QR-code-printer

Raspberry Pi based QR code printer, based on Tornado and the Brother QL line of thermal sticker printers. The first version of this codebase was based on some scrappy php and bash.

Installation

Copy the files from www into the root of your web server, and copy scripts into the root of your Pi. Make sure to set the permissions correctly, as that is what usually breaks (particularly for the files in the scripts directory, as well as the /dev/usb/lp0 device).

Printer library

Install the neccesary dependencies:

sudo aptitude install build-essential libpng12-0 libpng12-dev pkg-config

You will then need to run make in order to use the ql570 library (in the scripts/ql570 directory).

autostart file

You will need to create an autostart file. Edit /home/pi/.config/autostart/kiosk.desktop and add the following:

[Desktop Entry]
Type=Application
Name=Kiosk
Exec=/home/pi/kiosk.sh
X-GNOME-Autostart-enabled=true

Next, you'll need the following in your home repository in the file kiosk.sh:

#!/bin/bash
 
# Run this script in display 0 - the monitor
export DISPLAY=:0
 
# If Chrome crashes (usually due to rebooting), clear the crash flag so we don't have the annoying warning bar
sed -i 's/"exited_cleanly":false/"exited_cleanly":true/' /home/pi/.config/chromium/Default/Preferences
sed -i 's/"exit_type":"Crashed"/"exit_type":"Normal"/' /home/pi/.config/chromium/Default/Preferences
 
# Run Chromium and open tabs
/usr/bin/chromium-browser -kiosk https://kiwicampus.com & 

To disable the screensaver from switching off the display, you need to edit /etc/lightdm/lightdm.conf and add the following to a section with [SeatDefaults] or [Seat*] in its name:

xserver-command=X -s 0 dpms

Note - I changed the instructions recently, and didn't figure out how to set the correct permissions on the printer. It's chmod 777 /dev/usb/lp0 run at boot. This is important for several reaons - first of all, this disables screen blanking, then it fixes the permissions for the printer, then it opens up chromium whilst ignoring any errors that may clutter the screen.

Usage

Go to the /web page from your computer or phone, or set up the /kiosk page to autostart in fullscreen kiosk mode on your Pi.

Useful shortcuts

# export your screen
export DISPLAY=:0

# see what's breaking
tail -f /var/log/apache2/access.log
tail -f /var/log/apache2/error.log

# print a file manually
/home/pi/ql570/ql570 /dev/usb/lp0 w /scripts/qrcode.png