Installing EW-7811Un WifiDongle
Contents
Install Dongle
With your raspberry pi already running plug in the Dongle.
The reason for doing this is that from a cold boot the default driver [rtl8192cu] causes a problem with udev and a number of errors were thrown that prevented the Rpi from booting properly.
Check the device has been detected.
dmesg | tail
[ 76.830012] usb 1-1.2: new high speed USB device number 4 using dwc_otg [ 76.932126] usb 1-1.2: New USB device found, idVendor=7392, idProduct=7811 [ 76.932172] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 76.932194] usb 1-1.2: Product: 802.11n WLAN Adapter [ 76.932210] usb 1-1.2: Manufacturer: Realtek [ 76.932226] usb 1-1.2: SerialNumber: 00e04c000001 [ 77.032579] cfg80211: Calling CRDA to update world regulatory domain
Replace the Driver =
New Driver Location
Download the driver from http://www.electrictea.co.uk/rpi/8192cu.tar.gz
wget http://www.electrictea.co.uk/rpi/8192cu.tar.gz
--2012-07-20 19:08:39-- http://www.electrictea.co.uk/rpi/8192cu.tar.gz Resolving www.electrictea.co.uk (www.electrictea.co.uk)... 184.173.73.187 Connecting to www.electrictea.co.uk (www.electrictea.co.uk)|184.173.73.187|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 213532 (209K) [application/x-gzip] Saving to: `8192cu.tar.gz' 100%[=====================>] 213,532 229K/s in 0.9s 2012-07-20 19:08:40 (229 KB/s) - `8192cu.tar.gz' saved [213532/213532]
Unzip the driver
tar -zxvf 8192cu.tar.gz
which should do something like this.
jake@raspberrypi ~ $ tar -zxvf 8192cu.tar.gz 8192cu.ko
Move the kernel module to the correct location using
sudo mv 8192cu.ko /lib/modules/3.1.9+/kernel/net/wireless/
Disable the current driver
This requires blacklisting
the current modules, edit the blacklist configuration file
sudo nano /etc/modprobe.d/raspi-blacklist.conf
add the line blacklist rtl8192cu
, exit and save the file.
Enable the new driver at runtime
Append the new kernel module name to the modules file using the following short cut
sudo nano /etc/modules
add a line 8192cu
depmod
create the required dependency links for the kernel using
sudo depmod -a
Wifi Configuration
Edit Network Settings
Edit /etc/network/interfaces
and add a wifi section for wlan0
sudo nano /etc/network/interfaces
add the wlan0 settings to the end of the file as follows.
auto wlan0 iface wlan0 inet dhcp pre-up wpa_supplicant -Dwext -i wlan0 -c /etc/wpa_supplicant.conf -B
Create WPA conf
create and edit the file /etc/wpa_supplicant.conf
sudo nano /etc/wpa_supplicant.conf
populate the file with the following information
ctrl_interface=/var/run/wpa_supplicant ctrl_interface_group=0 ap_scan=2 network={ ssid="<YOUR WIFI SSID HERE>" scan_ssid=1 proto=RSN key_mgmt=WPA-PSK pairwise=CCMP group=CCMP # choose one of the following psk=”<YOUR WPA/WPA2 PASS PHRASE HERE>” psk=<YOUR HASH CODE HERE> }
Note if you don't wish to expose your wifi pass phrase in this file, use the following process to create a hashed replacement of the form
psk=58cfe1c8a36ce8a1f3cd938e281ca1222707df58e27df4745148bfebca7c4197
To get your hash code use the following
wpa_passphrase <YOUR WIFI SSID HERE>
Enter the correct pass phrase to get the required hash:
network={ ssid="<YOUR WIFI SSID HERE>" #psk="<YOUR WPA/WPA2 PASS PHRASE HERE>" psk=2419cc182b52c63dcbfa18af4ed56262c4dca24c2a772216cff9e84b0ea77949 }
Copy the last line to the wifi conf file instead of entering your pass phrase.
ISSUES
After completing this, the boot screen reports the driver
disagrees about symbol module layout.
Could not read interface wlan0: no such device
Basically this means the downloaded version doesn't match the kernel and it isn't installed.
get kernel version
uname -r
Tested Using
Raspian