D3 Tips and Tricks v4

Sunday, 11 January 2015

Setting up a WiFi network connection on your Raspberry Pi

The following post is a section of the book 'Raspberry Pi: Measure, Record, Explore'.  The entire book can be downloaded in pdf format for free from Leanpub or you can read it online here.
Since this post is a snapshot in time. I recommend that you download a copy of the book which is updated frequently to improve and expand the content.

Setting up a WiFi Network Connection

Our set-up of the Raspberry Pi has us at a point where we are able to carry out all the (computer interface) interactions we will require via a remote desktop. However, the Raspberry Pi is making that remote connection via a fixed network cable. It could be argued that to fulfill the ultimate aspirations of sensing different aspects of our world we will need to be able to place the platform that we want to do the measuring in a position where we have no physical network connection. The most obvious solution to this conundrum is to enable a wireless connection.
It should be noted that enabling a wireless network will not be a requirement for everyone and as such, I would only recommend it if you need to. It means that you will need to purchase a USB WiFi dongle and correctly configure it which as it turns out can be something of an exercise. In my own experience, I found that choosing the right wireless adapter was the key to making the job simple enough to be able to recommend it to new comers. Not all WiFi adapters are well supported and if you are unfamiliar with the process of installing drivers or compiling code, then I would recommend that you opt for an adapter that is supported and will work ‘out of the box’. There is an excellent page on elinux.org which lists different adapters and their requirements. I eventually opted for the Edimax EW-7811Un which literally ‘just worked’ and I would recommend it to others for it’s ease of use and relatively low cost (approximately $15 US).
Edimax WiFi USB Adapter
Bearing in mind that we are going to be adjusting our network connection, it is highly recommended that the following configuration changes take place with the keyboard / mouse and monitor connected to the Raspberry Pi (I.e. not via a remote desktop).
To install the wireless adapter we should start with the Pi powered off and install it into a convenient USB connection. When we turn the power on we will see the normal range of messages scroll by, but if we’re observant we will note that there are a few additional lines concerning a USB device. These lines will most likely scroll past, but once the device has finished powering up and we have logged in we can type in…
… which will show us a range of messages about drivers that are loaded to support discovered hardware.
Towards the end of the list (it shouldn’t have scrolled off the window) will be a series of messages that describe the USB connectors and what is connected to them. In particular we could see a group that looks a little like the following;
[3.382731] usb 1-1.2: new high-speed USB device number 4 using dwc_otg
[3.494250] usb 1-1.2: New USB device found, idVendor=7392, idProduct=7811
[3.507749] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[3.520230] usb 1-1.2: Product: 802.11n WLAN Adapter
[3.542690] usb 1-1.2: Manufacturer: Realtek
[3.560641] usb 1-1.2: SerialNumber: 00345767831a5e
That is our USB adapter which is plugged into USB slot 2 (which is the ‘2’ in usb 1-1.2:). The manufacturer is listed as ‘Realtek’ as this is the manufacturer of the chip-set in the adapter that Edimax uses.
In the same way that we edited the /etc/network/interfaces file earlier to set up the static IP address we will now edit it again with the command…
sudo nano /etc/network/interfaces
This time we will edit the interfaces file so that it looks like the following;
auto lo

iface lo inet loopback
iface eth0 inet dhcp

allow-hotplug wlan0
auto wlan

iface wlan0 inet static
  wpa-ssid "homenetwork"
  wpa-psk "h0mepassw0rd"
Here we have reverted the eth0 interface (the wired network connection) to have it’s network connection assigned dynamically (iface eth0 inet dhcp).
Our wireless lan (wlan0) is now designated to be a static IP address (with the details that we had previously assigned to our wired connection) and we have added the ‘ssid’ (the network name) of the network that we are going to connect to and the password for the network. Save the file.
If you’re not sure about the name (ssid) of your network, a simple test would be to use a phone or tablet to see what WiFi connection is is using (assuming that you are using your own wifi connection).
To allow the changes to become operative we can type in;
sudo reboot
Once we have rebooted, we can check the status of our network interfaces by typing in;
This will display the configuration for our wired Ethernet port, our ‘Local Loopback’ (which is a fancy way of saying a network connection for the machine that you’re using, that doesn’t require an actual network (ignore it in the mean time)) and the wlan0 connection which should look a little like this;
wlan0 Link encap:Ethernet HWaddr 80:1f:02:f4:21:85
      inet addr: Bcast: Mask:
      RX packets:213 errors:0 dropped:90 overruns:0 frame:0
      TX packets:54 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:88729 (86.6 KiB) TX bytes:6467 (6.3 KiB)
This would indicate that our wireless connection has been assigned the static address that we were looking for (
We should be able to test our connection by connecting to the Pi via the TightVNC Viewer on the Windows desktop.
In theory you are now the proud owner of a computer that can be operated entirely separate from all connections except power.

The post above (and heaps of other stuff) is in the book 'Raspberry Pi: Measure, Record, Explore' that can be downloaded for free (or donate if you really want to :-)).

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