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<sect1 id="howto">
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<sect1info>
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<author>
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<firstname>Connor</firstname>
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<surname>Wolf</surname>
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</author>
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</sect1info>
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<!-- Only as a comment, as inline presentation is awful in Docbook 4.5
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Imaginary Industries
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imaginaryindustries.com
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Email: lcdproc@imaginaryindustries.com
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-->
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<title>The *Really* Simple Serial interface (rawserial)</title>
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<para>
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This section talks about using LCDproc with custom hardware.
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</para>
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<para>
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This driver is intended for using LCDproc with custom hardware. In the
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original implementation, this was for a PFsense router with a homemade
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arduino-style circuit that controlled analog panel meters to display network
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traffic. It is intended for this sort of application, where the LCD control
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characters emitted normally, as well as the partial screen drawing, make
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parsing the serial stream a considerably complex affair, particularly on
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small (generally 8 bit) microprocessors.
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</para>
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<sect2 id="features">
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<title>Features</title>
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<para>
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The driver emulates a 40x4 display, and simply dumps the entire framebuffer
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out the serial port at a rate configured in the config file (default of 1
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Hz), post-pended with a single "\n" character. At 1 Hz, it therefore
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generates 161 serial characters per second.
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</para>
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<para>
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The maximum update-rate is limited by the internal update-rate of LCDproc,
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which is currently 8 Hz, so speeds greater then 8 Hz will be simply limited
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to 8 Hz. The update-rate is also granular at 1 second/8 time-intervals (125
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ms), so interesting fractional update-rates will behave oddly. The
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event-loop is rigidly deterministic, so fractional rates will *average* out
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to the desired rate, but that will be achieved by dithering between nearby
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available intervals.
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</para>
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<para>
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The baud rate is configurable, with a default of 9600 baud. Baud rate will
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have to be chosen with the required data-per-second in mind, since at 1 Hz,
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there are 161 characters (40x4+1) per second, which requires that's a
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theoretical minimum baud of 161*10 = 1610 baud. Higher frame-rates will
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require higher baud rates.
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</para>
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</sect2>
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<sect2 id="requirements">
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<title>Requirements</title>
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<para>
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None. The only requirement is a serial port of some sort.
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</para>
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</sect2>
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<sect2 id="config">
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<title>Configuration in LCDd.conf</title>
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<sect3 id="config-section">
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<title>[rawserial]</title>
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<variablelist>
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<varlistentry>
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<term>
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<property>Device</property> =
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<parameter><replaceable>DEVICE</replaceable></parameter>
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</term>
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<listitem><para>
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Serial port to use. Default: <filename>/dev/cuaU0</filename>
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<property>Speed</property> =
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<parameter><replaceable>NUMBER</replaceable></parameter>
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</term>
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<listitem><para>
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Desired baud-rate. Possible values:
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<literal>1200</literal>,
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<literal>2400</literal>,
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<literal>9600</literal> (default),
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<literal>19200</literal>, and
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<literal>115200</literal>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<property>Size</property> = ¶meters.size;
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</term>
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<listitem><para>
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Specifies the size of the LCD. If this driver is loaded as a secondary
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driver it always adopts to the size of the primary driver. If loaded as
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the only (or primary) driver, the size can be set.
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Default: <literal>40x4</literal>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<property>UpdateRate</property> =
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<parameter><replaceable>NUMBER</replaceable></parameter>
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</term>
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<listitem><para>
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Desired update-rate in Hertz (e.g. updates per second). Fractional
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values and values less than one are valid (e.g. 0.5). Legal values are
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<literal>0.0005</literal> (equals 2000 seconds) - <literal>10</literal>,
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with <literal>1.0 </literal> being the default.
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</para></listitem>
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</varlistentry>
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</variablelist>
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</sect3>
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</sect2>
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</sect1>
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mmdolze