WiFi

 

Introduction

WiFi enables devices to connect to local area networks using radio communications rather than cables. Wireless access points can be used to share files, printers and Internet connections with mobile devices. The WiFi standards are maintained by a group called the WiFi Alliance. There are currently two main standards for WiFi networking: IEEE 802.11b, which has transfer speeds of up to 11 Mb/s, and IEEE 802.11g, which provides transfer speeds of up to 54 Mb/s. WiFi connections have a range of around 150 meters in open air. WiFi provides sufficient bandwidth for Internet browsing, streaming media, and VoIP. WiFi is useful in mobile devices such as PDAs and devices embedded in vehicles where wired network connections are not possible.

While WiFi was originally conceived for laptop computer and the like, Embedded WiFi is becoming common with cellphones, cameras and printers including this technology.

WiFi networks can be run with open security, WEP (Wired Equivalent Privacy), or WPA (WiFi Protected Access). WEP security has been proven to be insecure (see: ) and is more recently being superseded by WPA and WPA 2.

Further Information

• The WiFi Alliance homepage:
• Wikipedia entry on WiFi: http://en.wikipedia.org/wiki/WiFi
• A guide to WiFi security:

Advantages:

• Embedded WiFi offers High speed wireless networking.
• Prices for WiFi chipsets has steadily decreased in recent years.
• WiFi hotspots provide free or subscription based Internet access to WiFi enabled devies.

 

Disadvantages:

• High power usage, compared to Bluetooth for example.
• Many access points have either no security, or poor security using WEP. WPA/WPA 2 security is becoming available on more devices recently.
• Connections are occasionally difficult to establish and maintain.

Bluewater Systems Experience

Bluewater Systems has provided support for Embedded WiFi on a number of projects by using plug-in WiFi compact flash cards. For the Rig 200 we have developed an on-board Embedded WiFi solution (measuring only 20mm square), which significantly reduces the amount of board space dedicated to WiFi.

Salmon

Salmon is the project name for a board which incorporates two Snapper CL15s, a six port Ethernet switch, WiFi and a number of other features onto a small 102mm square board.

The Salmon board has single Embedded WiFi module which is connected via the compact flash bus. It is initially controlled by the first Snapper CL15 module. The second module can 'grab' the WiFi module by driving a GPIO high.

WiFi on the Rig 200

The Rig 200 supports IEEE 802.11b/g WiFi using either the WiFi Option Plus Module or a WiFi compact flash card. The WiFi Option Plus module has the advantage of being directly attached to the baseboard and freeing the compact flash slot for other uses.

Bluewater Systems supports the Ambicom WL54-CF WiFi compact flash card. Both the Embedded WiFi Option Plus module and the Ambicom WiFi card support encryption using either WEP or WPA/WPA 2. Under Linux, WPA encryption support is provided using the wpa_supplicant tools (http://hostap.epitest.fi/wpa_supplicant/).

To use WiFi wireless networking on the Rig 200 you will need:

• Rig 200 baseboard.
• Either the WiFi option plus module or a WiFi compact flash card (such as the Ambicom WL54-CF).
• The wpa_supplicant (http://hostap.epitest.fi/wpa_supplicant/) tools if using WPA encryption in Linux.