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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
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