-<!doctype linuxdoc public "-//LinuxDoc//DTD LinuxDoc 96//EN">
+<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V3.1//EN"
+ "docbook/dtd/3.1/docbook.dtd" [
+<!ENTITY intro SYSTEM "intro.sgml">
+<!ENTITY install SYSTEM "install.sgml">
+<!ENTITY tutorial SYSTEM "tutorial.sgml">
+<!ENTITY other SYSTEM "other.sgml">
+<!ENTITY drivers SYSTEM "drivers.sgml">
+<!ENTITY reference SYSTEM "reference.sgml">
+<!ENTITY funcref SYSTEM "funcref.sgml">
+]>
<article>
-<title>Comedi Documentation
-<author>
-David Schleef <tt/ds@stm.lbl.gov/,
-Frank Hess <tt/fmhess@uiuc.edu/
+<artheader>
+ <title>
+ Comedi Documentation
+ </title>
+ <author>
+ <firstname>David</firstname>
+ <surname>Schleef</surname>
+ <affiliation>
+ <address>
+ ds@schleef.org
+ </address>
+ </affiliation>
+ </author>
+ <author>
+ <firstname>Frank</firstname>
+ <surname>Hess</surname>
+ <affiliation>
+ <address>
+ fmhess@uiuc.edu
+ </address>
+ </affiliation>
+ </author>
+</artheader>
+
+&intro
+
+&install
+
+&tutorial
+
+&other
+
+&drivers
+
+<section>
+ <title>
+ Comedi Reference
+ </title>
+ <para>
+ Reference for functions, macros, and constants.
+ </para>
+
+ &reference
+
+ &funcref
+
+</section>
-<sect>Introduction
-
-<p>
-This is preliminary documentation for Comedi and Comedilib.
-
-<sect>Installation and configuration
-<p>
-
-This section covers compiling, installing, and configuring
-comedi and comedlib.
-
-
-<sect1>Compiling and Installing
-<p>
-
-This section has not been written.
-
-<p>
-<sect1>Insmod'ding the kernel module
-<p>
-
-This section has not been written.
-
-<p>
-<sect1>Configuring comedi for your hardware
-<p>
-
-
-I assume that your hardware device is in your computer, and that
-you know the relevant details about it, i.e., what kind of card
-it is, the I/O base, the IRQ, jumper settings related to input
-ranges, etc.
-
-To tell the comedi kernel module that you have a particular device, and
-some information about it, you will be running the <tt>comedi_config</tt>
-command. Perhaps you should read the man page now.
-
-In this tutorial, I will go through the process of configuring comedi
-for two devices, a National Instruments AT-MIO-16E-10
-and a Data Translation DT2821-F-8DI.
-
-The NI board is plug-and-play, and the man page tells me that I need
-to configure the PnP part of the board with isapnptools. The isapnptools
-package is a little cryptic, but the concepts are simple. Once I
-learned how to use it, I settled on a /etc/isapnp.conf file that
-contained the lines:
-
-
-<tscreen><verb>
-# ANSI string -->National Instruments, AT-MIO-16E-10<--
-(CONFIGURE NIC2400/10725401 (LD 0
- (IO 0 (BASE 0x0260))
- (INT 0 (IRQ 3 (MODE +E)))
-# (DMA 0 (CHANNEL 5))
-# (DMA 1 (CHANNEL 6))
- (ACT Y)
-))
-</verb></tscreen>
-
-
-It also contains a few lines about overall configuration and about my
-sound card. I found out after a bit of trial-and-error that the NI
-board does not always work with interrupts other than IRQ 3. YMMV.
-Currently, the driver doesn't use DMA, but it may in the future, so
-I commented out the DMA lines. It is a curious fact that the device
-ignores the IRQ and DMA information given here, however, I keep the
-information here to remind myself that the numbers aren't arbitrary.
-
-When I run comedi_config (as root, of course), I provide the same
-information. Since I want to have the board configured every time
-I boot, I put the line
-
-<tscreen><verb>
-/usr/sbin/comedi_config /dev/comedi0 atmio-E 0x260,3
-</verb></tscreen>
-
-into <tt>/etc/rc.d/rc.local</tt>. You can, of course, run this command at
-a command prompt. The man page tells me that the option list
-is supposed to be "(I/O base),(IRQ)", so I used the same numbers
-as I put in /etc/isapnp.conf, i.e., 0x260,3.
-
-For the Data Translation board, I need to have a list of the
-jumper settings. Fortunately, I wrote them all down in the
-manual -- I hope they are still correct. However, I had to
-open the case to figure out which board in the series I had.
-It is a DT2821-f-8di. The man page of comedi_config tells
-me that I need to know the I/O base, IRQ, DMA 1, DMA 2. However,
-since I wrote the driver, I know that it also recognizes the
-differential/single-ended and unipolar/bipolar jumpers. As always,
-the source is the final authority, and looking in module/dt282x.c
-tells me that the options list is interpreted as:
-
-<itemize>
-<item>I/O base
-<item>IRQ
-<item>1=differential, 0=single ended
-<item>ai 0=unipolar, 1=bipolar
-<item>ao0 0=unipolar, 1=bipolar
-<item>ao1 0=unipolar, 1=bipolar
-<item>dma1
-<item>dma2
-</itemize>
-
-(ai=analog input, ao=analog output.) From this, I decide that
-the appropriate options list is
-
-<tscreen><verb>
-0x200,4,,1,1,1
-</verb></tscreen>
-
-I left the differential/single-ended number blank, since the
-driver already knowns (from the board name), that it is
-differential. I also left the DMA numbers blank, since I
-don't want the driver to use DMA. (Don't want it to interfere
-with my sound card -- life is full of difficult choices.)
-Keep in mind that things commented in the source, but not in
-the documentation are about as likely to change as the weather,
-so I put good comments next to the following line when I put
-it in rc.local.
-
-<tscreen><verb>
-/usr/sbin/comedi_config /dev/comedi1 dt2821-f-8di 0x200,4,,1,1,1
-</verb></tscreen>
-
-So now I think that I have my boards configured correctly.
-Since data acquisition boards are not typically well-engineered,
-comedi sometimes can't figure out if the board is actually there.
-If it can't, it assumes you are right. Both of these boards
-are well-made, so comedi will give me an error message if it
-can't find them. The comedi kernel module, since it is a part
-of the kernel, prints messages to the kernel logs, which you
-can access through the command 'dmesg' or /var/log/messages.
-Here is a configuration failure (from dmesg):
-
-<tscreen><verb>
-comedi0: ni_E: 0x0200 can't find board
-</verb></tscreen>
-
-When it does work, I get:
-
-<tscreen><verb>
-comedi0: ni_E: 0x0260 at-mio-16e-10 ( irq = 3 )
-</verb></tscreen>
-
-Note that it also correctly identified my board.
-
-
-<p>
-<sect1>Getting information from comedi
-<p>
-
-
-So now that we have comedi talking to the hardware, we want to
-talk to comedi. Here's some pretty low-level information --
-it's sometimes useful for debugging:
-
-<p>
-
-<tscreen><verb>
-cat /proc/comedi
-</verb></tscreen>
-
-Right now, on my computer, this command gives:
-
-<tscreen><verb>
-comedi version 0.6.4
-format string
- 0: atmio-E at-mio-16e-10 7
- 1: dt282x dt2821-f-8di 4
-</verb></tscreen>
-
-This is a feature that is not well-developed yet. Basically, it
-currently tells you driver name, device name, and number of
-subdevices.
-
-In the <tt>demo/</tt> directory, there is a command called
-<tt>info</tt>, which provides information about each subdevice on the
-board. The output of it is rather long, since I have 7
-subdevices (4 or fewer is common for other boards.)
-Here's part of the output of the NI board (which
-is on <tt>/dev/comedi0</tt>.) ('demo/info /dev/comedi0')
-
-<tscreen><verb>
-overall info:
- version code: 0x000604
- driver name: atmio-E
- board name: at-mio-16e-10
- number of subdevices: 7
-subdevice 0:
- type: 1 (unknown)
- number of channels: 16
- max data value: 4095
-</verb>
-...
-</tscreen>
-
-The overall info gives information about the device -- basically
-the same information as /proc/comedi.
-
-This board has 7 subdevices. Devices are separated into
-subdevices that each have a distinct purpose -- e.g., analog
-input, analog output, digital input/output. This board also
-has an EEPROM and calibration DACs that are also subdevices.
-
-Subdevice 0 is the analog input subdevice. You would have
-known this from the 'type: 1 (unknown)' line, if I've updated
-demo/info recently, because it would say 'type: 1 (analog input)'
-instead. The other lines should be self-explanitory. Comedi
-has more information about the device, but demo/info doesn't
-currently display this.
-
-<p>
-<sect>Individual drivers
-<p>
-
-This section contains information that is specific to each
-hardware driver. The most current information about a driver
-is included in the comedi source.
-
-<sect1>National Instruments AT-MIO E series
-<p>
-
-
-<sect1>Data Translation
-<p>
-
-
-
-<sect>Writing programs that use comedi and comedilib
-<p>
-
-<sect1>Your first comedi program
-<p>
-
-This example requires a card that has analog or
-digital input. Right to the source:
-
-<tscreen><verb>
-#include <stdio.h> /* for printf() */
-#include <comedilib.h>
-
-int subdev = 0; /* change this to your input subdevice */
-int chan = 0; /* change this to your channel */
-int range = 0; /* more on this later */
-int aref = AREF_GROUND; /* more on this later */
-
-int main(int argc,char *argv[])
-{
- comedi_t *it;
- lsampl_t data;
-
- it=comedi_open("/dev/comedi0");
-
- comedi_data_read(it,subdev,chan,range,aref,&data);
-
- printf("%d\n",data);
-
- return 0;
-}
-</verb></tscreen>
-
-
-Should be understandable: open the device, get the data,
-print it out. This is basically the guts of <tt>demo/inp.c</tt>,
-without error checking or fancy options.
-Compile it using
-
-<tscreen><verb>
-cc tut1.c -lcomedi -o tut1
-</verb></tscreen>
-
-A few notes: The range variable tells comedi which gain
-to use when measuring an analog voltage. Since we don't
-know (yet) which numbers are valid, or what each means,
-we'll use 0, because it won't cause errors. Likewise with
-aref, which determines the analog reference used.
-
-
-<p>
-<sect1>Converting samples to voltages
-<p>
-
-If you selected an analog input subdevice, you probably noticed
-that the output of <tt>tut1</tt> 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 <bf>always</bf> unsigned,
-with 0 representing the lowest voltage of the ADC, and 4095
-the highest. Comedi compensates for
-anything else the manual for your device says. However,
-you probably prefer to have this number translated to
-a voltage. Naturally, as a good programmer, your first
-question is: "How do I do this in a device-independent
-manner?"
-
-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"
-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 different input/output ranges for different
-channels in a subdevice.)
-
-The largest sample value can be found using the function:
-
- comedi_get_maxdata()
-
-The number of available ranges can be found using the function:
-
- comedi_get_n_ranges()
-
-For each value of the range parameter for a particular
-subdevice/channel, you can get range information using the
-function:
-
- ptr=comedi_get_range(comedi_file,subdevice,channel,
- range)
-
-which returns a pointer to a comedi_range structure.
-The comedi_range structure looks like
-
-<p>
-<tscreen><verb>
-typedef struct{
- double min;
- double max;
- unsigned int unit;
-}comedi_range;
-</verb></tscreen>
-
-The structure element 'min' represents
-the voltage corresponding to comedi_data_read() returning 0,
-and 'max' represents comedi_data_read() returning 'maxdata',
-(i.e., 4095 for 12 bit A/C converters, 65535 for 16 bit,
-or, 1 for digital input -- more on this in a bit.) The
-'unit' entry tells you if min and
-max refer to voltage, current, etc.
-
-"Could it get easier?", you say. Well, yes. Use
-the function comedi_to_phys(), which converts data
-values to physical units. Call it using something like
-
-<tscreen><verb>
-volts=comedi_to_phys(it,data,range,maxdata);
-</verb></tscreen>
-
-and the opposite
-
-<tscreen><verb>
-data=comedi_from_phys(it,volts,range,maxdata);
-</verb></tscreen>
-
-
-<p>
-<sect1>Another section
-<p>
-
-
-In addition to providing low level routines for data
-access, the comedi library provides higher-level access,
-much like the standard C library provides fopen(), etc.
-as a high-level (and portable) alternative to the direct
-UNIX system calls open(), etc. Similarily to fopen(),
-we have comedi_open():
-
-<p>
-<tscreen><verb>
-file=comedi_open("/dev/comedi0");
-</verb></tscreen>
-
-where file is of type <tt>(comedi_t *)</tt>. This function
-calls <tt>open()</tt>, like we did explicitly in a previous
-section, but also fills the <tt>comedi_t</tt> structure with
-lots of goodies -- information that we will need to use
-soon.
-
-Specifically, we needed to know maxdata for a specific
-subdevice/channel. How about:
-
-<tscreen><verb>
-maxdata=comedi_get_maxdata(file,subdevice,channel);
-</verb></tscreen>
-
-Wow. How easy. And the range type?
-
-<tscreen><verb>
-range_type=comedi_get_rangetype(file,subdevice,channel);
-</verb></tscreen>
-
-Cool. Other information you need to know about a channel
-can be gotten in a similar way.
-
-
-
-<sect1>Your second comedi program
-<p>
-
-
-Actually, this is the first comedi program again, just
-that we've added what we've learned.
-
-
-<tscreen><verb>
-#include <stdio.h> /* for printf() */
-#include <comedi.h> /* also included by comedilib.h */
-#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 */
-int range = 0; /* more on this later */
-int aref = 0; /* more on this later */
-
-int main(int argc,char *argv[])
-{
- comedi_t *cf;
- int chan=0;
- lsampl_t data;
- int maxdata,rangetype;
- double volts;
-
- cf=comedi_open("/dev/comedi0");
-
- maxdata=comedi_get_maxdata(cf,subdev,chan);
-
- rangetype=comedi_get_rangetype(cf,subdev,chan);
-
- comedi_data_read(cf->fd,subdev,chan,range,aref,&data);
-
- volts=comedi_to_phys(data,rangetype,range,maxdata);
-
- printf("%d %g\n",data,volts);
-
- return 0;
-}
-</verb></tscreen>
-
-
-<p>
-<sect>Application-specific functions
-<p>
-
-<sect1>Digital Input/Output
-<p>
-
-Many boards supported by comedi have digital input and output
-channels. Some boards allow the direction of a channel to be
-specified in software.
-
-Comedi groups digital channels into subdevice, which is a group
-of digital channels that have the same characteristics. For
-example, digital output lines will be grouped into a digital
-output subdevice, bidirectional digital lines will be grouped
-into a digital I/O subdevice. Thus, there can be multiple
-digital subdevices on a particular board.
-
-Individual digital lines can be read and written using the
-functions
-
- <tt/comedi_dio_read(device,subdevice,channel,unsigned int *bit);/
- <tt/comedi_dio_write(device,subdevice,channel,unsigned int bit);/
-
-The direction of bidirectional lines can be configured using
-the function
-
- <tt/comedi_dio_config(device,subdevice,channel,unsigned int dir);/
-
-The parameter <tt/dir/ should be either COMEDI_INPUT or COMEDI_OUTPUT.
-Many digital I/O subdevices group channels into blocks for
-configuring direction. Changing one channel in a block changes
-the entire block.
-
-Multiple channels can be read and written simultaneously using the
-function
-
- <tt/comedi_dio_bitfield(device,subdevice,unsigned int write_mask,unsigned int *bits);/
-
-Each channel is assigned to a bit in the <tt/write_mask/ and <tt/bits/
-bitfield. If a bit in <tt/write_mask/ is set, the corresponding bit
-in <tt/*bits/ will be written to the corresponding digital output line.
-Each digital line is then read and placed into <tt/*bits/. The value
-of bits in <tt/*bits/ corresponding to digital output lines is
-undefined and device-specific. Channel 0 is the least significant
-bit in the bitfield; channel 31 is the most significant bit. Channels
-higher than 31 cannot be accessed using this method.
-
-
-<p>
-<sect1>Slowly-varying inputs
-<p>
-
-
-Sometimes, your input channels change slowly enough that
-you are able to average many sucessive input values to get a
-more accurate measurement of the actual value. In general,
-the more samples you average, the better your estimate
-gets, roughly by a factor of sqrt(number_of_samples).
-Obviously, there are limitations to this:
-
-<p>
-<itemize>
-<item>
-you are ultimately limited by "spurious free dynamic range"
-
-<item>
-you need to have _some_ noise on the input channel,
-otherwise you will be averaging the same number N times.
-
-<item>
-the more noise you have, the greater your SFDR, but it
-takes many more samples to compensate for the increased
-noise
-
-<item>
-if you feel the need to average samples for 2 seconds,
-your signal will need to be _very_ slowly-varying, i.e.,
-not varying more than your target uncertainty for the
-entire 2 seconds.
-
-</itemize>
-
-As you might have guessed, the comedi library has functions
-to help you in your quest to accurately measure slowly varying
-inputs. I use these functions to measure thermocouple voltages
--- actually, the library functions came from a section of code
-that was previously part of the thermocouple reading program.
-
-The comedi self-calibration utility also uses these functions.
-On some hardware, it is possible to tell it to measure an
-internal stable voltage reference, which is typically going
-to be very slowly varying -- on the kilosecond time scale
-or more. So it is reasonable to measure millions of samples,
-to get a very accurate measurement of the A/D converter output
-value that corresponds to the voltage reference. Sometimes,
-however, this is overkill, since there is no need to
-perform a part-per-million calibration to a standard that
-is only accurate to part-per-thousand.
-
-
-<p>
-<sect1>Commands
-<label id="command_section">
-<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 <ref id="comedi_cmd" name="comedi_cmd"> structure is
-used to control acquisition and query the capabilities of a device
-(see also <ref id="comedi_command" name="comedi_command()">,
-<ref id="comedi_command_test" name="comedi_command_test()">, and
-<ref id="comedi_get_cmd_src_mask" name="comedi_get_cmd_src_mask()">).
-
-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
-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.
-
-Each of these 5 types of events are caused by a triggering
-source, specified through the <tt/*_src/ members of the
-<ref id="comedi_cmd" name="comedi_cmd"> structure. The source types are:
-
-<itemize>
-<item>TRIG_NONE: don't ever cause an event
-<item>TRIG_NOW: cause event to occur immediately
-<item>TRIG_FOLLOW: see notes below
-<item>TRIG_TIME: cause event to occur at a particular time
-<item>TRIG_TIMER: cause event to occur repeatedly at a specific rate
-<item>TRIG_COUNT: cause event when count reaches specific value
-<item>TRIG_EXT: external signal causes event
-<item>TRIG_INT: internal signal causes event
-<item>TRIG_OTHER: driver-specific meaning
-</itemize>
-
-Not all triggers are applicable to all events. Supported triggers
-for specific events depend significantly on your particular
-device. The <ref id="comedi_get_cmd_src_mask" name="comedi_get_cmd_src_mask()">
-function is useful for determining what triggers a subdevice supports.
-
-For every trigger, there is a corresponding
-argument (the <tt/*_arg/ members of the <ref id="comedi_cmd" name="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 <tt/stop_src/. The argument for TRIG_NONE
-is reserved and should be set to 0.
-
-TRIG_NOW is most often used as a <tt/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 <tt/start_src/,
-it indicates a delay between issuing the command and the start of
-acquisition. Most drivers only support a delay of 0.
-
-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 <tt/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 <tt/start_src/ for analog
-output subdevices, it indicates that conversion of output samples
-should begin when samples are written to the buffer.
-
-TRIG_TIME is reserved for future use.
-
-TRIG_TIMER is most often used as a <tt/convert_src/, a <tt/scan_begin_src/, or
-both. It indicates that triggers should occur at a specific rate.
-The argument specifies the interval between triggers in nanoseconds.
-
-TRIG_COUNT is used for <tt/scan_end_src/ and <tt/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.
-
-TRIG_INT is typically used as a <tt/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.
-
-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.
-
-Ths <tt/subdev/ member of the <ref id="comedi_cmd" name="comedi_cmd">
-structure is the index of the subdevice the command is intended for. The
-<ref id="comedi_find_subdevice_by_type" name="comedi_find_subdevice_by_type()">
-function can be useful in discovering the index of your desired subdevice.
-
-The <tt/chanlist/ member of the <ref id="comedi_cmd" name="comedi_cmd">
-structure should point to an array whose number of elements is specificed by <tt/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 <ref id="CR_PACK" name="CR_PACK()"> macro.
-
-The <tt/data/ and <tt/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 <ref id="comedi_cmd" name="comedi_cmd"> structure is <tt/flags/.
-The following flags are valid, and can be bitwise-or'd together.
-
-<itemize>
-<item>TRIG_BOGUS: do the motions??
-<item>TRIG_DITHER: enable dithering??
-<item>TRIG_DEGLITCH: enable deglitching??
-<item>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.
-<item>TRIG_CONFIG: perform configuration, not triggering. This is a legacy of the
-deprecated comedi_trig_struct, and has no function at present.
-<item>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 high frequencies.
-<item>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.
-</itemize>
-There are also a few flags that indicate how timing arguments should be rounded
-if the hardware cannot achieve the exact timing requested.
-<itemize>
-<item>TRIG_ROUND_NEAREST: round to nearest supported timing period, the default.
-<item>TRIG_ROUND_DOWN: round period down.
-<item>TRIG_ROUND_UP: round period up.
-<item>TRIG_ROUND_UP_NEXT: this one doesn't do anything, and I don't know what it was intended
-to do??
-</itemize>
-
-<p>
-
-The typical sequence for executing a command is to first send
-the command through
-<ref id="comedi_command_test" name="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
-<ref id="comedi_command" name="comedi_command()">. For input/output commands, data
-is read from or written to the device file /dev/comedi[0..3] you are using.
-
-<sect>Libcomedi Reference
-<p>
-
-<sect1>Constants and Macros
-<p>
-
-<sect2>CR_PACK()
-<label id="CR_PACK">
-<p>
-
-<tt/CR_PACK(channel, range, aref)/
-
-<tt/CR_PACK/ is used to initialize the elements of the <tt/chanlist array/ in the
-<ref id="comedi_cmd" name="comedi_cmd"> structure, and the <tt/chanspec/ member
-of the <ref id="comedi_insn" name="comedi_insn"> structure.
-
-The <tt/channel/ argument is the channel you wish to use, with the channel numbering
-starting at zero.
-
-The <tt/range/ is an index, starting at zero, whose meaning
-is device dependent. The
-<ref id="comedi_get_n_ranges" name="comedi_get_n_ranges()"> and
-<ref id ="comedi_get_range" name = "comedi_get_range()"> functions
-are useful in discovering information about the available ranges.
-
-The <tt/aref/ argument indicates what reference you want the device to use. It
-can be any of the following:
-<itemize>
-<item>AREF_GROUND is for inputs/outputs referenced to ground
-<item>AREF_COMMON is for a `common' reference (the low inputs of all the channels are tied
-together, but are isolated from ground)
-<item>AREF_DIFF is for differential inputs/outputs
-<item>AREF_OTHER is for any reference that does not fit into the above categories
-</itemize>
-Particular drivers may or may not use the AREF flags. If they are not supported, they
-are silently ignored.
-
-<p>
-Source: <tt>/include/comedi.h</tt>
-
-
-<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>Source: <tt>/include/comedi.h</tt>
-
-<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 data type
-shorter than <tt/lsampl_t/ is useful. On most architectures, <tt/sampl_t/
-is defined to be <tt/uint16/.
-
-<p>
-Most drivers represent data trasferred by <tt/read()/ and <tt/write()/
-using <tt/sampl_t/. Applications should check the subdevice flag
-<tt/SDF_LSAMPL/ to determine if the subdevice uses <tt/sampl_t/ or
-<tt/lsampl_t/.
-
-<p>Source: <tt>/include/comedi.h</tt>
-
-<p>
-<sect2>lsampl_t
-<label id="lsampl_t">
-
-<p>
-The data type <tt/lsampl_t/ is the data type typically used to represent
-data values in libcomedi. On most architectures, <tt/lsampl_t/ is
-defined to be <tt/uint32/.
-
-
-<p>Source: <tt>/include/comedi.h</tt>
-
-<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>Source: <tt>/include/comedi.h</tt>
-
-<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>Source: <tt>comedilib.h</tt>
-
-<p>
-<sect2>comedi_cmd
-<label id="comedi_cmd">
-<p>
-
-<tscreen><verb>
-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;
-};
-</verb></tscreen>
-
-<p>
-More information on using commands can be found in the
-<ref id="command_section" name="command"> section.
-
-<p>Source: <tt>comedilib.h</tt>
-
-<p>
-<sect2>comedi_insn
-<label id="comedi_insn">
-<p>
-
-<tscreen><verb>
-typedef struct comedi_insn_struct comedi_insn;
-
-struct comedi_insn_struct{
- unsigned int insn;
- unsigned int n;
- lsampl_t *data;
- unsigned int subdev;
- unsigned int chanspec;
- unsigned int unused[3];
-};
-</verb></tscreen>
-
-<p>
-Comedi instructions are described by the <tt/comedi_insn/ structure.
-Applications send instructions to the driver in order to preform
-control and measurement operations that are done immediately or
-synchronously, i.e., the operations complete before program control
-returns to the application. In particular, instructions cannot
-describe acquisition that involves timers or external events.
-
-<p>
-The field <tt/insn/ determines the type of instruction that is sent
-to the driver. Valid instruction types are
-
-<itemize>
-<item>INSN_READ read values from an input channel
-<item>INSN_WRITE write values to an output channel
-<item>INSN_BITS read/write values on multiple digital I/O channels
-<item>INSN_CONFIG configure a subdevice
-<item>INSN_GTOD read a timestamp, identical to <tt/gettimeofday()/
-<item>INSN_WAIT wait a specified number of nanoseconds
-</itemize>
-
-<p>
-The number of samples to read or write, or the size of the configuration
-structure is specified by the field <tt/n/, and the buffer for those
-samples by <tt/data/. The field <tt/subdev/ is the subdevice index
-that the instruction is sent to. The field <tt/chanspec/ specifies
-the channel, range, and analog reference (if applicable).
-
-<p>
-Instructions can be sent to drivers using <tt/comedi_do_insn()/.
-Multiple instructions can be sent to drivers in the same system
-call using <tt/comedi_do_insnlist()/.
-
-<p>Source: <tt>comedi.h</tt>
-
-<p>
-<sect2>comedi_range
-<label id="comedi_range">
-<p>
-
-<tscreen><verb>
-typedef struct{
- double min;
- double max;
- unsigned int unit;
-}comedi_range;
-</verb></tscreen>
-
-<p>
-The <tt/comedi_range/ structure conveys part of the information
-necessary to translate sample values to physical units, in particular,
-the endpoints of the range and the physical unit type. The
-physical unit type is specified by the field <tt/unit/, which may
-take the values <tt/UNIT_volt/ for volts, <tt/UNIT_mA/ for milliamps,
-or <tt/UNIT_none/ for unitless. The endpoints are specified by
-the fields <tt/min/ and <tt/max/.
-
-<p>
-XXX RF_EXTERNAL
-
-<p>Source: <tt>comedilib.h</tt>
-
-
-<p>
-<sect2>comedi_krange
-<label id="comedi_krange">
-<p>
-
-<tscreen><verb>
-struct comedi_krange_struct{
- int min;
- int max;
- unsigned int flags;
-};
-</verb></tscreen>
-
-<p>
-The <tt/comedi_krange/ structure is used to transfer range information
-between the driver and Comedilib, and should not normally be used
-by applications. The structure conveys the same information as the
-<tt/comedi_range/ structure, except the fields <tt/min/ and <tt/max/
-are integers, multiplied by a factor of 1000000 compared to the
-counterparts in <tt/comedi_range/.
-
-<p>Source: <tt>comedi.h</tt>
-
-<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_command()
-<label id="comedi_command">
-<p>
-
-<tt>int comedi_command(comedi_t *it, comedi_cmd *cmd);</tt>
-<p>
-Issues the command pointed at by <tt/cmd/ to the open device <tt/it/. It
-is usually necessary to pass the command through
-<ref id="comedi_command_test" name="comedi_command_test()"> to
-fix up the command before it can be successfully executed with
-<tt/comedi_command()/.
-See
-<ref id="command_section" name="commands"> for more information.
-
-<p>
-Source: <tt>/lib/comedi.c</tt>
-
-
-<sect2>comedi_command_test()
-<label id="comedi_command_test">
-<p>
-
-<tt>int comedi_command_test(comedi_t *it, comedi_cmd *cmd);</tt>
-<p>
-
-Tests and fixes up the command pointed at by <tt/cmd/ according
-to the limitations of the driver configured on the open device <tt/it/.
-The return value has the following meaning:
-<itemize>
-<item>0: the command passed the test and can be successfully executed
- by <ref id="comedi_command" name="comedi_command()">. The one exception
- to this rule is that the test will allow a NULL chanlist for the command.
-<item>1: invalid trigger. One or more of the trigger sources (the *_src members
- of the <ref id="comedi_cmd" name="comedi_cmd"> structure) is not
- supported by the driver.
-<item>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.
-<item>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 <tt/cmd/.
-<item>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.
-<item>negative: some other error has occured.
-</itemize>
-See
-<ref id="command_section" name="commands"> for more information.
-
-<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>
-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 <tt/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>
-This function is equivalent to <tt/comedi_data_write(it,subd,chan,0,0,bit)/.
-
-<p>
-Source: <tt>/lib/dio.c</tt>
-
-<p>
-<sect2>comedi_fileno()
-<p>
-
-<tt/int comedi_fileno(comedi_t *dev);/
-<p>
-
-The function <tt/comedi_fileno/
-returns the integer descriptor for the device <tt/dev/. It
-is functionally similar to the standard C library function
-<tt/fileno()/. If <tt>dev</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 a matching range is found, the index of the matching range is
-returned. If no matching range is available, the function 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()
-<label id="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>
-
-
-<sect2>comedi_get_cmd_src_mask()
-<label id="comedi_get_cmd_src_mask">
-<p>
-
-<tt>int comedi_get_cmd_src_mask(comedi_t *dev, unsigned int subdevice,
-comedi_cmd *cmd);</tt>
-
-undocumented
-
-Source: <tt>/lib/cmd.c</tt>
-
-
-<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()
-<label id="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()
-<label id="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_poll()
-<item>comedi_get_buffer_contents()
-<item>comedi_mark_buffer_read()
-<item>comedi_get_buffer_offset()
-<item>comedi_set_global_oor_behavior()
-</itemize>
-
-
-<sect>Interface reference
-
-<p>
-This chapter is meant to be a reference for some of the advanced
-features of Comedi.
-
-<sect1>Digital input combining machines
-
-<p>
-When one or several digital inputs are used to modify an output
-value, either an accumulator or a single digital line or bit,
-a bitfield structure is typically used in the Comedi interface.
-The digital inputs have two properties, "sensitive" inputs and
-"modifier" inputs. Edge transitions on sensitive inputs cause
-changes in the output signal, whereas modifier inputs change the
-effect of edge transitions on sensitive inputs. Note that inputs
-can be both modifier inputs and sensitive inputs.
-
-<p>
-For simplification purposes, it is assumed that multiple digital
-inputs do not change simultaneously.
-
-<p>
-The combined state of the modifier inputs determine a modifier
-state. For each combination of modifier state and sensitive
-input, there is a set of bits that determine the effect on the
-output value due to positive or negative transitions of the
-sensitive input. For each transition direction, there are two
-bits defined as follows:
-
-<itemize>
-<item>00 - transition is ignored
-<item>01 - accumulator is incremented, or output is set
-<item>10 - accumulator is decremented, or output is cleared
-<item>11 - reserved
-</itemize>
-
-<p>
-For example, a simple digital follower is specified by the bit
-pattern 01 10, because it sets the output on positive transitions
-of the input, and clears the output on negative transitions. A
-digital inverter is similarily 10 01. These systems have only
-one sensitive input.
-
-<p>
-As another example, a simple up counter, which increments on
-positive transitions of one input, is specified by 01 00. This
-system has only one sensitive input.
-
-<p>
-When multiple digital inputs are used, the inputs are divided
-into two types, inputs which cause changes in the accumulator, and
-those that only modify the meaning of transitions on other inputs.
-Modifier inputs do not require bitfields, but there needs to be
-a bitfield of length 4*(2^(N-1)) for each edge sensitive input,
-where N is the total number of inputs. Since N is usually 2 or
-3, with only one edge sensitive input, the scaling issues are
-not significant.
-
-
-
-<sect1>INSN_CONFIG
-
-<p>
-Configuration instructions are used to access device and driver features
-that do not fit well into other parts of the Comedi interface. This
-includes changing the direction of configurable digital I/O lines,
-configuring complex triggering engines, and counter/timer configuration.
-
-<p>
-If a specified ID is not supported, the driver must return -EINVAL.
-
-
-<sect2>Digital I/O configuration
-
-<p>Status: Implemented
-<p>ID: COMEDI_INPUT, COMEDI_OUTPUT, COMEDI_OPENDRAIN
-<p>Length: 1
-<p>Chanspec: used to specify channel
-
-<p>
-These IDs are used to configure direction of digital I/O lines.
-Direction is chosen by the ID. On typical devices, multiple
-channels are grouped together in blocks for determining direction.
-Configuring one channel in a block configures the entire block.
-
-<p>
-There should also be a method to read the configuration.
-
-<p>
-Errors: Should return -EINVAL if the ID is not supported.
-
-
-<sect2>Analog conversion configuration
-
-<p>Status: design
-<p>ID: not assigned
-<p>Length:
-<p>Chanspec: used to specify channel
-
-<p>Description:
-<p>
-Some devices have the capability to add white noise (dithering) to
-analog input measurement. This additional noise can then be averaged
-out, to get a more accurate measurement of the input signal. It
-should not be assumed that channels can be separately configured.
-A simple design can use 1 bit to turn this feature on/off.
-
-<p>
-Some devices have the capability of changing the glitch characteristics
-of analog output subsytems. The default (off) case should be where
-the average settling time is lowest. A simple design can use 1 bit
-to turn this feature on/off.
-
-<p>
-Some devices have a configurable analog filters as part of the analog
-input stage. A simple designe can use 1 bit to enable/disable the
-filter. Default is disabled, i.e., the filter being bypassed, or if
-the choice is between two filters, the filter with the largest
-bandwidth.
-
-
-
-<sect2>Analog Output Waveform Generation
-
-<p>Status: design
-<p>ID: not assigned
-<p>Length:
-<p>Chanspec: ignored
-
-<p>
-Some devices have the ability to cyclicly loop through samples kept in
-an on-board analog output FIFO. This config should allow the user to
-enable/disable this mode.
-
-<p>
-This config should allow the user to configure the number of samples
-to loop through. It may be necessary to configure the channels used.
-
-
-<sect2>Extended Triggering
-
-<p>Status: alpha
-<p>ID: not assigned
-<p>Chanspec: ignored
-
-<p>
-This section covers common information for all extended
-triggering configuration, and doesn't describe a particular
-type of extended trigger.
-
-<p>
-Extended triggering is used to configure triggering engines that
-do not fit into commands. In a typical programming sequence, the
-application will use configuration instructions to configure an
-extended trigger, and the issue a command, specifying TRIG_OTHER
-as one of the trigger sources.
-
-<p>
-Extended trigger configuration should be designed in such a way
-that the user can probe for valid parameters, similar to how
-command testing works. An extended trigger config instruction
-should not configure the hardware directly, rather, the configuration
-should be saved until the subsequent command is issued. This
-allows more flexibility for future interface changes.
-
-<p>
-It has not been decided whether the config stage should return a
-token that is then used as the trigger argument in the command.
-Using tokens is one method to satisfy the problem that extended
-trigger configurations may have subtle compatiblity issues with
-other trigger sources/arguments that can only be determined at
-command test time. Passing all stages of a command test should
-only be allowed with a properly configured extended trigger.
-
-<p>
-Extended triggers must use data[1] as flags. The upper 16 bits
-are reserved and used only for flags that are common to
-all extended triggers. The lower 16 bits may be defined by the
-particular type of extended trigger.
-
-<p>
-Various types of extended triggers must use data[1] to know which
-event the extended trigger will be assigned to in the command
-structure. The possible values are an OR'd mask of the following:
-
-<itemize>
-<item>COMEDI_EV_START
-<item>COMEDI_EV_SCAN_BEGIN
-<item>COMEDI_EV_CONVERT
-<item>COMEDI_EV_SCAN_END
-<item>COMEDI_EV_STOP
-</itemize>
-
-
-
-<sect2>Analog Triggering
-
-<p>Status: alpha
-<p>ID: not assigned
-<p>Implementation: ni_mio_common
-<p>Chanspec: ignored
-
-<itemize>
-<item>data 1 - trigger and combining machine configuration
-<item>data 2 - analog triggering signal chanspec
-<item>data 3 - primary analog level
-<item>data 4 - secondary analog level
-</itemize>
-
-<p>
-Analog triggering is described by a digital combining machine that
-has two sensitive digital inputs. The sensitive digital inputs are
-generated by configurable analog comparators. The analog comparators
-generate a digital 1 when the analog triggering signal is greater
-than the comparator level. The digital inputs are not modifier
-inputs. Note, however, there is an effective modifier due to the
-restriction that the primary analog comparator level must be less
-than the secondary analog comparator level.
-
-<p>
-If only one analog comparator signal is used, the combining machine
-for the secondary input should be set to ignored, and the secondary
-analog level should be set to 0.
-
-<p>
-The interpretation of the chanspec and voltage levels is device
-dependent, but should correspond to similar values of the analog
-input subdevice, if possible.
-
-<p>
-Notes: Reading range information is not addressed. This makes it
-difficult to convert comparator voltages to data values.
-
-<p>
-Possible extensions: A parameter that specifies the necessary time
-that the set condition has to be true before the trigger is generated.
-A parameter that specifies the necessary time that the reset condition
-has to be true before the state machine is reset.
-
-
-<sect2>Bitfield Pattern Matching Extended Trigger
-
-<p>Status: design
-<p>ID: not assigned
-<p>Chanspec: ignored
-
-<p>
-<itemize>
-<item>data 1 - trigger flags
-<item>data 2 - mask
-<item>data 3 - pattern
-</itemize>
-
-<p>
-The pattern matching trigger issues a trigger when all of a specifed
-set of input lines match a specified pattern. If the device allows,
-the input lines should correspond to the input lines of a digital input
-subdevice, however, this will necessarily be device dependent. Each
-possible digital line that can be matched is assigned a bit in the
-mask and pattern. A bit set in the mask indicates that the
-input line must match the corresponding bit in the pattern.
-A bit cleared in the mask indicates that the input line is ignored.
-
-<p>
-Notes: This only allows 32 bits in the pattern/mask, which may be
-too few. Devices may support selecting different sets of lines from
-which to match a pattern.
-
-<p>
-Discovery: The number of bits can be discovered by setting the mask
-to all 1's. The driver must modify this value and return -EAGAIN.
-
-
-<sect2>Counter configuration
-
-<p>Status: design
-<p>ID: not assigned
-<p>Chanspec: used to specify counter
-
-<p>
-<itemize>
-<item>data 1 - trigger configuration
-<item>data 2 - primary input chanspec
-<item>data 3 - primary combining machine configuration
-<item>data 4 - secondary input chanspec
-<item>data 5 - secondary combining machine configuration
-<item>data 6 - latch configuration
-</itemize>
-
-<p>
-Counters can be operated either in synchronous mode (using insn_read)
-or asynchronous mode (using commands), similar to analog input subdevices.
-The input signal for both modes is the accumulator.
-Commands on counter subdevices are almost always specified using
-scan_begin_src=TRIG_OTHER, with the counter configuration also serving
-as the extended configuration for the scan begin source.
-
-<p>
-Counters are made up of an accumulator and a combining machine that
-determines when the accumulator should be incremented or decremented
-based on the values of the input signals. The combining machine
-optionally determines when the accumulator should be latched and
-put into a buffer. This feature is used in asynchronous mode.
-
-
-<p>
-Notes: How to access multiple pieces of data acquired at each event?
-
-
-<sect2>One source plus auxiliary counter configuration
-
-<p>Status: design
-<p>ID: not assigned
-<p>Chanspec: ?
-
-<p>
-data[1] is flags, including the flags for the command triggering
-configuration. If a command is not subsequently issued on the
-subdevice, the command triggering portion of the flags are ignored.
-
-<p>
-data[2] determines the mode of operation. The mode of operation
-is actually a bitfield that encodes what to do for various
-transitions of the source signals.
-
-<p>
-data[3] and data[4] determine the primary source for the counter,
-similar to _src and _arg used in commands.
-
-
-<p>
-Notes: How to specify which events cause a latch and push, and what
-should get latched.
+++ /dev/null
-Driver: 8255.o
-Description: generic 8255 support
-Devices: [standard] 8255 (8255)
-Author: ds
-
-The classic in digital I/O. Three channels of 8 bit digital I/O,
-each channel is I/O configurable, channels 0 and 1 in 8 bit units,
-channel 2 in 4 bit units. The driver does not support modes 1 or 2
-yet, since I don't really understand how they would potentially be used.
-(Send me email if you want to use these modes.) If and when
-modes 1 and 2 are supported, there is a strong possibility that the
-3rd channel will be split into two 4-bit channels. (Refer to the
-8255 spec for clues as to why.)
-
-You should configure this driver if you plan to use a board that
-has an 8255 chip. For multifunction boards, the main driver will
-configure the 8255 subdevice automatically.
-
-This driver also works independently with ISA cards that directly
-map the 8255 registers to I/O ports, including cards with multiple
-8255 chips. To configure the driver for such a card, the option
-list should be a list of the I/O port bases for each of the 8255
-chips.
-
-
-
-Driver: adl_pci9118.o
-Description: Adlink PCI-9118DG, PCI-9118HG, PCI-9118HR
-Author: Michal Dobes <majkl@tesnet.cz>
-Devices: [ADLink] PCI-9118DG (pci9118dg), PCI-9118HG (pci9118hg),
- PCI-9118HR (pci9118hr)
-Status: works
-
-This driver supports AI, AO, DI and DO subdevices.
-AI subdevice supports cmd and insn interface,
-other subdevices support only insn interface.
-For AI:
-- If cmd->scan_begin_src=TRIG_EXT then trigger input is TGIN (pin 46).
-- If cmd->convert_src=TRIG_EXT then trigger input is EXTTRG (pin 44).
-- If cmd->start_src/stop_src=TRIG_EXT then trigger input is TGIN (pin 46).
-- It is not neccessary to have cmd.scan_end_arg=cmd.chanlist_len but
- cmd.scan_end_arg modulo cmd.chanlist_len must by 0.
-- If return value of cmdtest is 5 then you've bad channel list
- (it isn't possible mixture S.E. and DIFF inputs or bipolar and unipolar
- ranges).
-There is know problem with this driver:
-- If you use scan_begin_src=TRIG_EXT & convert_src=TRIG_TIMER
- then this mode sometimes discards some samples. :-((
-
-Configuration options:
- [0] - PCI bus of device (optional)
- [1] - PCI slot of device (optional)
- If bus/slot is not specified, the first available PCI
- device will be used.
-
-If you have an external multiplexer, the third option in the option
-list should be used to indicate the number of channels in the
-multiplexer.
-
-
-
-Driver: adv_pci1710.o
-Description: Advantech PCI-1710, PCI-1710HG, PCI-1711, PCI-1713,
- Advantech PCI-1720, PCI-1731
-Author: Michal Dobes <majkl@tesnet.cz>
-Devices: [Advantech] PCI-1710 (pci1710), PCI-1710HG (pci1710hg),
- PCI-1711 (pci1711), PCI-1713 (pci1713), PCI-1720 (pci1720),
- PCI-1731 (pci1731)
-Status: works
-
-This driver supports AI, AO, DI and DO subdevices.
-AI subdevice supports cmd and insn interface,
-other subdevices support only insn interface.
-
-The PCI-1710 and PCI-1710HG have the same PCI device ID, so the
-driver cannot distinguish between them, as would be normal for a
-PCI driver.
-
-Configuration options:
- [0] - PCI bus of device (optional)
- [1] - PCI slot of device (optional)
- If bus/slot is not specified, the first available PCI
- device will be used.
-
-
-
-Driver: amplc_pci230.o
-Description: Driver for Amplicom PCI230 and PCI260 Multifunction I/O boards
-Author: Allan Willcox <allanwillcox@ozemail.com.au>
-Updated: Mon, 3 Sep 2001 17:37:12 -0700
-Devices: [Amplicon] PCI230 (amplc_pci230), PCI260
-
-
-
-Driver: cb_pcidas.o
-Description: Driver for the ComputerBoards/MeasurementComputing cards
- of the PCI-DAS series with the AMCC S5933 PCI controller.
-Author: Ivan Martinez <ivanmr@altavista.com>,
- Frank Mori Hess <fmhess@uiuc.edu>
-Status:
- - PCI-DAS1602/16: Analog input is tested, works. Analog output untested.
- - PCI-DAS1602/16jr: Driver should work, but untested. Please
- report usage.
- - PCI-DAS1602/12: Same as above.
- - PCI-DAS1200, 1200jr: Tested, works.
- - PCI-DAS1000, 1001, 1002: Should work, but untested. Please report
- usage.
-
- The boards' autocalibration features are not yet supported.
-
-Updated: 2002-1-09
-Devices: [Measurement Computing] PCI-DAS1602/16 (cb_pcidas),
- PCI-DAS1602/16jr, PCI-DAS1602/12, PCI-DAS1200, PCI-DAS1200jr,
- PCI-DAS1000, PCI-DAS1001, PCI_DAS1002
-
-Configuration options:
- [0] - PCI bus of device (optional)
- [1] - PCI slot of device (optional)
- If bus/slot is not specified, the first available PCI
- device will be used.
-
-For commands, the scanned channels must be consecutive
-(i.e. 4-5-6-7, 2-3-4,...), and must all have the same
-range and aref.
-
-
-
-Driver: cb_pcidas64.o
-Description: Driver for the ComputerBoards/MeasurementComputing
- PCI-DAS64xxx series with the PLX 9080 PCI controller.
-Author: Frank Mori Hess <fmhess@uiuc.edu>
-Status: Experimental
-Updated: 2001-9-19
-Devices: [Measurement Computing] PCI-DAS6402/16 (cb_pcidas64),
- PCI-DAS6402/12, PCI-DAS64/M1/16, PCI-DAS64/M2/16,
- PCI-DAS64/M3/16, PCI-DAS6402/16/JR, PCI-DAS64/M1/16/JR,
- PCI-DAS64/M2/16/JR, PCI-DAS64/M3/16/JR, PCI-DAS64/M1/14,
- PCI-DAS64/M2/14, PCI-DAS64/M3/14
-Configuration options:
- [0] - PCI bus of device (optional)
- [1] - PCI slot of device (optional)
-
-Basic insn support should work, but untested as far as I know.
-Has command support for analog input, which may also work. Support
-for pci dma transfers can be enabled by editing the source to #define
-PCIDMA instead of #undef'ing it. This driver is in need of stout-hearted
-testers who aren't afraid to crash their computers in the name of progress.
-Feel free to send and success/failure reports to author.
-
-Some devices are not identified because the PCI device IDs are not known.
-
-
-
-Driver: cb_pcidda.o
-Description: ComputerBoards/MeasurementComputing PCI-DDA series
-Author: Ivan Martinez <ivanmr@altavista.com>, Frank Mori Hess <fmhess@users.sourceforge.net>
-Status: Supports 08/16, 04/16, 02/16, 08/12, 04/12, and 02/12
-Devices: [Measurement Computing] PCI-DDA08/12 (cb_pcidda), PCI-DDA04/12,
- PCI-DDA02/12, PCI-DDA08/16, PCI-DDA04/16, PCI-DDA02/16
-
-Configuration options:
- [0] - PCI bus of device (optional)
- [1] - PCI slot of device (optional)
- If bus/slot is not specified, the first available PCI
- device will be used.
-
-Only simple analog output writing is supported.
-
-SO FAR IT HAS ONLY BEEN TESTED WITH:
- - PCI-DDA08/12
-PLEASE REPORT IF YOU ARE USING IT WITH A DIFFERENT CARD
-<ivanmr@altavista.com>.
-
-
-
-Driver: comedi_parport.o
-Description: Standard PC parallel port
-Author: ds
-Status: works in immediate mode
-Devices: [standard] parallel port (comedi_parport)
-
-A cheap and easy way to get a few more digital I/O lines. Steal
-additional parallel ports from old computers or your neighbors'
-computers.
-
-Option list:
- 0: I/O port base for the parallel port.
- 1: IRQ
-
-Parallel Port Lines:
-
-pin subdev chan aka
---- ------ ---- ---
-1 2 0 strobe
-2 0 0 data 0
-3 0 1 data 1
-4 0 2 data 2
-5 0 3 data 3
-6 0 4 data 4
-7 0 5 data 5
-8 0 6 data 6
-9 0 7 data 7
-10 1 3 acknowledge
-11 1 4 busy
-12 1 2 output
-13 1 1 printer selected
-14 2 1 auto LF
-15 1 0 error
-16 2 2 init
-17 2 3 select printer
-18-25 ground
-
-Notes:
-
-Channel 0 and 2 are output, channel 1 is input. I know that it
-is possible to change this with ECP/EPP parallel ports, but this
-driver is a cheap hack.
-
-Pins 13 and 14 are inverted once by comedi and once by the
-hardware, thus cancelling the effect.
-
-Pin 1 is a strobe, thus acts like one. There's no way in software
-to change this, at least on a standard parallel port.
-
-Subdevice 3 pretends to be a digital input subdevice, but it always
-returns 0 when read. However, if you run a command with
-scan_begin_src=TRIG_EXT, it uses pin 13 as a external triggering
-pin, which can be used to wake up tasks. (or is that pin 10. --ds)
-
-
-
-Driver: comedi_rt_timer.o
-Description: Command emulator using real-time tasks
-Authors: ds, fmhess
-Devices:
-Status: works
-
-This driver requires RTAI or RTLinux to work correctly. It doesn't
-actually drive hardware directly, but calls other drivers and uses
-a real-time task to emulate commands for drivers and devices that
-are incapable of native commands. Thus, you can get accurately
-timed I/O on any device.
-
-Since the timing is all done in software, sampling jitter is much
-higher than with a device that has an on-board timer, and maximum
-sample rate is much lower.
-
-Configuration options:
- [0] - device index
- [1] - subdevice index
-
-
-
-Driver: daqboard2000.o
-Description: IOTech DAQBoard/2000
-Author: Anders Blomdell <anders.blomdell@control.lth.se>
-Status: works
-Devices: [IOTech] DAQBoard/2000 (daqboard2000)
-
-Much of the functionality of this driver was determined from reading
-the source code for the Windows driver.
-
-The FPGA on the board requires initialization code, which can either
-be compiled into the driver or loaded by comedi_config using the -i
-option. The latter is recommended, in order to save a bit of kernel
-memory.
-
-Configuration options:
- [0] - pointer to FPGA initialization data
- The pointer and size options are handled automatically
- by comedi_config when you use the -i option.
- [1] - size of FPGA data
-
-
-
-Driver: das08.o
-Description: DAS-08 compatible boards
-Authors: Warren Jasper, ds, Frank Hess
-Devices: [ComputerBoards] DAS08 (das08), DAS08-PGM (das08-pgm),
- DAS08-PGH (das08-pgh), DAS08-PGL (das08-pgl), DAS08-AOH (das08-aoh),
- DAS08-AOL (das08-aol), DAS08-AOM (das08-aom), DAS08/JR-AO (das08/jr-ao),
- DAS08/JR-16-AO (das08jr-16-ao), PCI-DAS08 (pci-das08), PCM-DAS08 (pcm-das08),
- PC104-DAS08 (pc104-das08), DAS08/JR/16 (das08jr/16)
-Status: works
-
-This is a rewrite of the das08 and das08jr drivers.
-
-Options (for ISA cards):
- [0] - base io address
-
-Options (for pci-das08):
- [0] - bus (optional)
- [1] = slot (optional)
-Use the name 'pci-das08' for the pci-das08, NOT 'das08'.
-
-Options (for pcm-das08):
- NONE
-
-The das08 driver doesn't support asynchronous commands, since
-the cheap das08 hardware doesn't really support them (except for
-pcm-das08). The
-comedi_rt_timer driver can be used to emulate commands for this
-driver.
-
-
-
-Driver: das16.o
-Description: DAS16 compatible boards
-Authors: Sam Moore, Warren Jasper, ds, Chris Baugher, Frank Hess
-Devices: [Keithley Metrabyte] DAS-16 (das-16), DAS-16G (das-16g),
- DAS-16F (das-16f), DAS-1201 (das-1201), DAS-1202 (das-1202),
- DAS-1401 (das-1401), DAS-1402 (das-1402), DAS-1601 (das-1601),
- DAS-1602 (das-1602),
- [ComputerBoards] PC104-DAS16/JR (pc104-das16jr),
- PC104-DAS16JR/16 (pc104-das16jr/16),
- CIO-DAS16/JR (cio-das16/jr), CIO-DAS1401/12 (cio-das1401/12),
- CIO-DAS1402/12 (cio-das1402/12), CIO-DAS1402/16 (cio-das1402/16),
- CIO-DAS1601/12 (cio-das1601/12), CIO-DAS1602/12 (cio-das1602/12),
- CIO-DAS1602/16 (cio-das1602/16), CIO-DAS16/330 (cio-das16/330)
-Status: works in das16 mode, das-1600 enhanced mode features untested.
-Updated: 2001-8-27
-
-A rewrite of the das16 and das1600 drivers.
-Options:
- [0] - base io address
- [1] - irq (optional)
- [2] - dma (optional)
- [3] - master clock speed in MHz (optional, 1 or 10, ignored if
- board can probe clock, defaults to 1)
- [4] - analog input range lowest voltage in microvolts (optional,
- only useful if your board does not have software
- programmable gain)
- [5] - analog input range highest voltage in microvolts (optional,
- only useful if board does not have software programmable
- gain)
- [6] - analog output range lowest voltage in microvolts (optional)
- [7] - analog output range highest voltage in microvolts (optional)
-
-Passing a zero for an option is the same as leaving it unspecified.
-
-Both an irq line and dma channel are required for timed or externally
-triggered conversions.
-
-
-
-Driver: das16m1.o
-Description: CIO-DAS16/M1
-Authors: Frank Mori Hess <fmhess@uiuc.edu>
-Devices: [MeasurementComputing] CIO-DAS16/M1 (cio-das16/m1)
-Status: works
-
-This driver supports a single board - the CIO-DAS16/M1.
-As far as I know, there are no other boards that have
-the same register layout. Even the CIO-DAS16/M1/16 is
-significantly different.
-
-I was _barely_ able to reach the full 1 MHz capability
-of this board, using a hard real-time interrupt
-(set the TRIG_RT flag in your comedi_cmd and use
-rtlinux or RTAI). The board can't do dma, so the bottleneck is
-pulling the data across the ISA bus. I timed the interrupt
-handler, and it took my computer ~470 microseconds to pull 512
-samples from the board. So at 1 Mhz sampling rate,
-expect your CPU to be spending almost all of its
-time in the interrupt handler.
-
-This board has some unusual restrictions for its channel/gain list. If the
-list has 2 or more channels in it, then two conditions must be satisfied:
-(1) - even/odd channels must appear at even/odd indices in the list
-(2) - the list must have an even number of entries.
-
-Options:
- [0] - base io address
- [1] - irq (optional, but you probably want it)
-
-irq can be omitted, although the cmd interface will not work without it.
-
-
-
-Driver: das1800.o
-Description: Keithley Metrabyte DAS1800 (& compatibles)
-Author: Frank Mori Hess <fmhess@uiuc.edu>
-Devices: [Keithley Metrabyte] DAS-1701ST (das-1701st),
- DAS-1701ST-DA (das-1701st-da), DAS-1701/AO (das-1701ao),
- DAS-1702ST (das-1702st), DAS-1702ST-DA (das-1702st-da),
- DAS-1702HR (das-1702hr), DAS-1702HR-DA (das-1702hr-da),
- DAS-1702/AO (das-1702ao), DAS-1801ST (das-1801st),
- DAS-1801ST-DA (das-1801st-da), DAS-1801HC (das-1801hc),
- DAS-1801AO (das-1801ao), DAS-1802ST (das-1802st),
- DAS-1802ST-DA (das-1802st-da), DAS-1802HR (das-1802hr),
- DAS-1802HR-DA (das-1802hr-da), DAS-1802HC (das-1802hc),
- DAS-1802AO (das-1802ao)
-Status: works
-
-The waveform analog output on the 'ao' cards is not supported.
-If you need it, send me (Frank Hess) an email.
-
-Configuration options:
- [0] - I/O port base address
- [1] - IRQ (optional, required for timed or externally triggered conversions)
- [2] - DMA0 (optional, requires irq)
- [3] - DMA1 (optional, requires irq and dma0)
-
-
-
-Driver: das6402.o
-Description: Keithley Metrabyte DAS6402 (& compatibles)
-Author: Oystein Svendsen <svendsen@pvv.org>
-Status: unknown
-Devices: [Keithley Metrabyte] DAS6402 (das6402)
-
-
-
-Driver: das800.o
-Description: Keithley Metrabyte DAS800 (& compatibles)
-Author: Frank Mori Hess <fmhess@uiuc.edu>
-Devices: [Keithley Metrabyte] DAS-800 (das-800), DAS-801 (das-801),
- DAS-802 (das-802),
- [Measurement Computing] CIO-DAS800 (cio-das800),
- CIO-DAS801 (cio-das801), CIO-DAS802 (cio-das802),
- CIO-DAS802/16 (cio-das802/16)
-Status: works, cio-das802/16 untested - email me if you have tested it
-
-Configuration options:
- [0] - I/O port base address
- [1] - IRQ (optional, required for timed or externally triggered conversions)
-
-
-
-Driver: dt2801.o
-Description: Data Translation DT2801 series and DT01-EZ
-Author: ds
-Status: works
-Devices: [Data Translation] DT2801 (dt2801), DT2801-A, DT2801/5716A,
- DT2805, DT2805/5716A, DT2808, DT2818, DT2809, DT01-EZ
-
-This driver can autoprobe the type of board.
-
-Configuration options:
- [0] - I/O port base address
- [1] - unused
- [2] - A/D reference 0=differential, 1=single-ended
- [3] - A/D range
- 0 = [-10,10]
- 1 = [0,10]
- [4] - D/A 0 range
- 0 = [-10,10]
- 1 = [-5,5]
- 2 = [-2.5,2.5]
- 3 = [0,10]
- 4 = [0,5]
- [5] - D/A 1 range (same choices)
-
-
-
-Driver: dt2811.o
-Description: Data Translation DT2811
-Author: ds
-Devices: [Data Translation] DT2811-PGL (dt2811-pgl), DT2811-PGH (dt2811-pgh)
-Status: works
-
-Configuration options:
- [0] - I/O port base address
- [1] - IRQ, although this is currently unused
- [2] - A/D reference
- 0 = signle-ended
- 1 = differential
- 2 = pseudo-differential (common reference)
- [3] - A/D range
- 0 = [-5,5]
- 1 = [-2.5,2.5]
- 2 = [0,5]
- [4] - D/A 0 range (same choices)
- [4] - D/A 1 range (same choices)
-
-
-
-Driver: dt2814.o
-Description: Data Translation DT2814
-Author: ds
-Status: complete
-Devices: [Data Translation] DT2814 (dt2814)
-
-Configuration options:
- [0] - I/O port base address
- [1] - IRQ
-
-This card has 16 analog inputs multiplexed onto a 12 bit ADC. There
-is a minimally useful onboard clock. The base frequency for the
-clock is selected by jumpers, and the clock divider can be selected
-via programmed I/O. Unfortunately, the clock divider can only be
-a power of 10, from 1 to 10^7, of which only 3 or 4 are useful. In
-addition, the clock does not seem to be very accurate.
-
-
-
-Driver: dt2815.o
-Description: Data Translation DT2815
-Author: ds
-Status: mostly complete, untested
-Devices: [Data Translation] DT2815 (dt2815)
-
-I'm not sure anyone has ever tested this board. If you have information
-contrary, please update.
-
-Configuration options:
- [0] - I/O port base base address
- [1] - IRQ (unused)
- [2] - Voltage unipolar/bipolar configuration
- 0 == unipolar 5V (0V -- +5V)
- 1 == bipolar 5V (-5V -- +5V)
- [3] - Current offset configuration
- 0 == disabled (0mA -- +32mAV)
- 1 == enabled (+4mA -- +20mAV)
- [4] - Firmware program configuration
- 0 == program 1 (see manual table 5-4)
- 1 == program 2 (see manual table 5-4)
- 2 == program 3 (see manual table 5-4)
- 3 == program 4 (see manual table 5-4)
- [5] - Analog output 0 range configuration
- 0 == voltage
- 1 == current
- [6] - Analog output 1 range configuration (same options)
- [7] - Analog output 2 range configuration (same options)
- [8] - Analog output 3 range configuration (same options)
- [9] - Analog output 4 range configuration (same options)
- [10] - Analog output 5 range configuration (same options)
- [11] - Analog output 6 range configuration (same options)
- [12] - Analog output 7 range configuration (same options)
-
-
-
-Driver: dt2817.o
-Description: Data Translation DT2817
-Author: ds
-Status: complete
-Devices: [Data Translation] DT2817 (dt2817)
-
-A very simple digital I/O card. Four banks of 8 lines, each bank
-is configurable for input or output. One wonders why it takes a
-50 page manual to describe this thing.
-
-The driver (which, btw, is much less than 50 pages) has 1 subdevice
-with 32 channels, configurable in groups of 8.
-
-Configuration options:
- [0] - I/O port base base address
-
-
-
-Driver: dt282x.o
-Description: Data Translation DT2821 series (including DT-EZ)
-Author: ds
-Devices: [Data Translation] DT2821 (dt2821), DT2823 (dt2823),
- DT2824-PGH (dt2824-pgh), DT2824-PGL (dt2824-pgl), DT2825 (dt2825),
- DT2827 (dt2827), DT2828 (dt2828), DT21-EZ (dt21-ez), DT23-EZ (dt23-ez),
- DT24-EZ (dt24-ez), DT24-EZ-PGL (dt24-ez-pgl)
-Status: complete
-Updated: Wed, 22 Aug 2001 17:11:34 -0700
-
-Configuration options:
- [0] - I/O port base address
- [1] - IRQ
- [2] - DMA 1
- [3] - DMA 2
- [4] - AI jumpered for 0=single ended, 1=differential
- [5] - AI jumpered for 0=straight binary, 1=2's complement
- [6] - AO 0 jumpered for 0=straight binary, 1=2's complement
- [7] - AO 1 jumpered for 0=straight binary, 1=2's complement
- [8] - AI jumpered for 0=[-10,10]V, 1=[0,10], 2=[-5,5], 3=[0,5]
- [9] - AO 0 jumpered for 0=[-10,10]V, 1=[0,10], 2=[-5,5], 3=[0,5],
- 4=[-2.5,2.5]
- [10]- A0 1 jumpered for 0=[-10,10]V, 1=[0,10], 2=[-5,5], 3=[0,5],
- 4=[-2.5,2.5]
-
-Notes:
- - AO commands might be broken.
- - If you try to run a command on both the AI and AO subdevices
- simultaneously, bad things will happen. The driver needs to
- be fixed to check for this situation and return an error.
-
-
-
-Driver: dt3000.o
-Description: Data Translation DT3000 series
-Author: ds
-Devices: [Data Translation] DT3001 (dt3000), DT3001-PGL, DT3002, DT3003,
- DT3003-PGL, DT3004, DT3005, DT3004-200
-Status: untested
-
-
-
-Driver: fl512.o
-Description: unknown
-Author: unknown
-Devices: [unknown] FL512 (fl512)
-
-Digital I/O is not supported.
-
-Configuration options:
- [0] - I/O port base address
-
-
-
-Driver: icp_multi.o
-Description: Inova ICP Multi
-Author: Anne Smorthit <anne.smorthit@sfwte.ch>
-Devices: [Inova] ICP Multi (icp_multi)
-
-
-
-
-Driver: ii_pci20kc.o
-Description: Intelligent Instruments PCI-20001C carrier board
-Author: Markus Kempf <kempf@matsci.uni-sb.de>
-Devices: [Intelligent Instrumentation] PCI-20001C (ii_pci20kc)
-Status: works
-
-Supports the PCI-20001 C-2a Carrier board, and could probably support
-the other carrier boards with small modifications. Modules supported
-are:
- PCI-20006 M-2 16-bit analog output module
- PCI-20341 M-1A 16-bit analog input module
-
-Options:
- 0 Board base address
- 1 IRQ
- 2 first option for module 1
- 3 second option for module 1
- 4 first option for module 2
- 5 second option for module 2
- 6 first option for module 3
- 7 second option for module 3
-
-options for PCI-20006M:
- first: Analog output channel 0 range configuration
- 0 bipolar 10 (-10V -- +10V)
- 1 unipolar 10 (0V -- +10V)
- 2 bipolar 5 (-5V -- 5V)
- second: Analog output channel 1 range configuration
-
-options for PCI-20341M:
- first: Analog input gain configuration
- 0 1
- 1 10
- 2 100
- 3 200
-
-
-
-Driver: mpc8260cpm.o
-Description: MPC8260 CPM module generic digital I/O lines
-Devices: [Motorola] MPC8260 CPM (mpc8260cpm)
-Author: ds
-
-This driver is specific to the Motorola MPC8260 processor, allowing
-you to access the processor's generic digital I/O lines.
-
-
-
-Driver: multiq3.o
-Description: Quanser Consulting MultiQ-3
-Author: Anders Blomdell <anders.blomdell@control.lth.se>
-Status: works
-Devices: [Quanser Consulting] MultiQ-3 (multiq3)
-
-
-
-
-Driver: ni_670x.o
-Description: National Instruments 670x
-Author: Bart Joris <bjoris@advalvas.be>
-Updated: Wed, 22 Aug 2001 22:47:32 -0700
-Devices: [National Instruments] PCI-6703 (ni_670x), PCI-6704
-
-The driver currently does not recognize the 6704, because the PCI
-ID is not known.
-
-
-
-Driver: ni_at_a2150.o
-Description: National Instruments AT-A2150
-Author: Frank Mori Hess
-Status: works
-Devices: [National Instruments] AT-A2150C (at_a2150c), AT-2150S (at_a2150s)
-
-If you want to ac couple the board's inputs, use AREF_OTHER.
-
-Configuration options:
- [0] - I/O port base address
- [1] - IRQ (optional, required for timed conversions)
- [2] - DMA (optional, required for timed conversions)
-
-
-
-
-Driver: ni_atmio.o
-Description: National Instruments AT-MIO-E series
-Author: ds
-Devices: [National Instruments] AT-MIO-16E-1 (ni_atmio),
- AT-MIO-16E-2, AT-MIO-16E-10, AT-MIO-16DE-10, AT-MIO-64E-3,
- AT-MIO-16XE-50, AT-MIO-16XE-10, AT-AI-16XE-10
-
-The isapnptools package is required to use this board. Use isapnp to
-configure the I/O base for the board, and then pass the same value as
-a parameter in comedi_config. A sample isapnp.conf file is included
-in the etc/ directory.
-
-Assuming that the NI spec is correct, the driver should correctly
-identify every board in the series. Each channel should have the
-appropriate parameters, i.e., input/output ranges, number of bits,
-etc. If the driver fails to recognize your card or does not have
-the correct parameters, please contact me.
-
-Comedilib includes a utility to autocalibrate these boards. The
-boards seem to boot into a state where the all calibration DACs
-are at one extreme of their range, thus the default calibration
-is terrible. Calibration at boot is strongly encouraged.
-
-External triggering is supported for some events. The channel index
-(scan_begin_arg, etc.) maps to PFI0 - PFI9.
-
-
-
-Driver: ni_atmio16d.o
-Description: National Instruments AT-MIO-16D
-Author: Chris R. Baugher <baugher@enteract.com>
-Status: unknown
-Devices: [National Instruments] AT-MIO-16 (atmio16), AT-MIO-16D (atmio16d)
-
-
-
-Driver: ni_labpc.o
-Description: National Instruments Lab-PC (& compatibles)
-Author: Frank Mori Hess <fmhess@users.sourceforge.net>
-Devices: [National Instruments] DAQCard-1200 (daqcard-1200), Lab-PC-1200 (labpc-1200),
- Lab-PC-1200AI (labpc-1200ai), Lab-PC+ (lab-pc+), PCI-1200 (pci-1200)
-Status: Works (tested with lab-pc-1200). For the older Lab-PC+, not all input
- ranges and analog references will work, the available
- ranges/arefs will depend on how you have configured
- the jumpers on your board (see your owner's manual).
-
-Configuration options - ISA boards:
- [0] - I/O port base address
- [1] - IRQ (optional, required for timed or externally triggered conversions)
- [2] - DMA channel (optional)
-
-Configuration options - PCI boards:
- [0] - bus (optional)
- [1] - slot (optional)
-
-Configuration options - PCMCIA boards:
- none
-
-Lab-pc+ has quirky chanlist when scanning multiple channels. Scan sequence must start
-at highest channel, then decrement down to channel 0. 1200 series cards can scan down
-like lab-pc+ or scan up from channel zero.
-
-
-
-
-Driver: ni_mio_cs.o
-Description: National Instruments DAQCard E series
-Author: ds
-Status: works
-Devices: [National Instruments] DAQCard-AI-16XE-50 (ni_mio_cs),
- DAQCard-AI-16E-4, DAQCard-6062E, DAQCard-6024E
-
-See the notes in the ni_atmio.o driver.
-
-
-
-Driver: ni_pcidio.o
-Description: National Instruments PCI-DIO32HS, PCI-DIO96, PCI-6533, PCI-6503
-Author: ds
-Status: works in immediate mode
-Devices: [National Instruments] PCI-DIO-32HS (ni_pcidio), PXI-6533,
- PCI-DIO-96, PCI-DIO-96B, PXI-6508, PCI-6503, PCI-6503B, PCI-6503X,
- PXI-6503
-
-The DIO-96 appears as four 8255 subdevices. See the 8255
-driver notes for details.
-
-The DIO32HS board appears as one subdevice, with 32 channels.
-Each channel is individually I/O configurable. The channel order,
-as one might guess, is 0=A0, 1=A1, 2=A2, ... 8=B0, 16=C0, 24=D0.
-
-DMA is halfway completed, but not operational, for the PCI-DIO32HS.
-
-This driver could be easily modified to support AT-MIO32HS and
-AT-MIO96.
-
-
-
-Driver: ni_pcimio.o
-Description: National Instruments PCI-MIO-E series (all boards)
-Author: ds
-Status: mainly limited by Comedi infrastructure
-Devices: [National Instruments] PCI-MIO-16XE-50 (ni_pcimio),
- PCI-MIO-16XE-10, PXI-6030E, PCI-MIO-16E-1, PCI-MIO-16E-4, PCI-6040E,
- PXI-6040E, PCI-6031E, PCI-6032E, PCI-6033E, PCI-6071E, PCI-6023E,
- PCI-6024E, PCI-6025E, PXI-6025E, PCI-6034E, PCI-6035E, PCI-6052E,
- PCI-6110E, PCI-6111E, PCI-6711, PCI-6713, PXI-6071E, PXI-6070E,
- PXI-6052E, PCI-6036E
-
-These boards are almost identical to the AT-MIO E series, except that
-they use the PCI bus instead of ISA (i.e., AT). See the notes above for
-ni_atmio.o for additional information about these boards.
-
-Comedi knows the PCI ID codes for many of the boards in this series,
-but the NI documentation is incomplete in this matter. If you have
-a PCI-MIO board that Comedi doesn't recognize, send me the PCI device
-ID, as can be found in /proc/pci or the output of lspci. The vendor
-code for National Instruments is 0x1093. I will include the ID in
-the next version.
-
-DMA is halfway completed, but not yet operational.
-
-
-
-Driver: pcl711.o
-Description: Advantech PCL-711 and 711b, ADLink ACL-8112
-Authors: ds, Janne Jalkanen <jalkanen@cs.hut.fi>, Eric Bunn <ebu@cs.hut.fi>
-Status: mostly complete
-Devices: [Advantech] PCL-711 (pcl711), PCL-711B (pcl711b),
- [AdLink] ACL-8112HG (acl8112hg), ACL-8112DG (acl8112dg)
-
-Since these boards do not have DMA or FIFOs, only immediate mode is
-supported.
-
-
-
-
-Driver: pcl724.o
-Description: Advantech PCL-724, PCL-722, PCL-731 ADLink ACL-7122, ACL-7124,
- PET-48DIO
-Author: Michal Dobes <majkl@tesnet.cz>
-Devices: [Advantech] PCL-724 (pcl724), PCL-722 (pcl722), PCL-731 (pcl731),
- [ADLink] ACL-7122 (acl7122), ACL-7124 (acl7124), PET-48DIO (pet48dio)
-Status: untested
-
-This is driver for digital I/O boards PCL-722/724/731 with 144/24/48 DIO
-and for digital I/O boards ACL-7122/7124/PET-48DIO with 144/24/48 DIO.
-It need 8255.o for operations and only immediate mode is supported.
-See the source for configuration details.
-
-
-
-Driver: pcl725.o
-Description: Advantech PCL-725 (& compatibles)
-Author: ds
-Status: unknown
-Devices: [Advantech] PCL-725 (pcl725)
-
-
-
-Driver: pcl726.o
-Description: Advantech PCL-726 & compatibles
-Author: ds
-Status: untested
-Devices: [Advantech] PCL-726 (pcl726), PCL-727 (pcl727), PCL-728 (pcl728),
- [ADLink] ACL-6126 (acl6126), ACL-6128 (acl6128)
-
-Interrupts are not supported.
-
- Options for PCL-726:
- [0] - IO Base
- [2]...[7] - D/A output range for channel 1-6:
- 0: 0-5V, 1: 0-10V, 2: +/-5V, 3: +/-10V,
- 4: 4-20mA, 5: unknown (external reference)
-
- Options for PCL-727:
- [0] - IO Base
- [2]...[13] - D/A output range for channel 1-12:
- 0: 0-5V, 1: 0-10V, 2: +/-5V,
- 3: 4-20mA
-
- Options for PCL-728 and ACL-6128:
- [0] - IO Base
- [2], [3] - D/A output range for channel 1 and 2:
- 0: 0-5V, 1: 0-10V, 2: +/-5V, 3: +/-10V,
- 4: 4-20mA, 5: 0-20mA
-
- Options for ACL-6126:
- [0] - IO Base
- [1] - IRQ (0=disable, 3, 5, 6, 7, 9, 10, 11, 12, 15)
- [2]...[7] - D/A output range for channel 1-6:
- 0: 0-5V, 1: 0-10V, 2: +/-5V, 3: +/-10V,
- 4: 4-20mA
- NOTE: IRQ operations isn't now supported.
-
-
-
-Driver: pcl812.o
-Description: Advantech PCL-812/PG, PCL-813/B,
- ADLink ACL-8112DG/HG/PG, ACL-8113, ACL-8216,
- ICP DAS A-821PGH/PGL/PGL-NDA, A-822PGH/PGL, A-823PGH/PGL, A-826PG,
- ICP DAS ISO-813
-Author: Michal Dobes <majkl@tesnet.cz>
-Devices: [Advantech] PCL-812 (pcl812), PCL-812PG (pcl812pg),
- PCL-813 (pcl813), PCL-813B (pcl813b), [ADLink] ACL-8112DG (acl8112dg),
- ACL-8112HG (acl8112hg), ACL-8113 (acl-8113), ACL-8216 (acl8216),
- [ICP] ISO-813 (iso813), A-821PGH (a821pgh), A-821PGL (a821pgl),
- A-821PGL-NDA (a821pclnda), A-822PGH (a822pgh), A-822PGL (a822pgl),
- A-823PGH (a823pgh), A-823PGL (a823pgl), A-826PG (a826pg)
-Status: works (I hope. My board fire up under my hands
- and I cann't test all features.)
-
-This driver supports insn and cmd interfaces. Some boards support only insn
-becouse their hardware don't allow more (PCL-813/B, ACL-8113, ISO-813).
-Data transfer over DMA is supported only when you measure only one
-channel, this is too hardware limitation of these boards.
-See the head of the source file pcl812.c for configuration options.
-
-
-
-Driver: pcl818.o
-Description: Advantech PCL-818 cards, PCL-718
-Author: Michal Dobes <majkl@tesnet.cz>
-Devices: [Advantech] PCL-818L (pcl818l), PCL-818H (pcl818h),
- PCL-818HD (pcl818hd), PCL-818HG (pcl818hg), PCL-818 (pcl818),
- PCL-718 (pcl718)
-Status: works
-
-All cards have 16 SE/8 DIFF ADCs, one or two DACs, 16 DI and 16 DO.
-Differences are only at maximal sample speed, range list and FIFO
-support.
-The driver support AI mode 0, 1, 3 other subdevices (AO, DI, DO) support
-only mode 0. If DMA/FIFO/INT are disabled then AI support only mode 0.
-PCL-818HD and PCL-818HG support 1kword FIFO. Driver support this FIFO
-but this code is untested.
-A word or two about DMA. Driver support DMA operations at two ways:
-1) DMA uses two buffers and after one is filled then is generated
- INT and DMA restart with second buffer. With this mode I'm unable run
- more that 80Ksamples/secs without data dropouts on K6/233.
-2) DMA uses one buffer and run in autoinit mode and the data are
- from DMA buffer moved on the fly with 2kHz interrupts from RTC.
- This mode is used if the interrupt 8 is available for allocation.
- If not, then first DMA mode is used. With this I can run at
- full speed one card (100ksamples/secs) or two cards with
- 60ksamples/secs each (more is problem on account of ISA limitations).
- To use this mode you must have compiled kernel with disabled
- "Enhanced Real Time Clock Support".
- Maybe you can have problems if you use xntpd or similar.
- If you've data dropouts with DMA mode 2 then:
- a) disable IDE DMA
- b) switch text mode console to fb.
-See the head of the source file pcl818.c for configuration options.
-
-
-
-Driver: pcm3730.o
-Description: PCM3730
-Author: Blaine Lee
-Devices: [Advantech] PCM-3730 (pcm3730)
-
-Configuration options:
- [0] - I/O port base
-
-
-
-Driver: pcmad.o
-Description: Winsystems PCM-A/D12, PCM-A/D16
-Author: ds
-Devices: [Winsystems] PCM-A/D12 (pcmad12), PCM-A/D16 (pcmad16)
-Status: untested
-
-This driver was written on a bet that I couldn't write a driver
-in less than 2 hours. I won the bet, but never got paid. =(
-
-Configuration options:
- [0] - I/O port base
- [1] - unused
- [2] - Analog input reference
- 0 = single ended
- 1 = differential
- [3] - Analog input encoding (must match jumpers)
- 0 = straight binary
- 1 = two's complement
-
-
-
-Driver: poc.o
-Description: Generic driver for very simple devices
-Device names: dac02
-Author: ds
-Devices: [Keithley Metrabyte] DAC-02 (dac02)
-
-This driver is indended to support very simple ISA-based devices,
-including:
- dac02 - Keithley DAC-02 analog output board
-
-Configuration options:
- [0] - I/O port base
-
-
-
-Driver: quatech_daqp_cs.o
-Description: Quatech DAQP PCMCIA data capture cards
-Author: Brent Baccala <baccala@freesoft.org>
-Status: unkown
-Devices: [Quatech] DAQP-208 (daqp), DAQP-308
-
-
-
-Driver: rtd520.o
-Description: Real Time Devices PCI4520/DM7520
-Author: Dan Christian
-Devices: [Real Time Devices] DM7520HR-1 (DM7520), DM7520HR-8 (DM7520-8),
- PCI4520 (PCI4520), PCI4520-8 (PCI4520-8)
-
-Configuration options:
- [0] - PCI bus of device (optional)
- If bus/slot is not specified, the first available PCI
- device will be used.
- [1] - PCI slot of device (optional)
-
-
-
-Driver: rti800.o
-Description: Analog Devices RTI-800/815
-Author: ds
-Status: unknown
-Devices: [Analog Devices] RTI-800 (rti800), RTI-815 (rti815)
-
-Configuration options:
- [0] - I/O port base address
- [1] - IRQ
- [2] - A/D reference
- 0 = differential
- 1 = pseudodifferential (common)
- 2 = single-ended
- [3] - A/D range
- 0 = [-10,10]
- 1 = [-5,5]
- 2 = [0,10]
- [4] - A/D encoding
- 0 = two's complement
- 1 = straight binary
- [5] - DAC 0 range
- 0 = [-10,10]
- 1 = [0,10]
- [5] - DAC 0 encoding
- 0 = two's complement
- 1 = straight binary
- [6] - DAC 1 range (same as DAC 0)
- [7] - DAC 1 encoding (same as DAC 0)
-
-
-
-Driver: rti802.o
-Description: Analog Devices RTI-802
-Author: Anders Blomdell <anders.blomdell@control.lth.se>
-Devices: [Analog Devices] RTI-802 (rti802)
-Status: works
-
-
-
-Driver: skel.o
-Description: Skeleton driver, an example for driver writers
-Devices:
-Author: ds
-
-This driver is a documented example on how Comedi drivers are
-written.
-
-
-
-Driver: ssv_dnp.o
-Description: SSV Embedded Systems DIL/Net-PC
-Author: Robert Schwebel <robert@schwebel.de>
-Devices: [SSV Embedded Systems] DIL/Net-PC 1486 (dnp-1486)
-
-
-
+++ /dev/null
-
-Comedi tutorial
-
-0. Compiling and Installing
-0. Insmod'ding the kernel module
-0. Configuring comedi to use your hardware
-0. Getting information from comedi
-0. Your first comedi program
-0. Converting samples to voltages
-
-
-
-0. Compiling and Installing
-
-needs to be written
-
-
-
-
-0. Insmod'ding the kernel module
-
-needs to be written
-
-
-
-0. Configuring comedi to use your hardware
-
-
-I assume that your hardware device is in your computer, and that
-you know the relevant details about it, i.e., what kind of card
-it is, the I/O base, the IRQ, jumper settings related to input
-ranges, etc.
-
-To tell the comedi kernel module that you have a particular device, and
-some information about it, you will be running the 'comedi_config'
-command. Perhaps you should read the man page now.
-
-For this tutorial, I have two devices, a National Instruments AT-MIO-16E-10
-and a Data Translation DT2821-F-8DI.
-
-The NI board is plug-and-play, and the man page tells me that I need
-to configure the PnP part of the board with isapnptools. The isapnptools
-package is a little cryptic, but the concepts are simple. Once I
-learned how to use it, I settled on a /etc/isapnp.conf file that
-contained the lines:
-
-
-# ANSI string -->National Instruments, AT-MIO-16E-10<--
-(CONFIGURE NIC2400/10725401 (LD 0
- (IO 0 (BASE 0x0260))
- (INT 0 (IRQ 3 (MODE +E)))
-# (DMA 0 (CHANNEL 5))
-# (DMA 1 (CHANNEL 6))
- (ACT Y)
-))
-
-
-It also contains a few lines about overall configuration and about my
-sound card. I found out after a bit of trial-and-error that the NI
-board does not always work with interrupts other than IRQ 3. YMMV.
-Currently, the driver doesn't use DMA, but it may in the future, so
-I commented out the DMA lines. It is a curious fact that the device
-ignores the IRQ and DMA information given here, however, I keep the
-information here to remind myself that the numbers aren't arbitrary.
-
-When I run comedi_config (as root, of course), I provide the same
-information. Since I want to have the board configured every time
-I boot, I put the line
-
- /usr/sbin/comedi_config /dev/comedi0 atmio-E 0x260,3
-
-into /etc/rc.d/rc.local. You can, of course, run this command at
-a command prompt. The man page tells me that the option list
-is supposed to be "<I/O base>,<IRQ>", so I used the same numbers
-as I put in /etc/isapnp.conf, i.e., 0x260,3.
-
-For the Data Translation board, I need to have a list of the
-jumper settings. Fortunately, I wrote them all down in the
-manual -- I hope they are still correct. However, I had to
-open the case to figure out which board in the series I had.
-It is a DT2821-f-8di. The man page of comedi_config tells
-me that I need to know the I/O base, IRQ, DMA 1, DMA 2. However,
-since I wrote the driver, I know that it also recognizes the
-differential/single-ended and unipolar/bipolar jumpers. As always,
-the source is the final authority, and looking in module/dt282x.c
-tells me that the options list is interpreted as:
-
- i/o base
- irq
- 1=differential, 0=single ended
- ai 0=unipolar, 1=bipolar
- ao0 0=unipolar, 1=bipolar
- ao1 0=unipolar, 1=bipolar
- dma1
- dma2
-
-(ai=analog input, ao=analog output.) From this, I decide that
-the appropriate options list is
-
- 0x200,4,,1,1,1
-
-I left the differential/single-ended number blank, since the
-driver already knowns (from the board name), that it is
-differential. I also left the DMA numbers blank, since I
-don't want the driver to use DMA. (Don't want it to interfere
-with my sound card -- life is full of difficult choices.)
-Keep in mind that things commented in the source, but not in
-the documentation are about as likely to change as the weather,
-so I put good comments next to the following line when I put
-it in rc.local.
-
- /usr/sbin/comedi_config /dev/comedi1 dt2821-f-8di 0x200,4,,1,1,1
-
-So now I think that I have my boards configured correctly.
-Since data acquisition boards are not typically well-engineered,
-comedi sometimes can't figure out if the board is actually there.
-If it can't, it assumes you are right. Both of these boards
-are well-made, so comedi will give me an error message if it
-can't find them. The comedi kernel module, since it is a part
-of the kernel, prints messages to the kernel logs, which you
-can access through the command 'dmesg' or /var/log/messages.
-Here is a configuration failure (from dmesg):
-
- comedi0: ni_E: 0x0200 can't find board
-
-When it does work, I get:
-
- comedi0: ni_E: 0x0260 at-mio-16e-10 ( irq = 3 )
-
-Note that it also correctly identified my board.
-
-
-
-
-0. Getting information from comedi
-
-
-So now that we have comedi talking to the hardware, we want to
-talk to comedi. Here's some pretty low-level information --
-it's sometimes useful for debugging:
-
- cat /proc/comedi
-
-Right now, on my computer, this command gives:
-
- comedi version 0.6.4
- format string
- 0: atmio-E at-mio-16e-10 7
- 1: dt282x dt2821-f-8di 4
-
-This is a feature that is not well-developed yet. Basically, it
-currently tells you driver name, device name, and number of
-subdevices.
-
-In the demo/ directory, there is a command called
-'info', which provides information about each subdevice on the
-board. The output of it is rather long, since I have 7
-subdevices (4 or fewer is more common.)
-Here's part of the output of the NI board (which
-is on /dev/comedi0.) ('demo/info /dev/comedi0')
-
-overall info:
- version code: 0x000604
- driver name: atmio-E
- board name: at-mio-16e-10
- number of subdevices: 7
-subdevice 0:
- type: 1 (unknown)
- number of channels: 16
- max data value: 4095
-
-
-The overall info gives information about the device -- basically
-the same information as /proc/comedi.
-
-This board has 7 subdevices. Devices are separated into
-subdevices that each have a distinct purpose -- e.g., analog
-input, analog output, digital input/output. This board also
-has an EEPROM and calibration DACs that are also subdevices.
-
-Subdevice 0 is the analog input subdevice. You would have
-known this from the 'type: 1 (unknown)' line, if I've updated
-demo/info recently, because it would say 'type: 1 (analog input)'
-instead. The other lines should be self-explanitory. Comedi
-has more information about the device, but demo/info doesn't
-currently display this.
-
-
-
-0. Your first comedi program
-
-This example requires a card that has analog or
-digital input. Right to the source:
-
-#include <stdio.h> /* for printf() */
-#include <comedilib.h>
-
-int subdev = 0; /* change this to your input subdevice */
-int chan = 0; /* change this to your channel */
-int range = 0; /* more on this later */
-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);
-
- printf("%d\n",data);
-
- return 0;
-}
-
-
-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. Including all
-the appropriate headers is sometimes a little tricky.
-Compile it using 'cc tut1.c -lcomedi -o tut1'. Hopefully
-it works.
-
-A few notes: The range variable tells comedi which gain
-to use when measuring an analog voltage. Since we don't
-know (yet) which numbers are valid, or what each means,
-we'll use 0, because it won't cause errors. Likewise with
-aref, which determines the analog reference used.
-
-
-0. Converting samples to voltages
-
-
-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, depending on the number of bits
-in the A/D converter. Comedi samples are *always* unsigned,
-with 0 representing the lowest voltage of the ADC, and 4095
-the highest. The hardware driver compensates for
-anything else the manual for your device says. However,
-you probably prefer to have this number translated to
-a voltage. Naturally, as a good programmer, your first
-question is: "How do I do this in a device-independent
-manner?"
-
-For each subdevice, the comedi kernel module keeps a
-'range_type' variable. This variable contains the number
-of available ranges (i.e., gains) that you can select,
-along with an offset in a list of range information
-structures. If you know the range_type variable, you
-can use these macros:
-
- RANGE_OFFSET(range_type)
- RANGE_LENGTH(range_type)
-
-to extract such information. However, you want the
-actual voltage information, not some integer offset
-in a table. Rather than messing with the library
-internals, use the function
-
- ptr=comedi_get_range(comedi_file,subdevice,channel,
- range)
-
-which returns a pointer to a comedi_range structure.
-The comedi_range structure looks like
-
- typedef struct{
- double min;
- double max;
- unsigned int unit;
- }comedi_range;
-
-The element 'min' represents the voltage corresponding to
-comedi_data_read() returning 0, and 'max' represents
-comedi_data_read() returning 'maxdata', (i.e., 4095 for 12
-bit A/C converters, 65535 for 16 bit, or, 1 for digital input
--- more on this in a bit.) The 'unit' entry tells you if min and
-max refer to voltage, current, etc.
-
-"Could it get easier?", you say. Well, yes. Use
-the function comedi_to_phys(), which converts data
-values to physical units. Call it using something like
-
- volts=comedi_to_phys(it,data,range,maxdata);
-
-and the opposite
-
- data=comedi_from_phys(it,volts,range,maxdata);
-
-You probably noticed (and were worried) that we haven't
-discussed how to determine maxdata and range_type. Well,
-you could ask the kernel this information each time you need
-it, but since there are other variables, special cases,
-and several subdevices to worry about, it would be nice
-if the library could take care of this... (read on...)
-
-
-
-0.
-
-
-In addition to providing low level routines for data
-access, the comedi library provides higher-level access,
-much like the standard C library provides fopen(), etc.
-as a high-level (and portable) alternative to the direct
-UNIX system calls open(), etc. Similarily to fopen(),
-we have comedi_open():
-
- file=comedi_open("/dev/comedi0");
-
-where file is of type (comedi_t *). This function
-calls open(), like we did explicitly in a previous
-section, but also fills the comedi_t structure with
-lots of goodies -- information that we will need to use
-soon.
-
-Specifically, we needed to know maxdata for a specific
-subdevice/channel. How about:
-
- maxdata=comedi_get_maxdata(file,subdevice,channel);
-
-Wow. How easy. And the range type?
-
- range_type=comedi_get_rangetype(file,subdevice,channel);
-
-Cool. Other information you need to know about a channel
-can be gotten in a similar way.
-
-
-
-0. Your second comedi program
-
-
-Actually, this is the first comedi program again, just
-that we've added what we've learned.
-
-
-#include <stdio.h> /* for printf() */
-#include <comedi.h> /* also included by comedilib.h */
-#include <comedilib.h> /* for comedi_get() */
-
-int subdev = 0; /* change this to your input subdevice */
-int chan = 0; /* change this to your channel */
-int range = 0; /* more on this later */
-int aref = 0; /* more on this later */
-
-int main(int argc,char *argv[])
-{
- comedi_t *cf;
- int chan=0;
- int data;
- int maxdata,rangetype;
- double volts;
-
- cf=comedi_open("/dev/comedi0");
-
- maxdata=comedi_get_maxdata(cf,subdev,chan);
-
- rangetype=comedi_get_rangetype(cf,subdev,chan);
-
- data=comedi_get(cf->fd,subdev,chan,range,aref);
-
- volts=comedi_to_phys(data,rangetype,range,maxdata);
-
- printf("%d %g\n",data,volts);
-
- return 0;
-}
-
-
-By now, the comedi_read_data() line looks a little archaic, using
-the UNIX file descriptor cf->fd instead of just cf. (By the
-way, somewhere in the heart of comedi_open() is the line
-cf->fd=open(filename,O_RDWR).) Well, there isn't one good
-replacement, since it highly depends on your application
-what additional features you might want in a comedi_get()
-replacement. But this is the topic of a different section.
-
-
-0. stuff
-
-
-
-0. Slowly-varying inputs
-
-
-Sometimes, your input channels change slowly enough that
-you are able to average many sucessive input values to get a
-more accurate measurement of the actual value. In general,
-the more samples you average, the better your estimate
-gets, roughly by a factor of sqrt(number_of_samples).
-Obviously, there are limitations to this:
-
- - you are ultimately limited by "spurious free dynamic range"
-
- - you need to have _some_ noise on the input channel,
- otherwise you will be averaging the same number N times.
-
- - the more noise you have, the greater your SFDR, but it
- takes many more samples to compensate for the increased
- noise
-
- - if you feel the need to average samples for 2 seconds,
- your signal will need to be _very_ slowly-varying, i.e.,
- not varying more than your target uncertainty for the
- entire 2 seconds.
-
-As you might have guessed, the comedi library has functions
-to help you in your quest to accurately measure slowly varying
-inputs. I use these functions to measure thermocouple voltages
--- actually, the library functions came from a section of code
-that was previously part of the thermocouple reading program.
-
-The comedi self-calibration utility also uses these functions.
-On some hardware, it is possible to tell it to measure an
-internal stable voltage reference, which is typically going
-to be very slowly varying -- on the kilosecond time scale
-or more. So it is reasonable to measure millions of samples,
-to get a very accurate measurement of the A/D converter output
-value that corresponds to the voltage reference. Sometimes,
-however, this is overkill, since there is no need to
-perform a part-per-million calibration to a standard that
-is only accurate to part-per-thousand.
-
-
-
-
-
projects / comedilib.git / commitdiff