Radio-frequency identification (RFID) design presents unique challenges to engineers looking to build low-cost, robust designs able to meet a broad range of requirements. The availability of complete RFID design kits offers a ready-made solution to diverse design challenges and can help accelerate development cycles. Development kits combine software with a complete hardware complement, and are available to speed design of RFID transponders and readers for application-specific and general-purpose requirements. Manufacturers include Atmel, austriamicrosystems, Maxim Integrated Products, Melexis, RF Solutions, Skyetek, and Texas Instruments, among others.
RFID offers a conceptually simple solution to containing a corporation's physical assets within its extended electronic network. By drawing on a broad range of RFID transponder types and capabilities, corporations can deploy identification and tracking strategies ranging from passive identification of individual assets at key locations to active in-route tracking of vehicles, containers and shipments.
For engineers charged with developing suitable RFID transponders and complementary readers, meeting the requirements for those systems involves a highly efficient combination of RF design technique and digital logic design – all tuned to deliver the required operating modes and performance levels in the most cost-effective manner possible.
An RFID system includes a reader, and active or passive transponders built to operate in specific low-, high- or ultra-high-frequency bands. Readers, or base stations, combine a matching antenna and transceiver with a processor or microcontroller unit (MCU), system interface and basic indicators (Figure 1).
Typically intended for placement on individual items, passive transponders (or tags) include a semiconductor chip and antenna to draw power from the RF signal transmitted by the reader. Tags are sophisticated systems able to transmit signals across relatively large distances. They send wake-up signals from readers or operate as beacons periodically transmitting their status. Active transponders tend to be more expensive MCU-based systems, and so are typically limited to placement on transportation vehicles or containers.
Figure 1: RFID readers can be sophisticated systems able to collect data from low-, high-, or ultra-high-frequency tags, and interact with PCs or dedicated programmable logic controllers (PLC). Mobile readers add the further complication of battery-management circuitry. (Source: Texas Instruments)
To address the broad range of RFID options and capabilities, semiconductor manufacturers offer an extensive array of evaluation and development kits. RFID kits typically supplement the hardware required to build specific classes of RFID readers and transponders with the necessary development tools. Those include an applications programming interface (API), software libraries, sample source code, user interface, and a serial or USB connection from the development kit hardware to a PC.
Atmel offers a set of kits intended to help engineers evaluate available ICs and develop suitable RFID designs. Engineered to support diverse Atmel RFID reader ICs, the Atmel ATA2270-EK1 offers all the hardware and software components needed to experiment with RFID design and create complete applications. The kit includes reference designs and source code, along with an LCD and control buttons for interacting with the RFID system. Also included is a graphical user interface that allows engineers to control the design. But engineers can use a variety of development tools, including the Atmel AVR Studio, an Integrated Development Environment (IDE) for designs based on Atmel's 8- and 32-bit AVR microcontrollers.
Another Atmel RFID design kit, the ATAB5570, includes a board that demonstrates the simple parts list required to build an RFID tag operating in the 125-kHz range (Figure 2). In fact, the board provides a working tag design comprising only the antenna coil, associated passive components and the tag IC itself.
Figure 2: A passive RFID tag typically includes only a transponder IC and single-coil antenna, which serves as both the IC's power source and bidirectional communications interface. (Source: Atmel)
The Texas Instruments eZ430-TMS37157 provides all the hardware and software needed to evaluate 134.2-kHz passive low-frequency RFID designs based on the MSP430F2274 microcontroller and TMS37157 RFID transponder. Engineers can use the kit's target board as a development tool, sending and receiving data from a PC using the USB interface. Alternatively, engineers can detach the kit's target board from the debugging interface and use it as the foundation for an application-specific RFID solution.
For its DVK90109 RFID reader development kit, Melexis combines an RFID development board with the Melexis EVB90109, which is an evaluation daughter board based on the Melexis MLX90109 transceiver IC (Figure 3). The EVB90109 daughter board plugs into the development board through a 10-pin connector and provides data communications between the MLX90109 IC and a host MCU built into the development board. The kit also includes a 125-kHz transponder and RS232 PC interface software for accessing reader data while testing reader designs.
Figure 3: RFID development boards, such as the Melexis DVK90109 shown here, typically offer easy access to input and outputs for detailed signal monitoring during RFID reader design. (Source: Melexis)
Austriamicrosystems offers its AS399x "Roger" UHF RFID Reader System demo kit in two configurations designed to speed development of RFID readers based on its AS399x UHF RFID reader IC. In one configuration, the kit uses its on-board MCU to operate as a stand-alone UHF RFID reader. The alternate configuration disables the on-board MCU, allowing engineers to directly control the reader IC with the development host system. The kit supports both USB or UART interfaces for host communication and includes C-based controller software.
SkyeTek offers a variety of development kits targeting diverse applications. For example, the SkyeModule M9 developer kit targets reader development in the 860-960 MHz frequency range, and includes a reader module, host interface board, extensive software development tool kit and a set of sample tags.
Maxim's MAX66901 kit offers RFID tags and reader hardware for development based on Maxim's line of HF RFID key transponders. Engineers can evaluate use of SHA-1-based mutual authentication in designs intended for security applications, including access control and e-cash systems. The kit provides configurable serial communications up to 115.2 kbits/s, using its fully documented serial command set. The MAX66901 supports standard protocols, including ISO 14443B and ISO 15693, and allows firmware updates to handle future RFID keys.
RF Solutions offers its RFID Universal Base Board and associated software development kit for RFID readers based on its reader modules. Billed as a complete "ready-to-use" RFID reader, the base board includes power, a 13.56-MHz PCB antenna, 125-kHz antenna coil, RS-232 interface and optional USB interface. The company supplements the Windows-based software development kit with Borland C++ source code and documentation, enabling engineers to modify the provided software for their own applications.
RFID development requires careful attention to both RF design and digital processing methods to deliver tags and readers able to achieve design objectives at minimal cost. For engineers, development kits serve as both lab tools for experimenting with RFID design and reference designs for understanding the characteristics of specific RFID ICs. Perhaps most importantly, available development kits offer a proven starting point for rapidly building new RFID designs able to meet the engineer's specific design requirements.