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picolcd - driver for Mini-box.com USB LCD picoLCD (Gatewood Green)

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marschap
2007-03-18 13:45:12 +00:00
parent 99daf2fa4b
commit 2d20fd83c6
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docs/lcdproc-user/drivers.docbook
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@@ -33,6 +33,7 @@ well as the configuration of LCDd.
&mtc_s16209x;
&MtxOrb;
&NoritakeVFD;
&picolcd;
&pylcd;
&sed1330;
&sed1520;
docs/lcdproc-user/drivers/picolcd.docbook
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<sect1 id="picolcd">
<title>The Mini-Box USB LCD (picoLCD 20x2) Driver (picolcd)</title>
<para>
This section covers the installation and use of the Mini-Box USB LCD (picoLCD
20x2) display.
</para>
<para>
The picoLCD page indicates that the device can be connected via I2C or USART.
This lcdproc driver, however, is limited to the USB connected model.
</para>
<sect2 id="picolcd-setup">
<title>Setting up the picoLCD</title>
<para>
The picoLCD device as used by this driver is USB connected and may be purchased
with an internal USB header connector (5-pin to 5-pin) or an external cable
(Type-A to 5-pin). See: http://www.mini-box.com/picoLCD-20x2-OEM. It may also
come pre-installed on systems like the Mini-Box M300:
http://www.mini-box.com/Mini-Box-M300-LCD.
</para>
<para>
Using the USB LCD with this driver requires the usblcd library from Mini-box.com
(avaiable at http://www.mini-box.com/picoLCD-20x2-OEM). The usblcd library
requires libusb and libhcd. Your distribution may or may not already provide
these libraries. The only kernel driver required is the USB host controller
driver (uhci_hcd on the M300) required to fire up the usb bus to which the LCD is
attached.
</para>
<para>
Lastly, the usbfs file system must be mounted on /proc/bus/usb.
<code>mount -t usbfs usbfs /proc/bus/usb</code>
</para>
<para>
Once connected and with libusblcd, libusb and libhid installed, testing the USB LCD
can be done with the "usblcd" program that comes with the usblcd library. You can
also change the USB LCD's initial display (what it shows when you initialize the
device) by using the usblcd binary's "splash" command.
</para>
<para>
To use the picolcd with lcdproc, add picolcd to the lcdproc configure drivers option
(or use all) and then start LCDd with the "-d picolcd" option. The driver has
sane default options and the options that are user configurable are limited to mostly
simple items, like contrast and which keys to lights up.
</para>
</sect2>
<sect2 id="picolcd-options">
<para>
Contrast: 0-1000. 0 is visible, and 1000 is not on my M300. Default is 0.
</para>
<para>
Keylights: 0/1. 0 turns off the key LEDs and 1 turns them on. Default is 1.
</para>
</sect2>
<sect2>
<para>
Key0Light: if Keylights is set to 1, you can disable the directional pad LED by
setting this value to 0. Default is 1.
</para>
</sect2>
<sect2>
<para>
Key1Light: if Keylights is set to 1, you can disable the F1 LED by setting this value
to 0. Default is 1.
</para>
</sect2>
<sect2>
<para>
Key2Light: if Keylights is set to 1, you can disable the F2 LED by setting this value
to 0. Default is 1.
</para>
</sect2>
<sect2>
<para>
Key3Light: if Keylights is set to 1, you can disable the F3 LED by setting this value
to 0. Default is 1.
</para>
</sect2>
<sect2>
<para>
Key4Light: if Keylights is set to 1, you can disable the F4 LED by setting this value
to 0. Default is 1.
</para>
</sect2>
<sect2>
<para>
Key5Light: if Keylights is set to 1, you can disable the F5 LED by setting this value
to 0. Default is 1.
</para>
</sect2>
<sect2>
<para>
KeyTimeout: (Advanced) This value controls how long LCDd waits for a key press when
get_key is called. The value represents microseconds and the default is 500 or .5
seconds. Lowering this value will make LCDd more responsive but also causes LCDd to use
more CPU time and, as the timeout grows shorter, key presses become harder to detect.
Larger values make key presses more reliable if somewhat slow to take effect.
</para>
</sect2>
<sect2 id="picolcd-status">
<title>picolcd driver status</title>
<para>
The lcdproc picolcd driver relies upon Mini-Box's usblcd library to setup the USB/HID
interface. Unfortunately the usblcd library is very thin and tends to put function
results on stdout/stderr instead of in return values. They (Mini-Box) really had
scripting interfaces in mind.
</para>
<para>
The primary example of this is that I had to write a replacement (get_key_events) for
usblcd's read_events so that I could get the key presses back to the calling function
instead of on stdout. usblcd also has a large number of function shells for which no
code exists yet. I am not an expert on HID and USB coding, but if and as time permits
and hardware is available I will try and improve this drivers access to the hardware in
order to get back data (get_contrast for example) and to potentially drive multiple
pcioLCDs at once (or pick the one we want out of many).
</para>
<para>
To sum up, this driver right now stabs and hopes since response data is lacking.
</para>
<para>
The hardware also reports key-up events. Normally this would be of no issue (they are
usually a 0 or 'no key') except that when keys are used in combonation, the key-up
event may actually come back as multiple events depending on how the user released the
keys. If the key-up event for a multiple key press comes back as two events, the first
up event will actually look like a new key press. The algorithm in get_key tries to
deal with this in a sane way and toss out all key-up events for now. The hardware is
touchy and both combo key-down and key-up actions may be reported as mutiple events if
the user is more than a tenth of a second (maybe less?) off in motions.
</para>
</sect2>
<sect2 id="picolcd-copy">
<title>Copyright</title>
<para>
The lcdproc picolcd driver was written by Gatewood Green (woody@nitrosecurity.com)
or (woody@linif.org) and paid for by NitroSecurity, Inc (nitrosecurity.com).
</para>
</sect2>
</sect1>