I have a RT5572-based USB adaptor (a TeckNet dual-band one from Amazon) working now on my Raspberry Pi. Getting it going involved a lot of tries including building a kernel from scratch, but this might not be necessary if you know how to build a device driver against an pre-existing kernel.
From what I can glean from my typing history, this is what I did:
1. change the WPA supplicant and other things in the Ralink driver sources as per
http://www.ctheroux.com/2012/09/ralink- ... untu-12-04. Not everything needs to be changed now, some things are already present in the downloadable drivers.
2. get the latest RP kernel sources using “git clone --depth 1
https://github.com/raspberrypi/linux.git”
3. get the tools using “git clone
https://github.com/raspberrypi/tools.git”
4. build the kernel using the config from “zcat /proc/config.gz” (I cross-compiled it on a PC as 20 minutes waiting is better than 6 hours)
5. install the kernel.img and modules and reboot using them
6. clean the tree you just built the kernel from
7. create a folder called “build” in the modules folder you just created, e.g. 3.6.11+
8. copy the cleaned source tree to that folder
9. build the RT5572 drivers, they will find the necessary kernel sources. The build takes many minutes on an RP
10. sudo modprobe rt5572sta
11. ifup ra0 (add this to /etc/rc.local)
Then finally:
[email protected] ~ $ ifconfig -a
eth0 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:481 errors:0 dropped:1 overruns:0 frame:0
TX packets:418 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:51348 (50.1 KiB) TX bytes:79502 (77.6 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
ra0 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx
inet addr:192.168.1.16 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:73904 errors:0 dropped:86 overruns:3 frame:3
TX packets:925 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:71629732 (68.3 MiB) TX bytes:115491 (112.7 KiB)
[email protected] ~ $ # none of this would be here without the RT5572 working, as there is no other network connection