2.4GHz Wireless Modules Deliver "Drop-in" Ultra Low Power for Just $8 in Volume

(Product News, 2 Oct 2008)

Ultra low power (ULP) RF specialist Nordic Semiconductor ASA has announced its official design partner, California-based RF Digital, has released a fully FCC and CE-compliant 2.4GHz ULP wireless module that is supplied tape and reeled at a $8 unit cost for volume orders.

The tape and reeled format enables customers (or their subcontractors) to place the module on the PCB using automated placement equipment. Automated assembly, together with the low price and the fact that customers require no further certification prior to releasing products to market, makes the module a compelling solution for production runs from 10 to 100,000 units.

The RFD21733 measures just 15x15x3mm and is powered by Nordic's nRF24LE1 2.4GHz ULP transceiver, a high performance wireless device integrating radio, microcontroller and flash memory.

The RFD21733 is supplied with RF Digital's proven Frequency Hopping Spread Spectrum (FHSS) firmware, or alternatively with no pre-loaded firmware (module part number RFD21731). Both modules feature a built in chip antenna which is matched, tuned and radiation pattern optimized. A 32kHz crystal required for precision timing when operating in a low duty cycle ULP mode is also integrated into the RFD21732 module, which has no pre-loaded firmware. Full access to the wireless module is provided to three digital in/out lines, program line, reset line, power (+V) and ground (GND) connections.

The RFD21733 is particularly suitable for designers that may be new to wireless as everything on the RF side of the device is in place, tested and proven. In this configuration, the module runs at 9600 baud and features N, 8, 1 serial interface firmware allowing it to be connected directly to an RS232 level shifter. In addition, the module features a built in switch follower mode. Pressing a button on the transmitter will cause the corresponding button on the receiver to activate; this button could, for example, be connected to an LED to facilitate range testing or used in end-product applications such as keyless entry door openers or long range RFID applications.

For more experienced designers who want to take advantage of the modules' high bandwidth (up to 2Mbps raw data rate), ultra low power consumption (down to microamps average current) and ability to communicate with up to five other devices in a point-to-multipoint topology, the modules can be programmed using Nordic's nRF24LE1 Development and Evaluation Kit. Because the transceiver used in the modules is an integrated device, there is no requirement for a separate development and evaluation kit to access the microcontroller.

RF Digital is also releasing an adaptor board to interface the modules to the Nordic nRF24LE1 Development and Evaluation Kit, and a miniature evaluation board complete with module, three buttons and three LEDs (enabling range testing) powered by a CR2032 3V coin cell-type battery. Since this miniature evaluation board includes the RFD21733 compliance tested module, it no longer requires any further compliance testing and can even be used as the basis of a marketable product. The miniature evaluation board also has 0.100 spacing SIP header which allows it to easily plug into users' development boards.

Requiring only 15x15mm board area, the modules are suitable for all but the most space-constrained applications. And at a price of as low as $8 (in volume) they offer a cost effective alternative to a discrete component RF design for production runs numbering up to hundreds of thousands of pieces per year.

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