RPi Peripherals
Setup examples for various peripherals
Wireless: TP-Link TL-WN722N USB wireless adapter (Debian 6)
See also:
http://www.element14.com/community/docs/DOC-44703/l/raspberry-pi-wifi-adapter-testing
http://omer.me/2012/04/setting-up-wireless-networks-under-debian-on-raspberry-pi/
This will serve as a general guide for USB wireless devices but may need modifying for your specific one.
- Edit /etc/apt/sources.list to add the non-free archive and backports (eg: sudo vi /etc/apt/sources.list):
deb http://ftp.us.debian.org/debian/ squeeze main non-free deb http://security.debian.org/ squeeze/updates main non-free deb http://ftp.us.debian.org/debian/ squeeze-updates main non-free deb http://backports.debian.org/debian-backports squeeze-backports main non-free
- Update the package cache:
sudo apt-get update
- Download the wifi utils:
sudo apt-get install wireless-tools usbutils
- Download the required firmware and put it in the correct location - you may not need to do this for your adapter or you may need different firmware - see below.
sudo apt-get install firmware-atheros sudo wget http://linuxwireless.org/download/htc_fw/1.3/htc_9271.fw sudo cp htc_9271.fw /lib/firmware
- Add adapter definition to network config - eg: sudo vi /etc/network/interfaces - add the wlan0 section:
# Used by ifup(8) and ifdown(8). See the interfaces(5) manpage or # /usr/share/doc/ifupdown/examples for more information. auto lo iface lo inet loopback iface eth0 inet dhcp # The wireless interface auto wlan0 iface wlan0 inet dhcp wpa-conf /etc/wpa.conf
- Plug in adapter
- Confirm adapter is present:
root@raspberrypi:~# sudo iwconfig lo no wireless extensions. eth0 no wireless extensions. wlan0 IEEE 802.11bgn ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=20 dBm Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off
- Scan your network to see what wireless access points can be seen. You may need to do this to identify your network's SSID (name), but it also confirms that the wifi dongle is doing something. The first command just lists the SSIDs found, the second tells you probably more than you ever want to know:
sudo iwlist wlan0 scan | grep ESSID
or
sudo iwlist wlan0 scan
- Create the wpa.conf file - eg: sudo vi /etc/wpa.conf:
Note: The ssid is case sensitive - if your WLAN's SSID is MYLAN, using "mylan" will not work - you won't connect!
network={ ssid="NETWORK-SSID" proto=RSN key_mgmt=WPA-PSK pairwise=CCMP TKIP group=CCMP TKIP psk="YOUR-WLAN-PASSWORD" }
- Start the adapter
sudo ifup wlan0
- Double-check whether you are connected - below the WLAN interface has been given an IP address - looks good!
root@raspberrypi:~# ifconfig eth0 Link encap:Ethernet HWaddr b8:27:eb:76:7e:2e inet addr:192.168.202.75 Bcast:192.168.202.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1488 Metric:1 RX packets:1060 errors:0 dropped:0 overruns:0 frame:0 TX packets:146 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:95749 (93.5 KiB) TX bytes:48493 (47.3 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:8 errors:0 dropped:0 overruns:0 frame:0 TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:560 (560.0 B) TX bytes:560 (560.0 B) wlan0 Link encap:Ethernet HWaddr b0:48:7a:91:5c:f4 inet addr:192.168.222.161 Bcast:192.168.222.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:31 errors:0 dropped:0 overruns:0 frame:0 TX packets:10 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2260 (2.2 KiB) TX bytes:1542 (1.5 KiB)
If you are now connected, well done! If not, check your editing and also have a look at the output of dmesg to see if you have any error messages. You can also view the system log for messages - for example: sudo cat /var/log/messages | more
Notes
USB interrupt/dma system debug messages
Firing up the TP-Link USB WLAN interface generates a lot of debug messages in the system log like this:
DEBUG:handle_hc_chhltd_intr_dma:: XactErr without NYET/NAK/ACK
Things may calm down a bit if the following file is created in /etc/modprobe.d (eg: sudo vi /etc/modprobe.d/smscnonturbo.conf) and then the RPi rebooted:
smscnonturbo.conf:
options smsc95xx turbo_mode=N
This fix may slow down wired LAN performance but help with wireless and reduce the frequency of the debug messages - YMMV. If you want to undo this fix, just delete the file (sudo rm /etc/modprobe.d/smscnonturbo.conf) and reboot.
Firmware requirements
If no wlanx device is shown, you might need to download firmware for your USB wifi device (or track down other compatible drivers if they are available). To confirm this, check the dmesg output when you plug in your adapter - typing dmesg at the command prompt may be sufficient - and look for information related to your adapter - the example dmesg output below shows what is seen in the event of the TP-Link firmware not being present - notice that the name of the required firmware file is given (htc_9271.fw), the driver name (ath9k_htc) and an error -22 message:
usb 1-1.2.4.2: ath9k_htc: Firmware - htc_9271.fw not found ath9k_htc: probe of 1-1.2.4.2:1.0 failed with error -22 usbcore: registered new interface driver ath9k_htc
Armed with this information, try a web search for 'debian 6' and the name of the driver or driver file and/or head over to http://linuxwireless.org. Also check the links at the top of this page.
Power requirements
If you experience erratic network, keyboard, mouse or Raspberry Pi operation when using a USB wifi dongle, check that whatever is powering your RPi and/or USB hub can deliver sufficient current for everything that's connected together. The first setup tried with the TP-Link adapter had it, a keyboard, mouse and the RPi all connected to a Trust 7-port powered USB hub with a 5V 2A power supply, but in this configuration the mouse stopped working. In this case, the fix was to power the RPi from a separate 5V 1A phone power adapter.
wpasupplicant deamon failed to start
a) If you get this error when you attempt to
sudo ifup wlan0
Then there may be a syntax error in your
/etc/wpa.conf
For example, ensure that your SSID and Password have double quotes round them, and that the curly brackets are closed.
b) Another possible solution could be changing:
iface wlan0 inet dhcp
to
iface wlan0 inet manual
in /etc/network/interfaces. Then sudo ifup wlan0 then sudo ifdown wlan0 then changing manual to dhcp. Works me, as described [1]http://unix.stackexchange.com/a/7717.