NKM2401 Datasheet, PDF (1/15 Pages) List of Unclassifed Manufacturers – Code/decoder chip

Data Sheet and Application Notes NKM2401 Code/decoder chip
Part number 1-982
Description
The NKM2401 Radio Data Encoder/Decoder IC enables serial data to be easily transported over low
power radio links and therefore allows users to quickly and easily add short range “wireless” capabilities
to their systems. It is designed for use with licence exempt transmitter and receiver modules operating
in the VHF and UHF bands and provides the buffering, packetisation, encoding, error checking and ‘bit
bashing’ required for transmitters and the reverse processes for receivers.
It can be interfaced to any PC or microprocessor serial port to provide simplex (one way) transfer of
data with built in error checking ensuring data integrity. It is ideally suited for use with the Parallax
BASIC Stamp™ or other similar devices.
Features
Applications
♦ Simple to use
♦ Transparent operation
♦ Single chip solution
♦ Data acquisition
♦ Alarm systems
♦ Hand held terminals
Typical Application
Serial Data In
TxD
Busy*
TxEn
Serial Data Out
RxD
Data Ready*
Send Data*
User
Application
NKM2401
RF Transmitter
RF Receiver
* Optional handshake lines
NKM2401
User
Application
Introduction
Radio links comprising pre built and tested transmitter and receiver modules are now readily available
from a number of suppliers. These are easily connected to standard encoders and decoders allowing
simple On/Off remote control systems to be assembled.
However, sending data over these radio links is difficult as they are generally AC coupled, bandwidth
limited (100Hz to 5KHz typical) and may be subject to noise and interference. The receiver may
produce digital ‘white noise’ on its data output in the absence of any signal and in addition requires some
time to extract the data from the received audio signal. The format of the data must also be given
consideration as asymmetric data such as Serial ASCII (RS232) which is non DC balanced will cause the
‘data slicer’ in the receiver to give poor performance leading to errors after consecutive sequences of
ones or zeros. There may also be considerable pulse width distortion and ‘jitter’ produced by the link.
These radio links cannot therefore, usually be successfully connected directly to a UART, as such
devices will not tolerate these errors and almost certainly will produce erroneous data which may be
worse than useless !
NKM2401 Issue 1.1 Nov-98
© Milford Instruments/nikam electronics www.milinst.demon.co.uk
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