EW
N
16 April 2008
Radiometrix
Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233
NBEK-000-
NBEK-000-xxx
NBEK Controller As 1200 Baud Modem
The Narrow band Evaluation Kit (NBEK) IC can be used as 1200baud half-duplex serial modem
suitable for narrow band receivers, transmitters and transceivers (or any RF modules with >5kbps data
rate). It takes care of preamble, synchronisation, bit
balancing and error checking and enables a
transparent radio data link to be established
between radio devices
This is a half duplex unit, so collisions between
transmitted and received packets must be dealt
with by the user.
Provided no two devices attempt to transmit
simultaneously no further restrictions on data
Figure 1: NBEK-000-DIL
transmission need be made, as all transmit timing,
valid data identification and data stream buffering is conducted by the unit. Synchronisation and
framing words in the packet prevent the receiver outputting garbage in the absence of wanted RF
signal or presence of interference.
Supports 1200 baud asynchronous data: 1 start bit, 8 data bits, 1 stop bit.
With typical microcontrollers and UARTs, direct connection is usable as shown on figures 2 & 3.
To connect to a true RS232 device, inverting level shifters must be used (MAX232 type are ideal, but
simple NPN/PNP transistor switches often suffice as used in the application circuits figures 4 & 5).
Features
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Operating voltage (temperature): 5V for standard version (-40°C to +85°C)
Maximum usage of the range capability of an RF module
Adequate preamble to settle data slicer in the receiver
Extra wake up preamble to allow for transmitter power up time requirements
Differential Manchester encoding of address, data and checksum
Synchronisation codes and checksum to reduce false triggering on noise
Suitable to be used with Narrow Band FM radio modules
Serial modem baud rate at 1200bps (half-duplex)
Addressable point-to-point
Applications
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PDAs, organisers & laptops
Handheld / portable terminals
EPOS equipment, barcode scanners
In-building environmental monitoring and control
Remote data acquisition system, data logging
Fleet management, vehicle data acquisition
Radiometrix Ltd
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1200buad Modem IC
RADIOMETRIX [ RADIOMETRIX LTD ]
