Electronic Design

Low-Power SoC Improves Wi-Fi Battery Life For Sensor Networks

When implementing a wireless sensor network, most engineers look to ZigBee or other alternatives from CrossBow, Dust Networks, and Z-Wave. Wi-Fi enjoys widespread use, familiarity, and low cost. But its network topology and high power consumption usually cause it to be dismissed early as a viable option.

The GS1010 from GainSpan Corp., though, targets sensor networks. This 802.11 chip’s very low power consumption can provide up to 10 years of AA battery life in an industrial sensor network.

INDUSTRIAL WIRELESS • Initially, the industry shunned wireless solutions because of past reliability and security issues. But wireless networking technology has largely solved those problems. Thus, Wi-Fi, which is the most widespread wireless local-area network (WLAN) technology, is being widely adopted into a variety of industrial solutions.

The growing use of wireless sensor networks has forced the development of wireless technologies with features better suited to these applications than Wi- Fi. ZigBee is the best example. ZigBee and other technologies have focused on mesh topologies as a way to implement sensor networks. But while this format extends the range of the network with very low power consumption, each node has a limited transmission range.

Wi-Fi offers longer range and a higher data rate. It provides data-rate scalability, security, quality of service (QoS), authentication, and management tools. Wi-Fi products also are widely known. They have architecture support and are easier to deploy and less expensive than other wireless systems. Best of all, they link right up with the existing LAN infrastructure, making sensor data available to all parts of the enterprise.

Furthermore, Wi-Fi can provide for the implementation of video, which none of the other wireless sensor network technologies can handle. But its high power consumption and star topology have limited its use in sensor applications. That means reducing Wi-Fi transceiver power consumption, which is where the GS1010 comes in.

THE GAINSPAN RADIO CHIP • The GS1010, a complete system-on-a-chip (SoC), features a full 802.11b/g transceiver with enterprise-grade security and reliability using 802.11i, AES encryption, EAPFAST. It includes two ARM7 processors —one for the radio and the other for the application. A real-time clock is built in.

The chip supports location awareness using the received signal strength indicator (RSSI) and time difference of arrival (TDOA) methods. It includes all needed flash and SRAM and a power-management unit. Multiple I/O interfaces like SPI, I2C, PWM, ADC, and GPIO are provided. The chip comes in a 10- by 10-mm package. An evaluation kit with battery, antenna, UART-to-USB cable, and relevant software is available (see the figure).

The GS1010 software makes development faster and easier, saving many man-months of programming and debugging. It includes a Green Hills real-time operating system (RTOS), dozens of application programming interfaces, embedded firmware, and device drivers.

Most importantly, the software helps maximize battery life for each sensor device. It offers a way to efficiently configure, manage, and monitor sensor nodes. And, it provides intelligent data handling and can easily integrate with existing WLAN management systems.

The GS1010 costs $15 in quantities of 10,000 units.

GainSpan Corp.

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