The HD44780 has become the de-facto standard of alphanumeric character displays.
Although the original Hitachi HD44780 is long out of production, its command
set has survived in a variety of (fully or nearly) compatible LCD, VFD and
even OLED displays sold by a broad range of manufacturers all over the world.
To name only a few: KS0066, KS0070, KS0076, LC7985, NT3881, SED1278, ST7066 ...
The command set of these displays, which sometimes are advertised as being
"industry standards compatible", is thus the workhorse of controllers for
displays ranging from 8x1 to 20x4 or 40x2 characters.
There are even displays with larger dimensions sporting two controllers,
one for each half of the display.
The HD44780 driver supports various ways of connecting HD44780 devices
to your system.
Each of these different ways is called a connection type
of the driver.
Depending on the connection type and the display connected, the driver supports
various special features.
Input keys
Software controllable brightness / backlight
Software controllable contrast
multiple displays / multi-controller displays
The following table lists the available connection types, sorted by the kind
of connection (parallel port, serial port, USB, I2C, SPI or others).
ConnectionType
Wiring / Display Type
Parallel port connection types:
4bit
4-bit wiring. This is the default.
8bit
8-bit wiring ("lcdtime" style)
winamp
8-bit wiring ("winamp" style)
serialLpt
Serial LPT wiring
Serial (RS-232) connection types:
picanlcd
PIC-an-LCD serial device "picanlcd"
lcdserializer
LCD serializer "lcdserializer"
los-panel
LCD on Serial panel device "los-panel" ()
vdr-lcd
VDR LCD serial device "vdr-lcd"
vdr-wakeup
VDR-Wakeup module "vdr-wakeup"
USB connection types:
pertelian
Pertelian X2040 LCD display ()
lis2
LIS2 from VLSystem ()
mplay
MPlay Blast from VLSystem ()
usblcd
USBLCD adapter from Adams IT Services ()
bwctusb
BWCT USB device "bwctusb" ()
lcd2usb
Till Harbaum's LCD2USB ()
usbtiny
Dick Streefland's USBtiny ()
uss720
Belkin USS-720 USB-to-IEEE 1284 Bridge (Belkin F5U002)
USB-4-all
The USB-4-all controller board from Sprut ()
ftdi
Display connected to a FTDI RS2232 (dual channel) or
FTDI RS232 (single channel) USB chip
I2C connection types:
i2c
LCD driven by PCF8574(A)/PCA9554(A) connected via I2C
piplate
Adafruit RGB Positive 16x2 LCD+Keypad for Raspberry Pi
SPI (Serial Peripheral Interface):
spi
Display using a KS0073 or similar in serial mode accessed via Linux SPI device
pifacecad
PiFace Control and Display for Raspberry Pi
Other connection types:
ethlcd
Display connected via TCP to PoE powered ethlcd device
()
raspberrypi
LCD connected to the GPIO header of a Raspberry Pi
If you suspect the table above to be outdated, you might want to have a look at
server/drivers/hd44780-drivers.h in LCDproc's
source directory which contains the actual translation code.
No matter what connection type you choose, you will always need some
connections. They are explained here.
All variants use the same method of obtaining power. i.e., for each LCD:
LCD
Signal
name
pin
VEE
1
GND (connect to any of pins 18 - 25 of you parallel port)
VCC
2
+5V
VLC
3
(contrast adjustment)
Always double check your power connection, your display will probably
not survive a reversely connected supply !
There are several ways to get 5V:
Connect to a 5V line intended for disk drives (the red wire is 5V,
black is GND).
Get it from the VCC and GND pins of an USB connector.
For the USB connection types this is done automatically, as the circuits
used there automatically power the LCD.
Get it from a joystick port (pin 1 and 9 are 5V, 4, 5 and 12 are GND).
It seems that some soundcards can use these lines for communication,
so if you want to use this first check whether it really gives a 'clean' 5V.
If you don't have a backlight, you can sometimes get the needed mA's
from the LPT port itself. Connect a few diodes from the data pins to
a capacitor and you have the 5V. If it's strong enough is another question...
Get it from the keyboard connector. I do not recommend to use this with
a backlight, as the keyboard connector is often protected with a fuse
of 100mA or 200mA.
(variable resistor)
.------.
Vcc ---| 10k |--- GND
`---^--'
/|
|
Vlc
]]>
You can connect a keypad with most connection types. The maximum supported
number of keys differs per type. There are several ways to connect the keys
to the input pins.
If you connect a key like sketched below, then you can only connect one key
per input pin. It is a simple solution if you need only few keys.
O 5V
|
|
-
| | 10k
| |
-
|
+-----------o input (X)
|
|
o
\
o
|
|
=== GND
]]>
By default, the following keystrokes are generated by the different keys:
key index
mapped string
X1
A
X2
B
X3
C
X4
D
X5
E
You can change the mapping using the
KeyDirect_NUM
configuration option, where NUM
is the subscript to the X in the table above.
Using a matrix, we can connect much more keys. To simplify the drawing here,
we replace all switches with an @ symbol:
X line
|
|
Y line ---+---------
| | |
o | = --@--
\ | |
o |
| |
+---+
|
|
]]>
We connect the matrix of keys like this:
Y1 o---|<---@--@--@
| | |
Y2 o---|<---@--@--@
| | |
Y3 o---|<---@--@--@
| | |
Y4 o---|<---@--@--@ O 5V
| | | |
diodes | | | ___ |
1N4148 +----------||---+
| | | ___ |
| +-------||---+
| | | ___ |
| | +----|___|---+ resistors 22k
| | |
o o o
X1 X2 X3
]]>
As you can see, you need 1 resistor per X line, and 1 diode per Y line.
By default, lcdproc will presume that you have a keypad with a layout
like a telephone connected, with X and Y lines connected as show.
To be more precise, it assumes this mapping:
X1
X2
X3
X4
X5
Y1
1
2
3
A
E
Y2
4
5
6
B
F
Y3
7
8
9
C
G
Y4
*
0
#
D
H
This mapping can be changed using the
KeyMatrix_X_Y
configuration option, where X and
Y are the subscripts to the respective axes above.
If you only need e.g. 10 keys, leave the rest away.
You should modify and recompile the
driver to get an other keypad layout.
You can buy arrays of keys that are connected like this in the electronics
shop. They usually call it a matrix keypad. To hook it to lcdproc, you
would only need to add the resistors and diodes.
If you want to use just one return line, for example with the serialLpt
wiring, it looks (completely drawn) like this:
O 5V
|
.-.
| | 4k7 or 22k
diodes | |
1N4148 '-'
___ |
If the driver generates keypresses without that you actually press a key,
it might be that the unconnected input lines are picking up
electromagnetic waves from the air. In that case connect the unconnected
input lines (pin 10, 11, 12, 13 and 15 of the LPT) to VCC = 5V.
A small extension allows you to switch the backlight of the display on
and off. At the moment only the 4bit and winamp
connection types support this.
The extension uses one output pin, you cannot use that pin for other
functions anymore. The wiring looks like this:
Note: 4k7 means 4,7 kOhm.
The BC327 transistor has the following connections:
_____
| |
|BC327|
|_____|
| | |
| | |
| | |
c b e
]]>
Sometimes the backlight connections are not on the 'main' connector, but on
the side. If that is the case, there is usually NO RESISTOR present to limit
the current through the LEDs. Therefore you should then add a resistor after
the transistor of about 10 ohm (see display documentation).
If you want the backlight to light a bit while it is "switched off", you can
add a resistor bypassing the transistor from e to c, with a value of, say
47ohm or 22ohm. (My 4x20 has an internal resistor of 6ohm, so with 47 ohm
extra it lights at only 1/9th. I like this. Joris.)
This wiring is originally based on "lcdtext" (by Matthias Prinke).
printer port
<->
LCD
name
pin
name
pin
GND
VEE
1
+5V
VCC
2
(contrast adjustment)
VLC
3
D4
6
RS
4
GND
RW
5
D6
8
EN
6
D0
2
D4
11
D1
3
D5
12
D2
4
D6
13
D3
5
D7
14
The RW (pin 5) line of the display decides whether the display receives data from the
LPT port, or whether it sends data to the LPT port: if grounded it receives, if High or connected
to nothing at all it "sends" (i.e., will not work as intended). So, if you are not sure that
you need it otherwise, then connect it to GND. This certainly applies if you have only one display.
Theoretically this wiring sends the data over twice as slow as the
winamp or ext8bit wirings, because it only sends 4 bits at a time.
The 4bit connection type supports more than one display connected
to the same parallel port.
If you want to connect more than one display, then wire the all the displays to the
parallel port according to the scheme above with the exception of the EN
(pin 6) line of the LCDs.
For the second and further displays, you can find the wiring for the EN
(pin 6) line in the table below.
printer port
<->
LCD
name
pin
name
pin
D7
9
EN2
6 of 2nd display
D5
7
EN3
6 of 3rd display
STR
1
EN4
6 of 4th display
LF
14
EN5
6 of 5th display
INIT
16
EN6
6 of 6th display
SEL
17
EN7
6 of 7th display
The optional keypad can be connected as follows:
printer port
<->
keypad
remarks
name
pin
pin
D0
2
Y1
D1
3
Y2
D2
4
Y3
D3
5
Y4
D4
6
Y5
D5
7
Y6
Only if not used for backlight or 3rd controller.
nSTRB
1
Y7
Only if not used for additional controllers.
nLF
14
Y8
INIT
16
Y9
nSEL
17
Y10
nACK
10
X1
BUSY
11
X2
PAPEREND
12
X3
SELIN
13
X4
nFAULT
15
X5
The optional backlight wiring should be connected to D5, pin 7.
This type of connection should work with winamp.
printer port
<->
LCD
name
pin
name
pin
D0
2
D0
7
D1
3
D1
8
D2
4
D2
9
D3
5
D3
10
D4
6
D4
11
D5
7
D5
12
D6
8
D6
13
D7
9
D7
14
nSTRB
1
EN
6
nLF
14
RW
5 (EN3 6 - LCD 3) (optional (*) )
INIT
16
RS
4
nSEL
17
EN2
(6 - LCD 2) (optional)
(*) on the RW line of the display: this line decides whether the display receives data from the
LPT port, or whether it sends data to the LPT port: if grounded it receives, if High or connected
to nothing at all it "sends" (i.e., will not work as intended). So, if you are not sure that
you need it otherwise, then connect it to GND. This certainly applies if you have only one display.
If you want the display to work with the Winamp plugin, wire nLF (pin 14)
to RW of your LCD. You can then use the plugin in bidirectional mode (which
is much faster). With 3 connected LCDs this is not possible.
Note from Benjamin: I haven't tried using winamp while having the third LCD
connected to this line.
The optional keypad can be connected as follows:
printer port
<->
keypad
name
pin
pin
D0
2
Y1
D1
3
Y2
D2
4
Y3
D3
5
Y4
D4
6
Y5
D5
7
Y6
D6
8
Y7
D7
9
Y8
nACK
10
X1
BUSY
11
X2
PAPEREND
12
X3
SELIN
13
X4
nFAULT
15
X5
The optional backlight wiring should be connected to nSEL, pin 17.
This is originally based on "lcdtime" (by Benjamin Tse
blt@ComPorts.com) and allows you to combine the LCD with a LED
bargraph. The LCD is driven by LCDproc and the LEDs by another program
such as portato. Further details can be obtained from:
The LCD connections are:
printer port
<->
LCD
name
pin
name
pin
D0
2
D0
7
D1
3
D1
8
D2
4
D2
9
D3
5
D3
10
D4
6
D4
11
D5
7
D5
12
D6
8
D6
13
D7
9
D7
14
nSEL
17
-
nSTRB
1
RS
4
nLF
14
RW
5 (optional - pull LCD RW low (*)
INIT
16
EN
6
(*) on the RW line of the display: this line decides whether the display receives data from the
LPT port, or whether it sends data to the LPT port: if grounded it receives, if High or connected
to nothing at all it "sends" (i.e., will not work as intended). So, if you are not sure that
you need it otherwise, then connect it to GND.
See the lcdtime tar-ball (above) for full details of the bargraph
connections.
The optional keypad can be connected as follows:
printer port
<->
keypad
name
pin
pin
D0
2
Y1
D1
3
Y2
D2
4
Y3
D3
5
Y4
D4
6
Y5
D5
7
Y6
D6
8
Y7
D7
9
Y8
nSTRB
1
Y9
nSEL
17
Y10 (only if not used for backlight)
nACK
10
X1
BUSY
11
X2
PAPEREND
12
X3
SELIN
13
X4
nFAULT
15
X5
The backlight wiring should be attached to nSEL, pin 17. Because the portato
program (mentioned above) also uses this pin to control the bargraph, you
cannot use the backlight control together with the bargraph.
This interface uses a handful of wires to interface to the
HD44780. Suitable for high noise, long connections. Designed by
Andrew McMeikan andrewm@engineer.com.
I (Joris) have extended this driver and the wiring a bit. It now supports
keys again (it had earlier supported keys, but some time did not).
Further I have extended the driver and the wiring to be able to run
using 2 instead of 3 output pins. That's even one less pin ! :)
Of course the use of fewer lines than the other wirings can not stay
without drawbacks. In this case the simplicity of the long feeding wires
is compensated by some intelligence in the decoding of the data. If you
have no experience with the soldering iron, I do not recommend to build
this wiring.
OK, so here is the wiring. First of the 'simple' 3 wires version. IC1 is
the shift register, a 4094. Do not forget to connect the 5V to pin 16 and
GND to pin 8 of the IC.
To understand this part of the serialLpt documentation, you also need to
read the keypad section in this document.
serialLpt wiring supports a keypad. The 3 wires version supports
8 keys, or if you use multiple return lines up to 8 x 5 = 40 lines. The
2 wires version supports 7 keys, or with multiple return lines
7 x 5 = 35 keys.
printer port
<->
keypad
name
pin
pin
nACK
10
X1
BUSY
11
X2
PAPEREND
12
X3
SELIN
13
X4
nFAULT
15
X5
On lines longer than, say a meter, you should buffer the return line(s).
If you only have 1 return line, you can buffer it with two remaining
buffers from the 74HCT14:
Also a backlight is supported. You will also need a port from the 74HCT14 for
that. The BL output below should be connected to the BL input in the
backlight section
___ 3|\ 4
Data o-----|___|--+----| >o----o BL output
LPT-D3 470k | |/
--- IC1
---
|100nF
|
===
]]>
This connection type drives a LCD in serial mode (supported on Hitachi HD66712,
Samsung KS0073 and KS0074 (and clones) controllers) connected to some Linux
SPI device.
This connection type is currently only supported on Linux. It is strongly
recommended to use a SPI implementation with hardware support, e.g. on the
Raspberry Pi.
As the SPI communication to the display cannot drive a backlight switch, this
connection type features a BacklightDevice option
that can use a GPIO pin exposed via sysfs (see eLinux GPIO).
You can use a FTDI FT2232D dual channel USB <-> parallel FIFO chip
to connect a display via the USB bus. The chip is switched to bitbang mode
and drives both channels as outputs to control the display in 8bit mode.
FTDI chip
<->
LCD
name
pin
name
pin
ADBUS0
24
D0
7
ADBUS1
23
D1
8
ADBUS2
22
D2
9
ADBUS3
21
D3
10
ADBUS4
20
D4
11
ADBUS5
19
D5
12
ADBUS6
18
D6
13
ADBUS7
17
D7
14
BDBUS0
40
RS
4
BDBUS1
39
RW
5
BDBUS2
38
EN
6
BDBUS3
37
BL
Backlight (optional)
You can configure the USB vendor/product ID in LCDd.conf.
The wiring of the control lines can optionally be reconfigured,
please look at the driver source if you really need that.
The backlight line is driven high when the backlight is on.
Therefore the standard backlight circuit ()
will not work. Use the following instead.
Alternatively you can use a single channel FTDI FT245BM USB <-> parallel
FIFO chip and use the display in its 4 bit mode.
FTDI chip
<->
LCD
name
pin
name
pin
D0
25
D4
11
D1
24
D5
12
D2
23
D6
13
D3
22
D7
14
D4
21
EN
6
D5
20
RS
4
D6
19
RW
5
D7
18
BL
Backlight (optional)
The following special configuration settings are required to use a single
channel FTDI FIFO chip:
LIS2 from VLSystem ()
is a full featured USB VFD module with four channel fan controls.
This device can be accessed as a serial device with the help of the kernel
module ftdi_sio.ko that maps the USB port to a serial port
(e.g. /dev/ttyUSBx).
MPlay Blast from VLSystem ()
is a full featured USB VFD module with two channel fan controls and
two channel temperature sensors.
This device can be accessed as a serial device with the help of the kernel
module ftdi_sio.ko that maps the USB port to a serial port
(e.g. /dev/ttyUSBx).
The LoS-Panel is a DIY device built using an Atmel ATtiny2313 and
supports the following features:
Drives displays with one controller.
Switchable backlight.
One 4x4 matrix keypad and 4 direct keys.
The direct keys are reported as a fifth column of a matrix keypad to LCDd.
Column and rows are reported reverse (column 1 / row 1 is in the lower
right corner) to LCDd which expects (1/1) to be the upper left corner.
You have to take this into account when configuring keys.
See
for more information on this device.
… to be documented …
Please address Matteo Pillon for further information.
The VDR-Wake module by Frank Jepsen is a serial IO extension module for the
famous Linux-based VDR that allows to connect an LCD to it and supports LCDproc.
See
(German) for more information on VDR-Wakeup.
The Pertelian X2040 includes an HD44780 display with enclosure and USB
connection.
In order to work with LCDproc in Linux you need
the usbserial.ko and ftdi_sio.ko
kernel modules loaded. The display will then be available on a
serial port /dev/ttyUSBx.
See the
X4020 product page for more information.
The PIC-an-LCD module is also supported. It is not connected to the LPT port
but to a serial port, which saves you from a lot of potential problems.
To use it, specify the device to which you have connected the module in the
config file with the Device setting.
The default is /dev/lcd.
It does not support a keypad nor backlight switching.
As of 2012 these devices are not sold anymore. Search the Internet Archive for
a copy of if you need
the manual.
LCD serializer connection is technically the same as PIC-an-LCD with the same advantages,
it uses the serial port making things really simple.
Unlike PIC-an-LCD
LCD serializer
is not a commercial product. it's just a project found digging on the net and freely available.
You have all the tools and the code to build it yourself and to customize the behaviour of the device.
Some electronic knowledge and familiarity with the soldering iron
A PIC16F84 (I used PIC16F84A) or PIC16C54
JDM PIC programmer
gputils and picprog installed on your GNU/Linux box
First, you need to download the ASM source for your PIC and then make the hex:
$ gpasm lcd16f84_custom.asm
Now the binary is ready to be flashed to the PIC.
Connect the programmer with the PIC installed and issue the following command to see it burning ;-):
$ picprog --erase --burn --input lcd16f84.hex --pic /dev/ttyS0
It's time to build the operating circuit,
remember this driver uses a baud rate of 9600, so JP2 need to be closed.
Now power on the board. You should see OK on the LCD screen.
Otherwise double-check all the connections.
Change LCDd.conf to include the following statements in the [hd44780] section:
ConnectionType=lcdserializer
Device=/dev/ttyS0
Finally, start the daemon and relax watching lcdproc running.
The BWCT USB LCD module, sold by Bernd Walter Computing Technology
() is a little board
that can be piggy-packed to a HD44780 display and connects that to USB.
The board, driven by the bwctusb connection type,
does neither support a keypad for input, nor more than one single-controller
display, nor does it allow setting the backlight or brightness.
But you can set the display's contrast using software
(see the Contrast configuration parameter).
If there is more than one BWCT USB module connected to the system,
the SerialNumber configuration parameter allows
selecting which display is used in LCDd.
LCD2USB
is a cheap but powerful do-it-yourself interface to connect HD44780
based displays via USB, consisting of easily available parts only.
The device supports software adjustable contrast and backlight
as well as dual controller displays (required for 4*27 and 4*40).
It is based upon an Atmel AVR Mega8 CPU with a pure software implementation
of the USB protocol for the Atmel AVR microcontroller series.
The whole interface incl. the hardware layout is under a GPL like license.
This means that you can take these schematics and use it as a basis
for your own interface e.g. for a graphic LCD.
Two keys can be connected to the LCD2USB interface board.
They can generate three key events that can be mapped to key names using
the DirectKey_1 to DirectKey_3 commands:
one for each key and the third if the keys are pressed simultaneously.
With this 3-key setup, menus can be used (see example below).
This driver supports the original LCD2USB interface board as described above
as well as compatible devices like those sold by Lcdmod Kit
or those developed by Malte Pöggel.
Besides the standard configuration options for hd44780 displays, the
lcd2usb connection type supports three additional options:
Contrast to set the display's contrast,
Brightness to set the display's brightness when the backlight is switched on and
OffBrightness to set the display's brightness when is backlight is switched off.
All three options expect a number in the range from 0 to 1000.
[hd44780]
ConnectionType=lcd2usb
Contrast=850
Brightness=800
OffBrightness=0
Keypad=yes
Backlight=yes
Size=20x2
KeyDirect_1=Enter
KeyDirect_2=Down
KeyDirect_3=Escape
]]>
In order to make the lcd2usb connection type work with a 2-controller display
you may need to set the vSpan config option accordingly.
USBtiny
is a software implementation of the USB low-speed protocol for
the Atmel ATtiny microcontrollers. It is also the name of a 'reference
circuit' using the ATtiny2313.
The reference circuit features an IR receiver for remote controls and a LCD.
Due to hardware limitations of the ATtiny2313 the LCD does not have switchable
backlight, adjustable contrast, any keys, nor does it support displays with
more than one controller. If you want these features and do not require the
IR receiver we recommend to take a look at the LCD2USB
device.
LCDproc does not make use of the IR receiver. 3rd party software is required
to make it do anything, e.g. LIRC.
The USS-720 USB-to-IEEE 1284 Bridge is a fully featured USB to parallel chip that is used
in most (but not all) Belkin F5U002 USB Parallel Printer Adapters. Because these adapters are
inexpensive and readily available on the second-hand market, they provide an excellent solution
for users who want to experiment with a parallel port but only have USB ports on their computers.
Because the chip acts as a parallel port, the driver maintains the same features and wiring as
the 8-bit "winamp" driver. However, because most USB Parallel Printer Adapters use a centronics
printer connector, be sure to convert the pin numbering of the parallel port pins in the "winamp"
wiring to the pin numbering of the centronics port. Many tables are available on the internet
that illustrate how the pin numbering differs between the two.
Because several manufacturers used the USS720 chip in their USB Parallel Printer Adapters, the
VendorID and ProductID options are configurable in the
LCDd.conf file.
Not all Belkin F5U002 USB Parallel Printer Adapters used the USS720 chip. Look for the dark grey
adapters with the removable USB cable for best results.
If you have an I2C port available that is supported by your kernel
(through /dev/i2c*), you can add a I2C
port expander there (PCF8574P in this example).
If your port expander has different wiring you can re-assign the pins in the config file
The Device configuration setting denotes the device file
of your I2C bus (here /dev/i2c-0).
You have to load the kernel standard module i2c-dev.ko and
the bus driver, but no I2C
chip modules (e.g. pcf8574.ko)!
The Port config option contains the I2C
address of the I2C port expander
(here 0x20, the PCF8574 from the example above, with all address bits set to 0).
Bit 8 of the address (normally 0 in I2C addresses)
has a special meaning:
It tells the driver to treat the device as PCA9554 or similar,
a device that needs a 2-byte command, and it will be stripped
off the address.
Port value
Meaning
0x20…0x27
PCF8574 with A[012]=0…7
0x38…0x3f
PCF8574A with A[012]=0…7
0xa0…0xa7
PCA9554 with A[012]=0…7
0xa0…0xa7
PCA9554A with A[012]=0…7
The ethlcd () device is simply
an LCD display driven by an ATmega microcontroller, controlled and powered by
"home-made" Power over Ethernet. The hardware and software are open source.
ethernet connection using ENC28J60 ethernet controller
Power over Ethernet (data and power using single UTP cable)
Atmel's ATmega168 microcontroller
6 buttons (MENU, UP, DOWN, LEFT, RIGHT, ENTER)
backlight control in three states: ON, Night-Mode (partialy ON) and OFF
beeper
device act as a TCP server - LCDproc driver is connecting to device just by creating
a TCP socket - no need to PC-side additional hardware besides NIC
The device is "visible" to LCDproc just like any other HD44780 device. The difference
is the wiring - instead of connecting the display directly to PC (via serial/parallel/usb port),
it is connected via ethernet and the communication is done over TCP connection.
The main feature is - that to power and control the LCD is needed single UTP cable.
To use the driver, specify the device IP address or hostname, on which the ethlcd device
is accessible by setting in config file the Device value.
The default is ethlcd.
The USBLCD adapter from Adams IT Services ()
is a small interface board which allows you to connect an alphanumerical display
module based on the HD44780 or compatible controller to the USB. The display
will be powered by the USB. It features a switchable backlight (on or off) and
can be used with 16x2, 16x4 or 20x4 displays.
The usblcd connection type communicates with a kernel
driver by using a device file /dev/usb/lcdx.
The kernel driver providing this device currently only exists for Linux kernels
newer than 2.4.20-pre7.
As of 2007 these device are not sold anymore. This driver has been ported from
lcdproc 0.4.5 to support existing users.
The USB-4-all controller board from Sprut ()
is a small interface board which allows you to connect different hardware to the USB.
The subdriver for LCDproc supports dual HD44780 displays and a 4x4 keypad as well as
software adjustable contrast and brightness (backlight).
USB-4-all
LCD1
LCD2
name
pin
name
name
RB7
28
D7
D7
RB6
27
D6
D6
RB5
26
D5
D5
RB4
25
D4
D4
RB3
24
R/W
R/W
RB2
23
RS
RS
RB0
21
EN
RC0
11
EN
This connection type supports a LCD connected to the GPIO header P1 on
a Raspberry Pi. Displays with one or two controllers are supported.
It supports a switchable backlight connected to pin P1-11 by default. Use
the switch circuit as described in .
The signal level on the GPIO pins is 3.3 V and they are said not to
be 5 V tolerant. Therefore the R/W pin of the display must
be wired to GND to prevent 5V logic appearing on the GPIO
pins. For the same reason the backlight cicuit from must not be
used.
Powering a LCD that uses 5 V from pin P1-02 will work. Powering a
LCD from 3.3 V (pin P1-01) will only work if it is designed for 3.3 V
operation.
Connector
<->
LCD
Pin Name
Pin Number
Name
Pin
GPIO18
P1-12
D7
14
GPIO23
P1-16
D6
13
GPIO24
P1-18
D5
12
GPIO25
P1-22
D4
11
GPIO08
P1-24
EN
6
GPIO07
P1-26
RS
4
GND
P1-06
RW
5
GPIO22
P1-15
EN2
Second controller (optional)
GPIO17
P1-11
BL
Backlight (optional)
GPIO07 and GPIO08 used for RS and EN signal are also used by the SPI
bus. If you loaded the SPI driver you will need to assign them to a different
GPIO, e.g. GPIO04 and GPIO22.
When using a display with two controllers the vspan
option has to be configured as well (e.g. vspan=2,2 for a
40x4 display).
This connection driver can be configured to use other pins than the
one described in the table
above. Using the pin_
configuration option, any LCD pin can be assigned
to any GPIO pin.
The values for the pin_
configuration option are the number part from the
GPIO signal name, not the pin number from the header connector! To find
out which signal is routed to which connector pin refer to the RPi Low-level peripherals
description.
The connection driver contains a check for possible signal names. You
will receive an error message if you try to assign a pin to a signal that is
not available on connector P1 or P5.
The Adafruit RGB Positive 16x2 LCD+Keypad for Raspberry Pi (aka Pi Plate,
see ()) combines
a 16x2 Character LCD, up to 3 backlight pins AND 5 keypad pins using only
the two I2C pins on the Rasperry Pi.
Note that this connection type drives all RGB pins of the backlight at the
same time, resulting in a white backlight. You will need to modify the
source code if you want to have some other color.
Keypad=yes
KeyDirect_1=Enter
KeyDirect_2=Up
KeyDirect_3=Down
KeyDirect_4=Left
KeyDirect_5=Right
]]>
The PiFace Control and Display for Raspberry Pi
from OpenLX SP Ltd combines a 16x2 Character LCD and navigation buttons using
the SPI bus on the Rasperry Pi.
The PiFace Control and Display features a IR receiver, which LCDproc does not
make use of. You have to setup and use LIRC for that. See
Setting up PiFace Control And Display to use a remote.
Keypad=yes
KeyMatrix_1_1=Left
KeyMatrix_1_2=Down
KeyMatrix_1_3=Up
KeyMatrix_1_4=Right
KeyMatrix_1_5=Escape
KeyMatrix_1_6=Enter
KeyMatrix_1_7=Left
KeyMatrix_1_8=Right
]]>
Make sure that the HD44780 files are built when you run ./configure.
This can be done by specifying --enable-drivers=all or by including
hd44780 in the list of enabled drivers
(e.g. --enable-drivers=hd44780).
Port =
PORT
For parallel connections, specify the address of the parallel port the LCD is connected to.
Common values for PORT are 0x278,
0x378 and 0x3BC.
If not given, the default is 0x378.
For I2C connection types this sets the slave
address.
Device =
DEVICE
If you are using a serial or I2C connection,
you need to set this parameter to the device your LCD is connected to.
For example, if the display is connected to the first serial port,
you have to set it to /dev/ttyS0.
The default value is /dev/lcd.
ConnectionType =
{
4bit |
8bit |
serialLpt |
winamp |
picanlcd |
lcdserializer |
los-panel |
vdr-lcd |
vdr-wakeup |
pertelian |
lis2 |
mplay |
usblcd |
bwctusb |
lcd2usb |
usbtiny |
uss720 |
usb4all |
ftdi |
i2c |
piplate |
spi |
pifacecad |
ethlcd |
raspberrypi
}
Select the type of the wiring / display connection. See also
().
Speed =
BITRATE
For a serial connection, set to the serial port bitrate. To use
the default value for the chosen interface, just set to 0.
CharMap =
{
hd44780_default |
hd44780_euro |
ea_ks0073 |
sed12780f_0b |
hd44780_koi8_r |
hd44780_cp1251 |
hd44780_8859_5 |
upd16314 |
none
}
Set the character mapping depending on the display you have:
The default, hd44780_default, is for "classic"
HD44780 displays.
hd44780_euro is for displays with a ROM mask
supporting the european charset (ROM code A02).
ea_ks0073 is the charmap for Electronic
Assembly's KS0073 based displays. These devices have a richer
charset, including many icons and many more characters of the
ISO-8859-1 than standard HD44780s.
sed12780f_0b is for some SED 1278 displays.
The none charmap does not translate any characters.
It displays the characters the display controllers actually has
stored in its CGROM for that position instead. This setting is
intended for debugging purpose.
You only need to set this parameter if you have a non-standard
HD44780 display or charmap.
If LCDproc was configured with '--enable-extra-charmaps' option the
following character mappings are available, too:
hd44780_koi8_r maps input from a client in
Russian KOI8-R to displays with a ROM mask supporting the european
charset (ROM code A02).
hd44780_cp1251 maps input from a client in
Russian CP1251 (Windows-1251) to displays with a ROM mask supporting
the european charset (ROM code A02).
hd44780_8859_5 maps input from a client in
Russian ISO 8859-5 to displays with a ROM mask supporting the european
charset (ROM code A02).
upd16314 is for displays with a Nec uPD16314
vacuum fluorescent display (VFD) controller with ROM code 002
character set. If your display has ROM code 001 character set you
may use the hd44780_euro charmap instead.
See server/drivers/hd44780-charset.h
in LCDproc's source directory for the actual
mappings.
Keypad = ¶meters.yesnodef;
Tell whether you have a keypad connected.
You may also need to configure the keypad layout further on in this file.
Brightness =
BRIGHTNESS
Set the initial brightness when the backlight is on
for the lcd2usb connection type.
Legal values are 0 - 1000,
with 800 being the default.
OffBrightness =
BRIGHTNESS
Set the initial off-brightness, i.e. the brightness when the backlight is off,
for the lcd2usb connection type.
The legal range is 0 - 1000.
If not given, it defaults to 300.
Contrast =
CONTRAST
Set the initial contrast for the bwctusb and
lcd2usb connection types.
Legal values for CONTRAST are
0 - 1000.
If not given, it defaults to 500 which may
be too low or too high for the selected connection type.
So, if the screen is blank or dark, please try playing with
the contrast a bit.
Backlight = ¶meters.yesnodef;
Specify if you have a switchable backlight.
OutputPort = ¶meters.yesnodef;
Tell if you have the additional output port ("bargraph") and you want to
be able to control it with the lcdproc OUTPUT command.
Lastline = ¶meters.yesdefno;
Specifies whether the lowest pixel line of a character is pixel addressable
or if it controls an underline effect.
The default is yes, meaning a pixel addressable last pixel line.
Size = ¶meters.size;
Specifies the size of the LCD.
Default: 20x4
In case of multiple combined displays, this should be the total size.
vSpan =
HEIGHT
,…
The "vertical span" when using the driver with multi-controller displays
or with multiple displays that are treated as a single virtual display.
It is a comma separated list of the heights of each display.
In multi-controller displays it lists the number of lines each controller
is responsible for.
E.g. vSpan=2,2,1 means you have three physical displays, the first
two having two lines each, and the third having one line, that together form
a virtual display that is 5 lines high.
The sum of the HEIGHTs must match the total height
given in Size=.
ExtendedMode = ¶meters.yesnodef;
If you have a KS0073 or an other 'almost HD44780-compatible', set this
flag to get into extended,4-line linear addressing mode.
LineAddress =
ADDR
If the next line of your display doesn't start 0x20 higher in
DDRAM you can override the default value of the ExtendedMode with this parameter.
DelayMult =
DELAY
If your display is slow and cannot keep up with the flow of data from
LCDd, garbage can appear on the LCDd. Set this delay multiplier to
2 or 4 to increase the delays.
The default is 1 for a non-multiplied delay.
DelayBus = ¶meters.yesdefno;
You can reduce the inserted delays by setting this to no.
On fast PCs it is possible your LCD does not respond correctly.
Default: yes.
KeepAliveDisplay =
SECONDS
Some displays (e.g. vdr-wakeup) need a message from the driver to
indicate that it is still alive.
When set to a value greater than 0 the character in the
upper left corner is updated every SECONDS seconds.
The default 0 does not cause any extra updates.
RefreshDisplay =
SECONDS
If you experience occasional garbage on your display you can use this
option as workaround. If set to a value greater than 0 it forces a
full screen refresh every SECONDS seconds.
Default: 0.
KeyDirect_NUM =
KEY
KeyMatrix_X_Y =
KEY
If you have a keypad you can assign keystrings to the keys.
See the keypad section
for used terms and the section on the specific connection type how to
wire it.
To map, for example, the directly connected key 4
to the string Enter, use KeyDirect_4=Enter.
For matrix keys use the X and
Y coordinates of the key;
e.g. KeyMatrix_1_3=Enter.
VendorID =
VENDORID
USB vendor ID to look for in certain USB connection types.
When using an FTDI chip with connection type ftdi, the default value is
0x4003.
When using a USS720 chip with connection type uss720, the default value is
0x1293.
ProductID =
PRODUCTID
USB product ID to look for in certain USB connection types.
When using an FTDI chip with connection type ftdi, the default value is
0x6001.
When using a USS720 chip with connection type uss720, the default value is
0x0002.
SerialNumber =
SERIALNO
Serial number of the USB device to look for with
connection type bwctusb.
If not given, the first BWCT USB module found will be used.
This text has originally been taken from a message by Bill Farrow
bfarrow@arrow.bsee.swin.edu.au.
Updated February 2000, Benjamin Tse blt@ComPorts.com
Updated October 2001, Joris Robijn joris@robijn.net
Converted to Docbook March 2002, Rene Wagner reenoo@gmx.de
Updated April 2002, Rene Wagner reenoo@gmx.de
Updated and extended April 2006 to November 2007, Peter Marschall peter@adpm.de
