Raspberry Pi with Touch Display - Installation Instructions

Operating System

prepare an SD Card as described on archlinuxarm.org
SSH into your system, add your public key (initial root password is "root")
disable root password by calling passwd -d root
set a useful hostname by calling echo $hostname > /etc/hostname
run pacman -Suy to update packages

Hardware support

LCD Module

The LCD Module works is fb_ili9341compatible and is supported by the linux kernel. It needs enabled SPI support to work. Uncomment device_tree_param=spi=on in /boot/config.txt to enable.

Now, add the following to /etc/modules-load.d/fbtft_device.conf:

spi_bcm2708
fbtft_device

And set module parameters in /etc/modprobe.d/fbtft_device.conf:

options fbtft_device custom name=fb_ili9341 speed=48000000 gpios=dc:22,reset:27 bgr=1 rotate=0

After a reboot, this should generate a /dev/fb1 framebuffer device. For a quick test, you can cat /dev/urandom > /dev/fb1 which should show some noise on the display.

Touch controller

The Touch Controller ( probably XPT2046, compatible with ADS7843) is supported by the ads7846 kernel driver . However, there is no builtin way to add a new touch input device on demand by loading the module with some parameters, so we need to compile an external kernel module which does exactly that for us:

pacman -S base-devel linux-raspberrypi-headers git
git clone https://github.com/notro/fbtft_tools.git
cd fbtft_tools/ads7846_device
make
make install
depmod -a

Of course, we could also put this inside a PKGBUILD to keep everything clean. Remember you'll have to rebuild the module on each kernel update.

We now add the needed kernel modules and module parameters:

/etc/modules-load.d/ads7846_device.conf:

spi_bcm2708
ads7846_device

/etc/modprobe.d/ads7846_device.conf:

options ads7846_device model=7846 cs=1 gpio_pendown=17  speed=1000000 keep_vref_on=1 swap_xy=0 pressure_max=255 x_plate_ohms=60 x_min=200 x_max=3900 y_min=200 y_max=3900

This should generate a new input device in /proc/bus/input/devices. If you want, to can pacman -S evtest and watch some events when touching the display.

GPIO

TODO

Software

Utilities

Install some basic applications to make your life easier:

pacman -S vim wget rsync htop strace lsof tree

Graphical Interface

Install the following packages:

pacman -S xorg-server xorg-xinit xorg-xset xf86-video-fbdev xterm

Needed/Recommended packages

Install needed/recommended packages:

pacman -S matchbox-window-manager unclutter xdotool

Allow non-console users to start X

To allow non-console users to start X, add the following to /etc/X11/Xwrapper.config:

 allowed_users=anybody

/etc/X11/xorg.conf.d

This is where X server configuration should stay. To configure X11 to use the Framebuffer provided by the LCD, add the following to /etc/X11/xorg.conf.d/99-fbdev.conf:

Section "Device"
        Identifier "myfb"
        Driver "fbdev"
        Option "fbdev" "/dev/fb1"
EndSection

Custom keyboard layout

A custom keyboard layout can be set by adding a file /etc/X11/xorg.conf.d/20-keyboard.conf:

Section "InputClass"
        Identifier "German Keyboard"
        MatchIsKeyboard "yes"
        Option "XkbLayout" "de"
EndSection

Kiosk Mode (Midori Webbrowser)

This mode will start a fullscreen browser.

Required Packages

Of course, you need a Browser. We use Midori here, because its provided in Archlinux ARM and based on the WebbKit engine.

pacman -S midori

User

Create a kiosk user to run X:

useradd kiosk -m

.xinitrc

Create a .xinitrc in kiosk's home directory (su kiosk -):

#!/bin/sh
# disable screen blanking
xset -dpms
xset s off

# automatically hide mouse cursor after if idle
unclutter &

# start matchbox window manager
matchbox-window-manager -use_titlebar no &

# queue click event in webbrowser to focus webview
xdotool sleep 10 mousemove 0 0 click 1 &

# start webbrowser
midori -e Fullscreen -a $website_url

systemd unit file

To simplify starting a session, you could add a unit file to /etc/systemd/system/kiosk.service:

[Service]
Environment = "DISPLAY=:0"
ExecStart = /usr/bin/startx

ExecStop = /usr/bin/xset dpms force off
# screen will stay blank until there is something to be displayed again

SuccessExitStatus=1 SIGHUP SIGINT SIGTERM SIGPIPE 
# TODO: this needs further work

Restart = always
User = kiosk

[Install]
WantedBy = graphical.target

Normally, you want to automatically start one X session on bootup, so don't forget to systemctl enable kiosk.

Look & Feel

To get a nicer Look and Feel, install the following themes and fonts:

pacman -S ttf-bitstream-vera gtk-theme-orion

# as user 'kiosk' (`su kiosk -`)
echo 'include "/usr/share/themes/Orion/gtk-2.0/gtkrc"' > ~/.gtkrc-2.0

flokli/raspberry_pi_touch.md