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Table of Contents

1 Introduction

In June 2011, Technologic Systems released the WIFI-N-USB adapter (Asus USB-N13) to replace the existing two adapters: WIFI-G-USB and WIFI-G-USB-2 both of which have gone end of life.  The new adapter has different dimensions and new drivers which are detailed below.

   Dimensions:
      WIFI-G-USB  (IOGear): 6.0 cm L* 2.5 cm W* 1.0 cm H  (Unavailable)
      WIFI-G-USB-2(Asus):   7.5 cm L* 2.5 cm W* 0.9 cm H  (Unavailable)
      WIFI-N-USB  (Asus):   7.0 cm L* 2.2 cm W* 1.0 ccm H (Weight 12 gm)
   Chipset:
      WIFI-G-USB   (IOGear): Zydas1211  (Unavailable)
      WIFI-G-USB-2 (Asus):   rt2501usb  (Unavailable)
      WIFI-N-USB   (Asus):   rt3070L

Other areas of interest of differences between the devices include (specs taken from manufactures product page):

   Temp Range:
      WIFI-G-USB   (IOGear):    0 - 55C  (Unavailable)
      WIFI-G-USB-2 (Asus):   -10 - 55C  (Unavailable)
      WIFI-N-USB   (Asus):     0 - 45C
   RF Output Power:
      WIFI-G-USB   (IOGea): 17 dBm (Unavailable)
      WIFI-G-USB-2 (Asus): -14 ~ 17 dBm (Unavailable)
      WIFI-N-USB   (Asus):  B: 18 dBm  G: 15 dBm  N: 15 dBm
   Antennae Option:
      WIFI-G-USB   (IOGear): None
      WIFI-G-USB-2 (Asus):   One on-board Inverted-F antenna to support diversity (Gain: 1.77 dBi)
      WIFI-N-USB   (Asus):   Two on-board

   Range:
      WIFI-G-USB   (IOGear): 100 - 400m, depending on surrounding environment
      WIFI-G-USB-2 (Asus):   Indoor 130 ft (40 m), outdoor (LOS, Line-Of-Sight) 1000 ft (330 m)
      WIFI-N-USB   (Asus):   Up to 490 ft (150m)
  
   Accessories:
      WIFI-G-USB (IOGear): None
      WIFI-G-USB-2 (Asus): USB 2.0 Universal Joint
                           USB 2.0 extension cable (type A to type A)
                           Neck lace
      WIFI-N-USB   (Asus): None
                           Includes a flexible extension cable, approximately 5 inches (13 cm) in length
                           with a flexible joint approximately 2 inches (5 cm) in length.

2 Downloading Necessary Drivers and Tools

WPA support (wpa_supplicant) has to be obtained separately, it is not included or compiled with the ralink sources for this driver.  Code for this device is available here:

3 Setting up the WIFI Interface Connection

This section gives step by step instructions for how to connect to wireless Access Points (AP) using the rt2870sta and RT3070L chipset. It was tested using a Linksys WRT54GC Wireless Router as an AP. Master mode is not supported by this driver, but Adhoc is. As a note, WPA is generally disabled by default on startup, but can be enabled (see /etc/init.d/wpasupplicant).

The first step should be to locate the appropriate driver for the TS product in use, download it to the board, and then use the insmod command (ie. insmod rt2870sta-tsXXXX.ko). When inserted properly, you will see the device in /proc/net/wireless. Use cat /proc/net/wireless to verify:

   root@ts7000:root# cat /proc/net/wireless 
   Inter-| sta-|   Quality        |   Discarded packets               | Missed | WE
    face | tus | link level noise |  nwid  crypt   frag  retry   misc | beacon | 16
   ra0: 0000  100.  220   177        0      0      0      0      0        0

Wireless connections tested:

  • Unencrypted
  • WEP
  • WPA Personal (TKIP)
  • WPA2 Personal (TKIP or AES)
  • Adhoc Mode

Useful Commands:

  • iwconfig -- use to check status such as associations
  • iwlist scan -- reports wireless networks available
  • pump OR dhclient OR udhcpc -- assign a dynamic IP address
3.1 Unencrypted
   1) Bring the ra0 interface up
      * ifconfig ra0 up
   2) Associate with the AP
      * iwconfig ra0 essid the_essid
   3) Assign a static IP
      * ifconfig ra0 192.168.1.101
3.2 WEP Encryption
   1) Bring the ra0 interface up
      * ifconfig ra0 up
   2) Associate with AP
      * iwconfig ra0 essid the_essid key the_key
   3) Assign a static IP
      * ifconfig ra0 192.168.1.101
3.3 WPA Personal - TKIP
   1) Bring the ra0 interface up
      * ifconfig ra0 up
   2) Generate a configuration file for wpa_supplicant to use
      * ./wpa_passphrase the_essid the_password > /etc/wpa_supplicant_custom.conf
   3) Use wpa_supplicant to associate with AP and run it in the background (-B)
      * ./wpa_supplicant -ira0 -Dralink -c/etc/wpa_supplicant_custom.conf -B
   4) Assign a static IP 
      * ifconfig ra0 192.168.1.101
3.4 WPA2 Personal - TKIP or AES
   1) Bring the ra0 interface up
      * ifconfig ra0 up
   2) Generate a configuration file for wpa_supplicant to use
      * ./wpa_passphrase the_essid the_password > /etc/wpa_supplicant_custom.conf
   3) Insert "proto=RSN" into "network" block in /etc/wpa_supplicant_custom.conf
   4) Use wpa_supplicant to associate with AP and run it in the background (-B)
      * ./wpa_supplicant -ira0 -Dralink -c/etc/wpa_supplicant_custom.conf -B
   5) Assign a static IP 
      * ifconfig ra0 192.168.1.101
3.5 Adhoc Mode
   1) Bring the ra0 interface up
      * ifconfig ra0 up
   2) Setup ra0 for Adhoc mode
      * iwconfig ra0 mode ad-hoc channel 3 enc off essid the_essid
   3) Assign a static IP
      * ifconfig 169.254.114.101 netmask 255.255.0.0
   4) Add default gateway to route (optional)
      * route add default gw 169.254.114.100

Appendix A: Document History

Date of Issue/Revision Revision Number Comments
06/08/2011 1.0 Created as "WIFI-N-USB-2 Manual Based on the WIFI-G-USB-2 manual"

Appendix B: Troubleshooting

If you are having difficulties in pinging your AP, try to disconnect eth0 by using the command ifconfig eth0 down.

The message rt2870sta: Unknown symbol x means that the module dependencies have not been satisfied. Use the following as a guide as a basic checklist to insure the correct modules are loaded:

   ts7000:~# depmod        
   ts7000:~# modprobe hid     
   ts7000:~# modprobe usbcore     
   ts7000:~# modprobe usb_storage
   ts7000:~# modprobe scsi_mod
   ts7000:~# modprobe ohci_hcd

The message insmod: error inserting 'rt2870sta_tsXXXX.ko': -1 Invalid module format will occur if you are trying to insert a module into a kernel that it was not compiled for. Verify that you have the correct module for your board. If you're sure the module should work, try using the insmod command with the -f option (ie. insmod -f rt2870sta_tsXXXX.ko).

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