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Added a table with descriptions of a few configuration instructions.

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Frank Mori Hess 2006-10-25 19:57:49 +00:00
parent 01da122c40
commit 2d38396fcb
1 changed files with 112 additions and 16 deletions
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@ -1,4 +1,4 @@
<!-- <!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook V3.1//EN"> -->
<!-- <!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook V4.3//EN"> -->
<section id="acquisitionfunctions">
@ -244,7 +244,7 @@ data structure:
struct <anchor id="insn-data-structure">comedi_insn_struct{
<anchor id="insn-data-structure-insn">unsigned int insn; // integer encoding the type of acquisition
// (or configuration)
unsigned int n; // number of samples
unsigned int n; // number of elements in data array
<link linkend="ref-type-lsampl-t">lsampl_t</link> <anchor id="insn-data-structure-data">*data; // pointer to data buffer
unsigned int subdev; // subdevice
unsigned int <anchor id="insn-data-structure-chanspec"><link linkend="ref-macro-CR-PACK">chanspec</link>; // encoded channel specification
@ -344,7 +344,7 @@ Instructions for configuration
<para>
<xref linkend="instructions"> explains how instructions are used to do
<emphasis>acquisition</emphasis> on channels. This section explains
how they are used to <emphasis>configure</emphasis> a device.
how they are used to <emphasis>configure</emphasis> a subdevice.
There are various sorts of configurations, and the
specific information for each different configuration possibility is
to be specified via the
@ -362,22 +362,118 @@ Using INSN_CONFIG as the
indicates that the instruction will
<emphasis>not perform acquisition</emphasis> on a
channel, but will <emphasis>configure</emphasis> that channel.
For example, the configuration of digital I/O channels is done as
follows. The
The
<link linkend="ref-macro-CR-PACK">chanspec</link> field in the
<link linkend="insn-data-structure-chanspec">comedi_insn</link>
data structure, contains the channel to be configured. And
<link linkend="insn-data-structure-data">data</link>[0] contains
either COMEDI_INPUT or COMEDI_OUTPUT, depending on the desired
direction of the digital I/O lines.
On typical devices, multiple channels are grouped together in blocks
for determining their direction. And configuring one channel in a
block configures the entire block.
data structure, contains the channel to be configured.
The zeroth element of the data array
is always an id that specifies
what type of configuration instruction is being performed. The
meaning of rest of the elements in the data array
depend on the configuration instruction id.
Some of the
possible ids are summarised in the table below, along with the
meanings of the data array elements for
each type of configuration instruction.
</para>
<informaltable>
<tgroup cols='4' align='left'>
<thead>
<row>
<entry>data[0]</entry>
<entry>Description</entry>
<entry>n (number of elements in data array)</entry>
<entry>Meanings of data[1], ..., data[n-1]</entry>
</row>
</thead>
<tbody>
<row>
<entry>INSN_CONFIG_DIO_INPUT</entry>
<entry>
Configure a dio line as input. It is easier to use comedi_dio_config() than
to use this configuration instruction directly.
</entry>
<entry>1</entry>
<entry>
n/a
</entry>
</row>
<row>
<entry>INSN_CONFIG_DIO_OUTPUT</entry>
<entry>
Configure a dio line as output. It is easier to use comedi_dio_config() than
to use this configuration instruction directly.
</entry>
<entry>1</entry>
<entry>
n/a
</entry>
</row>
<row>
<entry>INSN_CONFIG_ALT_SOURCE</entry>
<entry>
Select an alternate input source. This instruction is
used by comedi_calibrate to configure analog input channels
which can be redirected to read internal calibration
references. You need to set the CR_ALT_SOURCE flag in the chanspec
when reading to actually read from the configured alternate input source.
If you are using comedi_data_read(), then the channel parameter can be
bitwise or'd with the CR_ALT_SOURCE flag.
</entry>
<entry>2</entry>
<entry>
<simplelist type='vert' columns='1'>
<member>
data[1]: alternate input source.
</member>
</simplelist>
</entry>
</row>
<row>
<entry>INSN_CONFIG_BLOCK_SIZE</entry>
<entry>
Specify block size for asynchonous command data.
When performing streaming input, many boards accumulate
samples in internal fifos and transfer them to the host
computer in chunks. Some drivers let you suggest a size in bytes for how big a
the chunks should be. This lets you tune how often the host computer is
interrupted with a new chunk of data.
</entry>
<entry>2</entry>
<entry>
<simplelist type='vert' columns='1'>
<member>
data[1]: The desired block size in bytes. The actual configured block size is
writen back to data[1] after the instruction completes. This instruction
acts purely as a query if the block size is set to zero.
</member>
</simplelist>
</entry>
</row>
<row>
<entry>INSN_CONFIG_DIO_QUERY</entry>
<entry>
Queries the configuration of a dio line to see if it is an input or output.
It is probably easier to use the comedilib function comedi_dio_get_config()
than to use this instruction directly.
</entry>
<entry>2</entry>
<entry>
<simplelist type='vert' columns='1'>
<member>
data[1]: The instruction sets this element to either COMEDI_INPUT or COMEDI_OUTPUT.
</member>
</simplelist>
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>
Another example of an INSN_CONFIG instruction is the configuration of
the <link linkend="trigother-event">TRIG_OTHER</link> event source.
See the comedilib demo program demo/choose_clock.c for an example
of using a configuration instruction.
</para>
</section>
@ -1766,7 +1862,7 @@ clock.
</entry>
</row>
<row>
<entry>unsigned NI_MIO_PLL_RTSI_CLOCK(unsigned n)</entry>
<entry><programlisting>unsigned NI_MIO_PLL_RTSI_CLOCK(unsigned n)</programlisting></entry>
<entry>
Only available for newer m-series boards.
The function returns a clock source which will cause the board's
@ -1856,7 +1952,7 @@ DAQ-STC Technical Reference Manual for more information.
</entry>
</row>
<row>
<entry>unsigned NI_RTSI_OUTPUT_RTSI_BRD(unsigned n)</entry>
<entry><programlisting>unsigned NI_RTSI_OUTPUT_RTSI_BRD(unsigned n)</programlisting></entry>
<entry>
RTSI_BRD0 though RTSI_BRD3 are four internal signals which can
have various other signals routed to them in turn. Currently, comedi