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EDITOR'S REPORT

Wireless Network Devices Set to Accelerate Connectivity in the Internet of Things

The introduction of increasing numbers of products and development support along with power savings, software and scales of integration are making the incorporation of wireless technology easier and more cost-effective.

TOM WILLIAMS, EDITOR-IN-CHIEF

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Among recent introductions of highly integrated wireless connectivity, Microchip Technology has come out with a major expansion of its embedded-wireless portfolio that includes Bluetooth, Wi-Fi and Zigbee in compact, integrated module forms. These are accompanied by development tools that have the potential to greatly expand the use of wireless connectivity in embedded devices that will span industrial through consumer users. Although Wi-Fi generally addresses wireless Internet access, the target designs for most of these devices are characterized by the intermittent sending of relatively small amounts of data mostly between devices or a human operator. And the user mostly interacts to set up a wireless network configuration of devices, then monitors their data, often after receiving an alert, or sends short, specific control commands to read status or change the state of some device like a light switch.

The Wi-Fi modules are intended to free the system designer from worrying about RF and antenna design, topics that digital developers are less familiar with in their daily work (Figure 1). They are also approved for use with their associated antennas. The Microchip model MRF24WG0MA is approved for use with its integrated PCB meander antenna, and the -MB model is approved for use with a list of antenna types that are associated with the module. This means the modules have received regulatory approval in the U.S. and Canada and do not require regulatory testing if no changes are made to the module circuitry.

The MRF24WG0MA/MB interfaces to Microchip PIC18, PIC24, dsPIC33 and pic32 microcontrollers via a four-wire SPI slave interface and runs on a single 2.8V to 3.6V operating voltage. They incorporate an IEEE 802.11 radio and handle all b/g data rates up to 54 Mbit/s. WEP64/128, WPA and WPA-EAP security are featured as well. Microchip also offers a PIC-based TCP/IP stack so that the PIC microcontroller can communicate with the module through a command API from within the TCP/IP stack. Data communications take place via the SPI interface.

To address the needs for wireless mesh networks including the Zigbee protocols, the Microchip suite includes the MRF24XA IEEE 802.15.4 and proprietary mode transceiver. The module supports both the Zigbee Alliance PRO and RF4CE protocol stacks as well as Microchip’s proprietary MiWi wireless mesh protocol. MiWi includes profiles for point-to-point as well as for 8- or 64-hop mesh networking. The transceiver operates at 256 Kbit/s in IEEE 802.15.4 standard mode, but can operate at 256 Kbit/s to 2 Mbit/s in its proprietary mode.

Some designers want an easy way to migrate their 802.15.4 designs to either Wi-Fi or Bluetooth, in order to make them accessible from smartphones and tablets, or to add Internet connectivity.  This includes applications such as wireless sensor networks, remote monitoring/control and measurement, and M2M cable replacements for home, commercial and industrial networks. Increasingly, home networks can consist of Zigbee or Wi-Fi devices, and a homeowner may not be aware of the differences when he or she picks up a light controller or motion sensor from a hardware store. At the same time, however, a growing number of homes have a local Wi-Fi network for multiple computers, which also serves as a gateway to the Internet.

Wi-Fi and Zigbee

Thus there is a need to be able to mix and match Wi-Fi and Zigbee devices as well as to make even an all-Zigbee network accessible to the Internet via a Wi-Fi gateway. In the case of Microchip, its RN XV series of Wi-Fi and Bluetooth socket modules provide agency-certified, drop-in connectivity for any XBee socket for designers who want to migrate an existing design from 802.15.4. To simplify designs, the stacks are integrated on the module, configured via simple ASCII commands, and can easily connect to any MCU via a serial interface.

In the case of Texas Instruments, the company offers its SimpleLink Wi-Fi CC3000 solution that covers 802.11 b/g, incorporates an IPv4 TCP/IP stack and operates up to 11 Mbit/s. TI also supplies the Zigbee CC2530, which is an SoC containing a network processor as well as the CC2530ZNP, which is a coprocessor containing the Zigbee stack and communicates with the system’s main processor via an SPI interface. In addition, there is the CC2520, which is an 802.15.4 transceiver that can be run using, for example, an ARM Cortex M3 processor. This option is available to designers who need a larger quantity of flash memory or RAM. In the case of both TI and Microchip, Zigbee devices would have to communicate with a Wi-Fi gateway to gain access to the Internet.

Addressing this, Gainspan has developed a single chip solution that brings together Wi-Fi and 802.15.4. The GS2000 is an integrated System on Chip (SoC) containing multi-standard RF as well as both 802.11b/g/n and 802.15.4 PHY/MAC functionality, dual ARM Cortex-M3 processors, networking stack and services, and large memory size to support various application profiles—all on a single silicon die. The new Wi-Fi and ZigBee IP chip is mainly targeted to accelerate the development and market adoption of home networked devices (Figure 2). 

By incorporating the two wireless IP-based Home Area Network (HAN) standards while supporting IPv4 and/or IPv6 devices, the GS2000 extends Internet connectivity wherever there is a Wi-Fi access point or hotspot, and leverages the key benefits of each technology—the high data rates and widespread availability of Wi-Fi along with the small channelization and meshing capability of ZigBee IP. In residential applications, for example, the solution will bridge the gap between smart meters using ZigBee and the new connected white appliances, which all integrate Wi-Fi. The addition of 802.11 n support additionally enables the use of high definition video and audio.

Lest anyone doubt the market potential of home networking, predictions are that annual shipments of “smart home” nodes will grow from under 20 million units in 2012, to over 90 million in 2017. Both ZigBee and Wi-Fi can be expected to show significant growth in this market, and the two technologies can be used together within a range of key smart home devices.  The use of such dual-mode devices can serve to shield the nontechnical user from being concerned with which protocols or standards to choose, moving the decision to “plug and use.”

Bluetooth

The other wireless technology that is now almost ubiquitous is of course Bluetooth. Texas Instruments WLAN technology is now integrated in a module designed by LS Research that combines 2.4 GHz IEEE 802.11 b/g/n with Bluetooth. The TiWi-R2 device also incorporates TI’s Enhanced Low Power (ELP) technology to address the needs of handheld and mobile devices. The TiWi-R2 has SDIO and UART interfaces for WLAN and Bluetooth and has a connector for an external antenna. Both Wi-Fi and Bluetooth use the same antenna port.

For its part, Microchip also offers distinct Bluetooth modules, which, like its Wi-Fi socket modules, can be used as plug-in replacements to migrate from 802.15.4 or, of course, be used in original designs (Figure3). The Bluetooth version 2.1 Class 1 (RN41) and Class 2 (RN42) modules are also backward compatible with Bluetooth 2.0, 1.2 and 1.1. The two classes represent ranges of 100 meters for the RN41 and 20 meters for the RN42. Both modules are certified.

All the devices described here also are supported by development kits and tools to ease the task of either developing a wireless-enabled device from scratch or integrating/migrating wireless technology in an existing design. The levels of integration, low power, power management and development support show the potential for the increasing connectivity of even the smallest embedded devices with monitoring and data aggregation gateways to servers, IT systems and even with the Cloud. This is one of the ways that small quantities of data become the Big Data about which we are currently hearing so much.  

Gainspan
San Jose, CA.
(408) 627-6500.
[www.gainspan.com].

 

LS Research
Cedarburg, WI.
(262) 375-4400.
[www.lsr.com].

 

Microchip
Chandler, AZ.
(480) 792-7200.
[www.microchip.com].

 

 

Texas Instruments
Dallas, TX.
(972) 995-2011.
[www.ti.com].