LCDd is the server part of LCDproc, a deamon which listens to a certain port (normally 13666)
and displays information on an LCD display. It works with several types
and sizes of displays.
Most settings of LCDd are configured through its configuration file
/etc/LCDd.conf, some of them can be overriden using command line options.
Before running LCDd you should carefully
read through that file and modify everything neccessary according to your needs.
Otherwise you might encounter LCDd not running properly on your system.
To make full use of LCDd, a client such as lcdproc(1), lcdexec(1), or lcdvc
is required.
OPTIONS
Available options are:
-h
Display help screen
-c config
Use a configuration file other than /etc/LCDd.conf
-d driver
Specify a driver to use (output only to first), overriding
the Driver parameter in the config file's [Server] section.
-f
Run in the foreground, overriding the Foreground parameter
in the config file's [Server] section.
The default, if not specified in the config file, is to
daemonize LCDd as it is intended to operate in the background.
-i bool
Tell whether the to enable (1) or disable (0) showing the LCDproc
server screen in n the screen rotation, overriding ServerScreen
in the config file's [Server] section.
-w waittime
Time to pause at each screen (in seconds), overriding the
WaitTime parameter in the config file's [Server] section.
-a addr
Bind to network address addr, overriding the
Bind parameter in the config file's [Server] section.
-p port
Listen on port port for incoming connections, overriding the
Port parameter in the config file's [Server] section.
-u user
Run as user user, overriding the
User parameter in the config file's [Server] section.
-s bool
Output messages to syslog (1) or to stdout (0), overriding the
ReportToSyslog parameter in the config file's [Server] section.
-r level
Set reporting level to level, overriding th
ReportLevel parameter in the config file's [Server] section.
SUPPORTED DRIVERS
Currently supported display drivers include:
bayrad
BayRAD LCD modules by EMAC Inc.
CFontz
CrystalFontz CFA-632 and CFA-634 serial LCD displays
CFontz633
CrystalFontz CFA-633 serial/USB LCD displays
CFontzPacket
CrystalFontz CFA-631, CFA-633 and CFA-635 serial/USB LCD displays
curses
Standard video display using the (n)curses library
Multiple drivers can be used simultaneously; thus, for example, a Matrix Orbital display (MtxOrb driver)
can be combined with an infrared driver (irmanin driver).
INVOCATION
LCDd -d MtxOrb -d joy
The invocation example above will start LCDd reading its configuration from the
default configuration file /etc/LCDd.conf but overriding the drivers
specified therein with the Matrix Orbital driver and the Joystick input driver.
LCDPROC CLIENT-SERVER PROTOCOL
There is a basic sequence:
1. Open a TCP connection to the LCDd server port (usually 13666).
2. Say "hello"
3. The server will return some information on the type
of display available.
4. Define (and use) a new screen and its widgets.
5. Close the socket when done displaying data.
CLIENT COMMANDS
There are many commands for the client to send to the LCDd server:
hello
This starts a client-server session with the LCDd server; the
server will return a data string detailing the type of display
and its size.
Set the data used to define a particular widget #id on screen
#screen.
HEARTBEAT MODES
Valid heartbeat mode values (for the screen_set command) are:
on
Display pulsing heart symbol.
off
No heartbeat display.
open
Use client's heartbeat setting. This is the default.
BACKLIGHT MODES
Valid heartbeat mode values (for the screen_set command) are:
on
Turn backlight on.
off
Turn backlight off
toggle
Turn backlight off when it is on and vice versa.
open
Use client's backlight setting. This is the default.
blink
Blinking backlight
flash
Flashing blacklight
Priorities
Valid priority settings (used in the screen_set command) are as follows:
input
The client is doing interactive input.
alert
The screen has an important message for the user.
foreground
an active client
info
Normal info screen, default priority.
background
The screen is only visible when no normal info screens exists.
hidden
The screen will never be visible.
For compatibility with older versions of clients a mapping of numeric
priority values is also supported:
1 - 64
foreground
65 - 192
normal
193 - (infinity)
background
An example of how to properly use priorities is as follows:
Imagine you're making an mp3 player for lcdproc. When the
song changes, it's nice to display the new name immediately.
So, you could set your screen's priority to foreground, wait for
the server to display (or ignore) your screen, then set the
screen back to normal. This would cause the mp3 screen to
show up as soon as the one on screen was finished, then
return to normal priority afterward.
Or, let's say your client monitors the health of hospital
patients. If one of the patients has a heart attack, you
could set the screen priority to alert, and it
would be displayed immediately. It wouldn't even wait for
the previous screen to finish. Also, the display would stay
on screen most of the time until the user did something about it.
WIDGET TYPES
Widgets can be any of the following:
string
A text string to display (as is).
hbar
A horizontal bar graph.
vbar
A vertical bar graph.
title
A title displayed across the top of the display, within a banner.
icon
A graphic icon.
scroller
A scrolling text display, scrolling either horizontally or vertically.
frame
A container to contain other widgets, permitting them to be refered to
as a single unit. A widget is put inside a frame by using the -in #id
parameter, where #id refers to the id of the frame.
num
Displays a large decimal digit
Widgets are drawn on the screen in the order they are created.
SETTING WIDGET DATA
In the widget_set command, the data argument depends on which widget is being
set. Each widget takes a particular set of arguments which defines its form and behavior:
string x y text
Displays text at position (x,y).
title text
Uses text as title to display.
hbar x y length
Displays a horizontal bar starting at position (x,y) that is length pixels wide.
vbar x y length
Displays a vertical bar starting at position (x,y) that is length pixels high.
icon x y name
Displays the icon name at position (x,y).
scroller left top right bottom direction speed text
The text defined will scroll in the direction defined. Valid directions
are h (horizontal) and v (vertical). The speed defines how many
"movements" (or changes) will occur per frame. A positive number indicates
frames per movement; a negative number indicates movements per frame.
frame left top right bottom wid hgt dir speed
Frames define a visible "box" on screen,
from the (left, top) corner to the
(right, bottom) corner. The actual data may be bigger,
and is defined as wid (width) by hgt (height); if it is
bigger, then the frame will scroll in the direction (dir)
and speed defined.
num x int
Displays large decimal digit int at the horizontal position x,
which is a normal character x coordinate on the display.
The special value 10 for int displays a colon.
BUGS
If LCDd seems not to work as expected, try to run it in the foreground
with reporting level set to maximum and reporting to stderr.
This can be achieved without changes to the config file by using the
command line:
The lcdproc package is released as "WorksForMe-Ware".
In other words, it is free, kinda neat, and we don't guarantee that it will do
anything in particular on any machine except the ones it was developed on.
It is technically released under the GNU GPL license (you should have received the file,
"COPYING", with LCDproc) (also, look on http://www.fsf.org/ for more information),
so you can distribute and use it for free -- but you must make the source code freely
available to anyone who wants it.
For any sort of real legal information, read the GNU GPL (GNU General Public License).
It's worth reading.