Category: Raspberry Pi (Page 3 of 3)

Edimax EW-7811Un USB adapter blue light

Lego Light Shield

Recently, I purchased a couple of Edimax EW-7811Un USB adapters for both of my Raspberry Pis, making them wireless.  The Pi I use for the print server is sometimes left on overnight.  “No problem there”, you say.  Well, there is if you’re trying to sleep.  The light from the wi-fi adapter constantly blinks, indicating it’s connected.  At night, this blinking light reflects off the whiteboard in the corner of my room, and it’s rather irritating when you’re dozing off.

Now, there are multiple solutions to the problem.  1) I could turn the Pi off at night.  2) I could modify the driver and turn the light off.  3)  Lego.  Yes, Lego.

If you want to hide the blue blinking light at night, then this Lego build is for you!  Problem solved.

Wireless Raspberry Pi- Edimax EW-7811Un Guide

I recently received a second Raspberry Pi as a gift, and decided to connect it to the internet via wi-fi. Initially, I was unsure as to which wi-fi adapters were compatible with the Pi however, the community suggested the Edimax EW-7811Un USB adapter. The adapter itself is tiny, and can be purchased for less than £10.

Whilst I was trying to set it up, I came across multiple guides offering various conflicting pieces of information, so I thought I’d share what worked for me. Before I go any further, I should state I’m running the Raspbian image.

First, update the repo

$ sudo apt-get update

Then, upgrade the system

$ sudo apt-get upgrade

Next, you need to generate a wpa passphrase based upon the name of your wi-fi network and the password you use to connect to it. Note the use of quotes around the name and password- I had spaces and certain awkward characters in both the name and the password- without the quotes, incorrect values were generated. The wpa_passphrase function will return a string- take a copy of this, you’ll need it later.

$ wpa_passphrase "name of your network" 'password for your network'

The interfaces file on the Pi now needs to be edited

sudo nano /etc/network/interfaces

The following code shows the contents of my interfaces file. There were many conversations online about what this file should contain In the end, this is what worked for me.

auto lo
iface lo inet loopback
iface eth0 inet dhcp
allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-ssid "network name"
wpa-psk the_string_wpa_passphrase_generated

Save the file and reboot the machine. Now the Pi should connect to your wireless home network.

Wireless Printing/AirPrint Server via the Raspberry Pi

NOTICE: Please read the entire post (and the comments) before proceeding.  This post was originally written at the end of 2012 and some of you have left comments noting fewer steps are required nowadays.  This guide should still work though. Updated guide (no Windows section) available at

NOTICE 2: Thank you for all of your emails regarding this post. Unfortunately, I can’t answer every one. If you’re struggling with printing, it might be worth reading through the comment section.

One of the first projects I wanted to attempt when I got my Raspberry Pi was to turn my wired Canon printer into a wireless printer. I managed to get it working so I thought I’d share the steps I went through.

Right, first things first, update the packages on your Pi:

sudo apt-get update

Next up, install all the packages required for printing. The following commands could be put on one line but I took the longer option of installing one package at a time.

sudo apt-get install avahi-daemon
sudo apt-get install avahi-discover
sudo apt-get install libnss-mdns
sudo apt-get install cups
sudo apt-get install cups-pdf
sudo apt-get install python-cups

It takes a while for the packages to install, so grab a cup of tea while you wait. Once everything has finished, you’ll need to add your username to the CUPS server so you’re able to add printers etc later on.

sudo usermod -aG lpadmin pi

Now, check that CUPS has installed correctly and that the service works (it stands for Common Unix Printing System and will let the Raspberry Pi act as a print server):

sudo /etc/init.d/cups start

You’ll need to check the Avahi service works too (it finds various devices on the network which are discoverable):

sudo /etc/init.d/avahi-daemon start

Next, you’ll need to edit the CUPS config file:

sudo nano /etc/cups/cupsd.conf

You’ll need to set-up the port we’re going to be listening on. Comment out the line that reads “Listen localhost:631”. Add in “Port 631”. It should look something like this:

#Listen localhost:631
Port 631

CUPS will need to be told to be used with any hostname, so it can work with AirPrint. The ServerAlias * directive needs to be added before the first occurence of <Location />

The config file will also need to be edited to control access to the server by adding “Allow @Local” in several places e.g.:

# Restrict access to the server...
Order allow,deny
Allow @Local

You need to include it in these areas of the config file:

# Restrict access to the server...
# Restrict access to the admin pages...
# Restrict access to configuration files...

Save the config file and restart the CUPS service:

sudo /etc/init.d/cups restart

Now, find the IP address of your Pi. It’ll be something like 192.168.1.x


Navigate to the CUPS configuration page by typing the IP address you just retrieved and the port number CUPS uses (so it’ll be an address like 192.168.1.x:631). A security exception message may pop up but that’s ok. Continue onwards!

Click on the Admin tab and view the server settings which are towards the right-hand side of the screen. Tick the box that says “share printers connected to this system”. At this stage, you’ll be asked for the username and password of the Raspberry Pi.

Plug your printer into one of the USB ports on the Pi. Click “add printer” in the CUPS web interface and it should appear under local printers. You’ll have to fill in details for the printer, such as name and location. You can enter whatever you want in here but the important part is ensuring you tick the “share this printer” box. Following this, you’ll have to select the appropriate printer driver from a (large) list that appears. Enter print and paper settings too. You’re now ready to click on maintenance > print test page. If everything has gone to plan, the test page will print successfully. You’re not done yet though….

You now need to set-up the Avahi service which will allow you to discover wireless printers on Apple devices. First, navigate to the opt directory, make a directory called airprint and move to it:

cd ../../opt
sudo mkdir airprint
cd airprint

Now, download the Python file which will help us generate the services we need (all one line):

sudo wget -O --no-check-certificate

The permissions of the script need to be edited so it can be executed:

sudo chmod 755

Generate the Avahi service and place the script in the appropriate folder:

sudo ./ -d /etc/avahi/services

On generating the service I got the error shown below. This is fine if you don’t have any Apple devices running iOS6 but I’m willing to bet that most people with capable devices are running it.

image/urf is not in mime types, what_the_printer_is_called may not be available on ios6

To fix this issue, you’ll have to create 2 files in the /usr/share/cups/mime directory. These files will be called airprint.types and airprint.convs. Let’s start with airprint.types.

Use nano to create a new file and edit it:

sudo nano airprint.types

Insert the following into the airprint.types file:

# "$Id: $"
# AirPrint type
image/urf urf string(0,UNIRAST)
# End of "$Id: $".

Again, use nano to create the second file:

sudo nano airprint.convs

Insert the following into airprint.convs

# "$Id: $"
# AirPrint
# Updated list with minimal set 25 Sept
image/urf application/pdf 100 pdftoraster
# End of "$Id: $".

Restart the CUPS service now that changes have been made:

sudo service cups restart

The Python file which helped us generate services earlier needs to be re-downloaded to the opt/airprint directory

sudo wget

Ensure that you’re in the airprint directory and regenerate the Avahi service (like before):

sudo ./ -d /etc/avahi/services

Various files have been edited so I’d recommend that you reboot the Raspberry Pi around now. If you only have Apple devices, that’s it, you’re done- hopefully, everything should work. In my experience, I’ve found that the printer can be a little laggy and sometimes, it just doesn’t bother printing certain jobs from my iPhone. Don’t let that put you off though- most of the time it works as expected. I’ve had no problems printing from my laptop or iPad.




Now, I’m aware some of you will want to use the Raspberry Pi to print from Windows machine. If you want to do this, you’ve got a few more steps to go. Before I go any further, I’ll say that I tested this with Windows XP only- things might be easier with Windows Vista/7/8. Maybe things will need to be done slightly differently, I don’t know.

Install Samba on the Raspberry Pi which allows cross-platform file/printer sharing (basically allows Linux and Windows file systems to connect to each other)

sudo apt-get install samba

Navigate to the samba config file which can be found at- /etc/samba/smb.conf. Ensure it contains the following data:

	# CUPS printing.  See also the cupsaddsmb(8) manpage in the
	# cupsys-client package.
	   printing = cups
	   printcap name = cups
	   comment = All Printers
	   browseable = no
	   path = /var/spool/samba
	   printable = yes
	   guest ok = yes
	   read only = yes
	   create mask = 0700
	# Windows clients look for this share name as a source of downloadable
	# printer drivers
	   comment = Printer Drivers
	   path = /usr/share/cups/drivers
	   browseable = yes
	   read only = yes
	   guest ok = no




You’re now finished with the Raspberry Pi. Again, I’d reboot it anyway, just to ensure that all appropriate files are running with the configuration that you’ve entered.

So, you want to print in Windows, eh? Here it goes-

I’ll reiterate, I used Windows XP. Things might be different in Vista/7/8

Install the drivers for your printer

Navigate to My Computer > View workgroup computers > Raspberrypi server > Printername

A few dialogue boxes may appear but they should be ok

Select the appropriate driver from the list of printer drivers that appears and click ok

The printer attached to the Raspberry Pi will now appear in the control panel under printers and faxes

My printer constantly displays “access denied, unable to connect” but it still works anyway (I’ve got no idea why)

Finally, try and print something- the new printer will appear in the list of available printers. Fingers crossed, you should now be able to print from Windows too!

This tutorial is based on content from a few other sources:
Configuring the Raspberry Pi as an AirPrint Server
iOS6 Doesn’t Recognise CUPS Print Shares
Printserver for Windows Clients

Edit- I’ve noticed this tutorial was ripped to shreds by a user on Reddit earlier in the year, so I thought I’d clarify a few things. The distro I used was Raspbian (my previous posts about my Raspberry Pi show the version I used). Technically the tutorial is not Raspberry Pi specific and should work on other Debian distros too however, the Pi is neat wee computer to turn into a print server. Yes, I typed “sudo apt-get install” multiple times, instead of installing packages using just the one line, but I’ve mentioned in previous posts that I was a Linux n00b at the time.

On the positive side, thank you to everyone who has posted comments about the guide on my blog :). I must have done something right if so many of you got wireless printing to work! A few of you have mentioned that some of the packages are no longer necessary when setting up the printer- I’m considering putting an updated guide together to make it easier for folks.

Setting up an SD card for the Raspberry Pi using a Mac

I had a few issues setting up the SD card for my Raspberry Pi. The main problem I had was that the operating system didn’t make full use of the capacity of the SD card. I thought I’d share the steps I used to get it to work.

Before I go any further, I’d like to note that it was a Kingston SDHC 16GB Class 4 SD card that I used- plenty of storage there and it seems to work perfectly with the Pi. My main computer is a Mac so that’s what I used for transferring the operating system onto the SD card.

Steps for getting the operating system onto the SD card (Mac users)-

  1. Download the Raspbian “wheezy” image from the downloads section of the Raspberry Pi site. Personally, I went with the .zip file which I downloaded to the Desktop and extracted.
  2. Insert your SD card into your computer/laptop. Click on the Apple logo in the top left-hand corner of the screen. Then click “about this Mac” > “more info” > “system report” > “card reader” and find the entry listed as “BSD name”. This will have disk and a number next to it (in my case it was disk2s1- I’ll stick with this example).
  3. Open up the Terminal. This can be found under “applications” > “utilities”
  4. Enter:
    sudo diskutil unmount /dev/disk2s1
  5. If this doesn’t work, try:
    sudo diskutil unmountDisk /dev/disk2s1
  6. One the card has unmounted, enter:
    sudo dd bs=1m if=path/to/where/you/downloaded/the/image/2012-12-16-wheezy-raspbian.img of=/dev/rdisk2

    Remember, in the “of” section of the command, remember to put the disk number of your own SD card. Also, you need to prefix “disk” with “r” so it becomes “rdisk”. Just be careful during this step- you don’t want to get the disk number wrong and accidentally overwrite the operating system on your Mac- double-check you’ve done it right!

  7. While it’s copying the image to the SD card, the Terminal won’t provide you with any progress information. Instead it’ll just show a blinking cursor. Be patient! In fact, now would be a good time to grab a cup of tea.
  8. When it’s done, the Terminal will just show the usual comand prompt along the lines of:
    computername:~ username$
  9. You’re not quite done yet- you need to eject the SD card:
    sudo diskutil eject /dev/rdisk2
  10. Previously at this stage I inserted the card and started using the Pi which quickly ran out of space. I was puzzled, as I couldn’t possibly have filled a 16GB SD card by installing some Bluetooth tools and gedit. It turns out I’d missed an important step allowing the Pi to utilise the full size of the card. Read on…
  11. Insert the SD card into the Raspberry Pi. This next bit is definitely easier with a monitor so I recommend you connect the Pi into one temporarily (along with a keyboard) and switch it on.
  12. You will be asked to log in once it’s booted. Your username is “pi” and the password is “raspberry”.
  13. Enter:

    This presents you with a menu. Choose “expand_rootfs” and confirm the changes. Exit the menu.

  14. The machine needs to be rebooted. Enter:
    sudo reboot
  15. The Pi will reboot and will start sorting out the size of the root partition, enabling you to use the full size of the SD card. This can take a bit of time so grab another cup of tea. Now for the reason I mentioned plugging it into a monitor while it’s resizing the partition- I tried to do this via ssh from the Mac. I couldn’t log in while it was resizing so I assumed something had gone wrong. In fact, it was doing exactly as I had asked it to do- I just couldn’t see it. If you have a monitor plugged in, it constantly tells you that it’s resizing the partition until it’s finished.
  16. When the Pi has finished resizing the root partition, you’re free to use it! That’s it (well unless you want to play around with the rest of the config options, but I’m not going to cover that)!

Raspberry Pi!

Raspberry Pi Logo

First off, I should say greetings and happy holidays folks! It seems I’ve been good this year as Santa brought me a Raspberry Pi (model B- 512MB RAM). For those that are confused, it’s not an edible pie- that would be ridiculous. I’d prefer a strawberry pie anyway. No, it’s a tiny little computer. According to the Raspberry Pi FAQ, it’s described as “a credit-card sized computer that plugs into your TV and a keyboard. It’s a capable little PC which can be used for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video.”.

Why did I want a Pi then? Well, I’d like to get to grips with Linux. Every year for the past 5 years, I’ve installed Linux on a machine and declared that I was going to use it as my main operating system. Generally it lasted for all of 2 days before I reverted back to Windows (or for the last few years, OS X). The Raspberry Pi gives me no excuse and offers me a chance to work with the command line. Also (as I’m sure you all know), I’m a massive nerd and I wanted a new geek toy to play with.

To get the Pi up and running as a desktop computer, you need to plug in a USB mouse and keyboard, a power supply, a monitor, a HDMI cable, an Ethernet cable and an SD card to provide the memory. I had all of the above apart from a monitor so I chose to run the Pi “headless”- basically, I accessed it via SSH from the terminal on my laptop. I have plugged it into the tv downstairs though and I’m very impressed- it looks fantastic.

I’ve been busy playing around with it since the 25th and so far, I’ve turned it into a print server (because when I bought my printer, I didn’t think about getting a wireless one). I’m going to detail how I did it in a separate blog post. I can’t wait to try some other projects on it- I love it!

If you want to know more about the Raspberry Pi, pop over to the website or have a look through the FAQs. Alternatively, check out the forums– there’s a bustling community of folks willing to help each other out.

Raspberry Pi is a trademark of the Raspberry Pi Foundation.

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