
||||
"comedi_from_phys()"></tt>.
|
||||
|
||||
Source: <tt>/lib/data.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_dio_bitfield();
|
||||
|
||||
<p>
|
||||
<tt/int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned
|
||||
int write_mask,unsigned int *bits);/
|
||||
|
||||
<p>
|
||||
The function <tt/comedi_dio_bitfield()/ allows multiple channels to
|
||||
be read simultaneously from a digital input or digital I/O device.
|
||||
The parameter <tt/write_mask/ and the value pointed to by <tt/bits/
|
||||
are interpreted as bit fields, with the least significant bit
|
||||
representing channel 0. For each bit in <tt/write_mask/ that is
|
||||
set, the cooresponding bit in <tt/*bits/ is written to the digital
|
||||
output channel. Each digital input channel is read, and the result
|
||||
placed in the approprate bits in <tt/*bits/.
|
||||
|
||||
<p>
|
||||
The current implementation reads and writes bits using separate
|
||||
system calls, which is not ideal. When the kernel driver supports
|
||||
simultaneous reading/writing, this will be fixed in the library.
|
||||
|
||||
<p>
|
||||
It should be noted that it is not possible to access channels
|
||||
greater than 31 using this function.
|
||||
|
||||
<p>
|
||||
Source: <tt>/lib/dio.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_dio_config()
|
||||
<p>
|
||||
<tt/int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned
|
||||
int chan,unsigned int dir);/
|
||||
|
||||
<p>
|
||||
The function <tt/comedi_dio_config/ configures individual channels
|
||||
in a digital I/O subdevice to be either input or output, depending
|
||||
on the value of parameter <tt/dir/. Depending on the capabilities
|
||||
of the hardware device, multiple channels may be affected by
|
||||
a single call to <tt/comedi_dio_config/.
|
||||
|
||||
|
||||
Valid directions are:
|
||||
<itemize>
|
||||
<item> COMEDI_INPUT
|
||||
<item> COMEDI_OUTPUT
|
||||
</itemize>
|
||||
|
||||
Source: <tt>/lib/dio.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_dio_read()
|
||||
<p>
|
||||
<tt/int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int
|
||||
chan,unsigned int *bit);/
|
||||
|
||||
<p>
|
||||
The function reads the status of channel <tt/chan/ belonging to the digital
|
||||
input subdevice <tt/subd/ of device <tt/it/. The result, 0 or 1, is stored
|
||||
in bit. Returns -1 on failure.
|
||||
|
||||
<p>
|
||||
This function is equivalent to <tt/comedi_data_read(it,subd,chan,0,0,bit)/.
|
||||
|
||||
|
||||
Source: <tt>/lib/dio.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_dio_write()
|
||||
<p>
|
||||
<tt/int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned
|
||||
int chan,unsigned int bit);/
|
||||
|
||||
<p>
|
||||
The function writes the value of <tt/bit/, 0 or 1, to channel <tt/chan/,
|
||||
belonging to the digital output device <tt/subd/ of device <tt/it/. Returns
|
||||
-1 on failure.
|
||||
|
||||
<p>
|
||||
Source: <tt>/lib/dio.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_fileno()
|
||||
<p>
|
||||
|
||||
<tt/int comedi_fileno(comedi_t *it);/
|
||||
<p>
|
||||
|
||||
The function <tt/comedi_fileno/
|
||||
returns the integer descriptor for the handle <tt/it/. It
|
||||
is equivalent to the standard function <tt/fileno/. If
|
||||
<tt>it</tt> is an invalid <tt>comedi_t</tt> pointer, the function
|
||||
returns -1 and sets the appropriate libcomedi error value.
|
||||
|
||||
Source: <tt>/lib/comedi.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_find_range()
|
||||
<p>
|
||||
|
||||
<tt/int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
|
||||
int chan, unsigned int unit, double min, double max);/
|
||||
|
||||
<p>
|
||||
The function <tt/comedi_find_range/ tries to
|
||||
locate the optimal (smallest) range for the channel <tt>chan</tt>
|
||||
belonging to a <tt>subdevice</tt> of the comedi device <tt>it</tt>,
|
||||
that includes both <tt>min</tt> and <tt>max</tt> in <tt>units</tt>.
|
||||
If it finds a matching range, it returns its index. If no
|
||||
matching range is available, it returns -1.
|
||||
|
||||
<p>
|
||||
Valid units are:
|
||||
|
||||
<itemize>
|
||||
<item>UNIT_volt
|
||||
<item>UNIT_mA
|
||||
<item>UNIT_none
|
||||
</itemize>
|
||||
|
||||
Source: <tt>/lib/range.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_errno()
|
||||
<label id="comedi_errno">
|
||||
<p>
|
||||
<tt/int comedi_errno(void);/
|
||||
|
||||
<p>
|
||||
The function <tt>comedi_errno()</tt>
|
||||
returns an integer describing the most recent comedilib error. This
|
||||
integer may be used as the <tt>errnum</tt> parameter for
|
||||
<tt><ref id="comedi_strerror" name ="comedi_strerror()"></tt>.
|
||||
|
||||
When a libcomedi function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<tt>comedi_errno()</tt>. This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<tt><ref id="comedi_perror" name ="comedi_perror()"></tt>
|
||||
and <tt><ref id="comedi_strerror" name ="comedi_strerror()"></tt>.
|
||||
|
||||
These functions are intended to mimic the behavior of the
|
||||
standard C library functions <tt>perror()</tt>,
|
||||
<tt>strerror</tt>, and <tt>errno()</tt>. In particular,
|
||||
libcomedi functions sometimes return an error that is generated
|
||||
by the C library; the Comedi error message in this case
|
||||
is the same as the C library.
|
||||
|
||||
Source: <tt>/lib/error.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_find_subdevice_by_type()
|
||||
<p>
|
||||
|
||||
<tt>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
|
||||
start_subdevice);</tt>
|
||||
|
||||
<p>
|
||||
The function <tt>comedi_find_subdevice_by_type</tt> tries to
|
||||
locate a subdevice belonging to comedi device <tt>it</tt>,
|
||||
having type <tt>type</tt>, starting with the subdevice
|
||||
<tt>start_subdevice</tt>. If it finds the requested subdevice,
|
||||
it returns its index. If it does not locate the requested
|
||||
subdevice, it returns -1 and sets the comedi error number to
|
||||
"subdevice not found". If there is an error, the function
|
||||
returns -1 and sets the appropriate error.
|
||||
|
||||
<p>
|
||||
For subdevice types, see the manual page for the function
|
||||
<tt><ref id="comedi_get_subdevice_type" name =
|
||||
"comedi_get_subdevice_type()"></tt>.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_from_phys()<label id="comedi_from_phys">
|
||||
<p>
|
||||
|
||||
<tt/lsampl_t comedi_from_phys(double data, comedi_range *rng,
|
||||
lsampl_t maxdata);/
|
||||
|
||||
Converts data given in physical units (<tt/data/) into sample values
|
||||
(lsampl_t, between 0 and maxdata). The parameter <tt>rng</tt>
|
||||
represents the conversion information to use, and the parameter
|
||||
<tt>maxdata</tt> represents the maximum possible data value for the
|
||||
channel that the data will be written to.
|
||||
|
||||
|
||||
Source: <tt>/lib/range.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_board_name()
|
||||
<p>
|
||||
|
||||
<tt/char *comedi_get_board_name(comedi_t *it);/
|
||||
|
||||
The function <tt/comedi_get_board_name/ returns a pointer
|
||||
to a string containing the name of the device. This pointer is
|
||||
valid until the comedi descriptor <tt/it/ is closed. This
|
||||
function returns <tt/NULL/ if there is an error.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_driver_name()
|
||||
<p>
|
||||
|
||||
<tt/char *comedi_get_driver_name(comedi_t *it);/
|
||||
|
||||
The function <tt/comedi_get_driver_name/ returns a pointer
|
||||
to a string containing the name of the driver being used by comedi
|
||||
for the comedi device represented by <tt/it/. This pointer is
|
||||
valid until the comedi descriptor <tt/it/ is closed. This
|
||||
function returns <tt/NULL/ if there is an error.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_maxdata()
|
||||
<p>
|
||||
|
||||
<tt/lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int
|
||||
subdevice,unsigned int chan);/
|
||||
|
||||
<p>
|
||||
The function <tt/comedi_get_maxdata()/ returns the maximum
|
||||
valid data value for channel <tt/chan/ of subdevice
|
||||
<tt/subdevice/ belonging to the comedi device <tt/it/
|
||||
This function returns 0 on error.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_n_channels()
|
||||
<p>
|
||||
|
||||
<tt/int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);/
|
||||
|
||||
The function <tt>comedi_get_n_channels()</tt> returns the number
|
||||
of channels of the subdevice belonging to the comedi device <tt>it</tt>
|
||||
and having index <tt>subdevice</tt>. This function returns -1 on error.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_n_ranges()
|
||||
<p>
|
||||
|
||||
<tt>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
|
||||
chan);</tt>
|
||||
|
||||
The function <tt>comedi_get_n_ranges()</tt> returns the number
|
||||
of ranges of the channel <tt>chan</tt> belonging to the <tt>subdevice</tt>
|
||||
of the comedi device <tt>it</tt>. This function returns -1 on error.
|
||||
|
||||
Source: <tt>/lib/range.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_n_subdevices()
|
||||
<p>
|
||||
|
||||
<tt>int comedi_get_n_subdevices(comedi_t *it);</tt>
|
||||
|
||||
The function <tt>comedi_get_n_subdevices</tt> returns the
|
||||
number of subdevices associated with the comedi descriptor
|
||||
<tt>it</tt>, or -1 if there is an error.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_range()
|
||||
<p>
|
||||
|
||||
<tt>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
|
||||
range);</tt>
|
||||
|
||||
The function <tt>comedi_get_range</tt> returns a pointer to a
|
||||
comedi_range structure that contains information that can be used to
|
||||
convert sample values to or from physical units. The pointer is valid
|
||||
until the comedi device <tt>it</tt> is closed. If there is an
|
||||
error, NULL is returned.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_rangetype()
|
||||
<p>
|
||||
|
||||
<tt>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
|
||||
chan);</tt>
|
||||
|
||||
The function <tt>comedi_get_rangetype()</tt> returns an integer
|
||||
that represents the number of range specifications available for a
|
||||
particular channel <tt/chan/ of the subdevice <tt/subdevice/, as well as a conversion table to convert sample
|
||||
values to/from physical units.
|
||||
|
||||
The macro
|
||||
<tt>RANGE_LENGTH(rangetype)</tt>
|
||||
can be used to determine the number of range specifications for a given
|
||||
range type.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_subdevice_type()<label id="comedi_get_subdevice_type">
|
||||
<p>
|
||||
|
||||
<tt>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</tt>
|
||||
|
||||
The function <tt>comedi_get_subdevice_type()</tt> returns an
|
||||
integer describing the type of subdevice that belongs to the comedi
|
||||
device <tt>it</tt> and has the index <tt>subdevice</tt>. The
|
||||
function returns -1 is there is an error.
|
||||
|
||||
Valid subdevice types are:
|
||||
|
||||
<itemize>
|
||||
<item><tt>COMEDI_SUBD_UNUSED</tt>
|
||||
Subdevice has no functionality, i.e., a place-holder.
|
||||
<item><tt>COMEDI_SUBD_AI</tt> Analog input
|
||||
<item><tt>COMEDI_SUBD_AO</tt> Analog output
|
||||
<item><tt>COMEDI_SUBD_DI</tt> Digital input
|
||||
<item><tt>COMEDI_SUBD_DO</tt> Digital output
|
||||
<item><tt>COMEDI_SUBD_DIO</tt>
|
||||
Digital input/output. Channels are configurable as to whether they
|
||||
are inputs or outputs.
|
||||
<item><tt>COMEDI_SUBD_COUNTER</tt> Counter
|
||||
<item><tt>COMEDI_SUBD_TIMER</tt> Timer
|
||||
<item><tt>COMEDI_SUBD_MEMORY</tt>
|
||||
Memory, e.g., EEPROM or dual-ported RAM
|
||||
<item><tt>COMEDI_SUBD_CALIB</tt>
|
||||
Calibration DACs
|
||||
<item><tt>COMEDI_SUBD_PROC</tt>
|
||||
Processor or DSP
|
||||
</itemize>
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_timer() <it/(deprecated)/
|
||||
<p>
|
||||
|
||||
<tt/int comedi_get_timer(comedi_t *it,unsigned int subdev, double
|
||||
freq,unsigned int *trigvar, double *actual_freq);/
|
||||
|
||||
<p>
|
||||
The function <tt>comedi_get_timer</tt> converts the frequency <tt/freq/
|
||||
to a number suitable to send to the driver in a <tt/comedi_trig/
|
||||
structure. This function remains for compatibility with very
|
||||
old versions of Comedi, that converted sampling rates to timer
|
||||
values in the libary. This conversion is now done in the kernel,
|
||||
and every device has the timer type <tt/nanosec_timer/, indicating
|
||||
that timer values are simply a time specified in nanoseconds.
|
||||
|
||||
<p>
|
||||
This function is deprecated and should not be used in new applications.
|
||||
|
||||
<p>
|
||||
Source: <tt>/lib/timer.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_version_code()
|
||||
<p>
|
||||
|
||||
<tt/int comedi_get_version_code(comedi_t *it);/
|
||||
|
||||
<p>
|
||||
The function <tt/comedi_get_version_code()/ returns the
|
||||
version code of the currently running comedi module. The version
|
||||
code is of the form 0x01072b, which is the version code for
|
||||
version 1.7.43.
|
||||
|
||||
<p>
|
||||
This function is of limited usefulness. A typical mis-application
|
||||
of this function is to use it to determine if a certain feature is
|
||||
supported. If the application needs
|
||||
to know of the existence of a particular feature, an existence
|
||||
test function should be written and put in the libcomedi source.
|
||||
|
||||
Source: <tt>/lib/get.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_loglevel()
|
||||
<P>
|
||||
|
||||
<tt>int comedi_loglevel(int loglevel);</tt>
|
||||
|
||||
<p>
|
||||
This function affects the output of debugging and error messages
|
||||
from libcomedi. By increasing the loglevel, additional debugging
|
||||
information will be printed. This function returns the previous
|
||||
loglevel. Error messages and debugging are printed to the
|
||||
stream <tt/stderr/. The loglevel can also be affected by the
|
||||
environment variable COMEDI_LOGLEVEL.
|
||||
|
||||
<p>
|
||||
In order to conserve resources, some debugging information is
|
||||
disabled when libcomedi is compiled.
|
||||
|
||||
<p>The meaning of the loglevels is as follows:
|
||||
|
||||
<itemize>
|
||||
<item><tt/COMEDILIB_LOGLEVEL=0/
|
||||
|
||||
Comedilib prints nothing.
|
||||
|
||||
<item><tt/COMEDILIB_LOGLEVEL=1/ (default)
|
||||
|
||||
Comedilib only prints error messages when there is a
|
||||
self-consistency error (i.e., internal bug).
|
||||
|
||||
<item><tt/COMEDILIB_LOGLEVEL=2/
|
||||
|
||||
Comedilib prints an error message when an invalid
|
||||
parameter is passed to comedilib.
|
||||
|
||||
<item><tt/COMEDILIB_LOGLEVEL=3/
|
||||
|
||||
Comedilib prints an error message whenever an error is generated
|
||||
in the comedilib library or is generated in the C library when
|
||||
called by comedilib.
|
||||
|
||||
<item><tt/COMEDILIB_LOGLEVEL=4/
|
||||
|
||||
Comedilib prints a lot of debugging messages.
|
||||
|
||||
</itemize>
|
||||
|
||||
Bugs: Libcomedi doesn't currently have much debugging information.
|
||||
|
||||
Source: <tt>/lib/error.c</tt>
|
||||
|
||||
<p>
|
||||
<sect2>comedi_open()
|
||||
<p>
|
||||
|
||||
<tt/comedi_t *comedi_open(char *filename);/
|
||||
|
||||
Opens a comedi device specified by the filename <tt/filename/.
|
||||
Returns NULL on error. On sucess, it returns a handle that is
|
||||
given as a parameter to other libcomedi functions.
|
||||
|
||||
<p>
|
||||
You are not supposed to have access to the internals of the
|
||||
<tt/comedi_t/ structure.
|
||||
|
||||
Bugs: Not strictly identical to <tt/fopen/
|
||||
|
||||
Source: <tt>/lib/comedi.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_perror()<label id="comedi_perror">
|
||||
<p>
|
||||
|
||||
<tt>void comedi_perror(const char *s);</tt>
|
||||
|
||||
When a comedilib function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<tt><ref id="comedi_errno" name ="comedi_errno()"></tt>.
|
||||
This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<tt>comedi_perror()</tt>
|
||||
and <tt><ref id="comedi_strerror" name ="comedi_strerror()"></tt>.
|
||||
|
||||
These functions are intended to mimic the behavior of the
|
||||
standard C library functions <tt>perror()</tt>,
|
||||
<tt>strerror</tt>, and <tt>errno()</tt>. In particular,
|
||||
comedilib functions sometimes return an error that is generated
|
||||
inside the C library; the comedi error message in this case
|
||||
is the same as the C library.
|
||||
|
||||
The function <tt>comedi_perror()</tt> prints an error
|
||||
message to stderr. The error message consists of the
|
||||
argument string, a colon, a space, a description of the error
|
||||
condition, and a new line.
|
||||
|
||||
Bugs: Does not support internationalization.
|
||||
|
||||
Source: <tt>/lib/error.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_strerror()<label id="comedi_strerror">
|
||||
<p>
|
||||
|
||||
<tt>*comedi_strerror(int errnum);</tt>
|
||||
|
||||
When a comedilib function fails, it usually returns -1 or
|
||||
NULL, depending on the return type. An internal library
|
||||
variable stores an error number, which can be retrieved with
|
||||
<tt><ref id="comedi_errno" name ="comedi_errno()"></tt>. This error number can be
|
||||
converted to a human-readable form by the functions
|
||||
<tt><ref id="comedi_perror" name ="comedi_perror()"></tt>
|
||||
and <tt>comedi_strerror()</tt>.
|
||||
|
||||
These functions are intended to mimic the behavior of the
|
||||
standard C library functions <tt>perror()</tt>,
|
||||
<tt>strerror</tt>, and <tt>errno()</tt>. In particular,
|
||||
comedilib functions sometimes return an error that is generated
|
||||
inside the C library; the comedi error message in this case
|
||||
is the same as the C library.
|
||||
|
||||
The function <tt>comedi_strerror()</tt> returns a pointer to a
|
||||
character string
|
||||
describing the comedilib error <tt>errnum</tt>. The persistence
|
||||
of the returned pointer is undefined, and should not be trusted
|
||||
after the next libcomedi call. An unrecognized error number will
|
||||
return a pointer to the string "undefined error", or similar.
|
||||
|
||||
Bugs: Does not support internationalization.
|
||||
|
||||
Source: <tt>/lib/error.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_sv_init()
|
||||
<p>
|
||||
|
||||
<tt/int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd,
|
||||
unsigned int chan);/
|
||||
|
||||
|
||||
<tt/comedi_sv_init/ initializes the slow varying comedi structure
|
||||
<tt/sv/ of the device <tt/dev/, the subdevice <tt/subd/ (analog input) and
|
||||
the channel <tt/chan/.
|
||||
The slow varying comedi structure <tt/sv/ of type <tt><ref id="comedi_sv_t"
|
||||
name="comedi_sv_t"</tt>
|
||||
specifies the signal measurement. The default number of averaged
|
||||
samples is 100. Returns zero on success, -1 on error.
|
||||
|
||||
Bugs: comedi_sv_* was very poorly designed.
|
||||
|
||||
Source: <tt>/lib/sv.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_sv_update()
|
||||
<p>
|
||||
|
||||
<tt/int comedi_sv_update(comedi_sv_t *sv);/
|
||||
|
||||
The function <tt/comedi_sv_update/ updates the slow varying comedi structure
|
||||
<tt/sv/.
|
||||
Returns zero on success, -1 on error.
|
||||
|
||||
Source: <tt>/lib/sv.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>int comedi_sv_measure()
|
||||
<p>
|
||||
|
||||
<tt>int comedi_sv_measure(comedi_sv_t *it,double *data);</tt>
|
||||
|
||||
<tt/comedi_sv_measure/ measures the slow variing signal. The measurement
|
||||
is specified by the slow varying comedi structure <tt/sv/, the result is
|
||||
stored in <tt/data/.
|
||||
On success returns the number of samples, -1 on error.
|
||||
|
||||
Source: <tt>/lib/sv.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_to_phys()<label id="comedi_to_phys">
|
||||
<p>
|
||||
|
||||
<tt/double comedi_to_phys(lsampl_t data, comedi_range *rng,
|
||||
lsampl_t maxdata);/
|
||||
|
||||
Converts data given in sample values (lsampl_t, between 0 and
|
||||
maxdata) into physical units (double). The parameter <tt/rng/
|
||||
represents the conversion information to use, and the parameter
|
||||
<tt/maxdata/ represents the maximum possible data value for the
|
||||
channel that the data was read.
|
||||
|
||||
Source: <tt>/lib/range.c</tt>
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_trigger() <it/(deprecated)/
|
||||
<p>
|
||||
|
||||
<tt/int comedi_trigger(comedi_t *it,comedi_trig *trig);/
|
||||
|
||||
The function <tt/comedi_trigger/ instructs comedi to
|
||||
perform the command specified by the <ref id="comedi_trig_struct" name
|
||||
="trigger structure"> <tt/trig/. Results depend on
|
||||
the particular command being issued. If there is an
|
||||
error, -1 is returned.
|
||||
|
||||
Lifetime: removal at 1.0.
|
||||
|
||||
Source: <tt>/lib/comedi.c</tt>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<p>
|
||||
<sect2>comedi_get_timer()
|
||||
<p>
|
||||
|
||||
<tscreen><verb>
|
||||
int comedi_get_timer(comedi_t *it,unsigned int subdev,double freq,unsigned int *trigvar,
|
||||
double *actual_freq);
|
||||
</verb></tscreen>
|
||||
|
||||
|
||||
<p>
|
||||
|
||||
</article>
|
||||
|
Loading…
Add table
Reference in a new issue