RTSI documentation from terry1@beam.ltd.uk (Terry Barnaby)
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doc/other.sgml
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doc/other.sgml
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@ -1693,6 +1693,260 @@ Notes: How to specify which events cause a latch and push, and what
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should get latched?
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</para>
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</section>
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<section id="RTSI">
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<title>
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National instruments RTSI trigger bus
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</title>
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<para>
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A number of NI boards support the RTSI bus. The RTSI Bus consists of an 48 pin
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IDC connector on the PCI-6143 and special bus signal lines on PXI boards.
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It's primary use is to synchronise multiple DAQ cards together.
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There are 8 digital signal lines that are bi-directional. Each of these signal lines
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can be configured as an input or output also the signal appearing on the output
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can be configured to one of many internal board timing signals. We have added
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basic RSTI support to enable a board to be set as a master and other boards to
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be set as slaves. To simplify the API and code we have hard-coded the actual
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set of internal timing signals that appear on the RTSI lines and just provide
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the ability to set the I/O direction of the lines. It would be good to add a
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new configure command to set up this routing to a different setup. The COMEDI
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API is provided as a Digital I/O subdevice number 10 with an extra config
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command to set up the master clock mode. This provides a number of configure
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commands through the COMEDI config API which can be accessed using the
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comedi_do_insn(), comedi_dio_config() and comedi_dio_get_config() functions.
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The config API calls are:
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</para>
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<informaltable>
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<tgroup cols='2' align='left'>
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<thead>
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<row>
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<entry>API Command</entry>
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<entry>Description</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>INSN_CONFIG_SET_RTSI_CLOCK_MODE</entry>
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<entry>
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This sets the boards main clock
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mode. The argument defines the setting as one of:
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COMEDI_RTSI_CLOCK_MODE_INTERNAL - Internal Clock.
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COMEDI_RTSI_CLOCK_MODE_OUTPUT - Run from internal clock and output this
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on the RTSI bus bit as RTSI_7.
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COMEDI_RTSI_CLOCK_MODE_SLAVE - Run from the clock on the RTSI bus bit
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RTSI_7.
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COMEDI_RTSI_CLOCK_MODE_MASTER - Output the clock on the RTSI bus bit as
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RTSI_7 and run from this external clock.
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</entry>
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</row>
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<row>
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<entry>INSN_CONFIG_DIO_OUTPUT</entry>
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<entry>
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Configure the "channel" bit as
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an output. Channel is one of NI_RTSI_[0-6]
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</entry>
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</row>
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<row>
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<entry>INSN_CONFIG_DIO_INPUT</entry>
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<entry>
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Configure the "channel" bit as
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an input. Channel is one of NI_RTSI_[0-6].
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</entry>
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</row>
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<row>
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<entry>INSN_CONFIG_DIO_QUERY</entry>
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<entry>
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Find the direction of one of the
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RTSI "channels". Channel is one of NI_RTSI_[0-6].
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>
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The RTSI bus pins and default output routing is:
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</para>
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<informaltable>
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<tgroup cols='2' align='left'>
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<thead>
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<row>
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<entry>Name</entry>
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<entry>Standard Routing</entry>
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<entry>Pin</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>RTSI_0
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</entry>
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<entry>NI_RTSI_STD_AI_START1
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</entry>
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<entry>20
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</entry>
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</row>
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<row>
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<entry>RTSI_1</entry>
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<entry>NI_RTSI_STD_AI_START2
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</entry>
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<entry>22
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</entry>
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</row>
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<row>
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<entry>RTSI_2</entry>
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<entry>NI_RTSI_STD_AI_CONV
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</entry>
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<entry>24
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</entry>
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</row>
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<row>
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<entry>RTSI_3</entry>
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<entry>NI_RTSI_STD_CT1_SRC
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</entry>
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<entry>26
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</entry>
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</row>
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<row>
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<entry>RTSI_4</entry>
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<entry>NI_RTSI_STD_CT1_GATE
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</entry>
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<entry>28
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</entry>
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</row>
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<row>
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<entry>RTSI_5</entry>
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<entry>NI_RTSI_STD_AO_SAMP_CLOCK
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</entry>
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<entry>30
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</entry>
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</row>
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<row>
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<entry>RTSI_6</entry>
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<entry>NI_RTSI_STD_AO_START_TRIG
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</entry>
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<entry>32
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</entry>
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</row>
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<row>
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<entry>RTSI_7 or RTSI_CLK
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</entry>
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<entry>Master Clock
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</entry>
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<entry>34
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>
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The RTSI bus pins are available to be used as trigger inputs for many of the
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COMEDI trigger functions. To use the RTSI bus pins set the source to be
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TRIG_EXT and the source argument to be a value between 10 and 16 corresponding
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to RTSI_0 through RTSI_6. We have provided the defines NI_EXT_PFI_[0-9] and
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NI_EXT_RTSI_[0-6] to define all the available external trigger sources.
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</para>
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<para>
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A simple example to set up a device as a master is given below.
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</para>
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<programlisting><![CDATA[
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void comediEnableMaster(comedi_t* dev){
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comedi_insn configCmd;
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lsampl_t configData[2];
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int ret;
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unsigned int d = 0;
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// Configure the PFI bus device
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memset(&configCmd, 0, sizeof(configCmd));
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memset(&configData, 0, sizeof(configData));
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configCmd.insn = INSN_CONFIG;
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configCmd.subdev = 10;
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configCmd.chanspec = 0;
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configCmd.n = 2;
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configCmd.data = configData;
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configCmd.data[0] = INSN_CONFIG_SET_RTSI_CLOCK_MODE;
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configCmd.data[1] = COMEDI_RTSI_CLOCK_MODE_MASTER;
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ret = comedi_do_insn(dev, &configCmd);
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if(ret < 0){
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comedi_perror("comedi_command: INSN_CONFIG");
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exit(1);
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}
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// Set direction of the 3 main AI RTSI signals to output
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ret = comedi_dio_config(dev, 10, NI_RTSI_0, INSN_CONFIG_DIO_OUTPUT);
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ret = comedi_dio_config(dev, 10, NI_RTSI_1, INSN_CONFIG_DIO_OUTPUT);
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ret = comedi_dio_config(dev, 10, NI_RTSI_2, INSN_CONFIG_DIO_OUTPUT);
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}
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]]></programlisting>
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<para>
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An example to slave a device from this master follows:
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</para>
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<programlisting><![CDATA[
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void comediEnableSlave(comedi_t* dev){
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comedi_insn configCmd;
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lsampl_t configData[2];
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int ret;
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unsigned int d = 0;;
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// Configure the PFI bus device
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memset(&configCmd, 0, sizeof(configCmd));
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memset(&configData, 0, sizeof(configData));
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configCmd.insn = INSN_CONFIG;
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configCmd.subdev = 10;
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configCmd.chanspec = 0;
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configCmd.n = 2;
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configCmd.data = configData;
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configCmd.data[0] = INSN_CONFIG_SET_RTSI_CLOCK_MODE;
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configCmd.data[1] = COMEDI_RTSI_CLOCK_MODE_SLAVE;
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ret = comedi_do_insn(dev, &configCmd);
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if(ret < 0){
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comedi_perror("comedi_command: INSN_CONFIG");
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exit(1);
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}
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}
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int comediSlaveStart(comedi_t* dev){
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comedi_cmd cmd;
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unsigned int nChannels = 8;
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double sampleRate = 50000;
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unsigned int chanList[8];
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int i;
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// Setup chan list
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for(i = 0; i < nChannels; i++){
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chanList[i] = CR_PACK(i, 0, AREF_GROUND);
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}
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// Set up command
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memset(&cmd, 0, sizeof(cmd));
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ret = comedi_get_cmd_generic_timed(dev, subdevice, &cmd, int(1e9/(nChannels * sampleRate)));
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if(ret<0){
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printf("comedi_get_cmd_generic_timed failed\n");
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return ret;
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}
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cmd.chanlist = chanList;
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cmd.chanlist_len = nChannels;
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cmd.scan_end_arg = nChannels;
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cmd.start_src = TRIG_EXT;
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cmd.start_arg = CR_EDGE | NI_EXT_RTSI_0;
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cmd.convert_src = TRIG_EXT;
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cmd.convert_arg = CR_INVERT | CR_EDGE | NI_EXT_RTSI_2;
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cmd.stop_src = TRIG_NONE;
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ret = comedi_command(dev0, &cmd0);
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if(ret<0){
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printf("comedi_command failed\n");
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return ret;
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}
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return 0;
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}
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]]></programlisting>
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</section>
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</section>
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