GETTING STARTED:
After installing comedi and comedilib, cd to this directory (comedilib*/demo).
Use ./info for a very first test. If hardware and software are correctly
installed, the program prints a list of subdevices it recognises. If the
device is not /dev/comedi0, use here and in the following the command-line
option -f <device>.
Continue with ./inp -s <subdevice> -c <channel> to read individual samples,
and with ./outp -s <subdevice> -c <channel> <integer value> to set an
output value. Other beginning demos are: cmd, dio, inpn, tut1, tut2.
You should understand how these work before trying to understand the
other demos.
The perl subdirectory contains a few examples for the perl wrapper.
DEMO PROGRAMS:
ao_waveform:
You need a device (and driver) capable of streaming analog output,
which currently is some of the members of the NI AT-MIO and PCI-MIO
E series. Creates a sine wave on an analog output channel.
common:
This is not an example. The file common.c just contains some code
that is common to many of the examples.
cmd:
An example for directly using Comedi commands. Comedi commands
are used for asynchronous acquisition, with the timing controlled
by on-board timers or external events.
dio:
Requirements: A board with a digital I/O subdevice. Not just
a 'digital input' or 'digital output' subdevice, but one in
which the channels can be configured between input and output.
eeprom_dump:
Dumps the EEPROM of a card, if it has one. Useful for debugging
devices/drivers.
info:
Displays some information that Comedi knows about a device.
inp:
Simple input: Reads one sample from one channel on one subdevice.
inpn:
Slightly more complicated input demo. (It has a for() loop.)
Reads each channel on a subdevice, at every possible input
range, and converts the data to a voltage.
insn:
Example showing how to use instructions directly. Not
recommended for beginners: use higher-level functions such
as comedi_data_read(), comedi_data_write(), etc., as demonstrated
in the inp, outp, and dio examples.
ledclock:
This demo requires a Fantazein clock modified to be directly
controlled by the parallel port on a computer. The original
demo used a real-time task and controlled the parallel port
directly. This version is not complete.
mmap:
This example shows how to map the internal Comedi buffer
and directly access samples instead of using read() and
write().
outp <value>:
Write one <value> to one channel of one subdevice. Requires
a digital or analog output subdevice.
receiver:
This demo is meant to be used in conjunction with the sender
demo. Receiver requires a digital input subdevice, and sender
requires a digital output subdevice. When the clock and data
pins are connected between the sending and receiving devices,
one should be able to send bits over the link.
select:
An example for using select() with asynchronous input. This
example requires an asynchronous input subdevice that can
handle TRIG_TIMER as a scan_begin_src.
sender:
See receiver.
sigio:
Similar to the cmd demo. This demo sets up a signal handler
for SIGIO, which is called whenever data is ready to be read
from the device.
sv:
Similar to inp, but measures the input using the comedi_sv_*()
functions, which average many samples to try to get a more accurate
estimate of the actual input.
tut1:
tut2:
Tutorial examples. See the Comedilib documentation.
COMMAND-LINE OPTIONS:
Many of these demos are linked with the file common.c, which parses
command line options. Some options don't make sense with all programs.
The options are:
-a <aref> use analog reference <aref> (default: 0 == ground)
-c <chan> use channel <chan> (default: 0)
-s <subd> use subdevice <subd> (default: 0)
-r <index> use voltage range <index> (default: 0)
-f <file> use device file <file> (default: /dev/comedi0)
-n <value> use <value> for the number of channels in a scan
-N <value> use <value> for the number of scans
-F <freq> use <freq> as the scan frequency
-v verbose
-d set analog reference to differential
-g set analog reference to ground
-o set analog reference to other
-m set analog reference to common
