mmdolze
b96b60b50d
Remove comments from the code that are already part of docbook documentation. Pass through indent. Remove unused prototypes.
210 lines
6.2 KiB
Plaintext
210 lines
6.2 KiB
Plaintext
<sect1 id="ula200-howto">
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<title>The ula200 Driver</title>
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<sect2 id="ula200-general">
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<title>General</title>
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<para>
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The ULA-200 (short for German <emphasis>USB-LCD-Ansteuerung</emphasis>),
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manufactured and sold by <ulink url="http://www.elv.de">ELV</ulink>,
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is a small board that connects a HD44780-compatible display to the computer
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using the USB interface.
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Additionally it provides 6 digital inputs that can be used for keys.
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</para>
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<para>
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The <code>ula200</code> driver controls this board supporting the features:
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<itemizedlist>
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<listitem><para>display on a single-controller HD44780 display</para></listitem>
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<listitem><para>standard icons (heart, checkbox)</para></listitem>
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<listitem><para>backlight control</para></listitem>
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<listitem><para>input buttons</para></listitem>
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<listitem><para><emphasis>no</emphasis> horizontal or vertical bars</para></listitem>
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</itemizedlist>
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</para>
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</sect2>
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<sect2 id="ula200-requirements">
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<title>Requirements</title>
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<para>
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The driver uses <filename>libftdi</filename>, which again uses <filename>libusb</filename>
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for communication with the device, so no kernel driver is needed on Linux, and the
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driver can be used on other operating systems as well.
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<note>
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<para>
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When using a <filename>libusb</filename> based driver like <code>IOWarrior</code>,
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<application>LCDd</application> needs to be started as root.
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</para>
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</note>
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<note>
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<para>
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On Linux, you have to take care that the <filename>ftdi_sio.ko</filename>
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kernel module doesn't claim the ELV device.
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If you didn't change the IDs in the kernel driver (<filename>ftdi_sio.c</filename>),
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this should not matter.
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</para>
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</note>
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</para>
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</sect2>
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<sect2 id="ula200-problems">
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<title>Known problems</title>
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<para>
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Sometimes the display hangs (the ACK response is not received) on shutdown.
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Reconnect the display in that case.
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Please do the same if it hangs while starting up.
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The latter only happens if it was not the first time <application>LCDd</application>
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talked to the display.
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</para>
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</sect2>
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<sect2 id="ula200-implementation-note">
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<title>Implementation note</title>
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<subtitle>(by the driver's author Bernhard Walle)</subtitle>
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<para>
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The ULA-200 talks a text protocol which allows to display text using a
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high-level language, i.e.
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<code>STX</code> <literal>s</literal> <replaceable>len</replaceable>
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<replaceable>char0</replaceable> <replaceable>char1</replaceable> ... <code>ETX</code>.
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It also allows low-level register access to the HD44780.
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So in theory, it would be possible to write a connection type for the
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<code>hd44780</code> driver and let the <code>hd44780</code> core do the rest.
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I tried this. It was slow and didn't work with user-specific characters
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(the hd44780 frequently changes this characters which seems to confuse the
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microcontroller, at least I cannot explain why it didn't work, there was
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garbage).
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</para>
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<para>
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So I wrote a separate driver, the <code>ula200</code>, which uses
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the high-level language and should work for displays with all sizes.
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I only tested 20x4, so maybe for other sizes the positioning code may be adapted.
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</para>
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<para>
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As I mentioned, there were problems with frequently changing the
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user-definable characters.
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I also tried to implement bar code in the <code>ula200</code> driver
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with similar effects.
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I gave it up because I don't need it personally and it can be done later.
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However, standard icons are implemented.
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The user-definable characters are set in startup and are not changed.
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This works like a charm.
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It is not possible to use character 0 with the high-level language
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(or at least it isn't documented how to escape it).
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It could be done with hd44780 code, but I replaced the character with
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a standard character which looks good.
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</para>
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</sect2>
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<!-- ## ELV ULA200 driver ## -->
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<sect2 id="ula200-config">
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<title>Configuration in LCDd.conf</title>
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<sect3 id="ula200-config-section">
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<title>[ula200]</title>
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<variablelist>
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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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Select the LCD size [default: <literal>20x4</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>KeyMap_A</property> =
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<parameter><replaceable>KEY</replaceable></parameter>
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</term>
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<term>
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<property>KeyMap_B</property> =
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<parameter><replaceable>KEY</replaceable></parameter>
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</term>
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<term>
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<property>KeyMap_C</property> =
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<parameter><replaceable>KEY</replaceable></parameter>
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</term>
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<term>
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<property>KeyMap_D</property> =
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<parameter><replaceable>KEY</replaceable></parameter>
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</term>
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<term>
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<property>KeyMap_E</property> =
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<parameter><replaceable>KEY</replaceable></parameter>
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</term>
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<term>
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<property>KeyMap_F</property> =
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<parameter><replaceable>KEY</replaceable></parameter>
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</term>
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<listitem><para>
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If you have a non standard keypad you can associate any keystrings to keys.
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There are 6 input keys in the ULA-200 hardware that generate characters
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from '<literal>A</literal>' to '<literal>F</literal>'.
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Legal values for <replaceable>KEY</replaceable> are <literal>Up</literal>,
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<literal>Down</literal>, <literal>Left</literal>, <literal>Right</literal>,
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<literal>Enter</literal> and <literal>Escape</literal>.
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</para>
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<para>
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The following table lists the built-in default mapping hardcoded in the driver.
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</para>
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<informaltable>
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<tgroup cols="2">
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<tbody>
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<row>
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<entry>KeyMap_A</entry>
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<entry><literal>Up</literal></entry>
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</row>
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<row>
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<entry>KeyMap_B</entry>
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<entry><literal>Down</literal></entry>
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</row>
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<row>
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<entry>KeyMap_C</entry>
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<entry><literal>Left</literal></entry>
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</row>
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<row>
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<entry>KeyMap_D</entry>
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<entry><literal>Right</literal></entry>
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</row>
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<row>
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<entry>KeyMap_E</entry>
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<entry><literal>Enter</literal></entry>
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</row>
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<row>
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<entry>KeyMap_F</entry>
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<entry><literal>Escape</literal></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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You may leave it unchanged if you have a standard keypad.
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You can change it if you want to report other keystrings or have a non-standard keypad.
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</para>
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</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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