Network Adapters

Wireless Adapter

Model: Edimax EW-7811Un

For SheevaPlug

The directions are adapted from page(http://elinux.org/RPi_edimax_EW-7811Un)

###Install Wi-Fi Adapter Driver

1. Copy the SheevaPlug Wi-Fi dongle driver 8192cu.ko(under SmartAmericaSensors/sheeva/) to the directory "/lib/modules/3.2.0-4-kirkwood/kernel/net/wireless".(3.2.0-4-kirkwood is the system version we use for our Sheevaplug, should be adopted to your own system.)
2. Add the line blacklist rtl8192cu(original driver) to /etc/modprobe.d/blacklist.conf.
3. Add the line 8192cu to /etc/modules so that Wi-Fi support is loaded at boot time.
4. Run the command: depmod -a.

###Wireless Network Management Software We use "wpa-supplicant" as our Wi-Fi network access and management software.

"wpa-supplicant" and its dependencies can be installed by execute: apt-get install wpasupplicant

###Configuration Two files need to be modified or created to enable Wi-Fi network access

1). Edit "/etc/network/interfaces" to enable Wi-Fi interface. Add following lines:

allow-hotplug wlan0
auto wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

Please note that: To make this configuration work, the device ID of your Wi-Fi adapter must be "wlan0". This may change when you plug a different Wi-Fi adapter. To fix this issue, you could edit "/etc/udev/rules.d/70-persistent-net.rules", and delete anything in this file about wlan0

2). Create "/etc/wpa_supplicant/wpa_supplicant.conf", and add the content:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
        ssid="UCInet Mobile Access"
        scan_ssid=1
        key_mgmt=NONE
}

More Wi-Fi networks could be added by editing "/etc/wpa_supplicant/wpa_supplicant.conf". For example, if you want to make client connect to a Wi-Fi network with ssid:"example_net" and key:"example_key" automatically, you should add following to "/etc/wpa_supplicant/wpa_supplicant.conf":

network={
        ssid="example_net"
        psk="example_key"
        priority=1
}

You can set priority for each network. The network in the scan result list with larger priority value is selected sooner.

More configuration detail could be found here : http://www.lsi.upc.edu/lclsi/Manuales/wireless/files/wpa_supplicant.conf