Getting Started Using 802.11b Wireless LAN on ST40 boards

Introduction

The aim of this guide is show how to use 802.11b devices on an ST40 based system. It is not intended to be an exhaustive guide to wireless lan. The drivers shipped are from the Linux Wlan project. It is essential that you read the documentation available there.

Supported Hardware

There is a wide variety of different wlan hardware. The driver supports only those based on the Prism 2 chipset from Intersil. This chip can be interfaced to the system as a PCMCIA card, a PCMCIA card plugged into the PCI bus via an adaptor board, a USB device, or finally as a real PCI card. The driver supports all 4 of these methods, but there are various restrictions on their use in ST40 based systems.

PCMCIA cards

This requires PCMCIA support on the board. Effectively, this limits support to the MB374.

PCMCIA in PCI based PLX carrier card

Due to a silicon bug, these will not work on a GX1 based system. ST40RA166 systems will work fine.

Real PCI cards

These should work fine in both GX1 and ST40RA166 systems. However, we have found that the one card we have tested with, the SparkLan WL-360F, is effectively unusable. This appears to be due to excessive RF interference. Quite why the ST40 based systems generate so much more noise than a PC remains a mystery.We would be very interested if anybody else has a different manufacturers card to try.

USB adaptors

These work fine on all systems. If you have a GX1 base system, it is the only method that we think will work reliably, based on current information.

Installing the RPMS

Install the approprate RPM for the board you are working with. Note that at the moment, the RPMS actually conflict with one another, so only install one at a time. Note that if you want to use the PCMCIA card (not the PCI adaptor board), you must also have installed the PCMCIA subsytem as well.

Next, you must run depmod on the target, to update the module info.

Configuring the Wireless LAN

If you are not using the PCMCIA card, you must load the appropriate kernel modules. You must have run depmod for this to work correctly. Thus for USB do modprobe prism2_usb, for the real pci do modprobe prism2_pci, and for the PLX based PCMCIA/PCI adaptor board do modprobe prism2_plx. These should not generate any errors, if they do you are loading the wrong driver most likely.

The next step is to configure the settings for the wireless LAN itself. The easiest way to do this is to edit the settings in /etc/wlan.conf. If you are not using WEP (Wireless equivalent protocol) security, simply set the DesiredSSID field to be whatever the SSID of your base station is. If you haven't got a clue what the SSID of the base station is, simply put in "" to associate with whatever base station happens to be in range.

If you are using WEP, you will need to enable dot11PrivacyInvoked and set up the appropriate keys as need be.

Once you have done this, you can then start up the wireless LAN by running /etc/init.d/wlan start. Hopefully, the Link LED should start flashing and then go on, indicating that it has succesfully associated with a base station.

If this is the case, you can now give the interface an ip address in the normal way, ifconfig wlan0 138.198.7.91 for example. You should now be able to ping other machines. If you can't and get a message something like "Tx prior to association", this means you haven't configured things correctly (or the base station isn't switched on!)

Resources

• Wireless LAN HOWTO
• Linux Wlan Project