How to configure Edimax EW-7811UN Wifi dongle on Raspbian
Posted on Tue 02 September 2014 in HowTo • Tagged with howto, Linux, RaspberryPI, WIFI, networking, Debian
If you want to connect your RaspberryPi to your home network and you want to avoid cables, I suggest you to use the Edimax wifi adapter. This device is quite cheap (around £8 on Amazon) and it's very easy to configure on Raspbian (I assume you are using a recent version of Raspbian. I'm using the one released on 20/06/2014).
Configure the wifi adapter
Edit /etc/network/interfaces and insert these configuration values:
auto lo iface lo inet loopback iface eth0 inet dhcp allow-hotplug wlan0 auto wlan0 iface wlan0 inet dhcp wpa-ssid YOURESSID wpa-psk YOURWPAPASSWORD
Power management issue
There is a known "issue" with this adapter default configuration that makes it to turn off if the wlan interface is not in use for some minutes. To avoid this you have to customize the parameters used to load the kernel module. First check that your adapter is using 8192cu module:
sudo lsmod | grep 8192 8192cu 551136 0
Create the file /etc/modprobe.d/8192cu.conf and insert the following lines inside:
# prevent power down of wireless when idle options 8192cu rtw_power_mgnt=0 rtw_enusbss=0
I also suggest to create a little entry in crontab to make the RaspberryPi ping your router every minute. This will ensure that your wifi connection will stay alive. To edit crontab just type (from pi user, you don't need to be root):
and insert this line at the end:
*/1 * * * * ping -c 1 192.168.0.1
where 192.168.0.1 is the IP of your router (of course substitute this value with the ip of your router).
Keep Alive Script
I created a further script to keep my WIFI alive. This script will ping the router (change the IP using the one of your router) every 5 minutes and if the ping fails it brings down the wlan0 interface, the kernel module for the wifi and bring them up again.
Just put this script in /root/wifi_recover.sh and then execute from root user:
chmod +x wifi_recover.sh crontab -e
Insert this line inside the crontab editor:
*/5 * * * * /root/wifi_recover.sh
The configuration is done. Just reboot your RaspberryPi and enjoy your wifi connection.