debian

KA Lite is an open source, web-based learning package. Today I’ll run through a simple setup which will allow a Raspberry Pi to provide a wireless learning resource server for a classroom, without the Internet.

The Raspberry Pi 2 is a surprisingly powerful single-board computer. You can use it for anything which a computer can do, in a relatively cheap circuit board the size of a credit card:

This setup takes around two hours.

Materials

You will need:

Raspberry Pi (The Raspberry Pi 2 Model B was used here), with micro SD card, mouse, keyboard, monitor with HDMI.
A good Micro USB power supply – Many Android phone chargers will be suitable.
A computer which can write to micro SD cards. If your computer has an SD card slot, get an SD-to-Micro-SD adapter for it.
A wired network with Internet for the setup
A USB wireless network adapter such as WiPi for deployment.
Any WiFi-enabled device for testing.

Install Raspbian

Raspbian is an operating system for the Pi, and is the perfect choice for embedded server setups like this. You need to write the image to the Micro SD card.

Obtain the image from https://www.raspberrypi.org/downloads/
This is zipped, so extract it to get the real image file.
Write the disk image to the SD card:
- Windows: Fetch a copy of “Win32 Disk Imager” to write this file to the SD card.
- Linux or Mac: Use dd (found in the terminal) to write to the card — guide available here
Boot the Pi, with mouse, keyboard, HDMI, and wired network. If it doesn’t work, remove any cable converters (use HDMI direct to monitor), and if it still doesn’t work, then the SD card was not correctly imaged.
Expand root filesystem, set your password, and enable “boot to desktop”.
After reboot, you should have a desktop. Click the black terminal icon to get to work.

Install some things

From the terminal, run these commands:

sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get install chromium python-m2crypto

This checks for new software (update), upgrades anything necessary (dist-upgrade), and then installs two packages:

python-m2crypto — this will help speed up KA Lite a bit by helping out with encryption.
chromium — this is Google Chrome’s open source cousin, and it’s worth installing so that you can Google things as you go, and test things locally.

If everything goes to plan, you should now be able to find Chrome on the menu and navigate the web.

Install KA Lite

These steps are a shortened version of the official guide

Once Raspbian is running, these commands will download & install KA Lite:

git clone https://github.com/learningequality/ka-lite.git
cd ka-lite/
./setup_unix.sh

The download is 150MB, so allow a few minutes. The installer then prompts for a few questions, like:

“Do you wish to download the assessment package now?” — Say yes, it fetches another 500MB.
“Do you wish to set the KA Lite server to run in the background automatically when you start this computer?” — say “y”.

At the end, you will be given a command to start the server, which you should type in as well:

/home/pi/ka-lite/bin/kalite start

Once it starts (it will take a while!), it will give you two web addresses. One of them is local to the computer (127.x), and the other will work from other computers on the network. Write both of them down!

The install & start-up together will look like a this:

Test it out locally

Open up Chromium, and navigate to one of the addresses that the installer suggested.

Click on “Manage”, then “Videos”

KA Lite will prompt for registration, which lets you download content. Use the “One click registration” on the left, then wait for it to connect.

Use the Videos section to fetch something. Here we fetch something from the ancient art & culture section:

Wait a few minutes before moving to the next section: The video downloads in the background.

Access over the network

From some other device which is on the same network, enter the web address that was given at the end of the installer (ignore the address which starts with 127.x — it wont work between two computers):

http://(IP address):8008/

From the browser, let’s test it out. Click over to Learn, and navigate to the video you just downloaded. It should display, so we can learn about those Egyptian artifacts:

This setup would be complete if you want to run on a wired network – you can simply bookmark this address on each computer which needs to use it, and manage it through the web.

Next post in this series: Raspberry Pi KA Lite wireless deployment

How to run Tetris on your Raspberry Pi

C++ debian howto just-for-fun linux raspberry-pi

April 9, 2015April 2, 2022

This is a simple walkthrough on how to install my Tetris clone, Blocks, on a Raspberry Pi.

On most computers running Debian (or Raspbian in the case of the Raspberry Pi), it’s as simple as clone, compile, run:

sudo apt-get install libncurses5-dev doxygen
git clone https://github.com/mike42/blocks
cd blocks
make
./bin/blocks

If you have any issues running this, then you need to fetch a newer version of GCC, as this needs C++11 support to compule (see last section for instructuins).

But if all goes to plan, you will get something like this in your terminal:

Use the keyboard to control the game:

Move: Right, down, left
Rotate: Up
Drop: Spacebar
Quit: q

Get a screen

Basically any project with graphics can benefit from one of these. Simply add on a TFT shield, such as PiTFT to create a tiny console:

Of course, this is still keyboard-controlled, but with some hacking, I’m sure you could map touch events to keyboard actions.

Troubleshooting: Update GCC

The Raspbian spftware image which many Raspberry Pi’s have is slightly too old to compile Blocks, which requires C++11 support.

Luckily, it’s very easy to upgrade from wheezy to jessie to add it. You know you need to do this if you get this error compiling:

$ git clone https://github.com/mike42/blocks
$ make
mkdir -p bin
g++ src/main.cpp src/blocks_game.cpp src/blocks_shape.cpp -o bin/blocks -lcurses -lrt -std=c++11 -Wall
cc1plus: error: unrecognized command line option ‘-std=c++11’
cc1plus: error: unrecognized command line option ‘-std=c++11’
cc1plus: error: unrecognized command line option ‘-std=c++11’
Makefile:2: recipe for target 'default' failed
make: *** [default] Error 1

Generally this means you don’t have GCC 4.8, which is not available in wheezy edition of Raspian.

$ g++ --version
g++ (Debian 4.6.3-14+rpi1) 4.6.3
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

So to summarise this thread, you need to:

nano /etc/apt/sources.list

Find this line:

deb http://mirrordirector.raspbian.org/raspbian/ wheezy main contrib non-free rpi

And change the word “wheezy” to “jessie”:

deb http://mirrordirector.raspbian.org/raspbian/ jessie main contrib non-free rpi

You can then update everything with:

sudo apt-get update && sudo apt-get dist-upgrade

You are now running the newer jessie release, which gives you access to the GCC 4.8 package we need:

apt-get install g++-4.8

So we can pick up where we left off, and compile the game:

make
./bin/blocks

Getting a USB receipt printer working on Linux

debian escpos hardware howto linux

March 8, 2015May 3, 2016

In this post, I’ll step through how to get a thermal receipt printer with USB interface appearing on Linux. The aim of this is to be able to point a driver such as escpos-php at the device. The printer used here is an Epson TM-T20, which is very common in point-of-sale environments.

I have previously written quite a bit about how to use thermal receipt printer protocols, but the previous printer I covered had only a network interface, not USB like this one:

The directions below are for Debian, but could be adapted for any other Linux.

Find the device file

Plug in your printer, and check that usblp sees it:

dmesg
[12724.994550] usb 8-4: new full-speed USB device number 5 using ohci-pci
[12725.168956] usb 8-4: New USB device found, idVendor=04b8, idProduct=0e03
[12725.168963] usb 8-4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[12725.168968] usb 8-4: Product: TM-T20
[12725.168971] usb 8-4: Manufacturer: EPSON
[12725.168975] usb 8-4: SerialNumber: ....
[12725.175114] usblp 8-4:1.0: usblp1: USB Bidirectional printer dev 5 if 0 alt 0 proto 2 vid 0x04B8 pid 0x0E03

This kernel module makes your printer visible as a device file, so that it can be accessed in the old-fashioned way. Find the new device file under /dev/usb:

ls /dev/usb

In my case, this was /dev/usb/lp1. The next step is to see if you can write to it:

echo "Hello" >> /dev/usb/lp1

Chances are, you will get a permission denied error at this point, so find out what group the printer is in:

stat /dev/usb/lp1

Which will show output something like:

File: ‘/dev/usb/lp1’
  Size: 0         	Blocks: 0          IO Block: 4096   character special file
Device: 5h/5d	Inode: 220997      Links: 1     Device type: b4,1
Access: (0660/crw-rw----)  Uid: (    0/    root)   Gid: (    7/      lp)
...

This file is owned by group lp (“line printer”). If your username was bob, you would add yourself to this group using:

sudo usermod -a -G lp bob

If you plan to build a web-based point-of-sale system with this, then also add the www-data user to that group.

Now log out and back in, and the previous test should now be working:

echo "Hello" >> /dev/usb/lp1

Troubleshooting: Check `usblp`

If these steps don’t work, then your computer ether doesn’t have, or isn’t using usblp You’ll need to check a few things:

Install a different linux-image if the driver is not on your computer at all.
modprobe or insmod usblp
blacklist a vendor driver which has claimed the interface.
- run lsusb -v and usb-devices (look for driver=)

Printing something useful

As a duplicated section from my earlier post, the printer uses ESC/POS, which means it accepts plaintext with some special commands for formatting.

A simple receipt-generator, foo.php, might look like this:

<?php
/* ASCII constants */
const ESC = "\x1b";
const GS="\x1d";
const NUL="\x00";

/* Output an example receipt */
echo ESC."@"; // Reset to defaults
echo ESC."E".chr(1); // Bold
echo "FOO CORP Ltd.\n"; // Company
echo ESC."E".chr(0); // Not Bold
echo ESC."d".chr(1); // Blank line
echo "Receipt for whatever\n"; // Print text
echo ESC."d".chr(4); // 4 Blank lines

/* Bar-code at the end */
echo ESC."a".chr(1); // Centered printing
echo GS."k".chr(4)."987654321".NUL; // Print barcode
echo ESC."d".chr(1); // Blank line
echo "987654321\n"; // Print number
echo GS."V\x41".chr(3); // Cut
exit(0);

And you would send it to the printer like this:

php foo.php > /dev/usb/lp1

Scaling this up

The codes are quite tricky to work with manually, which is why I put together the escpos-php driver. You can find it at:

The above example would be written using escpos-php as:

<?php
require __DIR__ . '/autoload.php';
use Mike42\Escpos\Printer;
use Mike42\Escpos\PrintConnectors\FilePrintConnector;
$connector = new FilePrintConnector("/dev/usb/lp1");
$printer = new Printer($connector);

/* Print some bold text */
$printer -> setEmphasis(true);
$printer -> text("FOO CORP Ltd.\n");
$printer -> setEmphasis(false);
$printer -> feed();
$printer -> text("Receipt for whatever\n");
$printer -> feed(4);

/* Bar-code at the end */
$printer -> setJustification(Printer::JUSTIFY_CENTER);
$printer -> barcode("987654321");
$printer -> cut();
?>

This would be sent to the printer by loading it from the web, or running the script on the command-line:

php foo2.php

Howto: Tethered photo capture on Linux

debian howto linux

January 15, 2015May 3, 2016

Have you ever wondered how professionals get photos to pop up on their computer as they snap them? Most higher-end cameras have mini USB connection, and software is available to retrieve images as they are taken.

Rather than use a GUI app, in this post I’ll use a command-line program called gphoto2 to drop the images into a folder. With large thumbnails set in your file browser, a desktop program would be redundant.

First, you need to install the program. Depending on your system, one of the following commands should do the trick:

apt-get install gphoto2
yum install gphoto2

Now, plug in the camera. The command to do a “tethered capture” is:

gphoto2 --capture-tethered

Unfortunately, in most desktop environments, your file manager will mount the camera automatically. If this is the case, then the command will give you an error:

mike@mikebox:~$ gphoto2 --capture-tethered
Waiting for events from camera. Press Ctrl-C to abort.                         

*** Error ***              
An error occurred in the io-library ('Could not claim the USB device'): Could not claim interface 0 (Device or resource busy). Make sure no other program (gvfs-gphoto2-volume-monitor) or kernel module (such as sdc2xx, stv680, spca50x) is using the device and you have read/write access to the device.
*** Error (-53: 'Could not claim the USB device') ***       

For debugging messages, please use the --debug option.
Debugging messages may help finding a solution to your problem.
If you intend to send any error or debug messages to the gphoto
developer mailing list , please run
gphoto2 as follows:

    env LANG=C gphoto2 --debug --debug-logfile=my-logfile.txt --capture-tethered

Please make sure there is sufficient quoting around the arguments.

Simply find the camera and unmount it using the eject button:

Now when you type the command, it will block until a photo is taken, and then show you the name of the photo:

mike@mikebox:~$ gphoto2 --capture-tethered
Waiting for events from camera. Press Ctrl-C to abort.                         
UNKNOWN PTP Property 5007 changed
...
Downloading 'DSC_0236.JPG' from folder '/store_00010001/DCIM/100NCD90'...
Saving file as DSC_0236.JPG                                                    
Deleting 'DSC_0236.JPG' from folder '/store_00010001/DCIM/100NCD90'...

Each of the photos is loaded into the working directory after you release the shutter, so you simply close gphoto2 when you’re done — no manual downloading or SD card required.

Extending this method

Ok, so now that I’ve covered this basic use case, the real reason I suggest gphoto2 is that it will let you script just about anything to do with your camera.

Just typing gphoto2 --help shows that it can let you trigger a photo or video on a timer, download and delete folders from the camera, or hook up programs via a pipe for processing the files in realtime.

Endless possibilities.

Productivity: De-activate social networking on a schedule with cron

cron debian just-for-fun linux productivity

October 17, 2014November 5, 2015

Sometimes you need to block out distractions for a set amount of time. One of these is social networking, and it’s fairly early to temporarily break it (all for productivity of course!).

Mac or Linux users can break example.com like this:

echo "127.0.0.1 example.com www.example.com" >> /etc/hosts

This tells the computer that it hosts example.com, so it wont load it from the internet.

And to compliment this, we have sed, which can delete lines from a file in-place based on a pattern:

sed -i '/example.com/d' /etc/hosts

Replace example.com above with your social network of choice, and have a shot. It will take a few minutes to have an effect, because of open connections and your computer’s DNS cache.

Scheduling it in

Cron is the go-to solution for scheduling any command on Unix. We’ll run this as root, as normal users don’t have permission to edit /etc/hosts:

su
crontab -e

If prompted, select nano as an editor.

If, for example, 6pm — 8pm weekdays is a distraction-free time for you, you would schedule the first command for 18:00 on days 1-5, and the second for 20:00 on days 1-5:

# m h  dom mon dow   command
0 18 * * 1-5 echo "127.0.0.1 example.com www.example.com" >> /etc/hosts
0 20 * * 1-5 sed -i '/example.com/d' /etc/hosts

If your use case calls for something more advanced, consider learning how to use squid to manage web traffic.

When you break something..

If you accidentally delete your /etc/hosts while experimenting, you can fetch its contents from /var/lib/dpkg/info/netbase.postinst (source).

QJoyPad update

debian

April 27, 2014November 5, 2015

As of April, there is now a qjoypad package available in the official Debian repository, see https://packages.debian.org/unstable/main/qjoypad. This program allows you to map joystick events to keyboard and mouse actions. This means that you could use, for example, a USB gamepad to browse the web.

I have previously blogged about the lack of usable, packaged programs to do this, and highly recommend getting your hands on a USB gamepad and giving this a shot. Depending on your distribution, you will soon be able to just run:

sudo apt-get install qjoypad

Then connect the gamepad and type:

qjoypad

You then get a window which shows you what buttons you can map:

Clicking a button prompts you to press a key on your keyboard or select a mouse button, and each profile can be saved and named for later use.

As far as small utility programs go, I now rely on this about as much as the Gnome calculator.

An alternative: AntiMicro

I’ll also give a mention to AntiMicro, which has similar goals, and looks very promising.

As a bit of background, there is a limitation in QJoyPad around adding modifier keys: For example, you simply can’t map a joystick button to <Ctrl>+Q, making it inefficient to use with most applications. The author of AntiMicro, Travis, sent me an email back in September to point out that his program both solves this issue, and has a Debian package available for download.

Whilst I was quite impressed with the functionality in AntiMicro, I found it a whole lot more complex to set up. I think this would be more useful for gamers, as mouse acceleration and key repeats are overkill for my use case (browsing the web and controlling VLC, MythTV, etc).

So, if you are a power user, then I suggest you give it a shot. Power users with apt-get may also consider joy2key, which is the best non-GUI tool for this, and is available in the Debian repositories.

A tour of ReactOS 0.3.15

debian kvm linux reactos

February 1, 2014November 5, 2015

ReactOS is a project which aims to create an open source operating system which is binary-compatible with Windows. Although it is still cautiously labelled “alpha”, its basic use is about as reliable as Windows once was.

This post runs through the steps to install ReactOS 0.3.15 as a KVM guest on Linux.

Preparation

Before attempting anything, check that you a CPU supports Intel VT or AMD-V. This command will return the number of CPU cores with svm or vmx flags:

cat /proc/cpuinfo | grep -E 'svm|vmx' | wc -l

Now download the ReactOS 0.3.15 disk from reactos.org, extract it to get the .iso, and fetch some packages if you don’t have them installed:

apt-get install libvirt-bin kvm qemu-utils

Prepare a disk image to install to. If your hardware is slower, then a raw image is a better idea than the qcow2:

qemu-img --help
qemu-img create -f qcow2 reactos.img 4G

The working directory now has:

mike@mikebox:~/vm/reactos$ ls -Ahl
total 77M
-rw-r--r-- 1 mike mike  77M May 19  2013 ReactOS-BootCD.iso
-rw-r--r-- 1 mike mike 193K Jan 30 21:05 reactos.img

Installation and first boot

The kvm command will pop up a window with the guest operating system. To boot from the install disk, run:

kvm -hda reactos.img --cdrom ReactOS-BootCD.iso -vga std -localtime -net nic,model=ne2k_pci -net user

The meaning of each of these options is:

-hda reactos.img: Sets the HDD image file.
--cdrom ReactOS-BootCD.iso: Sets the CDROM image file. Because reactos.img is blank, this will boot.
-vga std: Sets the VGA card.
-localtime: Emulates a system clock in local time, rather than UTC.
-net nic,model=ne2k_pci: Sets the network card to something ReactOS will recognise.
-net user: Enables user-mode networking. Your computer will emulate a network and pass on TCP and UDP connections. This is the easiest mode to use, but ICMP packets (such as pings) will not work, and the VM will not be accessible from other computers.

Installation was fast, error-free, and did not require a network connection. The first screen capture below was taken at 16:04:49, and the desktop was captured at 16:06:07 (1 minute 18 seconds later). Most of that time would have been wasted waiting for user input.

After copying files, the installer reboots to a more user-friendly mode (similar to the Windows installer):

ReactOS Install - Welcome to the ReactOS Setup Wizard

ReactOS Install - Personalize your Software

ReactOS Install - Computer name and Administrative Password

ReactOS Install - Registering Components

ReactOS Install - Completing the ReactOS Setup Wizard

The installed system

After installation, the --cdrom option can be dropped:

kvm -hda reactos.img -vga std -localtime -net nic,model=ne2k_pci -net user

The first thing I did was correct the colour depth, and then attempt to install VLC. This did not turn out well (the console screen is QEMU-monitor):

VLC installation in ReactOS Applications Manager

I used command prompt to verify that networking was fine (note the lack of ICMP in user-mode networking):

Ping from command prompt with user-mode networking as KVM guest

The Firefox 22 install worked, but it went awry after that. Several reboots later I gave up:

The built-in programs were much more usable:

ReactOS Start Menu showing Administrative Tools

PuTTY installed flawlessly, and I was able to SSH to the host computer:

Using command prompt to find host computer address:

PuTTY connected to host computer, showing 'uname -a' output

An example of a frozen program causing graphics glitches (Windows up to XP does this as well):

And an obligatory screenshot of the “Properties for System” dialog, showing the build as 20130518-r59037:

Conclusion

ReactOS is a cool idea and project, but the OS is still very glitchy. The built-in apps are stable and familiar-looking, but you would require a lot of patience (and a lot of rebooting) to use a ReactOS system for more than a few minutes.

Being open source is a big plus, as there is no need to activate the installation or enter software keys. GNU/Linux users will already be accustomed to this.

Recovering auto-saved files in MySQL Workbench

C++ debian howto mysql sql

February 1, 2014November 5, 2015

MySQL workbench is an open source tool for designing databases. As version 6.0.8, it is one of those programs where you need to save often, because the window you are working in will vanish every couple of hours.

Bug #1: Can’t recover files that weren’t saved

I was unlucky enough to have forgotten to save my work when it crashed today, and found this nasty flaw in the auto-recover feature:

Auto-save model interval: An open model that has not been saved will automatically be saved after this period. On loading a model file, MySQL Workbench will notify the user if the file was not previously saved correctly, due to a crash or power failure. MySQL Workbench can then attempt to recover the last auto-saved version. For automatic recovery to be available for a new file, it will have to have been saved at least once by the user.

Uh oh! The file hadn’t been saved yet, so it’s gone right? According to wb_model_file.cpp, this is not the case. The auto-save file is always written, but the recovery process wont be started until you try to use it again (which will never happen if you don’t have an old saved version):

/* Auto-saving
 *
 * Auto-saving works by saving the model document file (the XML) to the expanded document folder
 * from time to time, named as document-autosave.mwb.xml. The expanded document folder is
 * automatically deleted when it is closed normally.
 * When a document is opened, it will check if there already is a document folder for that file
 * and if so, the recovery function will kick in, using the autosave XML file.
 */

So under ~/.mysql/workbench/, I found a newmodel.mwbd folder. Workbench files are .zip files in disguise, so I compared it to a test file. It had all the same content, but with a document-autosave.xml, rather than a document.xml (see test file below):

Cool, so I’d just rename the file, compress the whole lot and make it a .mwb? No such luck.

Bug #2: File Roller can’t compress ‘@’ files

Possibly because of the -@ command-line option in the zip command, File Roller refused to work with these files.

Luckily, the document.mwb.xml file alone is enough for the file to be recognised and recovered from the auto-saved files:

The take-away from this? Save your work. In 2014, you still can’t count on auto-save to do this!

Scripted screen captures

debian howto linux x11

January 31, 2014November 5, 2015

This is a script I put together for capturing a window’s contents as it changes, because “Print Screen and crop” gets old very quickly!

It saves me a lot of time when working in virtual machines or creating user docs, as it means that every step (and error message) is captured.

The commands used are in the x11-utils and netpbm and x11-apps packages on Debian.

sudo apt-get install x11-utils netpbm x11-apps

capture.sh

#!/bin/bash
echo "Click a window to start capturing it."
window=`xwininfo -int | grep 'Window id:' | cut -d' ' -f4`
echo -n "Capturing window $window"
prev=""
i=1
empty=`echo -n "" | md5sum | cut -d' ' -f1`
captured="captured.txt"
echo -n "" > $captured
while [ "$prev" != "$empty" ]; do
	md5sum=`xwd -id $window 2> /dev/null | xwdtopnm 2> /dev/null | md5sum | cut -d' ' -f1`
	if grep -Fxq "$md5sum" "$captured"
	then
		echo -n "."
	else
		if [ "$md5sum" != "$empty" ]
		then
			echo $md5sum >> $captured
			echo ""
			echo -n $md5sum
			file=`date --iso`-capture-`printf "%03d" $i`.png
			xwd -id $window | xwdtopnm 2> /dev/null | pnmtopng 2> /dev/null > $file
			i=$[i+1]
		fi
	fi
	sleep 1
	prev=$md5sum
done
echo ""
echo "Empty screen capture received. Quitting. (did you close the window?)"

Example

If you wanted to document a “Malformed Expression” error in Gnome Calculator, you can run capture.sh and then demonstrate it:

$ ./capture.sh
Click a window to start capturing it.
Capturing window 31457283
3bbe32ef05f49ae65922fcfedc842828
c0cef7d3108263fbb1beaa7b52492e6a
fd6df04c4ad844bb4a2f27be29dffb29
6ba0fb7ee1ca85640998013c6a258520.
bb061cc56fa3822f9764c0f6af2156df
5f788568c7f34cda55a1680ac72e1cf0
dca714e6691a3a239914106996905047
0bf916ba3f96f3def57191174e55dea0.
2a4a2589662901d9a55d1e170ffbd322....
Empty screen capture received. Quitting. (did you close the window?)

The lines are checksums of PNM data, and the dots are times when no screenshot was saved. This guarantees that each file in the output is unique:

The captured.txt file simply contains the list of checksums, and is useless after the script terminates.

Brother HL-2270DW on Linux

brother debian howto linux

January 23, 2014November 5, 2015

The Brother HL-2270DW is one of the best budget laser printers around, with third party consumables readily available on eBay.

The printer has a network port on the back of it, which is great news for GNU/Linux users, because networked printers tend to speak standard protocols.

The fastest way to get this printer working without Windows is to plug it in and log in via the web. The default settings have DHCP enabled. Here are a few pieces of crytic voodoo magic that helped me:

To reset the print server settings, hold “GO” on startup, then let go and press it 6 times.
The default admin login is admin / access
On my printer (Firmware 1.10), printing network settings by holding “GO” for 10 seconds caused the network card (Brother NC-7800w) activity lights to go off, requiring a reboot.

On Debian, there is no “Brother HL-220DW” CUPS driver on the list, but I found the following driver to work fine (and allow duplex):

Brother HL-2170W Foomatic/hpijs-pcl5e (recommended)

To use this driver, you will need to install the HP Linux Printing and Imaging printer driver:

apt-get install printer-driver-hpijs

Tag: debian

How to install KA Lite on the Raspberry Pi

Materials

Install Raspbian

Install some things

Install KA Lite

Test it out locally

Access over the network

How to run Tetris on your Raspberry Pi

Get a screen

Troubleshooting: Update GCC

Getting a USB receipt printer working on Linux

Find the device file

Troubleshooting: Check `usblp`

Printing something useful

Scaling this up

Howto: Tethered photo capture on Linux

Extending this method

Productivity: De-activate social networking on a schedule with cron

Scheduling it in

When you break something..

QJoyPad update

An alternative: AntiMicro

A tour of ReactOS 0.3.15

Preparation

Installation and first boot

The installed system

Conclusion

Recovering auto-saved files in MySQL Workbench

Bug #1: Can’t recover files that weren’t saved

Bug #2: File Roller can’t compress ‘@’ files

Scripted screen captures

capture.sh

Example

Brother HL-2270DW on Linux

Materials

Install Raspbian

Install some things

Install KA Lite

Test it out locally

Access over the network

Get a screen

Troubleshooting: Update GCC

Find the device file

Troubleshooting: Check usblp

Printing something useful

Scaling this up

Extending this method

Scheduling it in

When you break something..

An alternative: AntiMicro

Preparation

Installation and first boot

The installed system

Conclusion

Bug #1: Can’t recover files that weren’t saved

Bug #2: File Roller can’t compress ‘@’ files

capture.sh

Example

Troubleshooting: Check `usblp`