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为了能让树莓派摆脱每次使用都要插网线的麻烦，我最终还是决定为它配备一块USB无线网卡。在Google了一番之后，我发现很多树莓派用户都提到基于Ralink RT5370芯片的USB无线网卡，于是我购买了一个基于RT5370芯片的腾达(Tenda)W311MI迷你无线USB网卡（如下图所示），非常便宜的白菜价：只要￥30。
To get rid of the inconveniency of connecting a network cable to Raspberry Pi I decided to equip it with a wireless USB adapter. After Googling the Internet I found that many Pi users mention the wireless USB adapter based on Ralink RT5370 chipset, so I bought one too - the Tenda W311MI 150Mbps Wireless Mini USB Adapter(shown as below), which based on RT5370 and has a very low price: only $4.8 .

关于如何在使用Arch Linux ARM系统的树莓派上使用RT5370芯片的USB无线网卡，网上很难找到完整的教程（用Debian系统的倒是有），所以我走了不少弯路，搞定了之后决定要写出来。所以，再次提醒你，如果你用的是Arch Linux ARM系统，并且使用的是RT5370芯片的USB无线网卡，那么阅读本文可能对你有所帮助；如果不是，那么就不用看下去了。
It's hard to find a detailed tutorial on how to use a RT5370-chipset-based wireless USB adapter on Raspberry Pi which runs the Arch Linux ARM os(but there are some good tutorials on Debian), so I wasted a lot of time in the setup process and when I figured it out I decided to write them down. So be sure again that if you are running the Arch Linux ARM on Pi and using a wireless USB adapter which based on RT5370 chipset, then you'll read something useful in this article, if not, don't waste your time and just close this webpage.
文章来源：http://www.codelast.com/
【1】关于驱动 / About the driver

这个页面是Ralink RT5370芯片的官方驱动下载页面，不过，在整个配置过程中我们完全不用下载此驱动，因为Arch Linux ARM已经自带了，非常方便。 This page is the official driver download page, but we don't need it in the whole setup process because Arch Linux ARM has it installed already.
插上USB无线网卡后，用如下命令查看一下：
After plugging the wireless USB adapter, use following command to have a check:

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[root@alarmpi ~]# lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp. LAN9500 Ethernet 10/100Adapter Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. Bus 001 Device 004: ID 148f:5370 Ralink Technology, Corp. RT5370 Wireless Adapter

可见Ralink RT5370芯片已经被识别出来了，这是成功的第一步。
So the Ralink RT5370 chipset has been recognized and this is the first step to success. 文章来源：http://www.codelast.com/ 然后我们还可以查看一下系统已经加载的模块：
Then we can check the modules which have been loaded by the OS:

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[root@alarmpi ~]# lsmod Module                  Size  Used by rt2800usb              12977  0 rt2800lib              47334  1 rt2800usb rt2x00usb              10895  1 rt2800usb rt2x00lib              40765  3 rt2x00usb,rt2800lib,rt2800usb spidev                  5028  0 mac80211              234117  3 rt2x00lib,rt2x00usb,rt2800lib cfg80211              173637  2 mac80211,rt2x00lib crc_ccitt               1433  1 rt2800lib spi_bcm2708             4357  0 i2c_bcm2708             3557  0 ipv6                  289527  16

根据这篇文章所言，其中，rt2x00是Ralink芯片组的统一驱动。
According to this article, the rt2x00 is the uniform driver for Ralink chipsets. 文章来源：http://www.codelast.com/ 【2】安装wireless_tools / Install wireless_tools
在配置过程中，我们要安装一个配置无线网络接口的工具——iwconfig。用如下命令安装：
First we need to install a wireless network interface configuration tool - iwconfig :

1	[root@alarmpi ~]# pacman -S wireless_tools

安装此工具后，你就可以用iwconfig命令看看你的无线网卡信息了：
Then you can use iwconfig to check the info of your wireless USB adapter:

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[root@alarmpi ~]# iwconfig ifb0      no wireless extensions.   lo        no wireless extensions.   wlan0     IEEE 802.11bgn  ESSID:"XXX"            Mode:Managed  Frequency:2.412 GHz  Access Point: XXXXXXXXXXX             Bit Rate=54 Mb/s  Tx-Power=20 dBm             Retry  long limit:7   RTS thr:off   Fragment thr:off           Encryption key:off           Power Management:on           Link Quality=70/70 Signal level=-39 dBm            Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0           Tx excessive retries:0  Invalid misc:18   Missed beacon:0   eth0      no wireless extensions.   ifb1      no wireless extensions.

“wlan0”就是你要关注的。
The "wlan0" is what you should focus on. 文章来源：http://www.codelast.com/ 【3】配置无线连接的帐户 / Setup the WiFi account
我的无线网络是WPA加密的，要连接到这样的无线网络，需要使用wpa_supplicant工具。如果不出意外，你会发现Arch Linux ARM已经安装好了这个工具：
In order to connected to a WPA encrypted wireless network we need to use a tool like wpa_supplicant. No accident that you'll find it already been installed:

1 2	[root@alarmpi ~]# pacman -Q | grep wpa     wpa_supplicant 1.0-2

所以我们直接用就可以了。如果你的系统没装，那么就用pacman装一下，也非常容易。
So we just use it. If you can't find the package, it's very easy to use pacman to install it.   为防止误操作，先备份wpa_supplicant的配置文件：
Backup the configuration file of wpa_supplicant to avoid misoperation:

1	mv/etc/wpa_supplicant/wpa_supplicant.conf/etc/wpa_supplicant/wpa_supplicant.conf.bak

文章来源：http://www.codelast.com/ 然后用wpa_passphrase工具生成一个简单的配置文件：
Use wpa_passphrase tool to generate a very simple configuration file:

1	wpa_passphrase myWirelessSSID myPassword >/etc/wpa_supplicant/wpa_supplicant.conf

其中，“myWirelessSSID”是你的无线网络的SSID，“myPassword”是连接该无线网络的密码。wpa_passphrase工具会根据你提供的这两个信息生成一个非常简单的配置文件，此处我们将输出的信息写入了文件 /etc/wpa_supplicant/wpa_supplicant.conf 中。
The "myWirelessSSID" is the SSID of your wireless network, "myPassword" is the password used to connect the network. wpa_passphrase tool will generate a very simple configuration file according to the info you provided and here we write the output to file /etc/wpa_supplicant/wpa_supplicant.conf.
  启动网卡：
Bring wlan0 up:

1	ifconfigwlan0 up

连接到网络：
Connect to the network:

1	wpa_supplicant -B -Dwext -i wlan0 -c/etc/wpa_supplicant/wpa_supplicant.conf

文章来源：http://www.codelast.com/ 但是，在没有获取IP前，我们还是无法通过无线网卡访问树莓派的，用下面的命令来获取一个IP地址：
But we can't access Pi until it get an available IP address, use following command to get one:

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[root@alarmpi ~]# dhcpcd wlan0 dhcpcd[286]: version 5.6.2 starting dhcpcd[286]: wlan0: sending IPv6 Router Solicitation dhcpcd[286]: wlan0: broadcastingfora lease dhcpcd[286]: wlan0: offered 192.168.X.X from 192.168.X.X dhcpcd[286]: wlan0: acknowledged 192.168.X.X from 192.168.X.X dhcpcd[286]: wlan0: checkingfor192.168.X.X dhcpcd[286]: wlan0: sending IPv6 Router Solicitation dhcpcd[286]: wlan0: leased 192.168.16.10for86400 seconds dhcpcd[286]: forked to background, child pid 327

现在树莓派应该可以连接无线网络了。
Now Pi should be able to connect the wireless network.
  【4】开机自动连接无线网络 / Connect on system startup
为了能让树莓派开机自动连接无线网络，将如下两句shell命令添加到开机执行的列表中：
To let Pi connects the wireless network automatically, add the following 2 shell commands to OS startup execution list:

1 2	wpa_supplicant -B -Dwext -i wlan0 -c/etc/wpa_supplicant/wpa_supplicant.conf dhcpcd wlan0

至于怎么添加，你可以参考这篇文章的第【2】条。
You can refer to this article, item 【2】 on how to execute shell command on startup.

最后展示一下USB无线网卡在树莓派上的工作图（可见有线网卡工作状态指示灯没亮）：
At last show you the wireless USB adapter working on Pi(it's obvious that the LNK status LED is off):

至此，本文的主要目的已经达到。