Price, complexity, and high power consumption have limited 802.11b's usefulness in monitoring and control applications. Alternative wireless technologies, like Bluetooth, ZigBee, WirelessUSB, and the plain no-protocol 433/915-MHz transceivers, have limited speed and range.
Now available in lower-power single chips, it's easy to use 802.11b in low-end applications. What might have been overkill before is now practical. Best of all, 802.11b offers speeds up to 11 Mbits/s at a range of 100 m, neither of which the other wireless technologies can touch.
To that end, DPAC Technology's Airborne Wireless LAN Node Module drops right into designs that need a wireless link (see the figure). It consists of a low-power, single-chip 802.11b radio; a baseband processor; an applications processor; and all of the related software. Even RF-challenged designers can use it to build wireless into any product in record time.
The radio, which conforms to the familiar 802.11b standard, operates in the designated 2.4-GHz band with 11-, 5.5-, 2-, or 1-Mbit/s data speeds. Also available is the Wired Equivalent Privacy (WEP) encryption. Support for diversity antennas ultimately improves range and reliability.
The built-in processor supports serial inputs from standard UARTs with RS-232 or RS-485 interfaces up to 230.4 kbits/s, I2C up to 400 kbits/s, and SPI up to 20 Mbits/s. Eight parallel I/O lines are available, and eight multiplexed analog-input channels are supplied for the 10-bit analog-to-digital converter.
The module includes an integrated real-time operating system (RTOS), a TCP/IP stack, and a full Web server that lets users develop a Web page offline to load into the flash memory. Each module features an IP address. Data collected by the application can be fed into the Web page, which can be accessed from anywhere there's Internet access. Control signals from a browser to the application can be used to initiate operations as desired. Uses include industrial, medical, scientific, and transportation applications that require longer range and higher speeds than other available wireless solutions.
Samples of the WLAN node module cost $110. A full evaluation and development kit is available for $499.