EW
N
Issue 1, 28 August 2007
Radiometrix
Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233
SMX2
Multi-
Small Multi-channel UHF Transceiver
Standard:
Variant:
SMX2-433-5 (10mW)
SMX2-XXX-5 (2mW-25mW)
SMX2
is
small
multi-channel
UHF
transceiver
operating
on
433.05MHz-
434.79MHz European licence exempt band.
SMX2 offers a fast-route to custom
frequency on any UHF band from 431MHz
to 436MHz with 25kHz channel spacing.
Features
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Conforms to ETSI EN 300 220-3 and EN 301 489-3
High performance double superhet, 128 channel PLL synthesizer
Data rates up to 5 kbps for standard module
Usable range over 500m
Fully screened. Low profile
Feature-rich interface (RSSI, analogue and digital baseband)
Incorporate a 1200baud dumb modem
Re-programmable via RS232 interface
Low power requirements
Figure 1: SMX2-433-5
Applications
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Handheld terminals
Heavy vehicle/machine remote controls
EPOS equipment, barcode scanners
Data loggers
Industrial telemetry and telecommand
In-building environmental monitoring and control
High-end security and fire alarms
Vehicle data up/download
Technical Summary
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Operating frequency: 433.05 - 434.79MHz
Custom variants from 431 - 436MHz on any 1MHz band
128 channels controlled via RS232 interface
Transmit power: +10dBm (10mW) nominal. Adjustable 2 – 25mW
Supply range: 4.2V - 15V
Current consumption: 30mA (10mW) transmit, 25mA receive
Data bit rate: 5kbps max. (standard module)
Receiver sensitivity: -120dBm (for 12 dB SINAD)
Size: 53 x 32 x 12mm
Radiometrix Ltd
SMX2 Data Sheet
page 1
Radiometrix Ltd
SMX2 Data Sheet
Figure 2: SMX2 block diagram
page 2
Figure 3: SMX2 footprint (Top) view
Pin Description
Pin
1a
2a
3a
4a
5a
6a
7a
8a
1b
2b
3b
4b
Name
RSSI
Vcc
TXD
AF out
RXD
TXE
PGM
0V
0V
S0
S1
S2
Function
DC level between 0.5V and 2.5V. 60dB dynamic range
DC supply input. (4.2 – 15V at 50mA max.)
DC coupled input for TTL/ CMOS logic.
500mV p-p audio. DC coupled, approx 0.8V bias.
Open collector output of data slicer. Need external pull-up
Transmit enable. Low = RX mode. High = TX. (10kΩ pull down)
Serial programming / control input (true RS232)
Ground
Ground
Parallel channel select LSB
Parallel channel select
Parallel channel select MSB
Pin description of SMX2 with Modem mode selected
The 'modem' mentioned is a 1200 baud RS232 semi-intelligent unit (Transmit keyed when valid serial
data is present, so no separate TX control needed. Coding in the datastream also permits the receiver to
ignore noise and only output valid serial data) This is a half duplex unit, so collisions between
transmitted and received packets must be dealt with by the user (if transmit data is sent to the unit
then a transmit burst commences immediately and the contents of the receive data buffer is lost)
Pin
1a
2a
3a
4a
5a
6a
7a
8a
1b
2b
3b
4b
NOTES:
1.
2.
3.
4.
No inversion occurs between TXD and RXD. However AF out
is
inverted relative to TXD.
Parallel channel selects are active LOW and have internal pullups to 4V
There are no pullups on the open collector outputs.
The software incorporates a 1200 baud modem, compatible with that implemented in other
Radiometrix narrowband units ( i1200 tones and format ). Modem operation is selected by the
SETMOD command. TXE pin (6a) becomes an RS232 input, and RS232 compatible data is output
on the RXD pin (5a). If true +/- levels are desired then an inverter and a MAX232 should be used on
data out.
SMX2 Data Sheet
page 3
Name
RSSI
Vcc
NC
NC
MOD RXD
MOD TXD
PGM
0V
0V
S0
S1
S2
Function
DC level between 0.5V and 2.5V. 60dB dynamic range
DC supply input. (4.2 – 15V at 50mA max.)
Leave unconnected
Leave unconnected
Open collector RS232 compatible data output
RS232 data input
Serial programming/control input (true RS232)
Ground
Ground
Parallel channel select LSB
Parallel channel select
Parallel channel select MSB
Radiometrix Ltd
5. RS232 input pins (6a and 7a) tolerate true +/- levels. No buffering is required.
6. If analogue transmit modulation is needed, then connect a series 1µF cap + 500kΩ trimmer in the
‘baseband in’ circuit. Adjust trimmer for 90% of peak deviation (+/- 2.7KHz) at mean input level.
7.
If parallel channel select is not wanted, the 4 pin connector 'b' can be removed
SMX2 serial interface commands
2400 baud at RS232 level. 8 bit data, no parity, 1 start bit, 1 or 2 stop bits, No flow control.
Transmit (pin 3 on DB9) and Signal Ground (pin 5 on DB9) should be connected to PGM and 0V
respectively.
SINGLE
GOCHAN
LOADMX
LOAD aa
LOADTB
RVALUE
SETPAR
SETSER
SETMOD
<cr>
/
nnnnn
xx
xx
nnnnn
nnnnn
rrrr
Set value of N for single channel operation (value not stored in eeprom)
Serial select of channel xx (0 to 127)
Set highest permitted (serial selected) channel xx (others default to ch0)
Set value of N for channel aa (channels 0 to 15)
Set value of N for channel 16 (channels 17 to 127 then in sequence)
Enter value for R register
Channel selected by 3 bit parallel input (0 to 7). Also disables modem
Channel selected by most recent 'gochan' operation
Enable internal modem. Frequency selected by most recent 'gochan' or 'single'
Process entry
Clear all buffers
xx = channel number from 00 to 127
aa = two digit channel number from 00 to 15
nnnnn = synthesizer N register value, (up to 65535)
rrrr = synthesizer R register value, (up to 16383)
N
=
f
RF
f
Channelspacing
=
433.05
MHz
=
17322
25
kHz
R
=
f
Xtal
f
channelspacing
=
13
MHz
, So R=520
25
kHz
Notes:
1. A pause of at least 50ms must be allowed between command strings (EEPROM programming
time).
SINGLE mode does not store the N value in EEPROM. Therefore the unit is inoperative after a
power down until either another valid SINGLE command is received, or mode is changed by a
GOCHAN, SETPAR or SETSER command. SINGLE mode is intended for frequency agile
applications.
2. /SETPAR command should be issued at the end of channel programming to put the module
back into parallel frequency select mode
Radiometrix Ltd
SMX2 Data Sheet
page 4
Condensed specifications
Frequency
Frequency stability
Channel spacing
Number of channels
433.05 - 434.79MHz (Any 1MHz band from 431 - 436MHz)
±2kHz
25kHz (12.5kHz by special order)
128 channels selected via serial RS232 interface
8 channels parallel selected (via 3 frequency select pins)
in 433MHz band only 69 channels are used as standard
4.2V-15V
30mA @ 10mW transmit [ 25mW version @ 45mA]
25mA receive (or modem ‘idle’)
-10 to +60 C (Storage -30 to +70 C)
53 x 32 x 12 mm
Compliant with ETSI EN 300 220-3 and EN 301 489-3
8 pin 0.1" pitch molex
4 pin 0.1" pitch molex
3 pin 0.1" pitch molex
1.2mm (min.)
Supply
voltage
Current
Operating temperature
Size
Spurious radiations
Interface
user
Power
RF
Recommended PCB hole size
Transmitter
Output power
TX on switching time
Modulation type
TX modulation bandwidth
Deviation
Adjacent channel TX power
TX spurii
Inputs
Receiver
Sensitivity
image / spurious
blocking
adjacent channel
Outputs
Power on to valid audio
Power on to stable data out
+10dBm(10mW)
±
1dB (factory adjustable: 2 - 25mW)
<50 ms
FM, FSK (F1D, F3D)
DC – 3kHz
±3kHz
-37dBm
<-45dBm
Data (CMOS/TTL compatible)
-120dBm for 12dB SINAD
-112dBm for 1 part per 1000 BER
-60dB
-85dB
-60dB (Tested per. ETSI EN 301 489-3)
RSSI, Audio, Data
28ms
50ms (for 50:50 mark / space)
Notes: 1. The data slicer cannot be depended upon for data waveform frequencies below 250Hz
2. When RX is on and a transmitter keys up, again a 50ms period is required to stabilise data
output mark/space. i.e. allow at least 50ms of preamble
Radiometrix Ltd
SMX2 Data Sheet
page 5
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