<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
- "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
+ "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
<!ENTITY % comedilib_entities SYSTEM "comedilib.ent">
%comedilib_entities;
]>
Individual bits on a digital I/O device can be read and written using
the functions
<programlisting>
- int <link linkend="func-ref-comedi-dio-read">comedi_dio_read</link>(device,subdevice,channel,unsigned int *bit);
- int <link linkend="func-ref-comedi-dio-write">comedi_dio_write</link>(device,subdevice,channel,unsigned int bit);
+int <link linkend="func-ref-comedi-dio-read">comedi_dio_read</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice, unsigned int channel,
+ unsigned int *bit);
+int <link linkend="func-ref-comedi-dio-write">comedi_dio_write</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice, unsigned int channel,
+ unsigned int bit);
</programlisting>
The <parameter class="function">device</parameter> parameter is a
<link linkend="ref-type-comedi-t">pointer</link>
The direction of bidirectional lines can be configured using
the function
<programlisting>
- <link linkend="func-ref-comedi-dio-config">comedi_dio_config</link>(device,subdevice,channel,unsigned int dir);
+int <link linkend="func-ref-comedi-dio-config">comedi_dio_config</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice, unsigned int channel,
+ unsigned int dir);
</programlisting>
The parameter <parameter class="function">dir</parameter> should be
either <literal>COMEDI_INPUT</literal> or
Multiple channels can be read and written simultaneously using the
function
<programlisting>
- <link linkend="func-ref-comedi-dio-bitfield">comedi_dio_bitfield</link>(device,subdevice,unsigned int write_mask,unsigned int *bits);
+int <link linkend="func-ref-comedi-dio-bitfield">comedi_dio_bitfield</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice,
+ unsigned int write_mask, unsigned int *bits);
</programlisting>
Each channel is assigned to a bit in the
<parameter class="function">write_mask</parameter> and
<para>
The
<programlisting>
- int <link linkend="func-ref-comedi-data-read">comedi_data_read</link>(<link linkend="ref-type-comedi-t">comedi_t</link> * device, unsigned int subdevice, unsigned int channel,
- unsigned int range, unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> * data);
+int <link linkend="func-ref-comedi-data-read">comedi_data_read</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice, unsigned int channel,
+ unsigned int range, unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> * data);
</programlisting>
function reads one such data value from a &comedi; channel, and puts it in
the user-specified <parameter>data</parameter> buffer. The
<programlisting>
- int <link linkend="func-ref-comedi-data-write">comedi_data_write</link>(<link linkend="ref-type-comedi-t">comedi_t</link> * device, unsigned int subdevice, unsigned int channel,
- unsigned int range, unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> data);
+int <link linkend="func-ref-comedi-data-write">comedi_data_write</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice, unsigned int channel,
+ unsigned int range, unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> data);
</programlisting>
works in the opposite direction. Data values returned by this function
are unsigned integers less than, or equal to, the maximum sample value
of the channel, which can be determined using the function
<programlisting>
- <link linkend="ref-type-lsampl-t">lsampl_t</link> <link linkend="func-ref-comedi-get-maxdata">comedi_get_maxdata</link>(<link linkend="ref-type-comedi-t">comedi_t</link> * device, unsigned int subdevice, unsigned int channel);
+<link linkend="ref-type-lsampl-t">lsampl_t</link> <link linkend="func-ref-comedi-get-maxdata">comedi_get_maxdata</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice,
+ unsigned int channel);
</programlisting>
Conversion of data values to physical units can be performed by the
function
<programlisting>
- double <link linkend="func-ref-comedi-to-phys">comedi_to_phys</link>(<link linkend="ref-type-lsampl-t">lsampl_t</link> data, comedi_range * range, <link linkend="ref-type-lsampl-t">lsampl_t</link> maxdata);
+double <link linkend="func-ref-comedi-to-phys">comedi_to_phys</link>(<link linkend="ref-type-lsampl-t">lsampl_t</link> data, comedi_range * range, <link linkend="ref-type-lsampl-t">lsampl_t</link> maxdata);
</programlisting>
There are two data structures in these commands that are not fully
self-explanatory:
the same channel, this overhead can be avoided by using a function
that can read more than one sample:
<programlisting>
- int <link linkend="func-ref-comedi-dio-read">comedi_data_read_n</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *it, unsigned int subdev, unsigned int chan, unsigned int range,
- unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> *data, unsigned int n)
+int <link linkend="func-ref-comedi-data-read-n">comedi_data_read_n</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *it, unsigned int subdev, unsigned int chan,
+ unsigned int range, unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> *data, unsigned int n);
</programlisting>
The number of samples, <parameter class="function">n</parameter>, is
limited by the &comedi; implementation (to a maximum of 100 samples),
The start of the data acquisition can also be delayed by a specified
number of nano-seconds:
<programlisting>
-int <link linkend="func-ref-comedi-data-read-delayed">comedi_data_read_delayed</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *it, unsigned int subdev, unsigned int chan, unsigned int range,
- unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> *data, unsigned int nano_sec)
+int <link linkend="func-ref-comedi-data-read-delayed">comedi_data_read_delayed</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *it, unsigned int subdev, unsigned int chan,
+ unsigned int range, unsigned int aref, <link linkend="ref-type-lsampl-t">lsampl_t</link> *data,
+ unsigned int nano_sec);
</programlisting>
All these read and write acquisition functions are implemented on top
of the generic <link linkend="instructions">instruction</link>
<link linkend="ref-type-comedi-insn">comedi_insn</link>
data structure:
<programlisting>
-struct <anchor id="insn-data-structure"/>comedi_insn_struct{
+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 elements in data array
Once an instruction data structure has been filled in, the
corresponding instruction is executed as follows:
<programlisting>
- int <link linkend="func-ref-comedi-do-insn">comedi_do_insn</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *it, <link linkend="ref-type-comedi-insn">comedi_insn</link> * instruction);
+int <link linkend="func-ref-comedi-do-insn">comedi_do_insn</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *it, <link linkend="ref-type-comedi-insn">comedi_insn</link> *instruction);
</programlisting>
Many &comedi; instructions are shortcuts that relieve the programmer
from explicitly filling in the data structure and calling the
<para>
The
<programlisting>
- int <link linkend="func-ref-comedi-do-insnlist">comedi_do_insnlist</link><link linkend="ref-type-comedi-t">comedi_t</link> *it, <link linkend="ref-type-comedi-insnlist">comedi_insnlist</link> * list)
+int <link linkend="func-ref-comedi-do-insnlist">comedi_do_insnlist</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *it, <link linkend="ref-type-comedi-insnlist">comedi_insnlist</link> *list)
</programlisting>
instruction allows to perform a list of instructions in one function
call. The number of instructions in the list is limited in the
<para>
A commands is executed by the following &comedi; function:
<programlisting>
- int <link linkend="func-ref-comedi-command">comedi_command</link>(<link linkend="ref-type-comedi-t">comedi_t</link> * device, <link linkend="ref-type-comedi-cmd">comedi_cmd</link> * command);
+int <link linkend="func-ref-comedi-command">comedi_command</link>(<link linkend="ref-type-comedi-t">comedi_t</link> *device, <link linkend="ref-type-comedi-cmd">comedi_cmd</link> *command);
</programlisting>
The following sections explain the meaning of the
<link linkend="ref-type-comedi-cmd">comedi_cmd</link> data structure.
<programlisting>
typedef struct comedi_cmd_struct comedi_cmd;
-struct comedi_cmd_struct{
+struct comedi_cmd_struct {
unsigned int subdev; // which subdevice to sample
unsigned int <anchor id="command-data-struct-flags"/>flags; // encode some configuration possibilities
// of the command execution; e.g.,
to help you in your quest to accurately measure slowly varying
inputs:
<programlisting>
- int <link linkend="func-ref-comedi-sv-init">comedi_sv_init</link>(<link linkend="ref-type-comedi-sv-t">comedi_sv_t</link> * sv, <link linkend="ref-type-comedi-t">comedi_t</link> * device, unsigned int subdevice, unsigned int channel);
+int <link linkend="func-ref-comedi-sv-init">comedi_sv_init</link>(<link linkend="ref-type-comedi-sv-t">comedi_sv_t</link> *sv, <link linkend="ref-type-comedi-t">comedi_t</link> *device, unsigned int subdevice,
+ unsigned int channel);
</programlisting>
This function initializes the
<link linkend="ref-type-comedi-sv-t">comedi_sv_t</link> data structure, used
to do the averaging acquisition:
<programlisting>
-struct comedi_sv_struct{
+struct comedi_sv_struct {
<link linkend="ref-type-comedi-t">comedi_t</link> *dev;
unsigned int subdevice;
unsigned int chan;
</programlisting>
The actual acquisition is done with:
<programlisting>
- int <link linkend="func-ref-comedi-sv-measure">comedi_sv_measure</link>(<link linkend="ref-type-comedi-sv-t">comedi_sv_t</link> * sv, double * data);
+int <link linkend="func-ref-comedi-sv-measure">comedi_sv_measure</link>(<link linkend="ref-type-comedi-sv-t">comedi_sv_t</link> *sv, double *data);
</programlisting>
The number of samples over which the
<function>comedi_sv_measure()</function> averages is limited by the
</para>
<programlisting><![CDATA[
-void comediEnableMaster(comedi_t* dev){
- comedi_insn configCmd;
- lsampl_t configData[2];
- int ret;
- unsigned int d = 0;
- static const unsigned rtsi_subdev = 10;
- static const unsigned rtsi_clock_line = 7;
-
- /* Route RTSI clock to line 7 (not needed on pre-m-series boards since their
- clock is always on line 7). */
- memset(&configCmd, 0, sizeof(configCmd));
- memset(&configData, 0, sizeof(configData));
- configCmd.insn = INSN_CONFIG;
- configCmd.subdev = rtsi_subdev;
- configCmd.chanspec = rtsi_clock_line;
- configCmd.n = 2;
- configCmd.data = configData;
- configCmd.data[0] = INSN_CONFIG_SET_ROUTING;
- configCmd.data[1] = NI_RTSI_OUTPUT_RTSI_OSC;
- ret = comedi_do_insn(dev, &configCmd);
- if(ret < 0){
- comedi_perror("comedi_do_insn: INSN_CONFIG");
- exit(1);
- }
- // Set clock RTSI line as output
- ret = comedi_dio_config(dev, rtsi_subdev, rtsi_clock_line, INSN_CONFIG_DIO_OUTPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
-
- /* Set routing of the 3 main AI RTSI signals and their direction to output.
- We're reusing the already initialized configCmd instruction here since
- it's mostly the same. */
- configCmd.chanspec = 0;
- configCmd.data[1] = NI_RTSI_OUTPUT_ADR_START1;
- ret = comedi_do_insn(dev, &configCmd);
- if(ret < 0){
- comedi_perror("comedi_do_insn: INSN_CONFIG");
- exit(1);
- }
- ret = comedi_dio_config(dev, rtsi_subdev, 0, INSN_CONFIG_DIO_OUTPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
-
- configCmd.chanspec = 1;
- configCmd.data[1] = NI_RTSI_OUTPUT_ADR_START2;
- ret = comedi_do_insn(dev, &configCmd);
- if(ret < 0){
- comedi_perror("comedi_do_insn: INSN_CONFIG");
- exit(1);
- }
- ret = comedi_dio_config(dev, rtsi_subdev, 1, INSN_CONFIG_DIO_OUTPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
-
- configCmd.chanspec = 2;
- configCmd.data[1] = NI_RTSI_OUTPUT_SCLKG;
- ret = comedi_do_insn(dev, &configCmd);
- if(ret < 0){
- comedi_perror("comedi_do_insn: INSN_CONFIG");
- exit(1);
- }
- ret = comedi_dio_config(dev, rtsi_subdev, 2, INSN_CONFIG_DIO_OUTPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
+void comediEnableMaster(comedi_t *dev){
+ comedi_insn configCmd;
+ lsampl_t configData[2];
+ int ret;
+ unsigned int d = 0;
+ static const unsigned rtsi_subdev = 10;
+ static const unsigned rtsi_clock_line = 7;
+
+ /* Route RTSI clock to line 7 (not needed on pre-m-series boards since their
+ clock is always on line 7). */
+ memset(&configCmd, 0, sizeof(configCmd));
+ memset(&configData, 0, sizeof(configData));
+ configCmd.insn = INSN_CONFIG;
+ configCmd.subdev = rtsi_subdev;
+ configCmd.chanspec = rtsi_clock_line;
+ configCmd.n = 2;
+ configCmd.data = configData;
+ configCmd.data[0] = INSN_CONFIG_SET_ROUTING;
+ configCmd.data[1] = NI_RTSI_OUTPUT_RTSI_OSC;
+ ret = comedi_do_insn(dev, &configCmd);
+ if(ret < 0){
+ comedi_perror("comedi_do_insn: INSN_CONFIG");
+ exit(1);
+ }
+ // Set clock RTSI line as output
+ ret = comedi_dio_config(dev, rtsi_subdev, rtsi_clock_line, INSN_CONFIG_DIO_OUTPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
+
+ /* Set routing of the 3 main AI RTSI signals and their direction to output.
+ We're reusing the already initialized configCmd instruction here since
+ it's mostly the same. */
+ configCmd.chanspec = 0;
+ configCmd.data[1] = NI_RTSI_OUTPUT_ADR_START1;
+ ret = comedi_do_insn(dev, &configCmd);
+ if(ret < 0){
+ comedi_perror("comedi_do_insn: INSN_CONFIG");
+ exit(1);
+ }
+ ret = comedi_dio_config(dev, rtsi_subdev, 0, INSN_CONFIG_DIO_OUTPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
+
+ configCmd.chanspec = 1;
+ configCmd.data[1] = NI_RTSI_OUTPUT_ADR_START2;
+ ret = comedi_do_insn(dev, &configCmd);
+ if(ret < 0){
+ comedi_perror("comedi_do_insn: INSN_CONFIG");
+ exit(1);
+ }
+ ret = comedi_dio_config(dev, rtsi_subdev, 1, INSN_CONFIG_DIO_OUTPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
+
+ configCmd.chanspec = 2;
+ configCmd.data[1] = NI_RTSI_OUTPUT_SCLKG;
+ ret = comedi_do_insn(dev, &configCmd);
+ if(ret < 0){
+ comedi_perror("comedi_do_insn: INSN_CONFIG");
+ exit(1);
+ }
+ ret = comedi_dio_config(dev, rtsi_subdev, 2, INSN_CONFIG_DIO_OUTPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
}
]]></programlisting>
best syncronization).
</para>
<programlisting><![CDATA[
-void comediEnableSlave(comedi_t* dev){
- comedi_insn configCmd;
- lsampl_t configData[3];
- int ret;
- unsigned int d = 0;;
- static const unsigned rtsi_subdev = 10;
- static const unsigned rtsi_clock_line = 7;
-
- memset(&configCmd, 0, sizeof(configCmd));
- memset(&configData, 0, sizeof(configData));
- configCmd.insn = INSN_CONFIG;
- configCmd.subdev = rtsi_subdev;
- configCmd.chanspec = 0;
- configCmd.n = 3;
- configCmd.data = configData;
- configCmd.data[0] = INSN_CONFIG_SET_CLOCK_SRC;
- configCmd.data[1] = NI_MIO_PLL_RTSI_CLOCK(rtsi_clock_line);
- configCmd.data[2] = 100; /* need to give it correct external clock period */
- ret = comedi_do_insn(dev, &configCmd);
- if(ret < 0){
- comedi_perror("comedi_do_insn: INSN_CONFIG");
- exit(1);
- }
- /* configure RTSI clock line as input */
- ret = comedi_dio_config(dev, rtsi_subdev, rtsi_clock_line, INSN_CONFIG_DIO_INPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
- /* Configure RTSI lines we are using for AI signals as inputs. */
- ret = comedi_dio_config(dev, rtsi_subdev, 0, INSN_CONFIG_DIO_INPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
- ret = comedi_dio_config(dev, rtsi_subdev, 1, INSN_CONFIG_DIO_INPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
- ret = comedi_dio_config(dev, rtsi_subdev, 2, INSN_CONFIG_DIO_INPUT);
- if(ret < 0){
- comedi_perror("comedi_dio_config");
- exit(1);
- }
+void comediEnableSlave(comedi_t *dev){
+ comedi_insn configCmd;
+ lsampl_t configData[3];
+ int ret;
+ unsigned int d = 0;;
+ static const unsigned rtsi_subdev = 10;
+ static const unsigned rtsi_clock_line = 7;
+
+ memset(&configCmd, 0, sizeof(configCmd));
+ memset(&configData, 0, sizeof(configData));
+ configCmd.insn = INSN_CONFIG;
+ configCmd.subdev = rtsi_subdev;
+ configCmd.chanspec = 0;
+ configCmd.n = 3;
+ configCmd.data = configData;
+ configCmd.data[0] = INSN_CONFIG_SET_CLOCK_SRC;
+ configCmd.data[1] = NI_MIO_PLL_RTSI_CLOCK(rtsi_clock_line);
+ configCmd.data[2] = 100; /* need to give it correct external clock period */
+ ret = comedi_do_insn(dev, &configCmd);
+ if(ret < 0){
+ comedi_perror("comedi_do_insn: INSN_CONFIG");
+ exit(1);
+ }
+ /* configure RTSI clock line as input */
+ ret = comedi_dio_config(dev, rtsi_subdev, rtsi_clock_line, INSN_CONFIG_DIO_INPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
+ /* Configure RTSI lines we are using for AI signals as inputs. */
+ ret = comedi_dio_config(dev, rtsi_subdev, 0, INSN_CONFIG_DIO_INPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
+ ret = comedi_dio_config(dev, rtsi_subdev, 1, INSN_CONFIG_DIO_INPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
+ ret = comedi_dio_config(dev, rtsi_subdev, 2, INSN_CONFIG_DIO_INPUT);
+ if(ret < 0){
+ comedi_perror("comedi_dio_config");
+ exit(1);
+ }
}
-int comediSlaveStart(comedi_t* dev){
- comedi_cmd cmd;
- unsigned int nChannels = 8;
- double sampleRate = 50000;
- unsigned int chanList[8];
- int i;
-
- // Setup chan list
- for(i = 0; i < nChannels; i++){
- chanList[i] = CR_PACK(i, 0, AREF_GROUND);
- }
- // Set up command
- memset(&cmd, 0, sizeof(cmd));
- ret = comedi_get_cmd_generic_timed(dev, subdevice, &cmd, int(1e9/(nChannels * sampleRate)));
- if(ret<0){
- printf("comedi_get_cmd_generic_timed failed\n");
- return ret;
- }
- cmd.chanlist = chanList;
- cmd.chanlist_len = nChannels;
- cmd.scan_end_arg = nChannels;
- cmd.start_src = TRIG_EXT;
- cmd.start_arg = CR_EDGE | NI_EXT_RTSI(0);
- cmd.convert_src = TRIG_EXT;
- cmd.convert_arg = CR_INVERT | CR_EDGE | NI_EXT_RTSI(2);
- cmd.stop_src = TRIG_NONE;
-
- ret = comedi_command(dev0, &cmd0);
- if(ret<0){
- printf("comedi_command failed\n");
- return ret;
- }
- return 0;
+int comediSlaveStart(comedi_t *dev){
+ comedi_cmd cmd;
+ unsigned int nChannels = 8;
+ double sampleRate = 50000;
+ unsigned int chanList[8];
+ int i;
+
+ // Setup chan list
+ for(i = 0; i < nChannels; i++){
+ chanList[i] = CR_PACK(i, 0, AREF_GROUND);
+ }
+ // Set up command
+ memset(&cmd, 0, sizeof(cmd));
+ ret = comedi_get_cmd_generic_timed(dev, subdevice, &cmd,
+ (int)(1e9/(nChannels * sampleRate)));
+ if(ret<0){
+ printf("comedi_get_cmd_generic_timed failed\n");
+ return ret;
+ }
+ cmd.chanlist = chanList;
+ cmd.chanlist_len = nChannels;
+ cmd.scan_end_arg = nChannels;
+ cmd.start_src = TRIG_EXT;
+ cmd.start_arg = CR_EDGE | NI_EXT_RTSI(0);
+ cmd.convert_src = TRIG_EXT;
+ cmd.convert_arg = CR_INVERT | CR_EDGE | NI_EXT_RTSI(2);
+ cmd.stop_src = TRIG_NONE;
+
+ ret = comedi_command(dev0, &cmd0);
+ if(ret<0){
+ printf("comedi_command failed\n");
+ return ret;
+ }
+ return 0;
}
]]></programlisting>
projects / comedilib.git / commitdiff