lcd-daemon package is a package consisting of lcd-daemon, notify-daemon, pilcd and pinotify. lcd-daemon implements a UDP server and also reads a local named pipe (FIFO) to read data from local and remote clients to print text on a LCD display. It works only for the Hitachi 4480 controller based 16x2 and 20x4 displays. The pilcd client can send text locally to lcd-daemon. One can also use the echo command instead of the pilcd command to write print the text on the LCD.
lcd-daemon uses libwiringpi and libwiringpidev from https://github.com/mbhangui/wiringPi. The original Author of Wiring Pi is Gordon Henderson. Wiring Pi was what made me love the Raspberry Pis.
The wiring scheme used by lcd-daemon is as below. If you wire it differently you don't have to rebuild the package. Instead you can set environment variables PIN_RS, PIN_EN, PIN_D0 to PIN_D7.
| Pin Name | WiringPI Number | GPIO Pin | RPI Board Number | LCD Pin Number |
|---|---|---|---|---|
| - | - | - | 6 | 01 Ground |
| - | - | - | 2 | 02 +5v |
| - | - | - | - | 03 Contrast Adjustment |
| PIN_RS | 6 | 25 | 22 | 04 Register Select |
| - | - | - | - | 05 Read Write Pin (connected to Ground) |
| PIN_EN | 5 | 24 | 18 | 06 Enable Pulse |
| PIN_D0 | - | - | - | 07 data pin 0 Not connected |
| PIN_D1 | - | - | - | 08 data pin 1 Not connected |
| PIN_D2 | - | - | - | 09 data pin 2 Not connected |
| PIN_D3 | - | - | - | 10 data pin 3 Not connected |
| PIN_D4 | 4 | 23 | 16 | 11 data pin 4 |
| PIN_D5 | 0 | 17 | 11 | 12 data pin 5 |
| PIN_D6 | 2 | 27 | 13 | 13 data pin 6 |
| PIN_D7 | 3 | 22 | 15 | 14 data pin 7 |
| - | - | - | 2 | 15 Anode of backlight LED |
| - | - | - | 9 | 16 Cathode of backlight LED |
With the above wiring scheme you may want to have the following lines in /boot/config.txt. This will allow you to access the LCD display using the device /dev/lcd.
# Enable HD44780 LCD controller
dtoverlay=hd44780-lcd,pin_d4=23,pin_d5=17,pin_d6=27,pin_d7=22
dtparam=pin_rs=25,pin_en=24,display_height=4,display_width=20
Anything written to this device will get displayed on the LCD display. Clearing the display is as simple as executing clear > /dev/lcd. This can be done without having to install the lcd-daemon package. But you can use the lcd-daemon package for having control on which row to print, scroll text and ability to display text on the LCD display from the network.
lcd-daemon reads a named pipe and a UDP socket in line mode and expects the line to be in a simple format of arguments, separated by whitespace, as detailed below.
rownum scroll clear:message
where
- rownum - value can be 0 or 1 for 16x2 display or 0, 1, 2 or 3 for 20x4 display.
- scroll - value can be 0 or 1. 1 turns on scrolling
- clear - The following values are supported for clear
- clear the screen
- clear and initialize
- initializing LCD display
- clear screen without displaying text
- clear and initialize screen without displaying text
- initialize screen without displaying text
pilcd is one client that writes to the named pipe in the above format. You can use any program/script to display text on the LCD display by using the above format. Expanding this further you can use any UDP client to send text to be printed on the LCD screen by sending the text to UDP port 1806.
notify-daemon server prints desktop notifications over requests received locally on /run/notify-desktop/notify-fifo or requests received on UDP port 1807.
notify-daemon reads a named piope and a UDP socket in line mode and expects the line to be in a simple format of arguments as detailed below summary:summary_text\nbody:body1\nbody:body2\nend:\n
where
- summary: This specifies to use summary_text as the value of summary for desktop notificaton. See the man page of notify-send(1)
- body: This specifies to use body_text as the body. You can speciffy multiple bodies ending with new line. Specifying multiple body: statements allows multi-line desktop notification
- end: This ends body of the desktop notification
On the server which has the LCD display connected, let us run lcd-daemon
Start lcd-daemon
$ sudo /usr/sbin/lcd-daemon -b 4 -c 20 -r 4 &
Send message locally using picd on the first row
$ pilcd -R 0 Hi from Localhost
Send message locally using echo command on the second row
$ echo 1 0 0:Hi from local > /run/lcd-daemon/lcdfifo
Scroll message to a remote server 192.168.2.101 having the LCD display on row 3
$ echo 2 1 0:Hi from overseas | nc -u 192.168.2.101 1806
Start notify-daemon
$ sudo /usr/sbin/notify-daemon
Send desktop notification locally using pinotify
$ pinotify notify-test "Hi From Local" "date is $(date)"
Send desktop notification to a remote desktop at 192.168.1.100
$ printf "summary:notify-test\nbody:Hi From Local\nbody:today is a good day\n"| nc -u 192.168.1.100 1807
Before building lcd-daemon, you need to build and install libwiringpi and libwiringpidev from https://github.com/mbhangui/libwiringPi.
$ cd /usr/local/src
$ git clone --no-tags --no-recurse-submodules --depth=1 https://github.com/mbhangui/lcd-daemon
$ cd lcd-daemon
$ ./default.configure
$ make && sudo make install-strip
This is done by running the create_rpm / create_debian scripts. (Here version refers to the existing version of lcd-daemon package)
To create the RPM package execute create_rpm script
$ pwd
/usr/local/src/lcd-daemon
$ ./create_rpm
$ ls -l $HOME/rpmbuild/RPMS/x86_64/*lcd-daemon*
-rw-r--r--. 1 pi pi 36584 Jun 19 17:41 /home/pi/rpmbuild/RPMS/x86_64/lcd-daemon-1.0-1.1.fc38.x86_64.rpm
-rw-r--r--. 1 pi pi 40876 Jun 19 17:40 /home/pi/rpmbuild/RPMS/x86_64/lcd-daemon-debuginfo-1.0-1.1.fc38.x86_64.rpm
-rw-r--r--. 1 pi pi 80848 Jun 19 17:40 /home/pi/rpmbuild/RPMS/x86_64/lcd-daemon-debugsource-1.0-1.1.fc38.x86_64.rpm
To install use the rpm command
$ sudo rpm -ivh /home/pi/rpmbuild/RPMS/x86_64/lcd-daemon-1.0-1.1.fc38.x86_64.rpm
To create the debian package execute create_debian script
$ pwd
/usr/local/src/lcd-daemon
$ ./create_debian
$ ls -l $HOME/stage
total 44
drwxr-xr-x 3 pi pi 4096 Jun 19 18:35 .
drwxr-xr-x 24 pi pi 4096 Jun 19 18:24 ..
-rw-r--r-- 1 pi pi 6059 Jun 19 18:35 lcd-daemon.0-1.1_arm64.buildinfo
-rw-r--r-- 1 pi pi 2552 Jun 19 18:35 lcd-daemon.0-1.1_arm64.changes
-rw-r--r-- 1 pi pi 2344 Jun 19 18:35 lcd-daemon.0-1.1_arm64.deb
To install use the debian command
$ sudo dpkg -i /home/pi/stage/lcd-daemon-1.0-1.1_arm64.deb
You can run lcd-daemon on the command line or put it in rc.local or create a systemd script or use your own favourite method. I use daemontools and use svscan. The RPM/debian installation creates a service for lcd-daemon as /service/lcd-daemon. My fork of Dan's daemontools package is here. svscan runs supervise which can run lcd-daemon continuously. If you have built lcd-daemon using the source, you can run the create_service to create the service. Run the create_service command to create a service for lcdDeamon in /service/lcd-daemon. Once you install the daemontools package, lcd-daemon will start automatically on boot. You can manually start or stop using the svc command.
Start lcd-daemon
$ sudo svc -u /service/lcd-daemon
Stop lcd-daemon
$ sudo svc -d /service/lcd-daemon
To install daemontools package run the command. This will require you to install the OBS repo. See the next chapter for details.
$ sudo apt-get update && sudo apt-get install daemontools
TODO
I need to upload the man pages for lcd-daemon and pilcd here. Will do it sometime later.
Prebuilt binaries using openSUSE Build Service are available for lcd-daemon for
- Debian 10 (including ARM images for Debian 10 which work (and tested) for RaspberryPI (model 2,3))
- Raspbian 10 and 11 for RaspberryPI (arm and aarch64 images)
- Ubuntu 20, 22, 23 (arm and aarch64 images)
Use the below url for installation
The above instructions will help you add the OBS repo in /etc/apt/sources.list.d for debian systems or /etc/yum.repos.d for rpm based systems. Once you have the repo can can install using the apt-get or the yum/dnf command
For debian based systems
$ sudo apt-get update && sudo apt-get install lcd-daemon
For RPM based systems
$ sudo dnf update && sudo dnf install lcd-daemon
You don't need to read this if you are going to have your own method to run lcd-daemon on startup. But if you want to use daemontools to run lcd-daemon you need to read this. debian/ubuntu repositories already has daemontools which is far behind in terms of feature list than the daemontools repo provides. When you install daemontools, apt-get may pull the wrong version with limited features. Also apt-get install daemontools or apt-get install daemontools will get installed with errors, leading to an incomplete setup. You need to ensure that the two packages get installed from the daemontools repository instead of the official debian repository.
All you need to do is set a higher preference for the daemontools repository by creating /etc/apt/preferences.d/preferences with the following contents
$ sudo /bin/bash
# cat > /etc/apt/preferences.d/preferences <<EOF
Package: *
Pin: origin download.opensuse.org
Pin-Priority: 1001
EOF
You can verify this by doing
$ apt policy daemontools ucspi-tcp
daemontools:
Installed: 2.11-1.1+1.1
Candidate: 2.11-1.1+1.1
Version table:
1:0.76-7 500
500 http://raspbian.raspberrypi.org/raspbian buster/main armhf Packages
*** 2.11-1.1+1.1 1001
1001 http://download.opensuse.org/repositories/home:/indimail/Debian_10 Packages
100 /var/lib/dpkg/status
ucspi-tcp:
Installed: 2.11-1.1+1.1
Candidate: 2.11-1.1+1.1
Version table:
1:0.88-6 500
500 http://raspbian.raspberrypi.org/raspbian buster/main armhf Packages
*** 2.11-1.1+1.1 1001
1001 http://download.opensuse.org/repositories/home:/indimail/Debian_10/ Packages
100 /var/lib/dpkg/status
Feel free to create an issue on github. I'm also available on matrix where you can leave a message if you have any issue.