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David Schleef 2001-07-15 23:58:14 +00:00
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@ -102,7 +102,7 @@ is only accurate to part-per-thousand.</P>
<H2><A NAME="ss5.3">5.3 Commands</A>
<H2><A NAME="command_section"></A> <A NAME="ss5.3">5.3 Commands</A>
</H2>
@ -124,7 +124,7 @@ 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, specified through the *_src members of the
source, specified through the <CODE>*_src</CODE> members of the
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure. The source types are:</P>
<P>
<UL>
@ -139,36 +139,37 @@ source, specified through the *_src members of the
<LI>TRIG_OTHER: driver-specific meaning</LI>
</UL>
</P>
<P>Not all triggers are applicable to all events. Supported triggers
for specific events depend significantly on your particular
device. The
<A HREF="comedilib-6.html#comedi_get_cmd_src_mask">comedi_get_cmd_src_mask()</A>
function is useful for determining what triggers a subdevice supports.</P>
<P>For every trigger, there is a corresponding
argument (the *_arg members of the
argument (the <CODE>*_arg</CODE> 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.</P>
<P>TRIG_NONE is typically used only as a stop_src. The arg for TRIG_NONE
<P>TRIG_NONE is typically used only as a <CODE>stop_src</CODE>. The argument 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
<P>TRIG_NOW is most often used as a <CODE>start_src</CODE>. The argument 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,
the event should occur. In the case of using TRIG now as a <CODE>start_src</CODE>,
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
as a <CODE>scan_begin_src</CODE>, 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
convert and scan_begin events. When used as a <CODE>start_src</CODE> 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
<P>TRIG_TIMER is most often used as a <CODE>convert_src</CODE>, a <CODE>scan_begin_src</CODE>, 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
<P>TRIG_COUNT is used for <CODE>scan_end_src</CODE> and <CODE>stop_src</CODE>. 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>
@ -178,7 +179,7 @@ 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
<P>TRIG_INT is typically used as a <CODE>start_src</CODE>. 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
@ -189,18 +190,26 @@ 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
<P>Ths <CODE>subdev</CODE> 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
structure is the index of the subdevice the command is intended for. The
<A HREF="comedilib-6.html#comedi_find_subdevice_by_type">comedi_find_subdevice_by_type()</A>
function can be useful in discovering the index of your desired subdevice.</P>
<P>The <CODE>chanlist</CODE> 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 <CODE>chanlist_len</CODE>
(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>
<A HREF="comedilib-6.html#CR_PACK">CR_PACK()</A> macro.</P>
<P>The <CODE>data</CODE> and <CODE>data_len</CODE> members can be safely ignored when issueing commands
from a user-space program. They only have meaning when a command is sent from a kernel
module using the kcomedilib interface, in which case they specify the buffer where
the driver should write/read its data to/from.</P>
<P>The final member of the
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure is 'flags'.
<A HREF="comedilib-6.html#comedi_cmd">comedi_cmd</A> structure is <CODE>flags</CODE>.
The following flags are valid, and can be bitwise-or'd together.</P>
<P>
<UL>
@ -212,11 +221,12 @@ reduce latency in handling interrupts from your data aquisition hardware. It ca
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_CONFIG: perform configuration, not triggering. This is a legacy of the
deprecated comedi_trig_struct, and has no function at present.</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>
may degrade a driver's performance at high 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>
@ -234,7 +244,15 @@ to do??</LI>
</P>
<P>The typical sequence for executing a command is to first send
the command through
<A HREF="comedilib-6.html#comedi_command_test">comedi_command_test()</A>
once or twice. The test will check that the command is valid for the particular
device, and often makes some adjustments to the command arguments, which
can then be read back by the user to see the actual values used. The
command is executed with
<A HREF="comedilib-6.html#comedi_command">comedi_command()</A>. For input/output commands, data
is read from or written to the device file /dev/comedi[0..3] you are using.</P>
<HR>
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@ -20,10 +20,36 @@ Next
<H3><A NAME="CR_PACK"></A> CR_PACK(channel, range, aref)</H3>
<H3><A NAME="CR_PACK"></A> CR_PACK()</H3>
<P>undocumented</P>
<P><CODE>CR_PACK(channel, range, aref)</CODE></P>
<P><CODE>CR_PACK</CODE> is used to initialize the elements of the <CODE>chanlist array</CODE> in the
<A HREF="#comedi_cmd">comedi_cmd</A> structure, and the <CODE>chanspec</CODE> member
of the
<A HREF="#comedi_insn">comedi_insn</A> structure.</P>
<P>The <CODE>channel</CODE> argument is the channel you wish to use, with the channel numbering
starting at zero.</P>
<P>The <CODE>range</CODE> is an index, starting at zero, whose meaning
is device dependent. The
<A HREF="#comedi_get_n_ranges">comedi_get_n_ranges()</A> and
<A HREF="#comedi_get_range">comedi_get_range()</A> functions
are useful in discovering information about the available ranges.</P>
<P>The <CODE>aref</CODE> argument indicates what reference you want the device to use. It
can be any of the following:
<UL>
<LI>AREF_GROUND is for inputs/outputs referenced to ground</LI>
<LI>AREF_COMMON is for a `common' reference (the low inputs of all the channels are tied
together, but are isolated from ground)</LI>
<LI>AREF_DIFF is for differential inputs/outputs</LI>
<LI>AREF_OTHER is for any reference that does not fit into the above categories</LI>
</UL>
Particular drivers may or may not use the AREF flags. If they are not supported, they
are silently ignored.</P>
<P>Source: <CODE>/include/comedi.h</CODE></P>
<H3>RANGE_LENGTH() <I>(deprecated)</I></H3>
@ -142,9 +168,42 @@ details.</P>
<H3><A NAME="comedi_cmd"></A> comedi_cmd</H3>
<P>undocumented</P>
<P>
<BLOCKQUOTE><CODE>
<PRE>
typedef struct comedi_cmd_struct comedi_cmd;
<P>Related functions are described in section XXX.</P>
struct comedi_cmd_struct{
unsigned int subdev;
unsigned int flags;
unsigned int start_src;
unsigned int start_arg;
unsigned int scan_begin_src;
unsigned int scan_begin_arg;
unsigned int convert_src;
unsigned int convert_arg;
unsigned int scan_end_src;
unsigned int scan_end_arg;
unsigned int stop_src;
unsigned int stop_arg;
unsigned int *chanlist;
unsigned int chanlist_len;
sampl_t *data;
unsigned int data_len;
};
</PRE>
</CODE></BLOCKQUOTE>
</P>
<P>More information on using commands can be found in the
<A HREF="comedilib-5.html#command_section">command</A> section.</P>
<P>This structure is defined as part of the Comedi kernel interface.</P>
@ -189,7 +248,14 @@ order to match <CODE>fclose</CODE>.</P>
<P><CODE>int comedi_command(comedi_t *it, comedi_cmd *cmd);</CODE></P>
<P>undocumented</P>
<P>Issues the command pointed at by <CODE>cmd</CODE> to the open device <CODE>it</CODE>. It
is usually necessary to pass the command through
<A HREF="#comedi_command_test">comedi_command_test()</A> to
fix up the command before it can be successfully executed with
<CODE>comedi_command()</CODE>.
See
<A HREF="comedilib-5.html#command_section">commands</A> for more information.</P>
<P>Source: <CODE>/lib/comedi.c</CODE></P>
@ -197,7 +263,36 @@ order to match <CODE>fclose</CODE>.</P>
<P><CODE>int comedi_command_test(comedi_t *it, comedi_cmd *cmd);</CODE></P>
<P>undocumented</P>
<P>Tests and fixes up the command pointed at by <CODE>cmd</CODE> according
to the limitations of the driver configured on the open device <CODE>it</CODE>.
The return value has the following meaning:
<UL>
<LI>0: the command passed the test and can be successfully executed
by
<A HREF="#comedi_command">comedi_command()</A>. The one exception
to this rule is that the test will allow a NULL chanlist for the command.</LI>
<LI>1: invalid trigger. One or more of the trigger sources (the *_src members
of the
<A HREF="#comedi_cmd">comedi_cmd</A> structure) is not
supported by the driver.</LI>
<LI>2: incompatible triggers. Two or more of the triggers selected are
incompatible with each other. For example, a driver might allow either
the scan_begin_src or the convert_src to be TRIG_TIMER, but not both.</LI>
<LI>3: argument invalid. One or more argument is invalid, for example
a timing argument might be in excess of the card's maximum speed. The
command test will correct the arguments by modifying the command pointed
at by <CODE>cmd</CODE>.</LI>
<LI>4: argument fix up. The command underwent minor adjustment and should
now be valid. For example, a timing argument might not be exactly achievable
by the card so the timing argument will be adjusted to the actual timing
the card will use.</LI>
<LI>negative: some other error has occured.</LI>
</UL>
See
<A HREF="comedilib-5.html#command_section">commands</A> for more information.</P>
<P>Source: <CODE>/lib/comedi.c</CODE></P>
@ -417,7 +512,7 @@ is the same as the C library.</P>
<H3>comedi_find_subdevice_by_type()</H3>
<H3><A NAME="comedi_find_subdevice_by_type"></A> comedi_find_subdevice_by_type()</H3>
<P><CODE>int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int
@ -512,7 +607,7 @@ and having index <CODE>subdevice</CODE>. This function returns -1 on error.</P>
<H3>comedi_get_n_ranges()</H3>
<H3><A NAME="comedi_get_n_ranges"></A> comedi_get_n_ranges()</H3>
<P><CODE>int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int
@ -535,7 +630,7 @@ number of subdevices associated with the comedi descriptor
<H3>comedi_get_range()</H3>
<H3><A NAME="comedi_get_range"></A> comedi_get_range()</H3>
<P><CODE>comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int
@ -907,8 +1002,6 @@ returns 0. On error, this function returns -1.</P>
<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>

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@ -270,12 +270,11 @@
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,XXX data);
comedi_data_read(it,subdev,chan,range,aref,&data);
printf("%d\n",data);
@ -284,9 +283,9 @@
Should be understandable. Open the device, get the data, print it
out. This is basically the guts of demo/inp.c, without error checking
or fancy options. Compile it using
Should be understandable: open the device, get the data, print it out.
This is basically the guts of demo/inp.c, without error checking or
fancy options. Compile it using
@ -305,8 +304,8 @@
44..22.. CCoonnvveerrttiinngg ssaammpplleess ttoo vvoollttaaggeess
If you selected an analog input subdevice, you should notice that the
output of tut1 is a number between 0 and 4095, or 0 and 65535,
If you selected an analog input subdevice, you probably noticed that
the output of tut1 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 aallwwaayyss unsigned, with 0 representing the lowest voltage of the
ADC, and 4095 the highest. Comedi compensates for anything else the
@ -318,8 +317,8 @@
Most devices give you a choice of gain and unipolar/bipolar 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 and the unipolar/bipolar aspects.
analog input (or "output range" for analog output.) The range
parameter represents both the gain and the unipolar/bipolar aspects.
Comedi keeps the number of available ranges and the largest sample
value for each subdevice/channel combination. (Some devices allow
@ -425,7 +424,7 @@
added what we've learned.
#include <stdio.h> /* for printf() */
#include <comedi.h> /* also included by comedilib.h */
#include <comedilib.h> /* for comedi_get() */
#include <comedilib.h> /* 'cuz we're using comedilib */
int subdev = 0; /* change this to your input subdevice */
int chan = 0; /* change this to your channel */
@ -446,7 +445,7 @@
rangetype=comedi_get_rangetype(cf,subdev,chan);
comedi_data_read(cf->fd,subdev,chan,range,aref,XXX data);
comedi_data_read(cf->fd,subdev,chan,range,aref,&data);
volts=comedi_to_phys(data,rangetype,range,maxdata);
@ -570,67 +569,87 @@
The source types are:
+o TRIG_NONE: don't ever cause an event, sometimes used as a
stop_src.
+o TRIG_NONE: don't ever cause an event
+o TRIG_NOW: cause event to occur immediately, the most common
start_src. It is also used sometimes as a convert_src for 'burst
mode' aquisition where the individual channels in a scan are
scanned through as quickly as possible.
+o TRIG_NOW: cause event to occur immediately
+o TRIG_FOLLOW: see notes below, usually used as a scan_begin_src.
+o TRIG_FOLLOW: see notes below
+o TRIG_TIME: cause event to occur at a particular time
+o TRIG_TIMER: cause event to occur repeatedly at a specific rate,
often used as a scan_begin_src or convert_src.
+o TRIG_TIMER: cause event to occur repeatedly at a specific rate
+o TRIG_COUNT: cause event when count reaches specific value,
almost always used as the scan_end_src and often for stop_src.
+o TRIG_COUNT: cause event when count reaches specific value
+o TRIG_EXT: external signal causes event, used as start_src for
externally triggered conversions, and as scan_begin_src or
convert_src for externally paced conversions.
+o TRIG_EXT: external signal causes event
+o TRIG_INT: internal signal causes event, will probably be used
as start_src for output commands in the future.
+o TRIG_INT: internal signal causes event
+o TRIG_OTHER: driver-specific meaning
Not all triggers are applicable to all events. Supported triggers for
specific events depend significantly on your particular device. The
``comedi_get_cmd_src_mask()'' function is useful for determining what
triggers a subdevice supports.
For every trigger, there is a corresponding argument (the *_arg
members of the ``comedi_cmd'' structure) whose meaning depends on the
type of trigger. The meanings of the arguments are as follows:
TRIG_NONE is typically used only as a stop_src. The argument for
TRIG_NONE is reserved and should be set to 0.
+o trigger src = TRIG_NONE: argument has no meaning
TRIG_NOW is most often used as a start_src. The argument 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.
+o trigger src = TRIG_NOW: argument is the delay in nanoseconds before
triggering
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.
+o trigger src = TRIG_FOLLOW: argument has no meaning
TRIG_TIME is reserved for future use.
+o trigger src = TRIG_TIME: argument is the time at which to trigger
(in what units??), but no drivers support this yet.
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.
+o trigger src = TRIG_TIMER: argument is the period in nanoseconds
between triggers
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.
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.
+o trigger src = TRIG_COUNT: argument is the number of 'counts' per
trigger. For comedi_cmd.stop_arg, this is the number of scans to
perform before ending aquisition. For comedi_cmd.scan_end_arg,
this is the number of conversions to perform per scan.
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.
+o trigger src = TRIG_EXT: argument is the digital input channel to
trigger on.
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.
+o trigger src = TRIG_INT: argument meaning is unknown??
Not all triggers are applicable to all events. Supported triggers for
specific events depends significantly on your particular device.
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.
Ths subdev member of the ``comedi_cmd'' structure is the index of the
subdevice the command is intended for. The
``comedi_find_subdevice_by_type()'' function can be useful in
discovering the index of your desired subdevice.
The chanlist member of the ``comedi_cmd'' structure should point to an
array whose number of elements is specificed by chanlist_len (this
@ -638,10 +657,15 @@
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 ``CR_PACK(channel, range,
aref)'' macro.
reference information together with the ``CR_PACK()'' macro.
The final member of the ``comedi_cmd'' structure is 'flags'. The
The data and data_len members can be safely ignored when issueing
commands from a user-space program. They only have meaning when a
command is sent from a kernel module using the kcomedilib interface,
in which case they specify the buffer where the driver should
write/read its data to/from.
The final member of the ``comedi_cmd'' structure is flags. The
following flags are valid, and can be bitwise-or'd together.
@ -658,13 +682,15 @@
must have a real-time kernel (RTAI or RTLinux) and must compile
comedi with real-time support or this flag will do nothing.
+o TRIG_CONFIG: perform configuration, not triggering.
+o TRIG_CONFIG: perform configuration, not triggering. This is a
legacy of the deprecated comedi_trig_struct, and has no function at
present.
+o 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.
driver's performance at high frequencies.
+o TRIG_WRITE: write to bidirectional devices. Could be useful in
principle, if someone wrote a driver that supported commands for a
@ -679,7 +705,6 @@
+o TRIG_ROUND_DOWN: round period down.
+o TRIG_ROUND_UP: round period up.
+o TRIG_ROUND_UP_NEXT: this one doesn't do anything, and I don't know
@ -687,6 +712,16 @@
The typical sequence for executing a command is to first send the
command through ``comedi_command_test()'' once or twice. The test
will check that the command is valid for the particular device, and
often makes some adjustments to the command arguments, which can then
be read back by the user to see the actual values used. The command
is executed with ``comedi_command()''. For input/output commands,
data is read from or written to the device file /dev/comedi[0..3] you
are using.
66.. LLiibbccoommeeddii RReeffeerreennccee
@ -695,10 +730,42 @@
66..11..11.. CCRR__PPAACCKK((cchhaannnneell,, rraannggee,, aarreeff))
66..11..11.. CCRR__PPAACCKK(())
undocumented
CR_PACK(channel, range, aref)
CR_PACK is used to initialize the elements of the chanlist array in
the ``comedi_cmd'' structure, and the chanspec member of the
``comedi_insn'' structure.
The channel argument is the channel you wish to use, with the channel
numbering starting at zero.
The range is an index, starting at zero, whose meaning is device
dependent. The ``comedi_get_n_ranges()'' and ``comedi_get_range()''
functions are useful in discovering information about the available
ranges.
The aref argument indicates what reference you want the device to use.
It can be any of the following:
+o AREF_GROUND is for inputs/outputs referenced to ground
+o AREF_COMMON is for a `common' reference (the low inputs of all
the channels are tied together, but are isolated from ground)
+o AREF_DIFF is for differential inputs/outputs
+o AREF_OTHER is for any reference that does not fit into the
above categories
Particular drivers may or may not use the AREF flags. If they are
not supported, they are silently ignored.
Source: /include/comedi.h
66..11..22.. RRAANNGGEE__LLEENNGGTTHH(()) ((ddeepprreeccaatteedd))
@ -812,10 +879,39 @@
66..22..66.. ccoommeeddii__ccmmdd
undocumented
typedef struct comedi_cmd_struct comedi_cmd;
struct comedi_cmd_struct{
unsigned int subdev;
unsigned int flags;
unsigned int start_src;
unsigned int start_arg;
unsigned int scan_begin_src;
unsigned int scan_begin_arg;
unsigned int convert_src;
unsigned int convert_arg;
unsigned int scan_end_src;
unsigned int scan_end_arg;
unsigned int stop_src;
unsigned int stop_arg;
unsigned int *chanlist;
unsigned int chanlist_len;
sampl_t *data;
unsigned int data_len;
};
Related functions are described in section XXX.
More information on using commands can be found in the ``command''
section.
This structure is defined as part of the Comedi kernel interface.
@ -868,7 +964,12 @@
int comedi_command(comedi_t *it, comedi_cmd *cmd);
undocumented
Issues the command pointed at by cmd to the open device it. It is
usually necessary to pass the command through
``comedi_command_test()'' to fix up the command before it can be
successfully executed with comedi_command(). See ``commands'' for
more information.
Source: /lib/comedi.c
@ -879,7 +980,38 @@
int comedi_command_test(comedi_t *it, comedi_cmd *cmd);
undocumented
Tests and fixes up the command pointed at by cmd according to the
limitations of the driver configured on the open device it. The
return value has the following meaning:
+o 0: the command passed the test and can be successfully
executed by ``comedi_command()''. The one exception to this rule
is that the test will allow a NULL chanlist for the command.
+o 1: invalid trigger. One or more of the trigger sources (the *_src
members of the ``comedi_cmd'' structure) is not supported by the
driver.
+o 2: incompatible triggers. Two or more of the triggers selected are
incompatible with each other. For example, a driver might allow
either the scan_begin_src or the convert_src to be TRIG_TIMER, but
not both.
+o 3: argument invalid. One or more argument is invalid, for example
a timing argument might be in excess of the card's maximum speed.
The command test will correct the arguments by modifying the
command pointed at by cmd.
+o 4: argument fix up. The command underwent minor adjustment and
should now be valid. For example, a timing argument might not be
exactly achievable by the card so the timing argument will be
adjusted to the actual timing the card will use.
+o negative: some other error has occured.
See ``commands'' for more information.
Source: /lib/comedi.c
@ -1698,10 +1830,6 @@
+o comedi_cancel()
+o comedi_command()
+o comedi_command_test()
+o comedi_poll()
+o comedi_get_buffer_contents()