Updates from (someone), plus corrections and additions by ds.
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David Schleef
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1 changed files with 46 additions and 35 deletions
81
demo/README
81
demo/README
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@ -5,27 +5,30 @@ After installing comedi and comedilib, cd to this directory (comedilib*/demo).
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Use ./info for a very first test. If hardware and software are correctly
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installed, the program prints a list of subdevices it recognises. If the
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device is not /dev/comedi0, you can use the command-line option
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'-f <device file>'.
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device is not /dev/comedi0, use here and in the following the command-line
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option -f <device>.
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Continue with ./inp -s <subdevice> -c <channel> to read individual samples,
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or with ./outp -s <subdevice> -c <channel> <integer value> to set an
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output value.
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and with ./outp -s <subdevice> -c <channel> <integer value> to set an
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output value. Other beginning demos are: cmd, dio, inpn, tut1, tut2.
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You should understand how these work before trying to understand the
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other demos.
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The perl subdirectory contains a few examples for the perl wrapper.
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Examples
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DEMO PROGRAMS:
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ao_waveform:
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You need a device (and driver) capable of streaming analog output,
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which currently is some of the members of the NI AT-MIO and PCI-MIO
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E series. Creates a sine wave on an analog output channel.
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cmd:
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An example for using Comedi commands. Comedi commands
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cmd:
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An example for directly using Comedi commands. Comedi commands
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are used for asynchronous acquisition, with the timing controlled
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by on-board timers or external events.
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dio:
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Requirements: A board with a digital I/O subdevice. Not just
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a 'digital input' or 'digital output' subdevice, but one in
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@ -50,38 +53,46 @@ insn:
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Example showing how to use instructions directly. Not
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recommended for beginners: use higher-level functions such
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as comedi_data_read(), comedi_data_write(), etc., as demonstrated
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in the inp, outp, and dio examples.
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in the inp, outp, and dio examples.
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ledclock:
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Requirements: A board with a digital I/O subdevice. Not just
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a 'digital input' or 'digital output' subdevice, but one in
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which the channels can be configured between input and output.
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This demo requires a Fantazein clock modified to be directly
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controlled by the parallel port on a computer. The original
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demo used a real-time task and controlled the parallel port
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directly. This version is not complete.
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main:
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This is not a demo. The file main.c contains just an auxiliary
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function. See below.
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This is not a demo. The file main.c just contains auxiliary
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functions and parses options.
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mmap:
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Similar to the cmd demo, except the data is obtained through
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a memory mapping instead of doing read() on /dev/comediX.
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This example shows how to map the internal Comedi buffer
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and directly access samples instead of using read() and
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write().
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outp:
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Write one <value> to one channel of one subdevice.
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outp <value>:
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Write one <value> to one channel of one subdevice. Requires
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a digital or analog output subdevice.
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receiver:
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Requirements: A board with a digital I/O subdevice. Not just
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a 'digital input' or 'digital output' subdevice, but one in
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which the channels can be configured between input and output.
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This demo is meant to be used in conjunction with the sender
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demo. Receiver requires a digital input subdevice, and sender
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requires a digital output subdevice. When the clock and data
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pins are connected between the sending and receiving devices,
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one should be able to send bits over the link.
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select:
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An example for using select() with asynchronous input. This
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example requires an asynchronous input subdevice that can
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handle TRIG_TIMER as a scan_begin_src.
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sender:
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Requirements: A board with a digital I/O subdevice. Not just
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a 'digital input' or 'digital output' subdevice, but one in
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which the channels can be configured between input and output.
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See receiver.
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sigio:
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Similar to the cmd demo. This demo sets up a signal handler
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for SIGIO, which is called whenever data is ready to be read
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from the device.
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sv:
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Similar to inp, but measures the input using the comedi_sv_*()
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@ -90,23 +101,23 @@ sv:
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tut1:
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tut2:
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Tutorial examples.
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Tutorial examples. See the Comedilib documentation.
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COMMAND-LINE OPTIONS:
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Many of these demos are linked with the file main.c, which parses
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command line options. Some options don't make sense with all programs.
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The options are:
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-a <aref> uses analog reference <aref> (default: 0)
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-c <chan> uses channel <chan>
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-s <subd> uses subdevice <subd>
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-r <range> uses voltage range <range>
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-f <file> uses device file <file> (default: /dev/comedi0)
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-a <aref> use analog reference <aref> (default: 0 == ground)
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-c <chan> use channel <chan> (default: 0)
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-s <subd> use subdevice <subd> (default: 0)
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-r <index> use voltage range <index> (default: 0)
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-f <file> use device file <file> (default: /dev/comedi0)
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-v verbose
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-d set analog reference to differential
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-g set analog reference to ground
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-o set analog reference to other
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-m set analog reference to common
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