236 lines
8.6 KiB
Plaintext
236 lines
8.6 KiB
Plaintext
<sect1 id="picolcd">
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<title>The Mini-Box USB LCD (picoLCD 20x2) Driver (picolcd)</title>
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<para>
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This section covers the installation and use of the Mini-Box USB LCD (picoLCD
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20x2) display.
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</para>
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<para>
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The picoLCD page indicates that the device can be connected via I<superscript>2</superscript>C
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or USART.
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This LCDproc driver, however, is limited to the USB connected model.
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</para>
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<sect2 id="picolcd-setup">
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<title>Setting up the picoLCD</title>
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<para>
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The picoLCD device as used by this driver is USB connected and may be purchased
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with an internal USB header connector (5-pin to 5-pin) or an external cable
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(Type-A to 5-pin). See: <ulink url="http://www.mini-box.com/picoLCD-20x2-OEM"/>.
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It may also come pre-installed on systems like the Mini-Box M300:
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<ulink url="http://www.mini-box.com/Mini-Box-M300-LCD"/>.
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</para>
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<para>
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Building and using the USB LCD with this driver requires the
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<filename>libusb</filename> library.
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Most distributions do provide this library.
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The only kernel module required is the USB host controller driver
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(<filename>uhci_hcd</filename> on the M300) to fire up the USB bus
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to which the LCD is attached.
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</para>
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<para>
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Lastly, the <filename>usbfs</filename> file system must be mounted on
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<filename>/proc/bus/usb</filename>, e.g. using the command
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<code>mount -t usbfs usbfs /proc/bus/usb</code> or by your disptributions
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default configuration.
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</para>
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<para>
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You can also change the USB LCD's initial display (what it shows when you
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initialize the device) by using the <command>usblcd</command> binary's
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<command>splash</command> command.
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</para>
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<para>
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To use the picoLCD with LCDproc, add <literal>picolcd</literal>
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to the LCDproc <code>./configure</code> <code>--drivers</code> option
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(or use <literal>all</literal>), set the <code>Driver=</code> to
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<literal>picolcd</literal> in the <filename>LCDd.conf</filename> config
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file, and then start <application>LCDd</application> either directly or using startup scripts.
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The driver has sane default options and the options that are user configurable
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are limited to mostly simple items, like contrast and which keys to light up.
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</para>
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</sect2>
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<sect2 id="picolcd-config">
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<title>Configuration in LCDd.conf</title>
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<sect3 id="picolcd-config-section">
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<title>[picolcd]</title>
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<variablelist>
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<varlistentry>
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<term>
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<command>Contrast</command> =
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<arg choice="plain"><replaceable>CONTRAST</replaceable></arg>
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</term>
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<listitem><para>
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Contrast: <literal>0</literal>-<literal>1000</literal>.
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<literal>0</literal> is visible, and <literal>1000</literal> is not on my M300.
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Default is <literal>0</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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<command>KeyLights</command> =
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<arg choice="plain">
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<group choice="req">
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<arg choice="plain"><literal><emphasis>yes</emphasis></literal></arg>
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<arg choice="plain"><literal>no</literal></arg>
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</group>
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</arg>
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</term>
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<listitem><para>
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Allow key LEDs to be turned on or off. Default is <literal>yes</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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<command>Key0Light</command> =
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<arg choice="plain">
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<group choice="req">
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<arg choice="plain"><literal><emphasis>yes</emphasis></literal></arg>
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<arg choice="plain"><literal>no</literal></arg>
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</group>
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</arg>
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</term>
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<listitem><para>
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If <command>Keylights</command> is set, you can disable the directional pad LED by
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setting this value to <literal>no</literal>. Default is <literal>yes</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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<command>Key1Light</command> =
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<arg choice="plain">
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<group choice="req">
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<arg choice="plain"><literal><emphasis>yes</emphasis></literal></arg>
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<arg choice="plain"><literal>no</literal></arg>
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</group>
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</arg>
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</term>
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<listitem><para>
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If <command>Keylights</command> is set, you can disable the F1 LED by setting this value
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to <literal>no</literal>. Default is <literal>yes</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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<command>Key2Light</command> =
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<arg choice="plain">
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<group choice="req">
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<arg choice="plain"><literal><emphasis>yes</emphasis></literal></arg>
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<arg choice="plain"><literal>no</literal></arg>
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</group>
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</arg>
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</term>
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<listitem><para>
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If <command>Keylights</command> is set, you can disable the F2 LED by setting this value
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to <literal>no</literal>. Default is <literal>yes</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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<command>Key3Light</command> =
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<arg choice="plain">
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<group choice="req">
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<arg choice="plain"><literal><emphasis>yes</emphasis></literal></arg>
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<arg choice="plain"><literal>no</literal></arg>
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</group>
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</arg>
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</term>
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<listitem><para>
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If <command>Keylights</command> is set, you can disable the F3 LED by setting this value
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to <literal>no</literal>. Default is <literal>yes</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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<command>Key4Light</command> =
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<arg choice="plain">
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<group choice="req">
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<arg choice="plain"><literal><emphasis>yes</emphasis></literal></arg>
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<arg choice="plain"><literal>no</literal></arg>
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</group>
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</arg>
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</term>
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<listitem><para>
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If <command>Keylights</command> is set, you can disable the F4 LED by setting this value
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to <literal>no</literal>. Default is <literal>yes</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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<command>Key5Light</command> =
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<arg choice="plain">
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<group choice="req">
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<arg choice="plain"><literal><emphasis>yes</emphasis></literal></arg>
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<arg choice="plain"><literal>no</literal></arg>
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</group>
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</arg>
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</term>
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<listitem><para>
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If <command>Keylights</command> is set, you can disable the F5 LED by setting this value
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to <literal>no</literal>. Default is <literal>yes</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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<command>KeyTimeout</command> =
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<arg choice="plain"><replaceable>DURATION</replaceable></arg>
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</term>
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<listitem><para>
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(Advanced) This value controls how long <application>LCDd</application> waits for a key press when
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get_key() is called. The value represents microseconds and the default is <literal>500</literal>
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or .5 seconds. Lowering this value will make LCDd more responsive but also causes LCDd to use
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more CPU time and, as the timeout grows shorter, key presses become harder to detect.
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Larger values make key presses more reliable if somewhat slow to take effect.
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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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<sect2 id="picolcd-status">
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<title>picolcd driver status</title>
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<para>
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The lcdproc picolcd driver relies upon Mini-Box's usblcd library to setup the USB/HID
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interface. Unfortunately the usblcd library is very thin and tends to put function
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results on stdout/stderr instead of in return values. They (Mini-Box) really had
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scripting interfaces in mind.
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</para>
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<para>
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The primary example of this is that I had to write a replacement (get_key_events) for
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usblcd's read_events so that I could get the key presses back to the calling function
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instead of on stdout. usblcd also has a large number of function shells for which no
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code exists yet. I am not an expert on HID and USB coding, but if and as time permits
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and hardware is available I will try and improve this drivers access to the hardware in
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order to get back data (get_contrast for example) and to potentially drive multiple
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pcioLCDs at once (or pick the one we want out of many).
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</para>
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<para>
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To sum up, this driver right now stabs and hopes since response data is lacking.
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</para>
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<para>
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The hardware also reports key-up events. Normally this would be of no issue (they are
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usually a 0 or 'no key') except that when keys are used in combonation, the key-up
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event may actually come back as multiple events depending on how the user released the
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keys. If the key-up event for a multiple key press comes back as two events, the first
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up event will actually look like a new key press. The algorithm in get_key tries to
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deal with this in a sane way and toss out all key-up events for now. The hardware is
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touchy and both combo key-down and key-up actions may be reported as mutiple events if
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the user is more than a tenth of a second (maybe less?) off in motions.
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</para>
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</sect2>
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<sect2 id="picolcd-copy">
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<title>Copyright</title>
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<para>
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The lcdproc picolcd driver was written by Gatewood Green (woody@nitrosecurity.com)
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or (woody@linif.org) and paid for by NitroSecurity, Inc (nitrosecurity.com).
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</para>
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</sect2>
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</sect1>
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