From: David Schleef Date: Mon, 16 Jul 2001 00:05:36 +0000 (+0000) Subject: It doesn't make sense to keep regenerating these in CVS. They are X-Git-Tag: r0_7_17~54 X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=646587b1ea4cd8773223393b984367ec50be9156;p=comedilib.git It doesn't make sense to keep regenerating these in CVS. They are generated in the release script now. --- diff --git a/doc/comedilib-1.html b/doc/comedilib-1.html deleted file mode 100644 index 186db2e..0000000 --- a/doc/comedilib-1.html +++ /dev/null @@ -1,24 +0,0 @@ - - - - - Comedi Documentation: Introduction - - - - - -Next -Previous -Contents -

1. Introduction

- -

This is preliminary documentation for Comedi and Comedilib.

- -

-Next -Previous -Contents - - diff --git a/doc/comedilib-2.html b/doc/comedilib-2.html deleted file mode 100644 index eec5825..0000000 --- a/doc/comedilib-2.html +++ /dev/null @@ -1,241 +0,0 @@ - - - - - Comedi Documentation: Installation and configuration - - - - - -Next -Previous -Contents -

2. Installation and configuration

- - -

This section covers compiling, installing, and configuring -comedi and comedlib.

- - -

2.1 Compiling and Installing -

- - -

This section has not been written.

- - -

2.2 Insmod'ding the kernel module -

- - -

This section has not been written.

- - -

2.3 Configuring comedi for 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.

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:

- -


--# 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.

- - - -

2.4 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 common for other boards.) -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.

- - -

-Next -Previous -Contents - - diff --git a/doc/comedilib-3.html b/doc/comedilib-3.html deleted file mode 100644 index cc2b1d4..0000000 --- a/doc/comedilib-3.html +++ /dev/null @@ -1,40 +0,0 @@ - - - - - Comedi Documentation: Individual drivers - - - - - -Next -Previous -Contents -

3. Individual drivers

- - -

This section contains information that is specific to each -hardware driver. The most current information about a driver -is included in the comedi source.

- -

3.1 National Instruments AT-MIO E series -

- - - - -

3.2 Data Translation -

- - - - - -

-Next -Previous -Contents - - diff --git a/doc/comedilib-4.html b/doc/comedilib-4.html deleted file mode 100644 index c054c5c..0000000 --- a/doc/comedilib-4.html +++ /dev/null @@ -1,247 +0,0 @@ - - - - - Comedi Documentation: Writing programs that use comedi and comedilib - - - - - -Next -Previous -Contents -

4. Writing programs that use comedi and comedilib

- - - -

4.1 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;
-        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. -Compile it using


--cc tut1.c -lcomedi -o tut1
-
-

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.

- - - -

4.2 Converting samples to voltages -

- - -

If you selected an analog input subdevice, you probably noticed -that the output of tut1 is a number between -0 and 4095, or 0 and 65535, depending on the number of bits -in the A/D converter. Comedi samples are always 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

- -


--typedef struct{
-        double min;
-        double max;
-        unsigned int unit;
-}comedi_range;
-
-

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


--volts=comedi_to_phys(it,data,range,maxdata);
-
-

and the opposite


--data=comedi_from_phys(it,volts,range,maxdata);
-
-

- - - -

4.3 Another section -

- - - -

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.

- - - -

4.4 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>  /* '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;
-}
-
-

- - - -

-Next -Previous -Contents - - diff --git a/doc/comedilib-5.html b/doc/comedilib-5.html deleted file mode 100644 index 6267789..0000000 --- a/doc/comedilib-5.html +++ /dev/null @@ -1,262 +0,0 @@ - - - - - Comedi Documentation: Application-specific functions - - - - - -Next -Previous -Contents -

5. Application-specific functions

- - - -

5.1 Digital Input/Output -

- - -

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

comedi_dio_read(device,subdevice,channel,unsigned int *bit); -comedi_dio_write(device,subdevice,channel,unsigned int bit);

The direction of bidirectional lines can be configured using -the function

comedi_dio_config(device,subdevice,channel,unsigned int dir);

The parameter 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

comedi_dio_bitfield(device,subdevice,unsigned int write_mask,unsigned int *bits);

Each channel is assigned to a bit in the write_mask and bits -bitfield. If a bit in write_mask is set, the corresponding bit -in *bits will be written to the corresponding digital output line. -Each digital line is then read and placed into *bits. The value -of bits in *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.

- - - -

5.2 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.

- - - -

5.3 Commands -

- - - -

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 -comedi_cmd structure is -used to control acquisition and query the capabilities of a device -(see also -comedi_command(), -comedi_command_test(), and -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 *_src members of the -comedi_cmd structure. The source types are:

TRIG_NONE: don't ever cause an event
TRIG_NOW: cause event to occur immediately
TRIG_FOLLOW: see notes below
TRIG_TIME: cause event to occur at a particular time
TRIG_TIMER: cause event to occur repeatedly at a specific rate
TRIG_COUNT: cause event when count reaches specific value
TRIG_EXT: external signal causes event
TRIG_INT: internal signal causes event
TRIG_OTHER: driver-specific meaning

Not all triggers are applicable to all events. Supported triggers -for specific events depend significantly on your particular -device. The -comedi_get_cmd_src_mask() -function is useful for determining what triggers a subdevice supports.

For every trigger, there is a corresponding -argument (the *_arg members of the -comedi_cmd -structure) whose meaning depends on the type of trigger. The meanings -of the arguments are as follows:

TRIG_NONE is typically used only as a stop_src. The argument for TRIG_NONE -is reserved and should be set to 0.

TRIG_NOW is most often used as a start_src. The argument for TRIG_NOW is -the number of nanoseconds between when the command is issued and when -the event should occur. In the case of using TRIG now as a start_src, -it indicates a delay between issuing the command and the start of -acquisition. Most drivers only support a delay of 0.

TRIG_FOLLOW is a special type of trigger for events that trigger on -the completion of some other, logically connected event. The argument -is reserved and should be set to 0. When used -as a scan_begin_src, it indicates that a trigger should occur as a -logical continuation of convert events. This is done in order to -properly describe boards that do not have separate timers for -convert and scan_begin events. When used as a start_src for analog -output subdevices, it indicates that conversion of output samples -should begin when samples are written to the buffer.

TRIG_TIME is reserved for future use.

TRIG_TIMER is most often used as a convert_src, a scan_begin_src, or -both. It indicates that triggers should occur at a specific rate. -The argument specifies the interval between triggers in nanoseconds.

TRIG_COUNT is used for scan_end_src and stop_src. It indicates that -a trigger should occur when the specified number of corresponding -lower-level triggers (convert and scan_begin, respectively) occur. -The argument is the count of lower-level triggers.

TRIG_EXT can be useful as any of the trigger sources. It indicates -that an external digital line should be used to trigger the event. -The exact meaning of digital line is device-dependent. Some devices -have one dedicated line, others may allow generic digital input -lines to be used. The argument indicates the particular external -line to use as the trigger.

TRIG_INT is typically used as a start_src. This trigger occurs when -the application performs an INSN_INTTRIG instruction. Using TRIG_INT -is a method by which the application can accurately record the time of -the start of acquisition, since the parsing and setup time of a -particular command may be significant. The argument associated with -TRIG_INT is reserved and should be set to 0.

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 subdev member of the -comedi_cmd -structure is the index of the subdevice the command is intended for. The -comedi_find_subdevice_by_type() -function can be useful in discovering the index of your desired subdevice.

The chanlist member of the -comedi_cmd -structure should point to an array whose number of elements is specificed by chanlist_len -(this 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 -CR_PACK() macro.

The data and data_len members can be safely ignored when issueing commands -from a user-space program. They only have meaning when a command is sent from a kernel -module using the kcomedilib interface, in which case they specify the buffer where -the driver should write/read its data to/from.

The final member of the -comedi_cmd structure is flags. -The following flags are valid, and can be bitwise-or'd together.

TRIG_BOGUS: do the motions??
TRIG_DITHER: enable dithering??
TRIG_DEGLITCH: enable deglitching??
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.
TRIG_CONFIG: perform configuration, not triggering. This is a legacy of the -deprecated comedi_trig_struct, and has no function at present.
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.
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.

- -There are also a few flags that indicate how timing arguments should be rounded -if the hardware cannot achieve the exact timing requested. -

TRIG_ROUND_NEAREST: round to nearest supported timing period, the default.
TRIG_ROUND_DOWN: round period down.
TRIG_ROUND_UP: round period up.
TRIG_ROUND_UP_NEXT: this one doesn't do anything, and I don't know what it was intended -to do??

- - -

The typical sequence for executing a command is to first send -the command through -comedi_command_test() -once or twice. The test will check that the command is valid for the particular -device, and often makes some adjustments to the command arguments, which -can then be read back by the user to see the actual values used. The -command is executed with -comedi_command(). For input/output commands, data -is read from or written to the device file /dev/comedi[0..3] you are using.

- -

-Next -Previous -Contents - - diff --git a/doc/comedilib-6.html b/doc/comedilib-6.html deleted file mode 100644 index 81135d5..0000000 --- a/doc/comedilib-6.html +++ /dev/null @@ -1,1019 +0,0 @@ - - - - - Comedi Documentation: Libcomedi Reference - - - - -Next -Previous -Contents -

6. Libcomedi Reference

- - - -

6.1 Constants and Macros -

- - - -

CR_PACK()

- - -

CR_PACK(channel, range, aref)

CR_PACK is used to initialize the elements of the chanlist array in the -comedi_cmd structure, and the chanspec member -of the -comedi_insn structure.

The channel argument is the channel you wish to use, with the channel numbering -starting at zero.

The range is an index, starting at zero, whose meaning -is device dependent. The -comedi_get_n_ranges() and -comedi_get_range() functions -are useful in discovering information about the available ranges.

The aref argument indicates what reference you want the device to use. It -can be any of the following: -

AREF_GROUND is for inputs/outputs referenced to ground
AREF_COMMON is for a `common' reference (the low inputs of all the channels are tied -together, but are isolated from ground)
AREF_DIFF is for differential inputs/outputs
AREF_OTHER is for any reference that does not fit into the above categories

- -Particular drivers may or may not use the AREF flags. If they are not supported, they -are silently ignored.

- -

Source: /include/comedi.h

- - -

RANGE_LENGTH() (deprecated)

- -

RANGE_LENGTH(rangetype)

- -

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.

- -

The RANGE_LENGTH() macro returns the length of the array that is -specified by the rangetype token.

- -

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.

- - - -

6.2 Data Types and Structures -

- - -

comedi_t

- -

The data type comedi_t is used to represent an open Comedi -device. A valid comedi_t pointer is returned by a successful -call to comedi_open(), and should be used for subsequent -access to the device. -It is a transparent type, and pointers to type comedi_t -should not be dereferenced by the application.

- - - -

sampl_t

- -

The data type sampl_t is one of the generic types used to represent -data values in libcomedi. It is used in a few places where a shorter -data type is useful, but is limited to 16 bits on the i386 architecture.

- - - -

lsampl_t

- -

The data type lsampl_t is one of the generic types used to represent -data values in libcomedi. It is currently defined to be unsigned int.

- - - - - -

comedi_trig_struct (deprecated)

- - -

The comedi_trig structure


--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];
-}
-
-

The 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.

- -

This structure is defined as part of the Comedi kernel interface.

- - -

comedi_sv_t

- - -


--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;
-}
-
-

The comedi_sv_t structure is used by the comedi_sv_*() -functions to provide a simple method of accurately measuring -slowly varying inputs. See the relevant section for more -details.

- - - -

comedi_cmd

- - -


--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;
-};
-
-

- -

More information on using commands can be found in the -command section.

- -

This structure is defined as part of the Comedi kernel interface.

- - -

comedi_insn

- - -

undocumented

- -

Related functions are described in section XXX.

- -

This structure is defined as part of the Comedi kernel interface.

- - - -

comedi_range

- - -

undocumented

- - - -

6.3 Functions -

- - - -

comedi_close()

- - -

void comedi_close(comedi_t *it);

- -

Closes a device previously opened by comedi_open().

- -

The return type of this function will change to int, in -order to match fclose.

- -

Source: /lib/comedi.c

- - -

comedi_command()

- - -

int comedi_command(comedi_t *it, comedi_cmd *cmd);

Issues the command pointed at by cmd to the open device it. It -is usually necessary to pass the command through -comedi_command_test() to -fix up the command before it can be successfully executed with -comedi_command(). -See -commands for more information.

- -

Source: /lib/comedi.c

- - -

comedi_command_test()

- - -

int comedi_command_test(comedi_t *it, comedi_cmd *cmd);

- -

Tests and fixes up the command pointed at by cmd according -to the limitations of the driver configured on the open device it. -The return value has the following meaning: -

0: the command passed the test and can be successfully executed -by -comedi_command(). The one exception -to this rule is that the test will allow a NULL chanlist for the command.
1: invalid trigger. One or more of the trigger sources (the *_src members -of the -comedi_cmd structure) is not -supported by the driver.
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.
3: argument invalid. One or more argument is invalid, for example -a timing argument might be in excess of the card's maximum speed. The -command test will correct the arguments by modifying the command pointed -at by cmd.
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.
negative: some other error has occured.

- -See -commands for more information.

- -

Source: /lib/comedi.c

- - -

comedi_data_read()

- - -

int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan, -unsigned int range,unsigned int aref,lsampl_t *data);

- -

Reads a single sample on the channel that -is specified by the comedi device it, the -subdevice subd, and the channel chan. -For the A/D conversion (if appropriate), -the device is configured to use range specification -range and (if appropriate) analog reference type -aref. Analog reference types that are not supported -by the device are silently ignored.

- -

comedi_data_read() reads one data value from -the specified channel and places the -data value that is read in the location pointed to by -data.

- -

On sucess, comedi_data_read() returns 0. If there is an -error, -1 is returned.

- -

Valid analog reference numbers are:

AREF_GROUND Reference to analog ground
AREF_COMMON Reference to analog common
AREF_DIFF Differential reference
AREF_OTHER Board-specific meaning

Valid data values returned by these function is an unsigned integer -less than or equal to maxdata, which is channel-dependent. -Conversion of these data value to physical units can be performed -by -comedi_to_phys().

Source: /lib/data.c

- - -

comedi_data_write()

- - -

int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int chan, -unsigned int range,unsigned int aref,lsampl_t data);

- -

Writes a single sample on the channel that -is specified by the comedi device it, the -subdevice subd, and the channel chan. -For the D/A conversion (if appropriate), the device is -configured to use range specification -range and (if appropriate) analog reference type -aref. Analog reference types that are not supported -by the device are silently ignored.

comedi_data_write() writes the data value -specified by the argument data to -the specified channel.

On sucess, comedi_data_write() returns 0. If there is an error, -1 is -returned.

Valid analog reference numbers are:

AREF_GROUND Reference to analog ground
AREF_COMMON Reference to analog common
AREF_DIFF Differential reference
AREF_OTHER Board-specific meaning

Valid data values used by these functions is an unsigned integer -less than or equal to maxdata, which is channel-dependent. -Conversion of physical units to these data value can be performed -by -comedi_from_phys().

Source: /lib/data.c

- - - -

comedi_dio_bitfield();

- -

int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned -int write_mask,unsigned int *bits);

- -

The function comedi_dio_bitfield() allows multiple channels to -be read simultaneously from a digital input or digital I/O device. -The parameter write_mask and the value pointed to by bits -are interpreted as bit fields, with the least significant bit -representing channel 0. For each bit in write_mask that is -set, the cooresponding bit in *bits is written to the digital -output channel. Each digital input channel is read, and the result -placed in the approprate bits in *bits.

- -

The current implementation reads and writes bits using separate -system calls, which is not ideal. When the kernel driver supports -simultaneous reading/writing, this will be fixed in the library.

- -

It should be noted that it is not possible to access channels -greater than 31 using this function.

- -

Source: /lib/dio.c

- - - -

comedi_dio_config()

- -

int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned -int chan,unsigned int dir);

- -

The function comedi_dio_config configures individual channels -in a digital I/O subdevice to be either input or output, depending -on the value of parameter dir. Depending on the capabilities -of the hardware device, multiple channels may be affected by -a single call to comedi_dio_config.

- -

Valid directions are: -

COMEDI_INPUT
COMEDI_OUTPUT

Source: /lib/dio.c

- - - -

comedi_dio_read()

- -

int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int -chan,unsigned int *bit);

- -

The function reads the status of channel chan belonging to the digital -input subdevice subd of device it. The result, 0 or 1, is stored -in bit. Returns -1 on failure.

- -

This function is equivalent to comedi_data_read(it,subd,chan,0,0,bit).

- -

Source: /lib/dio.c

- - -

comedi_dio_write()

- -

int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned -int chan,unsigned int bit);

- -

The function writes the value of bit, 0 or 1, to channel chan, -belonging to the digital output device subd of device it. Returns --1 on failure.

- -

Source: /lib/dio.c

- - -

comedi_fileno()

- - -

int comedi_fileno(comedi_t *it);

- -

The function comedi_fileno -returns the integer descriptor for the handle it. It -is equivalent to the standard function fileno. If -it is an invalid comedi_t pointer, the function -returns -1 and sets the appropriate libcomedi error value.

Source: /lib/comedi.c

- - - -

comedi_find_range()

- - -

int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned -int chan, unsigned int unit, double min, double max);

- -

The function comedi_find_range tries to -locate the optimal (smallest) range for the channel chan -belonging to a subdevice of the comedi device it, -that includes both min and max in units. -If it finds a matching range, it returns its index. If no -matching range is available, it returns -1.

- -

Valid units are:

UNIT_volt
UNIT_mA
UNIT_none

Source: /lib/range.c

- - - -

comedi_errno()

- -

int comedi_errno(void);

- -

The function comedi_errno() -returns an integer describing the most recent comedilib error. This -integer may be used as the errnum parameter for --comedi_strerror().

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 -comedi_errno(). This error number can be -converted to a human-readable form by the functions --comedi_perror() -and -comedi_strerror().

These functions are intended to mimic the behavior of the -standard C library functions perror(), -strerror, and errno(). 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: /lib/error.c

- - - -

comedi_find_subdevice_by_type()

- - -

int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int -start_subdevice);

- -

The function comedi_find_subdevice_by_type tries to -locate a subdevice belonging to comedi device it, -having type type, starting with the subdevice -start_subdevice. 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.

- -

For subdevice types, see the manual page for the function --comedi_get_subdevice_type().

Source: /lib/get.c

- - - -

comedi_from_phys()

- - -

lsampl_t comedi_from_phys(double data, comedi_range *rng, -lsampl_t maxdata);

Converts data given in physical units (data) into sample values -(lsampl_t, between 0 and maxdata). The parameter rng -represents the conversion information to use, and the parameter -maxdata represents the maximum possible data value for the -channel that the data will be written to.

- -

Source: /lib/range.c

- - - -

comedi_get_board_name()

- - -

char *comedi_get_board_name(comedi_t *it);

The function comedi_get_board_name returns a pointer -to a string containing the name of the device. This pointer is -valid until the comedi descriptor it is closed. This -function returns NULL if there is an error.

Source: /lib/get.c

- - -

comedi_get_cmd_src_mask()

- - -

int comedi_get_cmd_src_mask(comedi_t *dev, unsigned int subdevice, -comedi_cmd *cmd);

undocumented

Source: /lib/cmd.c

- - -

comedi_get_driver_name()

- - -

char *comedi_get_driver_name(comedi_t *it);

The function 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 it. This pointer is -valid until the comedi descriptor it is closed. This -function returns NULL if there is an error.

Source: /lib/get.c

- - - -

comedi_get_maxdata()

- - -

lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int -subdevice,unsigned int chan);

- -

The function comedi_get_maxdata() returns the maximum -valid data value for channel chan of subdevice -subdevice belonging to the comedi device it -This function returns 0 on error.

Source: /lib/get.c

- - - -

comedi_get_n_channels()

- - -

int comedi_get_n_channels(comedi_t *it,unsigned int subdevice);

The function comedi_get_n_channels() returns the number -of channels of the subdevice belonging to the comedi device it -and having index subdevice. This function returns -1 on error.

Source: /lib/get.c

- - - -

comedi_get_n_ranges()

- - -

int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned int -chan);

The function comedi_get_n_ranges() returns the number -of ranges of the channel chan belonging to the subdevice -of the comedi device it. This function returns -1 on error.

Source: /lib/range.c

- - - -

comedi_get_n_subdevices()

- - -

int comedi_get_n_subdevices(comedi_t *it);

The function comedi_get_n_subdevices returns the -number of subdevices associated with the comedi descriptor -it, or -1 if there is an error.

Source: /lib/get.c

- - - -

comedi_get_range()

- - -

comedi_range * comedi_get_range(comedi_t *it,unsigned int subdevice,unsigned int chan,unsigned int -range);

The function comedi_get_range 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 it is closed. If there is an -error, NULL is returned.

Source: /lib/get.c

- - -

comedi_get_rangetype() deprecated

- - -

int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned int -chan);

The function comedi_get_rangetype() returns an integer -that represents the number of range specifications available for a -particular channel chan of the subdevice subdevice, as well as a conversion table to convert sample -values to/from physical units.

The macro -RANGE_LENGTH(rangetype) -can be used to determine the number of range specifications for a given -range type.

- -

This function is deprecated and should not be used in new code.

Source: /lib/get.c

- - -

comedi_get_subdevice_type()

- - -

int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice);

The function comedi_get_subdevice_type() returns an -integer describing the type of subdevice that belongs to the comedi -device it and has the index subdevice. The -function returns -1 is there is an error.

Valid subdevice types are:

COMEDI_SUBD_UNUSED -Subdevice has no functionality, i.e., a place-holder.
COMEDI_SUBD_AI Analog input
COMEDI_SUBD_AO Analog output
COMEDI_SUBD_DI Digital input
COMEDI_SUBD_DO Digital output
COMEDI_SUBD_DIO -Digital input/output. Channels are configurable as to whether they -are inputs or outputs.
COMEDI_SUBD_COUNTER Counter
COMEDI_SUBD_TIMER Timer
COMEDI_SUBD_MEMORY -Memory, e.g., EEPROM or dual-ported RAM
COMEDI_SUBD_CALIB -Calibration DACs
COMEDI_SUBD_PROC -Processor or DSP

Source: /lib/get.c

- - -

comedi_get_timer() (deprecated)

- - -

int comedi_get_timer(comedi_t *it,unsigned int subdev, double -freq,unsigned int *trigvar, double *actual_freq);

- -

The function comedi_get_timer converts the frequency freq -to a number suitable to send to the driver in a 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 nanosec_timer, indicating -that timer values are simply a time specified in nanoseconds.

- -

This function is deprecated and should not be used in new applications.

- -

Source: /lib/timer.c

- - -

comedi_get_version_code()

- - -

int comedi_get_version_code(comedi_t *it);

- -

The function 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.

- -

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: /lib/get.c

- - -

comedi_loglevel()

- - -

int comedi_loglevel(int loglevel);

- -

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 stderr. The loglevel can also be affected by the -environment variable COMEDI_LOGLEVEL.

- -

In order to conserve resources, some debugging information is -disabled when libcomedi is compiled.

- -

The meaning of the loglevels is as follows:

COMEDILIB_LOGLEVEL=0 - -Comedilib prints nothing. -
COMEDILIB_LOGLEVEL=1 (default) - -Comedilib only prints error messages when there is a -self-consistency error (i.e., internal bug). -
COMEDILIB_LOGLEVEL=2 - -Comedilib prints an error message when an invalid -parameter is passed to comedilib. -
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. -
COMEDILIB_LOGLEVEL=4 - -Comedilib prints a lot of debugging messages. -

Bugs: Libcomedi doesn't currently have much debugging information.

Source: /lib/error.c

- - -

comedi_open()

- - -

comedi_t *comedi_open(char *filename);

Opens a comedi device specified by the filename filename. -Returns NULL on error. On sucess, it returns a handle that is -given as a parameter to other libcomedi functions.

- -

You are not supposed to have access to the internals of the -comedi_t structure.

Bugs: Not strictly identical to fopen

Source: /lib/comedi.c

- - - -

comedi_perror()

- - -

void comedi_perror(const char *s);

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 --comedi_errno(). -This error number can be -converted to a human-readable form by the functions -comedi_perror() -and -comedi_strerror().

These functions are intended to mimic the behavior of the -standard C library functions perror(), -strerror, and errno(). 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 comedi_perror() 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: /lib/error.c

- - - -

comedi_strerror()

- - -

*comedi_strerror(int errnum);

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 --comedi_errno(). This error number can be -converted to a human-readable form by the functions --comedi_perror() -and comedi_strerror().

The function comedi_strerror() returns a pointer to a -character string -describing the comedilib error errnum. 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: /lib/error.c

- - - -

comedi_sv_init()

- - -

int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd, -unsigned int chan);

- -

comedi_sv_init initializes the slow varying comedi structure -sv of the device dev, the subdevice subd (analog input) and -the channel chan. -The slow varying comedi structure sv of type -comedi_sv_t -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: /lib/sv.c

- - - -

comedi_sv_update()

- - -

int comedi_sv_update(comedi_sv_t *sv);

The function comedi_sv_update updates the slow varying comedi structure -sv. -Returns zero on success, -1 on error.

Source: /lib/sv.c

- - - -

int comedi_sv_measure()

- - -

int comedi_sv_measure(comedi_sv_t *it,double *data);

comedi_sv_measure measures the slow variing signal. The measurement -is specified by the slow varying comedi structure sv, the result is -stored in data. -On success returns the number of samples, -1 on error.

Source: /lib/sv.c

- - - -

comedi_to_phys()

- - -

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 rng -represents the conversion information to use, and the parameter -maxdata represents the maximum possible data value for the -channel that the data was read.

Source: /lib/range.c

- - - -

comedi_trigger() (deprecated)

- - -

int comedi_trigger(comedi_t *it,comedi_trig *trig);

The function comedi_trigger instructs comedi to -perform the command specified by the -trigger structure trig. Results depend on -the particular command being issued. If there is an -error, -1 is returned.

Lifetime: removal at 1.0.

Source: /lib/comedi.c

- - - -

comedi_get_subdevice_flags()

- - -

int comedi_get_subdevice_flags(comedi_t *dev, unsigned int subdevice);

- -

This function returns a bitfield describing the capabilities of the -specified subdevice. If there is an error, -1 is returned.

- -

The bits are:

SDF_BUSY subdevice is running a command
SDF_BUSY_OWNER subdevice is running a command started by -the file descriptor used by dev.
SDF_LOCKED subdevice is locked
SDF_LOCKED_OWNER subdevice is locked by the file descriptor used -by dev.
SDF_MAXDATA maximum data values are channel dependent
SDF_FLAGS channel flags are channel dependent
SDF_RANGETYPE range types are channel dependent
SDF_MODE0 deprecated
SDF_MODE1 deprecated
SDF_MODE2 deprecated
SDF_MODE3 deprecated
SDF_MODE4 deprecated
SDF_CMD subdevice supports commands
SDF_READABLE subdevice can be read from
SDF_WRITEABLE subdevice can be written to
SDF_RT deprecated
SDF_GROUND subdevice is capable of ground analog reference
SDF_COMMON subdevice is capable of common analog reference
SDF_DIFF subdevice is capable of differential analog reference
SDF_OTHER subdevice is capable of other analog reference
SDF_DITHER subdevice recognizes dither flag
SDF_DEGLITCH subdevice recognizes deglitch flag
SDF_MMAP deprecated
SDF_RUNNING subdevice is acquiring data (i.e., command has not -completed)
SDF_LSAMPL subdevice uses samples of type lsampl_t (otherwise -sampl_t)
SDF_PACKED subdevice uses bitfield samples (otherwise it uses -one sample per channel)

- - - -

The bit definitions are part of the Comedi kernel interface.

- - - -

comedi_range_is_chan_specific()

- - -

int comedi_range_is_chan_specific(comedi_t *dev,unsigned int subdevice);

- -

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.

- - - -

Undocumented functions

- - - -

comedi_maxdata_is_chan_specific()
comedi_get_buffer_size()
comedi_get_max_buffer_size()
comedi_set_buffer_size()
comedi_set_max_buffer_size()
comedi_do_insnlist()
comedi_do_insn()
comedi_lock()
comedi_unlock()
comedi_get_cmd_src_mask()
comedi_get_cmd_generic_timed()
comedi_cancel()
comedi_poll()
comedi_get_buffer_contents()
comedi_mark_buffer_read()
comedi_get_buffer_offset()
comedi_set_global_oor_behavior()

- - -

-Next -Previous -Contents - - diff --git a/doc/comedilib.html b/doc/comedilib.html deleted file mode 100644 index 3a8eac0..0000000 --- a/doc/comedilib.html +++ /dev/null @@ -1,42 +0,0 @@ - - - - - Comedi Documentation - - - - - -Next -Previous -Contents -

Comedi Documentation

- -

David Schleef `ds@stm.lbl.gov`, -Frank Hess `fmhess@uiuc.edu`

1. Introduction

- -

2. Installation and configuration

- -

3. Individual drivers

- -

4. Writing programs that use comedi and comedilib

- -

5. Application-specific functions

- -

6. Libcomedi Reference

- -

-Next -Previous -Contents - - diff --git a/doc/comedilib.txt b/doc/comedilib.txt deleted file mode 100644 index b2d8258..0000000 --- a/doc/comedilib.txt +++ /dev/null @@ -1,1844 +0,0 @@ - Comedi Documentation - David Schleef ds@stm.lbl.gov, Frank Hess fmhess@uiuc.edu - - - 11.. IInnttrroodduuccttiioonn - - This is preliminary documentation for Comedi and Comedilib. - - - 22.. IInnssttaallllaattiioonn aanndd ccoonnffiigguurraattiioonn - - - This section covers compiling, installing, and configuring comedi and - comedlib. - - - - 22..11.. CCoommppiilliinngg aanndd IInnssttaalllliinngg - - - This section has not been written. - - - - 22..22.. IInnssmmoodd''ddiinngg tthhee kkeerrnneell mmoodduullee - - - This section has not been written. - - - - 22..33.. CCoonnffiigguurriinngg ccoommeeddii ffoorr yyoouurr hhaarrddwwaarree - - - - 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. - - 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: - - - - # 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: - - - +o I/O base - - +o IRQ - - +o 1=differential, 0=single ended - - +o ai 0=unipolar, 1=bipolar - - +o ao0 0=unipolar, 1=bipolar - - +o ao1 0=unipolar, 1=bipolar - - +o dma1 - - +o 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. - - - - 22..44.. GGeettttiinngg iinnffoorrmmaattiioonn ffrroomm ccoommeeddii - - - - 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 common for - other boards.) 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. - - - - 33.. IInnddiivviidduuaall ddrriivveerrss - - - This section contains information that is specific to each hardware - driver. The most current information about a driver is included in - the comedi source. - - - 33..11.. NNaattiioonnaall IInnssttrruummeennttss AATT--MMIIOO EE sseerriieess - - - - 33..22.. DDaattaa TTrraannssllaattiioonn - - - - 44.. WWrriittiinngg pprrooggrraammss tthhaatt uussee ccoommeeddii aanndd ccoommeeddiilliibb - - - - 44..11.. YYoouurr ffiirrsstt ccoommeeddii pprrooggrraamm - - - This example requires a card that has analog or digital input. Right - to the source: - - - - #include /* for printf() */ - #include - - 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; - } - - - - Should be understandable: open the device, get the data, print it out. - This is basically the guts of demo/inp.c, without error checking or - fancy options. Compile it using - - - - cc tut1.c -lcomedi -o tut1 - - - - 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. - - - - 44..22.. CCoonnvveerrttiinngg ssaammpplleess ttoo vvoollttaaggeess - - - If you selected an analog input subdevice, you probably noticed that - the output of tut1 is a number between 0 and 4095, or 0 and 65535, - depending on the number of bits in the A/D converter. Comedi samples - are aallwwaayyss unsigned, with 0 representing the lowest voltage of the - ADC, and 4095 the highest. Comedi compensates for anything else the - 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 - - - - typedef struct{ - double min; - double max; - unsigned int unit; - }comedi_range; - - - - 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 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); - - - - 44..33.. AAnnootthheerr sseeccttiioonn - - - - 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. - - - - 44..44.. YYoouurr sseeccoonndd ccoommeeddii pprrooggrraamm - - - - Actually, this is the first comedi program again, just that we've - added what we've learned. - #include /* for printf() */ - #include /* also included by comedilib.h */ - #include /* '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; - } - - - - 55.. AApppplliiccaattiioonn--ssppeecciiffiicc ffuunnccttiioonnss - - - - 55..11.. DDiiggiittaall IInnppuutt//OOuuttppuutt - - - 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 - - comedi_dio_read(device,subdevice,channel,unsigned int *bit); - comedi_dio_write(device,subdevice,channel,unsigned int bit); - - The direction of bidirectional lines can be configured using the - function - - comedi_dio_config(device,subdevice,channel,unsigned int dir); - - The parameter 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 - - comedi_dio_bitfield(device,subdevice,unsigned int write_mask,unsigned - int *bits); - - Each channel is assigned to a bit in the write_mask and bits bitfield. - If a bit in write_mask is set, the corresponding bit in *bits will be - written to the corresponding digital output line. Each digital line - is then read and placed into *bits. The value of bits in *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. - - - - 55..22.. SSlloowwllyy--vvaarryyiinngg iinnppuuttss - - - - 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: - - - - +o you are ultimately limited by "spurious free dynamic range" - - +o you need to have _some_ noise on the input channel, otherwise you - will be averaging the same number N times. - - +o the more noise you have, the greater your SFDR, but it takes many - more samples to compensate for the increased noise - - +o 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. - - - - 55..33.. CCoommmmaannddss - - - - 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 ``comedi_cmd'' structure is used to control acquisition and query - the capabilities of a device (see also ``comedi_command()'', - ``comedi_command_test()'', and ``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 *_src members of the ``comedi_cmd'' structure. - The source types are: - - - +o TRIG_NONE: don't ever cause an event - - +o TRIG_NOW: cause event to occur immediately - - +o TRIG_FOLLOW: see notes below - - +o TRIG_TIME: cause event to occur at a particular time - - +o TRIG_TIMER: cause event to occur repeatedly at a specific rate - - +o TRIG_COUNT: cause event when count reaches specific value - - +o TRIG_EXT: external signal causes event - - +o TRIG_INT: internal signal causes event - - +o TRIG_OTHER: driver-specific meaning - - Not all triggers are applicable to all events. Supported triggers for - specific events depend significantly on your particular device. The - ``comedi_get_cmd_src_mask()'' function is useful for determining what - triggers a subdevice supports. - - For every trigger, there is a corresponding argument (the *_arg - members of the ``comedi_cmd'' structure) whose meaning depends on the - type of trigger. The meanings of the arguments are as follows: - - TRIG_NONE is typically used only as a stop_src. The argument for - TRIG_NONE is reserved and should be set to 0. - - TRIG_NOW is most often used as a start_src. The argument for TRIG_NOW - is the number of nanoseconds between when the command is issued and - when the event should occur. In the case of using TRIG now as a - start_src, it indicates a delay between issuing the command and the - start of acquisition. Most drivers only support a delay of 0. - - TRIG_FOLLOW is a special type of trigger for events that trigger on - the completion of some other, logically connected event. The argument - is reserved and should be set to 0. When used as a scan_begin_src, it - indicates that a trigger should occur as a logical continuation of - convert events. This is done in order to properly describe boards - that do not have separate timers for convert and scan_begin events. - When used as a start_src for analog output subdevices, it indicates - that conversion of output samples should begin when samples are - written to the buffer. - - TRIG_TIME is reserved for future use. - - TRIG_TIMER is most often used as a convert_src, a scan_begin_src, or - both. It indicates that triggers should occur at a specific rate. - The argument specifies the interval between triggers in nanoseconds. - - TRIG_COUNT is used for scan_end_src and stop_src. It indicates that a - trigger should occur when the specified number of corresponding lower- - level triggers (convert and scan_begin, respectively) occur. The - argument is the count of lower-level triggers. - - TRIG_EXT can be useful as any of the trigger sources. It indicates - that an external digital line should be used to trigger the event. - The exact meaning of digital line is device-dependent. Some devices - have one dedicated line, others may allow generic digital input lines - to be used. The argument indicates the particular external line to - use as the trigger. - - TRIG_INT is typically used as a start_src. This trigger occurs when - the application performs an INSN_INTTRIG instruction. Using TRIG_INT - is a method by which the application can accurately record the time of - the start of acquisition, since the parsing and setup time of a - particular command may be significant. The argument associated with - TRIG_INT is reserved and should be set to 0. - - 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 subdev member of the ``comedi_cmd'' structure is the index of the - subdevice the command is intended for. The - ``comedi_find_subdevice_by_type()'' function can be useful in - discovering the index of your desired subdevice. - - The chanlist member of the ``comedi_cmd'' structure should point to an - array whose number of elements is specificed by chanlist_len (this - 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 ``CR_PACK()'' macro. - - The data and data_len members can be safely ignored when issueing - commands from a user-space program. They only have meaning when a - command is sent from a kernel module using the kcomedilib interface, - in which case they specify the buffer where the driver should - write/read its data to/from. - - The final member of the ``comedi_cmd'' structure is flags. The - following flags are valid, and can be bitwise-or'd together. - - - +o TRIG_BOGUS: do the motions?? - - +o TRIG_DITHER: enable dithering?? - - +o TRIG_DEGLITCH: enable deglitching?? - - +o 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. - - +o TRIG_CONFIG: perform configuration, not triggering. This is a - legacy of the deprecated comedi_trig_struct, and has no function at - present. - - +o TRIG_WAKE_EOS: some drivers will change their behaviour when this - flag is set, trying to transfer data at the end of every scan - (instead of, for example, passing data in chunks whenever the - board's onboard fifo is half full). This flag may degrade a - driver's performance at high frequencies. - - +o 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. - - There are also a few flags that indicate how timing arguments - should be rounded if the hardware cannot achieve the exact timing - requested. - - +o TRIG_ROUND_NEAREST: round to nearest supported timing period, the - default. - - +o TRIG_ROUND_DOWN: round period down. - - +o TRIG_ROUND_UP: round period up. - - +o TRIG_ROUND_UP_NEXT: this one doesn't do anything, and I don't know - what it was intended to do?? - - - - The typical sequence for executing a command is to first send the - command through ``comedi_command_test()'' once or twice. The test - will check that the command is valid for the particular device, and - often makes some adjustments to the command arguments, which can then - be read back by the user to see the actual values used. The command - is executed with ``comedi_command()''. For input/output commands, - data is read from or written to the device file /dev/comedi[0..3] you - are using. - - - 66.. LLiibbccoommeeddii RReeffeerreennccee - - - - 66..11.. CCoonnssttaannttss aanndd MMaaccrrooss - - - - 66..11..11.. CCRR__PPAACCKK(()) - - - CR_PACK(channel, range, aref) - - CR_PACK is used to initialize the elements of the chanlist array in - the ``comedi_cmd'' structure, and the chanspec member of the - ``comedi_insn'' structure. - - The channel argument is the channel you wish to use, with the channel - numbering starting at zero. - - The range is an index, starting at zero, whose meaning is device - dependent. The ``comedi_get_n_ranges()'' and ``comedi_get_range()'' - functions are useful in discovering information about the available - ranges. - - The aref argument indicates what reference you want the device to use. - It can be any of the following: - - +o AREF_GROUND is for inputs/outputs referenced to ground - - +o AREF_COMMON is for a `common' reference (the low inputs of all - the channels are tied together, but are isolated from ground) - - +o AREF_DIFF is for differential inputs/outputs - - +o AREF_OTHER is for any reference that does not fit into the - above categories - - Particular drivers may or may not use the AREF flags. If they are - not supported, they are silently ignored. - - - Source: /include/comedi.h - - - - 66..11..22.. RRAANNGGEE__LLEENNGGTTHH(()) ((ddeepprreeccaatteedd)) - - - RANGE_LENGTH(rangetype) - - - 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. - - - The RANGE_LENGTH() macro returns the length of the array that is - specified by the rangetype token. - - - 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. - - - - 66..22.. DDaattaa TTyyppeess aanndd SSttrruuccttuurreess - - - 66..22..11.. ccoommeeddii__tt - - The data type comedi_t is used to represent an open Comedi device. A - valid comedi_t pointer is returned by a successful call to - comedi_open(), and should be used for subsequent access to the device. - It is a transparent type, and pointers to type comedi_t should not be - dereferenced by the application. - - - - 66..22..22.. ssaammppll__tt - - The data type sampl_t is one of the generic types used to represent - data values in libcomedi. It is used in a few places where a shorter - data type is useful, but is limited to 16 bits on the i386 - architecture. - - 66..22..33.. llssaammppll__tt - - The data type lsampl_t is one of the generic types used to represent - data values in libcomedi. It is currently defined to be unsigned int. - - - - 66..22..44.. ccoommeeddii__ttrriigg__ssttrruucctt ((ddeepprreeccaatteedd)) - - - The comedi_trig structure - - - - 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]; - } - - - - The 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. - - - This structure is defined as part of the Comedi kernel interface. - - - - 66..22..55.. ccoommeeddii__ssvv__tt - - - - 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; - } - - - The comedi_sv_t structure is used by the comedi_sv_*() functions to - provide a simple method of accurately measuring slowly varying inputs. - See the relevant section for more details. - - - - 66..22..66.. ccoommeeddii__ccmmdd - - - - 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; - }; - - - - More information on using commands can be found in the ``command'' - section. - - - This structure is defined as part of the Comedi kernel interface. - - - - 66..22..77.. ccoommeeddii__iinnssnn - - - undocumented - - - Related functions are described in section XXX. - - - This structure is defined as part of the Comedi kernel interface. - - - - 66..22..88.. ccoommeeddii__rraannggee - - - undocumented - - - - 66..33.. FFuunnccttiioonnss - - - - 66..33..11.. ccoommeeddii__cclloossee(()) - - - void comedi_close(comedi_t *it); - - - Closes a device previously opened by comedi_open(). - - - The return type of this function will change to int, in order to match - fclose. - - - Source: /lib/comedi.c - - - - 66..33..22.. ccoommeeddii__ccoommmmaanndd(()) - - - int comedi_command(comedi_t *it, comedi_cmd *cmd); - - Issues the command pointed at by cmd to the open device it. It is - usually necessary to pass the command through - ``comedi_command_test()'' to fix up the command before it can be - successfully executed with comedi_command(). See ``commands'' for - more information. - - - Source: /lib/comedi.c - - - - 66..33..33.. ccoommeeddii__ccoommmmaanndd__tteesstt(()) - - - int comedi_command_test(comedi_t *it, comedi_cmd *cmd); - - - Tests and fixes up the command pointed at by cmd according to the - limitations of the driver configured on the open device it. The - return value has the following meaning: - - +o 0: the command passed the test and can be successfully - executed by ``comedi_command()''. The one exception to this rule - is that the test will allow a NULL chanlist for the command. - - +o 1: invalid trigger. One or more of the trigger sources (the *_src - members of the ``comedi_cmd'' structure) is not supported by the - driver. - - +o 2: incompatible triggers. Two or more of the triggers selected are - incompatible with each other. For example, a driver might allow - either the scan_begin_src or the convert_src to be TRIG_TIMER, but - not both. - - +o 3: argument invalid. One or more argument is invalid, for example - a timing argument might be in excess of the card's maximum speed. - The command test will correct the arguments by modifying the - command pointed at by cmd. - - +o 4: argument fix up. The command underwent minor adjustment and - should now be valid. For example, a timing argument might not be - exactly achievable by the card so the timing argument will be - adjusted to the actual timing the card will use. - - +o negative: some other error has occured. - - See ``commands'' for more information. - - - Source: /lib/comedi.c - - - - 66..33..44.. ccoommeeddii__ddaattaa__rreeaadd(()) - - - int comedi_data_read(comedi_t *it,unsigned int subd,unsigned int chan, - unsigned int range,unsigned int aref,lsampl_t *data); - - - Reads a single sample on the channel that is specified by the comedi - device it, the subdevice subd, and the channel chan. For the A/D - conversion (if appropriate), the device is configured to use range - specification range and (if appropriate) analog reference type aref. - Analog reference types that are not supported by the device are - silently ignored. - - - comedi_data_read() reads one data value from the specified channel and - places the data value that is read in the location pointed to by data. - - - On sucess, comedi_data_read() returns 0. If there is an error, -1 is - returned. - - - Valid analog reference numbers are: - - - +o AREF_GROUND Reference to analog ground - - +o AREF_COMMON Reference to analog common - - +o AREF_DIFF Differential reference - - +o AREF_OTHER Board-specific meaning - - Valid data values returned by these function is an unsigned integer - less than or equal to maxdata, which is channel-dependent. Conversion - of these data value to physical units can be performed by - ``comedi_to_phys()''. - - Source: /lib/data.c - - - - 66..33..55.. ccoommeeddii__ddaattaa__wwrriittee(()) - - - int comedi_data_write(comedi_t *it,unsigned int subd,unsigned int - chan, unsigned int range,unsigned int aref,lsampl_t data); - - - Writes a single sample on the channel that is specified by the comedi - device it, the subdevice subd, and the channel chan. For the D/A - conversion (if appropriate), the device is configured to use range - specification range and (if appropriate) analog reference type aref. - Analog reference types that are not supported by the device are - silently ignored. - - comedi_data_write() writes the data value specified by the argument - data to the specified channel. - - On sucess, comedi_data_write() returns 0. If there is an error, -1 is - returned. - - Valid analog reference numbers are: - - - +o AREF_GROUND Reference to analog ground - - +o AREF_COMMON Reference to analog common - - +o AREF_DIFF Differential reference - - +o AREF_OTHER Board-specific meaning - - Valid data values used by these functions is an unsigned integer less - than or equal to maxdata, which is channel-dependent. Conversion of - physical units to these data value can be performed by - ``comedi_from_phys()''. - - Source: /lib/data.c - - - - 66..33..66.. ccoommeeddii__ddiioo__bbiittffiieelldd(());; - - int comedi_dio_bitfield(comedi_t *it,unsigned int subd,unsigned int - write_mask,unsigned int *bits); - - - The function comedi_dio_bitfield() allows multiple channels to be read - simultaneously from a digital input or digital I/O device. The - parameter write_mask and the value pointed to by bits are interpreted - as bit fields, with the least significant bit representing channel 0. - For each bit in write_mask that is set, the cooresponding bit in *bits - is written to the digital output channel. Each digital input channel - is read, and the result placed in the approprate bits in *bits. - - - The current implementation reads and writes bits using separate system - calls, which is not ideal. When the kernel driver supports - simultaneous reading/writing, this will be fixed in the library. - - - It should be noted that it is not possible to access channels greater - than 31 using this function. - - - - Source: /lib/dio.c - - - - 66..33..77.. ccoommeeddii__ddiioo__ccoonnffiigg(()) - - int comedi_dio_config(comedi_t *it,unsigned int subd,unsigned int - chan,unsigned int dir); - - - The function comedi_dio_config configures individual channels in a - digital I/O subdevice to be either input or output, depending on the - value of parameter dir. Depending on the capabilities of the hardware - device, multiple channels may be affected by a single call to - comedi_dio_config. - - - Valid directions are: - - +o COMEDI_INPUT - - +o COMEDI_OUTPUT - - Source: /lib/dio.c - - - - 66..33..88.. ccoommeeddii__ddiioo__rreeaadd(()) - - int comedi_dio_read(comedi_t *it,unsigned int subd,unsigned int - chan,unsigned int *bit); - - - The function reads the status of channel chan belonging to the digital - input subdevice subd of device it. The result, 0 or 1, is stored in - bit. Returns -1 on failure. - - - This function is equivalent to comedi_data_read(it,subd,chan,0,0,bit). - - - Source: /lib/dio.c - - - - 66..33..99.. ccoommeeddii__ddiioo__wwrriittee(()) - - int comedi_dio_write(comedi_t *it,unsigned int subd,unsigned int - chan,unsigned int bit); - - - The function writes the value of bit, 0 or 1, to channel chan, - belonging to the digital output device subd of device it. Returns -1 - on failure. - - - Source: /lib/dio.c - - - - 66..33..1100.. ccoommeeddii__ffiilleennoo(()) - - - - int comedi_fileno(comedi_t *it); - - - The function comedi_fileno returns the integer descriptor for the - handle it. It is equivalent to the standard function fileno. If it - is an invalid comedi_t pointer, the function returns -1 and sets the - appropriate libcomedi error value. - - Source: /lib/comedi.c - - - - 66..33..1111.. ccoommeeddii__ffiinndd__rraannggee(()) - - - int comedi_find_range(comedi_t *it, unsigned int subdevice, unsigned - int chan, unsigned int unit, double min, double max); - - - The function comedi_find_range tries to locate the optimal (smallest) - range for the channel chan belonging to a subdevice of the comedi - device it, that includes both min and max in units. If it finds a - matching range, it returns its index. If no matching range is - available, it returns -1. - - - Valid units are: - - - +o UNIT_volt - - +o UNIT_mA - - +o UNIT_none - - Source: /lib/range.c - - - - 66..33..1122.. ccoommeeddii__eerrrrnnoo(()) - - int comedi_errno(void); - - - The function comedi_errno() returns an integer describing the most - recent comedilib error. This integer may be used as the errnum - parameter for ``comedi_strerror()''. - - 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 comedi_errno(). This error - number can be converted to a human-readable form by the functions - ``comedi_perror()'' and ``comedi_strerror()''. - - These functions are intended to mimic the behavior of the standard C - library functions perror(), strerror, and errno(). 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: /lib/error.c - - - - 66..33..1133.. ccoommeeddii__ffiinndd__ssuubbddeevviiccee__bbyy__ttyyppee(()) - - - int comedi_find_subdevice_by_type(comedi_t *it,int type,unsigned int - start_subdevice); - - - The function comedi_find_subdevice_by_type tries to locate a subdevice - belonging to comedi device it, having type type, starting with the - subdevice start_subdevice. 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. - - - For subdevice types, see the manual page for the function - ``comedi_get_subdevice_type()''. - - Source: /lib/get.c - - - - 66..33..1144.. ccoommeeddii__ffrroomm__pphhyyss(()) - - - lsampl_t comedi_from_phys(double data, comedi_range *rng, lsampl_t - maxdata); - - Converts data given in physical units (data) into sample values - (lsampl_t, between 0 and maxdata). The parameter rng represents the - conversion information to use, and the parameter maxdata represents - the maximum possible data value for the channel that the data will be - written to. - - - Source: /lib/range.c - - - - 66..33..1155.. ccoommeeddii__ggeett__bbooaarrdd__nnaammee(()) - - - char *comedi_get_board_name(comedi_t *it); - - The function comedi_get_board_name returns a pointer to a string - containing the name of the device. This pointer is valid until the - comedi descriptor it is closed. This function returns NULL if there - is an error. - - Source: /lib/get.c - - - - 66..33..1166.. ccoommeeddii__ggeett__ccmmdd__ssrrcc__mmaasskk(()) - - - int comedi_get_cmd_src_mask(comedi_t *dev, unsigned int subdevice, - comedi_cmd *cmd); - - undocumented - - Source: /lib/cmd.c - - 66..33..1177.. ccoommeeddii__ggeett__ddrriivveerr__nnaammee(()) - - - char *comedi_get_driver_name(comedi_t *it); - - The function 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 it. This pointer is valid until the comedi - descriptor it is closed. This function returns NULL if there is an - error. - - Source: /lib/get.c - - - - 66..33..1188.. ccoommeeddii__ggeett__mmaaxxddaattaa(()) - - - lsampl_t comedi_get_maxdata(comedi_t *it,unsigned int - subdevice,unsigned int chan); - - - The function comedi_get_maxdata() returns the maximum valid data value - for channel chan of subdevice subdevice belonging to the comedi device - it This function returns 0 on error. - - Source: /lib/get.c - - - - 66..33..1199.. ccoommeeddii__ggeett__nn__cchhaannnneellss(()) - - - int comedi_get_n_channels(comedi_t *it,unsigned int subdevice); - - The function comedi_get_n_channels() returns the number of channels of - the subdevice belonging to the comedi device it and having index - subdevice. This function returns -1 on error. - - Source: /lib/get.c - - - - 66..33..2200.. ccoommeeddii__ggeett__nn__rraannggeess(()) - - - int comedi_get_n_ranges(comedi_t *it,unsigned int subdevice, unsigned - int chan); - - The function comedi_get_n_ranges() returns the number of ranges of the - channel chan belonging to the subdevice of the comedi device it. This - function returns -1 on error. - - Source: /lib/range.c - - - - 66..33..2211.. ccoommeeddii__ggeett__nn__ssuubbddeevviicceess(()) - - - int comedi_get_n_subdevices(comedi_t *it); - - The function comedi_get_n_subdevices returns the number of subdevices - associated with the comedi descriptor it, or -1 if there is an error. - - Source: /lib/get.c - - - - 66..33..2222.. ccoommeeddii__ggeett__rraannggee(()) - - - comedi_range * comedi_get_range(comedi_t *it,unsigned int - subdevice,unsigned int chan,unsigned int range); - - The function comedi_get_range 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 it is closed. If there is an error, NULL is returned. - - Source: /lib/get.c - - - - 66..33..2233.. ccoommeeddii__ggeett__rraannggeettyyppee(()) ddeepprreeccaatteedd - - - int comedi_get_rangetype(comedi_t *it,unsigned int subdevice,unsigned - int chan); - - The function comedi_get_rangetype() returns an integer that represents - the number of range specifications available for a particular channel - chan of the subdevice subdevice, as well as a conversion table to - convert sample values to/from physical units. - - The macro RANGE_LENGTH(rangetype) can be used to determine the number - of range specifications for a given range type. - - - This function is deprecated and should not be used in new code. - - Source: /lib/get.c - - - - 66..33..2244.. ccoommeeddii__ggeett__ssuubbddeevviiccee__ttyyppee(()) - - - int comedi_get_subdevice_type(comedi_t *it,unsigned int subdevice); - - The function comedi_get_subdevice_type() returns an integer describing - the type of subdevice that belongs to the comedi device it and has the - index subdevice. The function returns -1 is there is an error. - - Valid subdevice types are: - - - +o COMEDI_SUBD_UNUSED Subdevice has no functionality, i.e., a place- - holder. - - +o COMEDI_SUBD_AI Analog input - - +o COMEDI_SUBD_AO Analog output - - +o COMEDI_SUBD_DI Digital input - - - +o COMEDI_SUBD_DO Digital output - - +o COMEDI_SUBD_DIO Digital input/output. Channels are configurable as - to whether they are inputs or outputs. - - +o COMEDI_SUBD_COUNTER Counter - - +o COMEDI_SUBD_TIMER Timer - - +o COMEDI_SUBD_MEMORY Memory, e.g., EEPROM or dual-ported RAM - - +o COMEDI_SUBD_CALIB Calibration DACs - - +o COMEDI_SUBD_PROC Processor or DSP - - Source: /lib/get.c - - - - 66..33..2255.. ccoommeeddii__ggeett__ttiimmeerr(()) ((ddeepprreeccaatteedd)) - - - int comedi_get_timer(comedi_t *it,unsigned int subdev, double - freq,unsigned int *trigvar, double *actual_freq); - - - The function comedi_get_timer converts the frequency freq to a number - suitable to send to the driver in a 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 nanosec_timer, indicating that timer values are simply a time - specified in nanoseconds. - - - This function is deprecated and should not be used in new - applications. - - - Source: /lib/timer.c - - - - 66..33..2266.. ccoommeeddii__ggeett__vveerrssiioonn__ccooddee(()) - - - int comedi_get_version_code(comedi_t *it); - - - The function 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. - - - 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: /lib/get.c - - - - 66..33..2277.. ccoommeeddii__lloogglleevveell(()) - - - int comedi_loglevel(int loglevel); - - - 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 - stderr. The loglevel can also be affected by the environment variable - COMEDI_LOGLEVEL. - - - In order to conserve resources, some debugging information is disabled - when libcomedi is compiled. - - - The meaning of the loglevels is as follows: - - - +o COMEDILIB_LOGLEVEL=0 - - Comedilib prints nothing. - - +o COMEDILIB_LOGLEVEL=1 (default) - - Comedilib only prints error messages when there is a self- - consistency error (i.e., internal bug). - - +o COMEDILIB_LOGLEVEL=2 - - Comedilib prints an error message when an invalid parameter is - passed to comedilib. - - +o 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. - - +o COMEDILIB_LOGLEVEL=4 - - Comedilib prints a lot of debugging messages. - - Bugs: Libcomedi doesn't currently have much debugging information. - - Source: /lib/error.c - - - - 66..33..2288.. ccoommeeddii__ooppeenn(()) - - - comedi_t *comedi_open(char *filename); - - Opens a comedi device specified by the filename filename. Returns - NULL on error. On sucess, it returns a handle that is given as a - parameter to other libcomedi functions. - - - You are not supposed to have access to the internals of the comedi_t - structure. - - Bugs: Not strictly identical to fopen - - Source: /lib/comedi.c - - - - 66..33..2299.. ccoommeeddii__ppeerrrroorr(()) - - - void comedi_perror(const char *s); - - 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 ``comedi_errno()''. This - error number can be converted to a human-readable form by the - functions comedi_perror() and ``comedi_strerror()''. - - These functions are intended to mimic the behavior of the standard C - library functions perror(), strerror, and errno(). 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 comedi_perror() 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: /lib/error.c - - - - 66..33..3300.. ccoommeeddii__ssttrreerrrroorr(()) - - - *comedi_strerror(int errnum); - - 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 ``comedi_errno()''. This - error number can be converted to a human-readable form by the - functions ``comedi_perror()'' and comedi_strerror(). - - These functions are intended to mimic the behavior of the standard C - library functions perror(), strerror, and errno(). 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 comedi_strerror() returns a pointer to a character string - describing the comedilib error errnum. 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: /lib/error.c - - - - 66..33..3311.. ccoommeeddii__ssvv__iinniitt(()) - - - int comedi_sv_init(comedi_sv_t *sv,comedi_t *dev,unsigned int subd, - unsigned int chan); - - - comedi_sv_init initializes the slow varying comedi structure sv of the - device dev, the subdevice subd (analog input) and the channel chan. - The slow varying comedi structure sv of type ``comedi_sv_t'' 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: /lib/sv.c - - - - 66..33..3322.. ccoommeeddii__ssvv__uuppddaattee(()) - - - int comedi_sv_update(comedi_sv_t *sv); - - The function comedi_sv_update updates the slow varying comedi - structure sv. Returns zero on success, -1 on error. - - Source: /lib/sv.c - - - - 66..33..3333.. iinntt ccoommeeddii__ssvv__mmeeaassuurree(()) - - - int comedi_sv_measure(comedi_sv_t *it,double *data); - - comedi_sv_measure measures the slow variing signal. The measurement is - specified by the slow varying comedi structure sv, the result is - stored in data. On success returns the number of samples, -1 on - error. - - Source: /lib/sv.c - - - - 66..33..3344.. ccoommeeddii__ttoo__pphhyyss(()) - - - 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 rng represents the - conversion information to use, and the parameter maxdata represents - the maximum possible data value for the channel that the data was - read. - - Source: /lib/range.c - - - - 66..33..3355.. ccoommeeddii__ttrriiggggeerr(()) ((ddeepprreeccaatteedd)) - - - int comedi_trigger(comedi_t *it,comedi_trig *trig); - - The function comedi_trigger instructs comedi to perform the command - specified by the ``trigger structure'' trig. Results depend on the - particular command being issued. If there is an error, -1 is - returned. - - Lifetime: removal at 1.0. - - Source: /lib/comedi.c - - - - 66..33..3366.. ccoommeeddii__ggeett__ssuubbddeevviiccee__ffllaaggss(()) - - - int comedi_get_subdevice_flags(comedi_t *dev, unsigned int subdevice); - - - This function returns a bitfield describing the capabilities of the - specified subdevice. If there is an error, -1 is returned. - - - The bits are: - - - +o SDF_BUSY subdevice is running a command - - +o SDF_BUSY_OWNER subdevice is running a command started by the file - descriptor used by dev. - - +o SDF_LOCKED subdevice is locked - - +o SDF_LOCKED_OWNER subdevice is locked by the file descriptor - used by dev. - - +o SDF_MAXDATA maximum data values are channel dependent - - +o SDF_FLAGS channel flags are channel dependent - - +o SDF_RANGETYPE range types are channel dependent - - +o SDF_MODE0 deprecated - - +o SDF_MODE1 deprecated - - +o SDF_MODE2 deprecated - - +o SDF_MODE3 deprecated - - +o SDF_MODE4 deprecated - - +o SDF_CMD subdevice supports commands - - +o SDF_READABLE subdevice can be read from - - +o SDF_WRITEABLE subdevice can be written to - - +o SDF_RT deprecated - - +o SDF_GROUND subdevice is capable of ground analog reference - - +o SDF_COMMON subdevice is capable of common analog reference - - +o SDF_DIFF subdevice is capable of differential analog - reference - - +o SDF_OTHER subdevice is capable of other analog - reference - - +o SDF_DITHER subdevice recognizes dither flag - - +o SDF_DEGLITCH subdevice recognizes deglitch flag - - +o SDF_MMAP deprecated - - +o SDF_RUNNING subdevice is acquiring data (i.e., command has not - completed) - - +o SDF_LSAMPL subdevice uses samples of type lsampl_t (otherwise - sampl_t) - - +o SDF_PACKED subdevice uses bitfield samples (otherwise it uses - one sample per channel) - - - - The bit definitions are part of the Comedi kernel interface. - - - - 66..33..3377.. ccoommeeddii__rraannggee__iiss__cchhaann__ssppeecciiffiicc(()) - - - int comedi_range_is_chan_specific(comedi_t *dev,unsigned int - subdevice); - - - 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. - - - - 66..33..3388.. UUnnddooccuummeenntteedd ffuunnccttiioonnss - - - - +o comedi_maxdata_is_chan_specific() - - +o comedi_get_buffer_size() - - +o comedi_get_max_buffer_size() - - +o comedi_set_buffer_size() - - +o comedi_set_max_buffer_size() - - +o comedi_do_insnlist() - - +o comedi_do_insn() - - +o comedi_lock() - - +o comedi_unlock() - - +o comedi_get_cmd_src_mask() - - +o comedi_get_cmd_generic_timed() - - +o comedi_cancel() - - +o comedi_poll() - - +o comedi_get_buffer_contents() - - +o comedi_mark_buffer_read() - - +o comedi_get_buffer_offset() - - +o comedi_set_global_oor_behavior() - - -

2.1 Compiling and Installing -

2.2 Insmod'ding the kernel module -

2.3 Configuring comedi for your hardware -

2.4 Getting information from comedi -

3.1 National Instruments AT-MIO E series -

3.2 Data Translation -

4.1 Your first comedi program -

4.2 Converting samples to voltages -

4.3 Another section -

4.4 Your second comedi program -

5.1 Digital Input/Output -

5.2 Slowly-varying inputs -

5.3 Commands -

6.1 Constants and Macros -

CR_PACK()

RANGE_LENGTH() (deprecated)

6.2 Data Types and Structures -

comedi_t

sampl_t

lsampl_t

comedi_trig_struct (deprecated)

comedi_sv_t

comedi_cmd

comedi_insn

comedi_range

6.3 Functions -

comedi_close()

comedi_command()

comedi_command_test()

comedi_data_read()

comedi_data_write()

comedi_dio_bitfield();

comedi_dio_config()

comedi_dio_read()

comedi_dio_write()

comedi_fileno()

comedi_find_range()

comedi_errno()

comedi_find_subdevice_by_type()

comedi_from_phys()

comedi_get_board_name()

comedi_get_cmd_src_mask()

comedi_get_driver_name()

comedi_get_maxdata()

comedi_get_n_channels()

comedi_get_n_ranges()

comedi_get_n_subdevices()

comedi_get_range()

comedi_get_rangetype() deprecated

comedi_get_subdevice_type()

comedi_get_timer() (deprecated)

comedi_get_version_code()

comedi_loglevel()

comedi_open()

comedi_perror()

comedi_strerror()

comedi_sv_init()

comedi_sv_update()

int comedi_sv_measure()

comedi_to_phys()

comedi_trigger() (deprecated)

comedi_get_subdevice_flags()

comedi_range_is_chan_specific()

Undocumented functions

Comedi Documentation

David Schleef ds@stm.lbl.gov, -Frank Hess fmhess@uiuc.edu

David Schleef `ds@stm.lbl.gov`, -Frank Hess `fmhess@uiuc.edu`