William Wong
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ED Online ID #11570 |
November 17, 2005
Just to simplify things, Ember’s board supports battery operation or Power over Ethernet (POE). POE makes it possible to just plug the unit into a POE switch or hub and be up and running in almost no time. The board gets its IP address via DHCP and the Ember Studio application automatically discovers nodes on the Ethernet network as well as tracking the nodes found via the wireless network.
Ember’s solution hits the mark for Plateau 1 (see “Developing Arms,” ED Online 11307) that covers out-of-the-box demonstrations. The boards and modules are preprogrammed with Ember’s sample application and stack that works with Ember Studio. Creating, configuring, and testing a system takes less than an hour. It actually takes more time to read the documentation to cover all the options available.
Network autodiscovery leads to a map showing how each node is connected to its neighbors. ZigBee has nodes with different capabilities, including a coordinator, router, and end node. I won’t go into details of ZigBee here, but you can check out more architecture details at the ZigBee Alliance website (www.zigbee.org).
This plateau shows how Ember Studio shines. Ember Studio provides access to the routing tables in each node. It can ping any node and each node has a speaker so you can hear, as well as see, what node is involved in the operation. Ember Studio has many more features that I can’t cover here, but it’s safe to say that it is one of the most sophisticated tools in this review.
Moving to Plateau 2—Hello World—highlights Ember’s sample applications. A 30-day evaluation version of IAR’s Embedded Workbench is included along with plenty of sample code and two ZigBee stacks. One handles the generic version of ZigBee while the other handles Ember’s enhanced version.
Ember hits the mark at Plateau 2 as well, because generating the application is only part of the task. Programming the modules is the other part. Unlike most embedded development, ZigBee includes many nodes that typically must be reprogrammed. Ember Studio’s backchannel Ethernet link makes quick work. Just select the application code generated using the IAR tools and then the nodes to be programmed. The process takes minutes rather than hours. This time can be a problem with the other kits that deal with each board via a dedicated debug connection. JTAG is available on Ember’s boards if the option is required, but remote debugging will more likely suffice.
Plateau 3 is reasonable with Ember’s kit. However, the 30-day time limitation on the development tools makes it less than desirable, requiring movement to Plateau 4 and full licensing of the development tools. That will significantly raise the overall cost of the solution, but it can easily save more than that amount given the Ember tools and stack sophistication.
One use for a ZigBee network is sensor networks. This makes the bundling of a 30-day evaluation of Daintree Networks’ Sensor Network Analyzer (SNA) package significant. It includes firmware for the ZigBee microcontroller as well as a Windows-based application that can control and manage a ZigBee sensor network. You need to download the software and key via the Internet, but a high-speed link handles this in minutes. Because documentation and sample code are provided, it’s possible to evaluate SNA within a day—at least for its basic operation.
Although somewhat on the expensive side, Ember’s QuickStart kit is actually a bargain because of how well it streamlines the development process.
Silicon Labs Development Kit Silicon Labs has put together a nice package with its 2.4-GHz ZigBee Development Kit. It includes six development boards (see Fig. 3) with external antennas like those found on Ember’s modules. Each board contains Silicon Labs’ 8051-based C8051F131 with an on-chip 10-bit ADC and a Chipcon CC2420 ZigBee transceiver chip.
The board has a JTAG interface and it can run off power from the USB interface, a 9-V battery, or an external power supply (not included). The built-in board interfaces include a temperature sensor, LEDS, buttons, and a potentiometer. The kit comes with a single USB-based JTAG interface.
Getting to Plateau 1 is simple but tedious. The modules come with the demonstration program installed, but each module is identical. Each must be connected to a Windows PC running the Silicon Lab’s ZigBee Demo program (see Fig. 4). Each module is then assigned a node ID letter. Labels are provided so it is easy to see each module’s designation. It is then a matter of powering all but the main module using the supplied 9-V batteries to get the network running.
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