Wireless Eval Kit Needs Support

DN Staff

October 5, 2010

7 Min Read
Wireless Eval Kit Needs Support

This Atmel kit gives engineers three pairs of wirelesstransceiver modules that operate as IEEE-802.15.4-compliant devices. The modulepair that includes an AT86RF212 RF IC operates in the 700-, 800-, or 900-MHzISM bands. The modules that offer an AT86RF230 or an AT86RF231 RF IC operate inthe 2.4-GHz ISM band. All three IC types use an SPI interface, include AES dataencryption, and can work with ZigBee 6LoPAN, RF4CE and other protocols. Thesecharacteristics should make the wireless ICs - and this kit - attractive todesigners who need wireless data exchanges over short distances. Keep in mindthat a host microcontroller will hold the protocol stack and communicatecommands to an RF IC through the SPI port. The RF ICs do not include their ownprocessor.

The kit also includes two boards based on Atmel's AT32UC3A3256MCU. These boards connect to a PC through a USB port and they run the protocolstack that communicates with an attached wireless module. The USB boards have a10-pin SPI connector that the wireless modules attach to. In addition to thestandard SPI signals, the connector includes Reset, Interrupt, Sleep,Chip-Select, and power signals. You can use these signals to connect wirelessmodules to a custom design. Two "squid" adapters in the kit connect toa wireless module and their color-coded wires to help simplify connections toprototypes. (You also can use the RF modules with several development kits fromAtmel, 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 informationabout the wireless modules and USB boards, schematic diagrams and firmwareinformation. (Find better schematics as PDF files on the RZ600 Webpage.)

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

I identified pairs of wireless modules by reading the MCU partnumber on each wireless chip. Mark the pairs with a label. After that, kit setup took only a few minutes. As I attached a 2.4-GHz module to each USB boardand connected them one at a time to a PC, Windows XP started the usualUSB-device routine and a search for drivers. The RZ600 manual explained theneed to install or locate a communication-device class (CDC) driver but itlisted the wrong directory. I had to point to: [my Atmeldirectory]/rz600_rel1.0/trunk. Windows identifies each USB device as a serialCOM port.

Next, I connected a second wireless module-and-USB board to a USBport and Windows "discovered" it, too. Use the Windows Device Managerto find the COM port number assigned to each of the two USB boards. My computeridentified the two boards as COM25 and COM26. I connected both board sets toone PC but spaced them about 3 ft (1m) apart with a USB extension cable (notsupplied).

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

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

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

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

You can glean a lot of information for each wireless-chip typefrom 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, severalstate diagrams can help you understand how to set up a wireless chip, butexamples of how to combine a minimum series of commands and operations tocreate a basic wireless link would help more. What's the simplest way to get onthe air quickly? What basic commands do I need to start? Unfortunately, you're left to answer thesequestions on your own. Beyond the wireless UART, I never found any examples.

Atmel provides a "Software Programming" model anddocumentation for its RF ICs that offers more details and describes a"Transceiver Access Toolbox," but again, the manual does not includeany examples. I bet most engineers will need a few basic code samples, flowcharts 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 Igot more information from Atmel via a member of the company's technical supportteam:

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

The full software IEEE MACsoftware package with multi-platform support and a detailed User Guide is foundin our software section - the number of this application note is AVR2025. Youcan 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 publicrelease Aug. 29, 2010 which offers a new TAL-API which has been reduced andfurther optimized - it's called TinyTAL and the Wireless UART code exists forthat new API, as well.

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

Editor's notes: During this review I downloaded the IAREmbedded Workbench software and hoped to get an AVR JTAGICE mkII pod. I sawmany listed on eBay coming from Asian sellers. The prices looked attractive - $99U.S. versus about $300 U.S. for a module through an authorized Atmeldistributor. But, after reading many negative comments from people who boughtChinese 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 toconnect with a JTAG connector on a programming/debugging pod because most JTAGconnectors have 0.100-inch-center spacing for contacts.

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