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Stress-less Wireless Add short-range wireless connectivity to your designs with these easy-to-use compact transceiver modules. Review: By PETER SMITH T HE ER400TRS IS an extremely compact intelligent radio transceiver that operates in the 434MHZ LIPD band. This UK designed and manufactured device integrates radio, microcontroller and power supply circuitry in a screened 9-pin single-inline module measuring just 37 x 14 x 4mm. All communications protocols are handled on-board, allowing OEMs to add wireless capabilities to their products without the need to understand radio technology. One obvious application for these new modules is in two-way data telemetry systems. They would also be suitable for applications where it is essential that a receiving node issues a “receipt” to confirm reception of transmitted data, such as in handheld terminals and electronic point-of-sale terminals. The ER400TRS transceiver is supplied ready-to-run from LPRS. Alternatively, designers can make use of a range of user-programmable functions to customise their radio links to their own specifications using simple software commands. In either case, the embedded Easy-Radio software ensures that the data stream from transmitter to receiver is efficiently packaged to maximise both the range and the data transfer rate of the radio link. The data rate defaults to the industry standard of 19.2kbps, but can be programmed to any rate between 4.8kbps and 38.4kbps. The units can be programmed for use in one ER400TRS Transceiver: Main Features • • • • • • • 10 programmable frequencies between 433-434MHz 10 programmable power output levels (10mW max.) Selectable data rate from 4.8kbps to 38.4kbps All options programmed via software commands Range in excess of 250m line-of-sight Low current consumption: receiver 17.0mA, transmitter 23mA Embedded software handles all data encoded & decoding and over-air transmission • RSSI output • 9-pin SIL package measuring 37.5 x 14 x 4mm 22  Silicon Chip The evaluation kit includes two of these modules, with in-built power supply, an RS232 serial interface and an antenna. siliconchip.com.au The ER400TRS radio transceiver operates in the 434MHZ LIPD band and is comes packaged in a screened 9-pin single-in-line module. of 10 channels within the 434MHz band so that systems can avoid specific congested or “dirty” frequencies. A crystal-controlled synthesiser is used to guarantee frequency accuracy. The transmitter power output is programmable in 1mW steps, up to a maximum of 10mW ERP. A standard 50Ω antenna, such as a whip, helical or PC-board loop can be used, with a line-of-sight range of 250m easily attainable. Connection between host equipment and transceiver is via a conventional serial interface. The interface includes two handshaking lines (“host ready” and “transceiver busy”) to control data flow. The module also features a received signal-strength indicator output, which can be put to good use when setting up fixed links or networks of devices. The modules are designed to run from a single 3.6V lithium cell but for added flexibility, can be used with any DC supply between 3.3V and 5.5V. Typical current drains for the transmit and receive functions are 23mA and 12.5mA, respectively. At idle, the transceiver draws a quiescent current of 2mA. Evaluation kit A complete evaluation kit is available for those wishing to determine the suitability of the Easy-Radio system for their applications. Each kit includes a pair of identical demonstration boards that can accommodate any of the Easy-Radio series of modules. The demo boards incorporate a power supply, RS232 serial interface and SMA connector for antenna hook-up. Basically, the kit is designed to allow two PCs to be connected together via a two-way radio link. Everything siliconchip.com.au Fig.1: block diagram of the ER400TRS module internals. A radio transceiver, microcontroller and power supply are all included in the small, single-in-line package. that’s required is provided with the kit, including PC software on CD, whip antennas, serial cables and 9V batteries. The software runs on Windows 95, 98, Me, 2000 & XP and gives access to all of the user-programmable options within the modules. Serial data rate, power output, frequency and handshake control, as well as several special test modes can all be controlled. In addition, the software provides a simple serial terminal window that allows messages to be sent between modules. The ER400TRS is just one of a new family of Easy-Radio devices from Low Power Radio Solutions in the UK. More information can be obtained from the Australian agent’s website at www.lprs.com.au LPRS are represented in Australia by Telelink Communications – phone (07) 4934 0413; fax (07) 4934 0311; email: sales<at>telelink.com.au or sales<at>lprs. SC com.au Fig.2: the software runs on Windows 95, 98, Me, 2000 & XP and gives access to all of the user-programmable options within the modules. October 2004  23