Wireless Eval Kit Needs Support

This Atmel kit gives engineers three pairs of wireless transceiver modules that operate as IEEE-802.15.4-compliant devices. The module pair that includes an AT86RF212 RF IC operates in the 700-, 800-, or 900-MHz ISM bands. The modules that offer an AT86RF230 or an AT86RF231 RF IC operate in the 2.4-GHz ISM band. All three IC types use an SPI interface, include AES data encryption, and can work with ZigBee 6LoPAN, RF4CE and other protocols. These characteristics should make the wireless ICs - and this kit - attractive to designers who need wireless data exchanges over short distances. Keep in mind that a host microcontroller will hold the protocol stack and communicate commands to an RF IC through the SPI port. The RF ICs do not include their own processor.

The kit also includes two boards based on Atmel's AT32UC3A3256 MCU. These boards connect to a PC through a USB port and they run the protocol stack that communicates with an attached wireless module. The USB boards have a 10-pin SPI connector that the wireless modules attach to. In addition to the standard SPI signals, the connector includes Reset, Interrupt, Sleep, Chip-Select, and power signals. You can use these signals to connect wireless modules to a custom design. Two "squid" adapters in the kit connect to a wireless module and their color-coded wires to help simplify connections to prototypes. (You also can use the RF modules with several development kits from Atmel, as described in the kit's manual.)

You must download and print the "AVR600: RZ600 HW Manual" from the RZ600 home page on the Atmel website. At http://www.atmel.com/, search for RZ600, or go directly to http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4702.  The 18-page document includes information about the wireless modules and USB boards, schematic diagrams and firmware information. (Find better schematics as PDF files on the RZ600 Web page.)

You also must download software from the RZ600 home page. In the Documents section, click on the "Register" label over a disk to the left of the "RZ600 HW Manual" description. Register and download the software. Unpack the ZIP file into a folder of your choice. This software includes source code for a wireless-UART example.

I identified pairs of wireless modules by reading the MCU part number on each wireless chip. Mark the pairs with a label. After that, kit set up took only a few minutes. As I attached a 2.4-GHz module to each USB board and connected them one at a time to a PC, Windows XP started the usual USB-device routine and a search for drivers. The RZ600 manual explained the need to install or locate a communication-device class (CDC) driver but it listed the wrong directory. I had to point to: [my Atmel directory]/rz600_rel1.0/trunk. Windows identifies each USB device as a serial COM port.

Next, I connected a second wireless module-and-USB board to a USB port and Windows "discovered" it, too. Use the Windows Device Manager to find the COM port number assigned to each of the two USB boards. My computer identified the two boards as COM25 and COM26. I connected both board sets to one PC but spaced them about 3 ft (1m) apart with a USB extension cable (not supplied).

The instructions explain how to use Windows HyperTerminal to set the properties for each serial port. Once set, you can type information into one HyperTerminal window and see it appear in the text window for the second instance of HyperTerminal via the wireless communications between board pairs. Each set of boards act like a wireless UART. You could connect a wireless-USB board pair to another computer and run HyperTerminal to send typed information back and forth.

A table in the "RZ600 HW Manual" lists sections of the UART firmware and explains the contents of folders and files. These include the main UART application files, a Processor Abstraction Layer (PAL) and a Transceiver Abstraction Layer (TAL).  Unfortunately, the right edge of the table gets cut off. The included DVD provides manuals and general documentation, but not information specific to this kit.

Unfortunately, the wireless UART demonstration is as far as you can go with this kit. Atmel's information didn't explain the need for additional hardware (an AVR JTAGICE mkII or an AVR ONE! pod) and software (AVR Studio or IAR Embedded Workbench) if you want to write and download your own code.

As of August 2010, you can only use the IAR Systems Embedded Workbench software to open, modify, compile and download the UART project. But you can open individual C-language files and examine them with a text editor. I don't recommend engineers try to decipher this code and use it as a framework for an application. (IAR Systems offers free versions of its Embedded Workbench for AVR processors, so you can play with the wireless-UART code, but you'll still need a hardware connection with the JTAG port on the USB MCU boards.)

You can glean a lot of information for each wireless-chip type from its data sheet, which explains the SPI commands used to set power levels, read register contents, load data, set frame retries and so on. And, several state diagrams can help you understand how to set up a wireless chip, but examples of how to combine a minimum series of commands and operations to create a basic wireless link would help more. What's the simplest way to get on the air quickly? What basic commands do I need to start?  Unfortunately, you're left to answer these questions on your own. Beyond the wireless UART, I never found any examples.

Atmel provides a "Software Programming" model and documentation for its RF ICs that offers more details and describes a "Transceiver Access Toolbox," but again, the manual does not include any examples. I bet most engineers will need a few basic code samples, flow charts and explanations before they can apply these interesting wireless chips. These Atmel wireless chips have a steep learning curve and some good, basic, tutorial-level information could help engineers get up it quickly.

As I wrote this review I got more information from Atmel via a member of the company's technical support team:

"Please note that this [wireless UART] code is actually directly derived from our highly configurable MAC software package that is available in full source code and allows the very flexible adaption and porting to any combination of an Atmel microcontroller and one of our RF transceivers. The architecture allows [you] to use the same application source code for the ATmega, the ATXmega or the SAM7, etc. So the API's are the same on all the platforms and we have abstracted the platform or RF specific code so that it's now easy to build multi-platform applications for the 2.4-GHZ band as well as for the ZigBee supported 868/915 MHz band. This MAC package also offers access to low layers of the MAC for applications that just want to use the RF interface directly without the need of the full IEEE protocol. This API is called TAL (transceiver abstraction layer) and the Wireless UART example directly uses the uc3 ported version of this TAL interface to show an implementation for the different radio boards that are part of the RZ600.

The full software IEEE MAC software package with multi-platform support and a detailed User Guide is found in our software section - the number of this application note is AVR2025. You can download the archive after a quick registration from this page: http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4675.

There will be a new public release Aug. 29, 2010 which offers a new TAL-API which has been reduced and further optimized - it's called TinyTAL and the Wireless UART code exists for that new API, as well.

I hope this information is useful. We always recommend reading the User Guide in the MAC package since it gives a good insight in the flexibility of our software architecture."

Editor's notes:  During this review I downloaded the IAR Embedded Workbench software and hoped to get an AVR JTAGICE mkII pod. I saw many listed on eBay coming from Asian sellers. The prices looked attractive - $99 U.S. versus about $300 U.S. for a module through an authorized Atmel distributor. But, after reading many negative comments from people who bought Chinese versions of the JTAGICE mkII module, I postponed coding experiments. Caveat emptor.

The kit includes two male headers for the 10-pin JTAG pads (0.050-inch centers) on each USB board. You might have to create an adapter to connect with a JTAG connector on a programming/debugging pod because most JTAG connectors have 0.100-inch-center spacing for contacts.