Remove comedilib_reference, rebuild comedilib*html

This commit is contained in:
David Schleef 2001-07-10 22:23:29 +00:00
parent 1f1293e649
commit 0f8fd728ae
10 changed files with 956 additions and 3021 deletions

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@ -36,12 +36,11 @@ int aref = AREF_GROUND; /* more on this later */
int main(int argc,char *argv[])
{
comedi_t *it;
int chan=0;
lsampl_t data;
it=comedi_open("/dev/comedi0");
comedi_data_read(it,subdev,chan,range,aref,& data);
comedi_data_read(it,subdev,chan,range,aref,&data);
printf("%d\n",data);
@ -51,10 +50,10 @@ int main(int argc,char *argv[])
</CODE></BLOCKQUOTE>
</P>
<P>Should be understandable. Open the device, get the data,
<P>Should be understandable: open the device, get the data,
print it out. This is basically the guts of <CODE>demo/inp.c</CODE>,
without error checking or fancy options.
Compile it using </P>
Compile it using</P>
<P>
<BLOCKQUOTE><CODE>
<PRE>
@ -74,7 +73,7 @@ aref, which determines the analog reference used.</P>
</H2>
<P>If you selected an analog input subdevice, you should notice
<P>If you selected an analog input subdevice, you probably noticed
that the output of <CODE>tut1</CODE> is a number between
0 and 4095, or 0 and 65535, depending on the number of bits
in the A/D converter. Comedi samples are <B>always</B> unsigned,
@ -89,7 +88,7 @@ manner?"</P>
input, and Comedi allows you to select which of these to
use. This parameter is called the "range parameter", since
it specifies the "input range" for analog input (or "output range"
analog output.) The range parameter represents both the gain
for analog output.) The range parameter represents both the gain
and the unipolar/bipolar aspects.</P>
<P>Comedi keeps the number of available ranges and the largest
sample value for each subdevice/channel combination. (Some
@ -205,7 +204,7 @@ that we've added what we've learned.</P>
<PRE>
#include &lt;stdio.h> /* for printf() */
#include &lt;comedi.h> /* also included by comedilib.h */
#include &lt;comedilib.h> /* for comedi_get() */
#include &lt;comedilib.h> /* 'cuz we're using comedilib */
int subdev = 0; /* change this to your input subdevice */
int chan = 0; /* change this to your channel */
@ -216,7 +215,7 @@ int main(int argc,char *argv[])
{
comedi_t *cf;
int chan=0;
int data;
lsampl_t data;
int maxdata,rangetype;
double volts;
@ -226,7 +225,7 @@ int main(int argc,char *argv[])
rangetype=comedi_get_rangetype(cf,subdev,chan);
data=comedi_get(cf->fd,subdev,chan,range,aref);
comedi_data_read(cf->fd,subdev,chan,range,aref,&amp;data);
volts=comedi_to_phys(data,rangetype,range,maxdata);
@ -238,14 +237,6 @@ int main(int argc,char *argv[])
</CODE></BLOCKQUOTE>
</P>
<P>By now, the <CODE>comedi_read_data()</CODE> line looks a little archaic, using
the UNIX file descriptor cf->fd instead of just cf. (By the
way, somewhere in the heart of <CODE>comedi_open()</CODE> is the line
<CODE>cf->fd=open(filename,O_RDWR)</CODE>.) Well, there isn't one good
replacement, since it highly depends on your application
what additional features you might want in a <CODE>comedi_get()</CODE>
replacement. But this is the topic of a different section.</P>
<HR>

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@ -3,11 +3,12 @@
<HEAD>
<META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.7.4">
<TITLE>Comedi Documentation: Application-specific functions</TITLE>
<LINK HREF="comedilib-6.html" REL=next>
<LINK HREF="comedilib-4.html" REL=previous>
<LINK HREF="comedilib.html#toc5" REL=contents>
</HEAD>
<BODY>
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<A HREF="comedilib-6.html">Next</A>
<A HREF="comedilib-4.html">Previous</A>
<A HREF="comedilib.html#toc5">Contents</A>
<HR>
@ -109,8 +110,13 @@ is only accurate to part-per-thousand.</P>
<P>Many data acquisition devices have the capability to directly
control acquisition using either an on-board timer or an external
triggering input. Comedi commands are used to control this kind
of acquisition. The same structure (comedi_cmd) used to control
acquisition is used to query the capabilities of a device.</P>
of acquisition. The
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure is
used to control acquisition and query the capabilities of a device
(see also
<A HREF="comedilib-6.html#comedi_command">comedi_command()</A>,
<A HREF="comedilib-6.html#comedi_command_test">comedi_command_test()</A>, and
<A HREF="comedilib-6.html#comedi_get_cmd_src_mask">comedi_get_cmd_src_mask()</A>).</P>
<P>Commands specify a particular data acquisition sequence, which
is comprised of a number of scans. Each scan is comprised of
a number of conversions, which usually corresponds to a single
@ -118,41 +124,120 @@ A/D or D/A conversion. The start and end of the sequence, and
the start and end of each scan, and each conversion is called an
event.</P>
<P>Each of these 5 types of events are caused by a triggering
source. The source types are:</P>
source, specified through the *_src members of the
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure. The source types are:</P>
<P>
<UL>
<LI>TRIG_NONE don't ever cause event</LI>
<LI>TRIG_NOW cause event to occur immediately</LI>
<LI>TRIG_FOLLOW (see notes below)</LI>
<LI>TRIG_TIME cause event to occur at a particular time</LI>
<LI>TRIG_TIMER cause event to occur repeatedly at a specific rate</LI>
<LI>TRIG_COUNT cause event when count reaches specific value</LI>
<LI>TRIG_EXT external signal causes event</LI>
<LI>TRIG_INT internal signal causes event</LI>
<LI>TRIG_NONE: don't ever cause an event</LI>
<LI>TRIG_NOW: cause event to occur immediately</LI>
<LI>TRIG_FOLLOW: see notes below</LI>
<LI>TRIG_TIME: cause event to occur at a particular time</LI>
<LI>TRIG_TIMER: cause event to occur repeatedly at a specific rate</LI>
<LI>TRIG_COUNT: cause event when count reaches specific value</LI>
<LI>TRIG_EXT: external signal causes event</LI>
<LI>TRIG_INT: internal signal causes event</LI>
<LI>TRIG_OTHER: driver-specific meaning</LI>
</UL>
</P>
<P>For every trigger, there is a corresponding
argument (the *_arg members of the
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A>
structure) whose meaning depends on the type of trigger. The meanings
of the arguments are as follows:</P>
<P>Not all triggers are applicable to all events. Supported triggers
for specific events depends significantly on your particular
device. In addition, for every trigger type, there is a cooresponding
argument that specifies the rate, the count, which external signal,
etc.</P>
<P>TRIG_FOLLOW is a special type of trigger for scan_begin events that
triggers on the next lower level trigger, in this case, the trigger
for convert events. It may or may not be supported. Later, it may
also be used for start events if you want to chain multiple commands.</P>
<P>In particular, scan_end events will almost always be triggered on
TRIG_COUNT, with the argument being the number of channels in the
scan. (Actually, samples in the scan, since on most boards you can
measure a single channel multiple times in a scan.) Also, until
otherwise supported, start events can only be TRIG_NOW.</P>
device.</P>
<P>TRIG_NONE is typically used only as a stop_src. The arg for TRIG_NONE
is reserved and should be set to 0.</P>
<P>TRIG_NOW is most often used as a start_src. The arg for TRIG_NOW is
the number of nanoseconds between when the command is issued and when
the event should occur. In the case of using TRIG now as a start_src,
it indicates a delay between issuing the command and the start of
acquisition. Most drivers only support a delay of 0.</P>
<P>TRIG_FOLLOW is a special type of trigger for events that trigger on
the completion of some other, logically connected event. The argument
is reserved and should be set to 0. When used
as a scan_begin_src, it indicates that a trigger should occur as a
logical continuation of convert events. This is done in order to
properly describe boards that do not have separate timers for
convert and scan_begin events. When used as a start_src for analog
output subdevices, it indicates that conversion of output samples
should begin when samples are written to the buffer.</P>
<P>TRIG_TIME is reserved for future use.</P>
<P>TRIG_TIMER is most often used as a convert_src, a scan_begin_src, or
both. It indicates that triggers should occur at a specific rate.
The argument specifies the interval between triggers in nanoseconds.</P>
<P>TRIG_COUNT is used for scan_end_src and stop_src. It indicates that
a trigger should occur when the specified number of corresponding
lower-level triggers (convert and scan_begin, respectively) occur.
The argument is the count of lower-level triggers.</P>
<P>TRIG_EXT can be useful as any of the trigger sources. It indicates
that an external digital line should be used to trigger the event.
The exact meaning of digital line is device-dependent. Some devices
have one dedicated line, others may allow generic digital input
lines to be used. The argument indicates the particular external
line to use as the trigger.</P>
<P>TRIG_INT is typically used as a start_src. This trigger occurs when
the application performs an INSN_INTTRIG instruction. Using TRIG_INT
is a method by which the application can accurately record the time of
the start of acquisition, since the parsing and setup time of a
particular command may be significant. The argument associated with
TRIG_INT is reserved and should be set to 0.</P>
<P>TRIG_OTHER can be useful as any of the trigger sources. The exact
meaning of TRIG_OTHER is driver-specific, and implements a feature
that otherwise does not fit into the command interface. Configuration
of TRIG_OTHER features are done by INSN_CONFIG insns. The argument
is reserved and should be set to 0.</P>
<P>The chanlist member of the
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A>
structure should point to an array whose number of elements is specificed by chanlist_len
(this will generally be the same as the scan_end_arg).
The chanlist specifies the sequence of channels and gains (and analog references)
that should be stepped through for each scan. The elements of the chanlist array
should be initialized by packing the channel, range and reference information
together with the
<A HREF="comedilib-6.html#CR_PACK">CR_PACK(channel, range, aref)</A> macro.</P>
<P>The final member of the
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure is 'flags'.
The following flags are valid, and can be bitwise-or'd together.</P>
<P>
<UL>
<LI>TRIG_BOGUS: do the motions??</LI>
<LI>TRIG_DITHER: enable dithering??</LI>
<LI>TRIG_DEGLITCH: enable deglitching??</LI>
<LI>TRIG_RT: ask driver to use a hard real-time interrupt handler. This will
reduce latency in handling interrupts from your data aquisition hardware. It can
be useful if you are sampling at high frequency, or if your hardware has a small onboard
fifo. You must have a real-time kernel (RTAI or RTLinux) and must compile
comedi with real-time support or this flag will do nothing.</LI>
<LI>TRIG_CONFIG: perform configuration, not triggering.</LI>
<LI>TRIG_WAKE_EOS: some drivers will change their behaviour when this flag is set,
trying to transfer data at the end of every scan (instead of, for example, passing
data in chunks whenever the board's onboard fifo is half full). This flag
may degrade a driver's performance at higher frequencies.</LI>
<LI>TRIG_WRITE: write to bidirectional devices. Could be useful in principle, if someone
wrote a driver that supported commands for a digital i/o device that could do either
input or output.</LI>
</UL>
There are also a few flags that indicate how timing arguments should be rounded
if the hardware cannot achieve the exact timing requested.
<UL>
<LI>TRIG_ROUND_NEAREST: round to nearest supported timing period, the default.</LI>
<LI>TRIG_ROUND_DOWN: round period down.</LI>
<LI>TRIG_ROUND_UP: round period up.</LI>
<LI>TRIG_ROUND_UP_NEXT: this one doesn't do anything, and I don't know what it was intended
to do??</LI>
</UL>
</P>
<HR>
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@ -14,7 +14,8 @@ Contents
<HR>
<H1>Comedi Documentation</H1>
<H2>David Schleef, <CODE>ds@stm.lbl.gov</CODE></H2>
<H2>David Schleef <CODE>ds@stm.lbl.gov</CODE>,
Frank Hess <CODE>fmhess@uiuc.edu</CODE></H2>
<P>
<H2><A NAME="toc1">1.</A> <A HREF="comedilib-1.html">Introduction</A></H2>
@ -30,6 +31,9 @@ Contents
<P>
<H2><A NAME="toc5">5.</A> <A HREF="comedilib-5.html">Application-specific functions</A></H2>
<P>
<H2><A NAME="toc6">6.</A> <A HREF="comedilib-6.html">Libcomedi Reference</A></H2>
<HR>
<A HREF="comedilib-1.html">Next</A>
Previous

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@ -1,906 +0,0 @@
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
<HEAD>
<META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.7.4">
<TITLE>Comedi Documentation: Libcomedi Reference</TITLE>
<LINK HREF="comedilib_reference.html#toc1" REL=contents>
</HEAD>
<BODY>
Next
Previous
<A HREF="comedilib_reference.html#toc1">Contents</A>
<HR>
<H2><A NAME="s1">1.</A> <A HREF="comedilib_reference.html#toc1">Libcomedi Reference</A></H2>
<H2><A NAME="ss1.1">1.1 Constants and Macros</A>
</H2>
<H3>RANGE_LENGTH() <I>(deprecated)</I></H3>
<P>
<A NAME="RANGE_LENGTH"></A> </P>
<P><CODE>RANGE_LENGTH(rangetype)</CODE></P>
<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>
<P>The RANGE_LENGTH() macro returns the length of the array that is
specified by the rangetype token.</P>
<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>
<H2><A NAME="ss1.2">1.2 Data Types and Structures</A>
</H2>
<H3><A NAME="comedi_t"></A> comedi_t</H3>
<P>The data type <CODE>comedi_t</CODE> is used to represent an open Comedi
device. A valid <CODE>comedi_t</CODE> pointer is returned by a successful
call to <CODE>comedi_open()</CODE>, and should be used for subsequent
access to the device.
It is a transparent type, and pointers to type <CODE>comedi_t</CODE>
should not be dereferenced by the application.</P>
<H3><A NAME="sampl_t"></A> sampl_t</H3>
<P>The data type <CODE>sampl_t</CODE> 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>
<H3><A NAME="lsampl_t"></A> lsampl_t</H3>
<P>The data type <CODE>lsampl_t</CODE> is one of the generic types used to represent
data values in libcomedi. It is currently defined to be <CODE>unsigned int</CODE>.</P>
<H3><A NAME="comedi_trig_struct"></A> comedi_trig_struct <I>(deprecated)</I></H3>
<P>The <CODE>comedi_trig</CODE> structure</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>The <CODE>comedi_trig</CODE> 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_trig is
deprecated, and should not be used in new applications.</P>
<P>This structure is defined as part of the Comedi kernel interface.</P>
<H3><A NAME="comedi_sv_t"></A> comedi_sv_t</H3>
<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>
<P>The <CODE>comedi_sv_t</CODE> structure is used by the <CODE>comedi_sv_*()</CODE>
functions to provide a simple method of accurately measuring
slowly varying inputs. See the relevant section for more
details.</P>
<H3><A NAME="comedi_cmd"></A> comedi_cmd</H3>
<P>undocumented</P>
<P>Related functions are described in section XXX.</P>
<P>This structure is defined as part of the Comedi kernel interface.</P>
<H3><A NAME="comedi_insn"></A> comedi_insn</H3>
<P>undocumented</P>
<P>Related functions are described in section XXX.</P>
<P>This structure is defined as part of the Comedi kernel interface.</P>
<H3><A NAME="comedi_range"></A> comedi_range</H3>
<P>undocumented</P>
<H2><A NAME="ss1.3">1.3 Functions</A>
</H2>
<H3><A NAME="comedi_close"></A> comedi_close()</H3>
<P><CODE>void comedi_close(comedi_t *it);</CODE></P>
<P>Closes a device previously opened by comedi_open().</P>
<P>The return type of this function will change to <CODE>int</CODE>, in
order to match <CODE>fclose</CODE>.</P>
<P>Source: <CODE>/lib/comedi.c</CODE></P>
<H3><A NAME="comedi_data_read"></A> comedi_data_read()</H3>
<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>
<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 A/D conversion (if appropriate),
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>
<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>
<P>On sucess, <CODE>comedi_data_read()</CODE> returns 0. If there is an
error, -1 is returned.</P>
<P>Valid analog reference numbers are:</P>
<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>
<P>Valid data values returned 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>
<P>Source: <CODE>/lib/data.c</CODE></P>
<H3>comedi_data_write()</H3>
<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>
<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 D/A conversion (if appropriate), 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>
<P><CODE>comedi_data_write()</CODE> writes the data value
specified by the argument <CODE>data</CODE> to
the specified channel.</P>
<P>On sucess, <CODE>comedi_data_write()</CODE> returns 0. If there is an error, -1 is
returned.</P>
<P>Valid analog reference numbers are:</P>
<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>
<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>
<P>Source: <CODE>/lib/data.c</CODE></P>
<H3>comedi_dio_bitfield();</H3>
<P><CODE>int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned
int write_mask,unsigned int *bits);</CODE></P>
<P>The function <CODE>comedi_dio_bitfield()</CODE> allows multiple channels to
be read simultaneously from a digital input or digital I/O device.
The parameter <CODE>write_mask</CODE> and the value pointed to by <CODE>bits</CODE>
are interpreted as bit fields, with the least significant bit
representing channel 0. For each bit in <CODE>write_mask</CODE> that is
set, the cooresponding bit in <CODE>*bits</CODE> is written to the digital
output channel. Each digital input channel is read, and the result
placed in the approprate bits in <CODE>*bits</CODE>.</P>
<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>
<P>It should be noted that it is not possible to access channels
greater than 31 using this function.</P>
<P>Source: <CODE>/lib/dio.c</CODE></P>
<H3>comedi_dio_config()</H3>
<P><CODE>int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned
int chan,unsigned int dir);</CODE></P>
<P>The function <CODE>comedi_dio_config</CODE> configures individual channels
in a digital I/O subdevice to be either input or output, depending
on the value of parameter <CODE>dir</CODE>. Depending on the capabilities
of the hardware device, multiple channels may be affected by
a single call to <CODE>comedi_dio_config</CODE>.</P>
<P>Valid directions are:
<UL>
<LI> COMEDI_INPUT</LI>
<LI> COMEDI_OUTPUT</LI>
</UL>
</P>
<P>Source: <CODE>/lib/dio.c</CODE></P>
<H3>comedi_dio_read()</H3>
<P><CODE>int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int
chan,unsigned int *bit);</CODE></P>
<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>
<P>This function is equivalent to <CODE>comedi_data_read(it,subd,chan,0,0,bit)</CODE>.</P>
<P>Source: <CODE>/lib/dio.c</CODE></P>
<H3>comedi_dio_write()</H3>
<P><CODE>int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned
int chan,unsigned int bit);</CODE></P>
<P>The function writes the value of <CODE>bit</CODE>, 0 or 1, to channel <CODE>chan</CODE>,
belonging to the digital output device <CODE>subd</CODE> of device <CODE>it</CODE>. Returns
-1 on failure.</P>
<P>Source: <CODE>/lib/dio.c</CODE></P>
<H3>comedi_fileno()</H3>
<P><CODE>int comedi_fileno(comedi_t *it);</CODE></P>
<P>The function <CODE>comedi_fileno</CODE>
returns the integer descriptor for the handle <CODE>it</CODE>. It
is equivalent to the standard function <CODE>fileno</CODE>. If
<CODE>it</CODE> is an invalid <CODE>comedi_t</CODE> pointer, the function
returns -1 and sets the appropriate libcomedi error value.</P>
<P>Source: <CODE>/lib/comedi.c</CODE></P>
<H3>comedi_find_range()</H3>
<P><CODE>int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned
int chan, unsigned int unit, double min, double max);</CODE></P>
<P>The function <CODE>comedi_find_range</CODE> tries to
locate the optimal (smallest) range for the channel <CODE>chan</CODE>
belonging to a <CODE>subdevice</CODE> of the comedi device <CODE>it</CODE>,
that includes both <CODE>min</CODE> and <CODE>max</CODE> in <CODE>units</CODE>.
If it finds a matching range, it returns its index. If no
matching range is available, it returns -1.</P>
<P>Valid units are:</P>
<P>
<UL>
<LI>UNIT_volt </LI>
<LI>UNIT_mA</LI>
<LI>UNIT_none</LI>
</UL>
</P>
<P>Source: <CODE>/lib/range.c</CODE></P>
<H3><A NAME="comedi_errno"></A> comedi_errno()</H3>
<P><CODE>int comedi_errno(void);</CODE></P>
<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>
<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>
<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>
<P>Source: <CODE>/lib/error.c</CODE></P>
<H3>comedi_find_subdevice_by_type()</H3>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3><A NAME="comedi_from_phys"></A> comedi_from_phys()</H3>
<P><CODE>lsampl_t comedi_from_phys(double data, comedi_range *rng,
lsampl_t maxdata);</CODE></P>
<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>
<H3>comedi_get_board_name()</H3>
<P><CODE>char *comedi_get_board_name(comedi_t *it);</CODE></P>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_get_driver_name()</H3>
<P><CODE>char *comedi_get_driver_name(comedi_t *it);</CODE></P>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_get_maxdata()</H3>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_get_n_channels()</H3>
<P><CODE>int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);</CODE></P>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_get_n_ranges()</H3>
<P><CODE>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
chan);</CODE></P>
<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>
<P>Source: <CODE>/lib/range.c</CODE></P>
<H3>comedi_get_n_subdevices()</H3>
<P><CODE>int comedi_get_n_subdevices(comedi_t *it);</CODE></P>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_get_range()</H3>
<P><CODE>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
range);</CODE></P>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_get_rangetype() <I>deprecated</I></H3>
<P><CODE>int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int
chan);</CODE></P>
<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>
<P>The macro
<CODE>RANGE_LENGTH(rangetype)</CODE>
can be used to determine the number of range specifications for a given
range type.</P>
<P>This function is deprecated and should not be used in new code.</P>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3><A NAME="comedi_get_subdevice_type"></A> comedi_get_subdevice_type()</H3>
<P><CODE>int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);</CODE></P>
<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>
<P>Valid subdevice types are:</P>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_get_timer() <I>(deprecated)</I></H3>
<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>
<H3>comedi_get_version_code()</H3>
<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>
<P>Source: <CODE>/lib/get.c</CODE></P>
<H3>comedi_loglevel()</H3>
<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>
<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>
<P>Bugs: Libcomedi doesn't currently have much debugging information.</P>
<P>Source: <CODE>/lib/error.c</CODE></P>
<H3>comedi_open()</H3>
<P><CODE>comedi_t *comedi_open(char *filename);</CODE></P>
<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>
<P>Bugs: Not strictly identical to <CODE>fopen</CODE></P>
<P>Source: <CODE>/lib/comedi.c</CODE></P>
<H3><A NAME="comedi_perror"></A> comedi_perror()</H3>
<P><CODE>void comedi_perror(const char *s);</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>
<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>
<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>
<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>
<P>Bugs: Does not support internationalization.</P>
<P>Source: <CODE>/lib/error.c</CODE></P>
<H3><A NAME="comedi_strerror"></A> comedi_strerror()</H3>
<P><CODE>*comedi_strerror(int errnum);</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>
<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>
<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>
<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>
<P>Bugs: Does not support internationalization.</P>
<P>Source: <CODE>/lib/error.c</CODE></P>
<H3>comedi_sv_init()</H3>
<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>
<P>Bugs: comedi_sv_* was very poorly designed.</P>
<P>Source: <CODE>/lib/sv.c</CODE></P>
<H3>comedi_sv_update()</H3>
<P><CODE>int comedi_sv_update(comedi_sv_t *sv);</CODE></P>
<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>
<P>Source: <CODE>/lib/sv.c</CODE></P>
<H3>int comedi_sv_measure()</H3>
<P><CODE>int comedi_sv_measure(comedi_sv_t *it,double *data);</CODE></P>
<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>
<P>Source: <CODE>/lib/sv.c</CODE></P>
<H3><A NAME="comedi_to_phys"></A> comedi_to_phys()</H3>
<P><CODE>double comedi_to_phys(lsampl_t data, comedi_range *rng,
lsampl_t maxdata);</CODE></P>
<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>
<P>Source: <CODE>/lib/range.c</CODE></P>
<H3>comedi_trigger() <I>(deprecated)</I></H3>
<P><CODE>int comedi_trigger(comedi_t *it,comedi_trig *trig);</CODE></P>
<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>
<P>Lifetime: removal at 1.0.</P>
<P>Source: <CODE>/lib/comedi.c</CODE></P>
<H3><A NAME="comedi_get_subdevice_flags"></A> comedi_get_subdevice_flags()</H3>
<P><CODE>int comedi_get_subdevice_flags(comedi_t *dev, unsigned int subdevice);</CODE></P>
<P>This function returns a bitfield describing the capabilities of the
specified subdevice. If there is an error, -1 is returned.</P>
<P>The bits are:</P>
<P>
<UL>
<LI>SDF_BUSY subdevice is running a command</LI>
<LI>SDF_BUSY_OWNER subdevice is running a command started by
the file descriptor used by <CODE>dev</CODE>.</LI>
<LI>SDF_LOCKED subdevice is locked</LI>
<LI>SDF_LOCKED_OWNER subdevice is locked by the file descriptor used
by <CODE>dev</CODE>.</LI>
<LI>SDF_MAXDATA maximum data values are channel dependent</LI>
<LI>SDF_FLAGS channel flags are channel dependent</LI>
<LI>SDF_RANGETYPE range types are channel dependent</LI>
<LI>SDF_MODE0 deprecated</LI>
<LI>SDF_MODE1 deprecated</LI>
<LI>SDF_MODE2 deprecated</LI>
<LI>SDF_MODE3 deprecated</LI>
<LI>SDF_MODE4 deprecated</LI>
<LI>SDF_CMD subdevice supports commands</LI>
<LI>SDF_READABLE subdevice can be read from</LI>
<LI>SDF_WRITEABLE subdevice can be written to</LI>
<LI>SDF_RT deprecated</LI>
<LI>SDF_GROUND subdevice is capable of ground analog reference</LI>
<LI>SDF_COMMON subdevice is capable of common analog reference</LI>
<LI>SDF_DIFF subdevice is capable of differential analog reference</LI>
<LI>SDF_OTHER subdevice is capable of other analog reference</LI>
<LI>SDF_DITHER subdevice recognizes dither flag</LI>
<LI>SDF_DEGLITCH subdevice recognizes deglitch flag</LI>
<LI>SDF_MMAP deprecated</LI>
<LI>SDF_RUNNING subdevice is acquiring data (i.e., command has not
completed)</LI>
<LI>SDF_LSAMPL subdevice uses samples of type lsampl_t (otherwise
sampl_t)</LI>
<LI>SDF_PACKED subdevice uses bitfield samples (otherwise it uses
one sample per channel)</LI>
</UL>
</P>
<P>The bit definitions are part of the Comedi kernel interface.</P>
<H3><A NAME="comedi_range_is_chan_specific"></A> comedi_range_is_chan_specific()</H3>
<P><CODE>int comedi_range_is_chan_specific(comedi_t *dev,unsigned int subdevice);</CODE></P>
<P>If each channel of the specified subdevice has a different range
specification, this function returns 1. Otherwise, this function
returns 0. On error, this function returns -1.</P>
<H3><A NAME="undocumented"></A> Undocumented functions</H3>
<P>
<UL>
<LI>comedi_maxdata_is_chan_specific()</LI>
<LI>comedi_get_buffer_size()</LI>
<LI>comedi_get_max_buffer_size()</LI>
<LI>comedi_set_buffer_size()</LI>
<LI>comedi_set_max_buffer_size()</LI>
<LI>comedi_do_insnlist()</LI>
<LI>comedi_do_insn()</LI>
<LI>comedi_lock()</LI>
<LI>comedi_unlock()</LI>
<LI>comedi_get_cmd_src_mask()</LI>
<LI>comedi_get_cmd_generic_timed()</LI>
<LI>comedi_cancel()</LI>
<LI>comedi_command()</LI>
<LI>comedi_command_test()</LI>
<LI>comedi_poll()</LI>
<LI>comedi_get_buffer_contents()</LI>
<LI>comedi_mark_buffer_read()</LI>
<LI>comedi_get_buffer_offset()</LI>
<LI>comedi_set_global_oor_behavior()</LI>
</UL>
</P>
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<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>
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<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>
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<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>
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<H1>Comedi Documentation</H1>
<H2>David Schleef, <CODE>ds@stm.lbl.gov</CODE> </H2>
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<!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 by the application.
<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_trig is
deprecated, and should not be used in new applications.
<p>
This structure is defined as part of the Comedi kernel interface.
<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.
<p>
<sect2>comedi_cmd
<label id="comedi_cmd">
<p>
undocumented
<p>
Related functions are described in section XXX.
<p>
This structure is defined as part of the Comedi kernel interface.
<p>
<sect2>comedi_insn
<label id="comedi_insn">
<p>
undocumented
<p>
Related functions are described in section XXX.
<p>
This structure is defined as part of the Comedi kernel interface.
<p>
<sect2>comedi_range
<label id="comedi_range">
<p>
undocumented
<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() <it/deprecated/
<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.
<p>
This function is deprecated and should not be used in new code.
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_subdevice_flags()
<label id="comedi_get_subdevice_flags">
<p>
<tt/int comedi_get_subdevice_flags(comedi_t *dev, unsigned int subdevice);/
<p>
This function returns a bitfield describing the capabilities of the
specified subdevice. If there is an error, -1 is returned.
<p>The bits are:
<itemize>
<item>SDF_BUSY subdevice is running a command
<item>SDF_BUSY_OWNER subdevice is running a command started by
the file descriptor used by <tt/dev/.
<item>SDF_LOCKED subdevice is locked
<item>SDF_LOCKED_OWNER subdevice is locked by the file descriptor used
by <tt/dev/.
<item>SDF_MAXDATA maximum data values are channel dependent
<item>SDF_FLAGS channel flags are channel dependent
<item>SDF_RANGETYPE range types are channel dependent
<item>SDF_MODE0 deprecated
<item>SDF_MODE1 deprecated
<item>SDF_MODE2 deprecated
<item>SDF_MODE3 deprecated
<item>SDF_MODE4 deprecated
<item>SDF_CMD subdevice supports commands
<item>SDF_READABLE subdevice can be read from
<item>SDF_WRITEABLE subdevice can be written to
<item>SDF_RT deprecated
<item>SDF_GROUND subdevice is capable of ground analog reference
<item>SDF_COMMON subdevice is capable of common analog reference
<item>SDF_DIFF subdevice is capable of differential analog reference
<item>SDF_OTHER subdevice is capable of other analog reference
<item>SDF_DITHER subdevice recognizes dither flag
<item>SDF_DEGLITCH subdevice recognizes deglitch flag
<item>SDF_MMAP deprecated
<item>SDF_RUNNING subdevice is acquiring data (i.e., command has not
completed)
<item>SDF_LSAMPL subdevice uses samples of type lsampl_t (otherwise
sampl_t)
<item>SDF_PACKED subdevice uses bitfield samples (otherwise it uses
one sample per channel)
</itemize>
<p>
The bit definitions are part of the Comedi kernel interface.
<p>
<sect2>comedi_range_is_chan_specific()
<label id="comedi_range_is_chan_specific">
<p>
<tt/int comedi_range_is_chan_specific(comedi_t *dev,unsigned int subdevice);/
<p>
If each channel of the specified subdevice has a different range
specification, this function returns 1. Otherwise, this function
returns 0. On error, this function returns -1.
<p>
<sect2>Undocumented functions
<label id="undocumented">
<p>
<itemize>
<item>comedi_maxdata_is_chan_specific()
<item>comedi_get_buffer_size()
<item>comedi_get_max_buffer_size()
<item>comedi_set_buffer_size()
<item>comedi_set_max_buffer_size()
<item>comedi_do_insnlist()
<item>comedi_do_insn()
<item>comedi_lock()
<item>comedi_unlock()
<item>comedi_get_cmd_src_mask()
<item>comedi_get_cmd_generic_timed()
<item>comedi_cancel()
<item>comedi_command()
<item>comedi_command_test()
<item>comedi_poll()
<item>comedi_get_buffer_contents()
<item>comedi_mark_buffer_read()
<item>comedi_get_buffer_offset()
<item>comedi_set_global_oor_behavior()
</itemize>
</article>