Sunday, August 12, 2012

Wireless on the RPi

My Raspberry Pi has been working very well since I started overclocking.
Currently I used the following config.txt additions:

arm_freq=905      ##CPU speed 905 MHz. Increased from default 700 MHz
sdram_freq=500  ## RAM clock increased to 500MHz from default 400 MHz
core_freq=450     ##GPU clock increased from default 250 MHz to 450 MHz
While my Pi functions well and I can do most simple tasks just as easily as on a normal modern laptop or Desktop despite being noticeably slower than either of the latter.
However, what's probably my biggest problem these days is functioning of my wireless keyboard (Logitech K260 which comes with a wireless mouse).
Letters are very frequently missed and repeating of letters and spaces is normal.
I wonder would I have the same problem with a wired keyboard and/or mouse.

I had been trying for some time to get an old Belkin wireless adapter (F5D7050 with zd1211 chipset) working but never quite succeeded.
I suspected that the limited power availability in the RPi was the key problem but it didn't really work either when plugged into a powered usb-hub.

OK, time to try something which is known to work so I bought a Micronet N150 (SP907NS) with a RTL8188CUS chipset.

First I tried the setup procedure outlined in this blogpost, however this didn't work for me for reasons which I didn't take the time to investigate.
However, the script described and presented here worked fine.

It works equally well whether the dongle is placed directly in the RPi or in my Belkin powered USB hub.
However, it fails to work if the hub is unpowered even though iwconfig detects dongle and assigns it to wlan1 but fails to associate the latter.

Other observations:

1. If I plug the Belkin F5D7050 dongle into the powered hub when the Micronet dongle is also plugged into the hub, the Micronet dis-associates itself and its blue LED stops flashing.
The connection resumes when the Belkin is removed from the hub.

2. After using the script to install the drivers and firmware for the RTL8188CUS, NetworkManager shows the etho interface as "unmanaged".
This can be overcome by editing the /etc/NetworkManager/NetworkManager.conf and changing



After this change and a reboot, eth0 is fully functional.
It can be switched on or off using the commands
sudo ifup eth0
sudo ifdown eth0 
3. In contrast, the wireless interface (wlan1 in my case) does not respond to the ifup or ifdown commands.
Instead, you can use
sudo ifconfig wlan1 up
sudo ifconfig wlan1 down 

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