Encoder/Decoder IC. NKM2401 Datasheet

NKM2401 IC. Datasheet pdf. Equivalent

NKM2401 Datasheet
Recommendation NKM2401 Datasheet
Part NKM2401
Description Radio Data Encoder/Decoder IC
Feature NKM2401; Data Sheet and Application Notes NKM2401 Code/decoder chip Part number 1-982 Description The NKM2.
Manufacture Milford
Datasheet
Download NKM2401 Datasheet




Milford NKM2401
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 Stampor 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
RxD
Serial Data Out
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
Page 1 of 15



Milford NKM2401
Data Sheet and Application Notes NKM2401 Code/decoder chip
Part number 1-982
Some form of communication protocol is required when using links over a noisy communication channel.
This needs to rugged, secure and have built in error checking. A number of complex standards do exist
but they are not really suited to simple radio links and they are not implemented on a simple to use IC.
The NKM2401 is intended to address this problem and provides the services required for an interface
between a data source and a radio module. It is intended for simplex (one way) communications and
transports short packets of data and is therefore suited to ‘control and sense’ (bytes) rather than ‘file
transfer’ (Megabytes) tasks.
The NKM2401 is configured as a ‘transmitter encoder’ or a ‘receiver decoder’ by the state of a single
mode pin.
It interfaces to the hosts by a simple serial interface operating at 2400 baud.
NKM2401 Issue 1.1 Nov-98
© Milford Instruments/nikam electronics www.milinst.demon.co.uk
Page 2 of 15



Milford NKM2401
Data Sheet and Application Notes NKM2401 Code/decoder chip
Pin Out Schematic & Description
Vcc
Serial Data In
Busy
Mode
High
1
NKM2401
Transmit Mode
Gnd
Transmit Enable
Transmit Data
Test
Part number 1-982
Pin Function - Mode Pin High - Transmit
1 Vcc +5V supply
2 Serial Data Input, 2400bps
3 Busy Output. Goes high whilst transmitting. Active High
4 Mode Pin high (Vcc) selects transmit mode
5 Test Input sends pre-set message. Active Low
6 Transmit Data Output to RF transmitter
7 Transmit Enable Output to RF transmitter. Active High
8 Ground. 0 Volt
Vcc
Rx Data Input
No Connect
Mode
Low
1
NKM2401
Receive Mode
Gnd
Data Ready Output
Serial Data Output
Send Data Input
Pin Function - Mode Pin Low - Receive
1 Vcc +5V supply
2 Data input from RF receiver
3 No connection. Do not connect. Factory test point.
4 Mode Pin low (0V) selects receive mode
5 Send Data Output. Pull high to send the data in receive buffer
6 Serial Data Output. 2400bps
7 Data Ready Output flag. Goes low when valid data in buffer
8 Ground. 0 Volt
NKM2401 Issue 1.1 Nov-98
© Milford Instruments/nikam electronics www.milinst.demon.co.uk
Page 3 of 15







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