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PDF NKM2401 Data sheet ( Hoja de datos )
| Número de pieza | NKM2401 | |
| Descripción | Radio Data Encoder/Decoder IC | |
| Fabricantes | Milford | |
| Logotipo |  |
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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
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
1 page  
Data Sheet and Application Notes NKM2401 Code/decoder chip
Part number 1-982
System Timing Diagram
Approx 128mS Overall
42mS
35mS
Host sends 8 Characters
NKM2401 RF Transmit
and RF Receive/Decode
Data Ready Output
Send Data Input
NKM2401 Serial Data Out
50mS
Handshake delay 1mS
NKM2401 Issue 1.1 Nov-98
© Milford Instruments/nikam electronics www.milinst.demon.co.uk
Page 5 of 15
5 Page 
Data Sheet and Application Notes NKM2401 Code/decoder chip
Part number 1-982
Connection to PC RS-232 Port
DCD
DSR
RXD
RTS
TXD
CTS
DTR
RI
GND
1
6
2
7
3
8
4
9
5
PC AT
0v
AERIAL
RF
GND
1
2
DTCT
GND
VCC
AF
DATA
SILRX-418F
3
4
5
6
7
100n 10k
+5V
AERIAL
SERIAL
DATA IN
47k BUSY
RXD
1
2
3
4
MODE
HIGH
NKM2401
VDD VSS
GP5 GP0
GP4 GP1
GP3 GP2
8
7
6
5
470R
10k
10R
BUSY LED
100n
TXEN
TXD
TEST
PB SW
100n
LED +5V
1
2
RF GND
RF OUT
3
4
5
VCC
GND
D IN
TXM-418F
5V VERSION ONLY
NKM2401
10k
RXD
TP
1
2
3
4
VDD VSS
GP5 GP0
GP4 GP1
GP3 GP2
8
7
6
5
MODE
LOW
DATA READY
470R
SERIAL DATA
SEND DATA 1k
1
6
2
7
3
8
4
9
5
DCD
DSR
RXD
RTS
TXD
CTS
DTR
RI
GND
PC AT
100n
0V
The NKM2401 can be directly connected to a PC RS232 port as shown above. A simple terminal
programme can be used to drive the devices.
In transmit mode the +/-12V PC RS232 output is connected to the RXD input via a series resistor of
47k. Internal protection diodes clamp the input voltage to ground and +5V.
In receive mode the serial data output is connected to the RXD input of the PC. The 0-5V logic levels
will usually drive most PC serial inputs (but not all!) A series resistor of 1k provides some short circuit
protection to the NKM2401.
The polarity of the signals is correct for these direct connections. If longer lines need to be driven a
logic level to RS232 level converter should be used. These are usually inverting so extra inverters
should be connected in the signal lines.
No handshaking is used in these examples as PC UARTs will usually accept the eight byte packets. The
hardware handshake lines of the PC should be tied as shown to defeat any hardware handshaking that
may be used on some PCs or .checked by software.
NKM2401 Issue 1.1 Nov-98
© Milford Instruments/nikam electronics www.milinst.demon.co.uk
Page 11 of 15
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet NKM2401.PDF ] | |
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