The demo program is more primitive than Ember Studio’s program, but it does provide some similar functions such as the ability to poll a node or see the routing tables. It does not provide the capability to diagnose problems at the code level, but it is very handy for checking out the hardware and the network. It has some new demos, such as tracking the potentiometer setting of a particular board in a running graph.
Silicon Labs provides a version of Keil’s uVision IDE customized for the company’s microcontrollers. There are sufficient demo apps to make Plateau 2 homey, although programming each module takes awhile since each must be plugged into the PC to be programmed. It would be handy to do programming over the wireless network for smaller programs, but the USB or JTAG interfaces are faster for programs that will fill up the flash memory.
Plateaus 3 and 4 are the same, as there is no restriction on the development tools. Likewise, the ZigBee protocol stack documentation provides sufficient information for developing your own application. Diagnostics are primarily those available through the JTAG interface and what you build into the application.
The ability to hook all the modules up to a single PC via the USB link has significant benefits when it comes to configuration and diagnostics. It may take a rather substantial USB hub to handle the half dozen modules, but it is well worth the investment depending upon how development occurs and how many modules are changed and tested at one time.
Microchip Development Kit
PIC developers will be happy to see Microchip’s PICDEM Z ZigBee development boards. Microchip supplied four PIC18-based boards (see Fig. 5) versus the two normally found in the kit. This allowed me to test out their demo application that supports up to four boards. Likewise, the boards were already programmed, saving a little time. Still, it is very easy to program the boards using Microchip’s MPLAB since the binary file is already supplied. It was no more difficult than downloading the other sample applications or my own.
The boards contain a PIC18 in a DIP socket so the kit can be used with range of PIC products. The board also has a nice patch area, making it more flexible for hardware integration development than the other two offerings. There is a Chipcon CC2420 ZigBee chip on module with a built-in PC board antenna to round out the configuration. This approach allows future modules to be tested using the same board. It is possible to solder in an external antenna mount, but the board-based solution is sufficient for many applications and is good enough for testbench work.
Microchip has a minimal solution for Plateau 1. The interface to the main demo application is via the serial port and a terminal application (see Fig. 6). On the plus side, the latter can run on any system, although the MPLAB development tools are designed for Windows. Also, the C compiler is an option.
Plateau 2 utilizes the demo applications that really need to be built using MPLAB in the stock kit. The application only provides the ability to check out the network and turn some LEDs on and off, but that is more than sufficient to demonstrate the ZigBee stack.
Microchip’s stack is small (20k for the coordinator) and less functional than the other two offerings. Configuration is designed for fixed architecture networks, but that is likely to be the first approach to most ZigBee applications anyway. Microchip will be providing mesh support and other ZigBee features in the future.
Developers will probably want to invest in a pair of MPLAB ICD 2 programming and debug systems for Plateaus 3 and 4 (actually the same since there is no restriction on the development tools). These are not included in the kit, which is typical for Microhip’s offerings that separate out the development hardware. The software is available for free and only works with Microchip’s hardware and microcontrollers.
Microchip’s offering is the least expensive solution and easy enough to use with under half a dozen network nodes. Things may get a little more difficult when a lot of nodes are involved. The application will have to be well debugged before programming a dozen systems.
Although Microchip’s ZigBee stack is the least developed, it is something that will improve over time as will the demo and support software. At this point, it is more than sufficient for a determined developer to take and run with. The patch area also makes the platform ideal for prototyping, not just learning about ZigBee.
Wrapping Up
All three kits let you reach Plateau 3 quickly. Microchip’s offering hits Plateau 4 out of the box. Which kit you choose depends upon your expertise with the microcontrollers, ZigBee, and the level of sophistication that your application requires. Ember handles a high level of sophistication, but you may be limited on your choice of microcontroller. Ember is working to get other microcontrollers supported by additional modules. It already provides support and stacks for other microcontroller architectures.
Developers familiar with the 8051 will feel very comfortable with Silicon Labs’ offering. Likewise, PIC programmers will find Microchip’s package almost perfect.