Radiometrix Ltd

Page 1

1200buad Modem IC

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

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

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Adequate preamble to settle data slicer in the receiver

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Extra wake up preamble to allow for transmitter power up time requirements

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Differential Manchester encoding of address, data and checksum

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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

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Remote data acquisition system, data logging

!

Fleet management, vehicle data acquisition

NBEK Controller As 1200 Baud Modem

NBEK Controller As 1200 Baud Modem

NBEK Controller As 1200 Baud Modem

NBEK Controller As 1200 Baud Modem

Radiometrix

Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England

16

16

16

16 April 2008

April 2008

April 2008

April 2008

NBEK

NBEK

NBEK

NBEK----000

000

000

000----xxx

xxx

xxx

xxx

NEW

Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233

Figure 1: NBEK-000-DIL