133 lines
5.5 KiB
Text
133 lines
5.5 KiB
Text
Digital I/O
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Function: comedi_dio_bitfield2 -- read/write multiple digital channels
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Retval: int
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Param: comedi_t * device
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Param: unsigned int subdevice
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Param: unsigned int write_mask
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Param: unsigned int * bits
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Param: unsigned int base_channel
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Description:
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The function <function>comedi_dio_bitfield2</function>
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allows multiple channels to
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be read or written together on a digital input, output,
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or configurable digital I/O device.
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The parameter <parameter class="function">write_mask</parameter>
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and the value pointed to by <parameter class="function">bits</parameter>
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are interpreted as bit fields, with the least significant bit
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representing channel <parameter class="function">base_channel</parameter>.
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For each bit in <parameter class="function">write_mask</parameter> that is
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set to 1, the corresponding bit in
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<code language="C">*<parameter class="function">bits</parameter></code>
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is written to the digital
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output channel. After writing all the output channels, each
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channel is read, and the result placed in the approprate bits in
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<code language="C">*<parameter class="function">bits</parameter></code>.
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The result of reading an output channel is the last value written to the
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output channel.
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All the channels might not be read or written at the exact same time.
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For example, the driver may need to sequentially write to
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several registers in order to set all the digital channels specified
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by the <parameter class="function">write_mask</parameter>
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and <parameter class="function">base_channel</parameter> parameters.
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Returns:
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If successful, <literal>0</literal> is returned, otherwise
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<literal>-1</literal>.
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Function: comedi_dio_config -- change input/output properties of channel
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Retval: int
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Param: comedi_t * device
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Param: unsigned int subdevice
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Param: unsigned int channel
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Param: unsigned int direction
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Description:
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The function <function>comedi_dio_config</function> configures individual channels
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in a digital I/O subdevice to be either input or output, depending
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on the value of <parameter class="function">direction</parameter>. Valid directions are
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<constant>COMEDI_INPUT</constant> or <constant>COMEDI_OUTPUT</constant>.
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Depending on the characteristics of the hardware device, multiple
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channels might be grouped together in hardware when
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configuring the input/output direction. In this
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case, a single call to <function>comedi_dio_config</function>
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for any channel in the group will affect the entire group.
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Returns:
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If successful, <literal>0</literal> is returned, otherwise
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<literal>-1</literal>.
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Function: comedi_dio_get_config -- query input/output properties of channel
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Retval: int
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Param: comedi_t * device
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Param: unsigned int subdevice
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Param: unsigned int channel
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Param: unsigned int * direction
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Description:
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The function <function>comedi_dio_get_config</function> queries the input/output configuration of
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an individual channel
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in a digital I/O subdevice (see
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<function><link linkend="func-ref-comedi-dio-config">comedi_dio_config</link></function>).
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On success, <code language="C">*<parameter
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class="function">direction</parameter></code> will
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be set to either <constant>COMEDI_INPUT</constant> or
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<constant>COMEDI_OUTPUT</constant>.
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Returns:
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If successful, <literal>0</literal> is returned, otherwise
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<literal>-1</literal>.
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Function: comedi_dio_read -- read single bit from digital channel
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Retval: int
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Param: comedi_t * device
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Param: unsigned int subdevice
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Param: unsigned int channel
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Param: unsigned int * bit
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Description:
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The function <function>comedi_dio_read</function> reads the channel
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<parameter class="function">channel</parameter>
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belonging to the
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subdevice <parameter class="functioN">subdevice</parameter> of device
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<parameter class="function">device</parameter>.
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The data value that is
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read is stored in the
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<code language="C">*<parameter class="function">bit</parameter></code>.
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This function is equivalent to:
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<programlisting>
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<link linkend="func-ref-comedi-data-read">comedi_data_read</link>(device, subdevice, channel, 0, 0, bit);
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</programlisting>
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This function does not require a digital subdevice or a subdevice
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with a maximum data value of 1 to work properly.
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If you wish to read multiple digital channels at once, it is more efficient to
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use
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<function><link
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linkend="func-ref-comedi-dio-bitfield2">comedi_dio_bitfield2</link></function>
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than to call this function multiple times.
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Returns:
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Return values and errors are the same as
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<function><link linkend="func-ref-comedi-data-read">comedi_data_read</link></function>.
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Function: comedi_dio_write -- write single bit to digital channel
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Retval: int
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Param: comedi_t * device
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Param: unsigned int subdevice
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Param: unsigned int channel
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Param: unsigned int bit
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Description:
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The function writes the value <parameter class="function">bit</parameter> to the channel
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<parameter class="function">channel</parameter> belonging
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to the subdevice <parameter class="function">subdevice</parameter> of device
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<parameter class="function">device</parameter>. This function
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is equivalent to:
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<programlisting>
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<link linkend="func-ref-comedi-data-write">comedi_data_write</link>(device, subdevice, channel, 0, 0, bit);
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</programlisting>
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This function does not require a digital subdevice or a subdevice
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with a maximum data value of 1 to work properly.
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If you wish to write multiple digital channels at once, it is more efficient to
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use
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<function><link
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linkend="func-ref-comedi-dio-bitfield2">comedi_dio_bitfield2</link></function>
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than to call this function multiple times.
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Returns:
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Return values and errors are the same as
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<function><link linkend="func-ref-comedi-data-write">comedi_data_write</link></function>.
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