mtxorb.docbook

linux下LCD驱动的例子代码

<sect1 id="MtxOrb">
<title>The MtxOrb Driver</title>

<para>
      This section covers the installation process for the Matrix Orbital LCD
      module intended for use with LCDproc.
</para>
<para>
      We will examine the installation process of the hardware in
      small steps, as it is vitally important to pay close attention to detail during
      hardware installation to avoid damaging equipment.
</para>

<sect2 id="MtxOrb-features">
<title>Matrix Orbital LCD Modules</title>
        <para>
          LCDproc was born out of original tinkering by William Ferrell with
          one of these LCD modules. Their ease of installation and use (as well
          as the amazing amount of patience demonstrated by the folks at
          Matrix Orbital whilst William figured things out) meant one less thing
          to worry about during the early stages of LCDproc's life.
        </para>
        <para>
          These 20x4 alphanumeric modules are connected via standard DB-9 cabling and
          connectors. They draw either 5V or 12V, depending on the module purchased,
          and are attached with a standard floppy cable connector (with a slightly
          modified wire configuration).
        </para>
        <para>
          Once connected, using them is a breeze. They can operate at any number of
          different baud rates and serial configurations, but normally they run at
          19,200 baud, 8-N-1, making them quite quick. Sending ASCII to the module
          will make it simply display that text at its current cursor position. The
          module has a built-in BIOS that recognizes commands (sent by transmitting a
          single-byte "marker" signifying that a command is on the way, followed by
          the single-byte command character itself along with any parameters, if needed)
          allowing the programmer to clear the screen, position the cursor anywhere,
          define custom characters (up to 8 at a time), draw bar graphs and large numbers,
          change the LCD's contrast, and so on.
        </para>
        <para>
          The BIOS included also implements line-wrapping (i.e. writing past the
          twentieth character on the first row will automatically move the cursor
          to the first character on the second row), and screen scrolling (i.e.
          writing past the twentieth character on the fourth row causes the whole
          screen to scroll up one row, clearing the fourth line and positioning the
          cursor at the first character on that line).
        </para>
        <para>
          These modules are fast. Using the auto-line-wrap feature and disabling
          the auto-scrolling feature, the screen can be updated thirty times per
          second if *every* character on the screen is changed. If updating less
          than the whole screen, the LCD can update faster than can be seen by
          the human eye. This, of course, more than meets LCDproc's needs.
        </para>
</sect2>

<sect2 id="MtxOrb-hardware">
<title>Matrix Orbital Hardware Installation</title>
      <para>
        Regardless of what specific type of hardware you intend to use with LCDproc,
        installation is usually straightforward, and requires only a few steps. Regardless,
        you must use caution while working inside your computer system or with any hardware
        attachments.
      </para>
      <warning>
        <para>
          Installing new hardware inside a computer system can be dangerous to both
          system components and the installer. Use caution whenever adding a component
          to the inside of your system, altering a power cable, or physically mounting
          a device inside a computer system.
        </para>
        <para>
          When installing hardware inside a computer, make sure it's turned off and that
          its power is disconnected. This is especially important when making changes to
          power cables (as some LCD modules require).
        </para>
      </warning>

      <sect3 id="MtxOrb-lcd_vfd-installation">
        <title>Matrix Orbital LCD/VFD Module Installation</title>
        <para>
          The LCD and VFD modules from Matrix Orbital are relatively straightforward
	  to install. With a small, regular (flat-head) screwdriver, a spare floppy drive
	  power cable, and a bit of luck, installation will take less than an hour.
	</para>
	<para>
	  These installation instructions assume that you are installing the module into
	  a PC or PC-style system (one with AT- or ATX-compliant power cabling) and that
	  you have some idea of where you intend to permanently mount the module. For
	  mounting ideas and tips, refer to the section "Mounting" below.
	</para>
	<tip>
	  <title>Before you start</title>
	  <para>
	    Your Matrix Orbital LCD or VFD module should be clearly marked with an
	    indication of the module's power requirements. It should be either a 5 volt
	    or 12 volt unit. You should have this information available before proceeding.
	  </para>
	</tip>
	<sect4 id="MtxOrb-powercable-modification">
	  <title>Power Cable Modification</title>
	  <para>
	    The first step in installing the module is making the necessary modifications
	    to a floppy drive power cable in order to provide power to the module. The
	    modifications must be made based on the module's power requirements -- either
	    5V or 12V -- depending on which module you purchased.
	  </para>
	  <para>
	    A standard floppy drive power cable has a smaller connection than a "normal"
	    PC power connector. However, like a "normal" power connector, it has four
	    wires: one yellow, one red, and two black. The red wire provides +5V power, and
	    is "hot" or live when the system is powered up. The yellow wire provides +12V
	    power, and is also hot when the system is powered up. Both black wires are
	    ground.
	    [TODO: INCLUDE A FIGURE HERE SHOWING A "STANDARD" FLOPPY CONNECTOR]
	  </para>
	  <para>
	    One of the hot wires and one of the black wires will not be needed for your
	    module's power connection; they will be completely removed when the power cable
	    modification is complete.
	  </para>
	  <warning>
            <para>
              Do NOT make this modification to a power cable attached to a running
              system! Electrocution resulting in personal injury and/or damage to the
              system can result.
            </para>
          </warning>
          <para>
            Using a regular screwdriver, press down the small metal locking flap of one
            of the two black wires on the small end of the cable, and pull the black wire
            from the connector. Using a pair of needle-nose pliers, squeeze the other end
            of the same black wire, and pull it out of the large end of the cable. This
            black wire can be set aside; it will not be used for the module's power
            connection. Either wire can be safely removed; you may safely remove either
            wire.
            [TODO: INCLUDE A FIGURE HERE SHOWING THIS PROCESS]
          </para>
          <para>
            Next, using the same procedure, remove the unneeded hot wire. If your module
            is 5V, you do not need the yellow (+12V) wire. Conversely, if your module is
            12V, you do not need the red (+5V) wire. The removed wire can be set aside;
            it will not be used for the module's power connection.
            [TODO: INCLUDE A FIGURE HERE]
          </para>
          <para>
            The floppy power connector should now have only two wires attached to it.
            Leave the larger end alone from now on; these connections are correct (the
            larger end connects to your system's power mains). Move the two remaining wires
            to the outside connectors on the small end of the cable. Orientation does not
            particularly matter here; the connector will fit on the module's receptacle
            in either orientation.
            [TODO: A FIGURE HERE]
          </para>
          <para>
            You should now have a properly modified power connector. When physically
            attaching this connector to the module, the black (ground) lead should be
            connected to the pin labelled GND, while the colored (+5V/+12V) lead should
            be connected to the pin labelled +5V/+12V.
          </para>
          <para>
            Test the power connection before connecting the data line or mounting the
            module. Connect the module to the power connector, and the connector to your
            system's power mains. Turn the system on.
          </para>
          <caution>
            <para>
              If the module does not immediately display its initial BIOS screen and light
              up its backlight (or light up the screen if a VFD module is being used),
              <emphasis>immediately</emphasis> power down the system, disconnect the module
	      and connector, and double-check the modification before trying again. Do NOT
	      leave the system on if the module does not immediately respond; module or
	      system damage could result.
            </para>
          </caution>
	  <para>
	    When the LCD powers up and displays its initial BIOS screen, you've gotten the
	    power connection wired properly and can now properly mount the module and make
	    its final connections. Matrix Orbital Corporation sells a PC bay insert mount
	    for the 20x4 and 20x2 modules (LCDproc, however, only supports the 20x4 at
	    present). The inserts provide an easy means of mounting the LCD modules inside
	    a PC using one (for the 20x2) or two (for the 20x4) 5 1/4" bays.
	  </para>
          <note>
  	    <para>
	      Describing how to physically mount the module in a PC case is beyond the
	      scope of this document; LCDproc's website contains more detailed mounting
	      information and examples.
	    </para>
	  </note>
        </sect4>
	<sect4 id="MtxOrb-serial-connection">
	  <title>Serial Connection</title>
	  <para>
	    The LCD module uses a standard DB9 serial connector. You can attach the module
	    to your system using a direct cable to the motherboard, or by removing one of
	    your system's serial ports from the back of the case, then connecting it to a
	    standard serial cable to the module.
	  </para>
	  <para>
	    While connecting the serial cable to the module, be sure to configure the
	    module's serial interface settings. Typically, setting the module to its fastest
	    setting (19,200 baud, 8-N-1) is recommended. The speed settings can
	    be configured from the config file <filename>/etc/LCDd.conf</filename>.
	    If not specified in the config file,
	    the Matrix Orbital module driver in LCDproc default to use these settings.
	  </para>
	</sect4>
      </sect3>
</sect2>

<!-- This is already covered in bookinfo.docbook
<sect2 id="MtxOrb-copy">
<title>Copyright</title>