Data Sheet

Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England
Issue 1, 20 May 2009
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233
Transparent Data Link on 868/914MHz band
A DWA3 is a single channel, 869 or
915MHz wideband, transparent data
link. It has a TDL2A pin out (and
firmware), but uses a BiM3 series
radio module. DWA3 acts as a
transparent serial cable to attached
host. DWA3 is an intermediate level
OEM radio modem which is in
between a raw FM radio module like
BiM3A/BiM3B and a sophisticated
OEM radio modem like RPM3. It takes
care of preamble, synchronisation, bit
balancing and error checking along
with automatic noise squelching.
Figure 1: DWA3-868.30-9 radio modem
The DWA3 provides a half duplex link. 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 datastream 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.
For multiple radio systems (polled networks) a DWA3 can be set to 1 of 8 unique addresses.
Conforms to EN 300 220-3 and EN 301 489-3
Crystal controlled PLL FM circuitry for both Tx and Rx
Built-in ceramic patch antenna
SAW front-end filter
Single conversion superhet
Serial modem baud rate at 9600bps (half-duplex)
Addressable point-to-point
PDAs, organisers & laptops
Handheld / portable terminals
EPOS equipment, barcode scanners
In-building environmental monitoring and control
Remote data acquisition system, data logging
Fleet management, vehicle data acquisition
Technical Summary
Operating frequency: 869.85 /868.30MHz (Europe), 914.5MHz (North America)
Modulation: 16kbps bi-phase FSK
Supply: 5V at 18mA transmit (@5mW), 15mA receive/idle
Transmit power: +5mW @ 869.85MHz
Receiver sensitivity: -106dBm (for 1% BER)
32 byte data buffer
Radiometrix Ltd
DWA3 Data Sheet
page 1
Figure 2: DWA3 footprint (top view)
Pin description
5V regulated power supply (4.75 - 5.25v)
Pull low to enable module
Pull low to enter Test/Setup mode (5V CMOS logic. Pull up to 5V)
Transmit Data (Inverted RS232 in at 5V CMOS logic, No pullup)
No Pin
Receive Data (Inverted RS232 output at 5V CMOS logic output)
RX Busy, Data in receive buffer (5V CMOS logic output)
1. ENABLE and SETUP have 10K pullups to Vcc. TXD has none (if used in RX only, tie this pin to +5v)
2. Vcc must be a 5v regulated supply (4.75 - 5.25v)
3. Pinout is as TDL2A. (It is, however, longer than 33mm, with a ceramic patch antenna replacing the
RF pins)
3. TXD / RXD are inverted RS232 at 5v cmos levels. To connect to a true RS232 device, inverting level
shifters must be used (MAX232 type are ideal, but simple NPN transistor switches with pullups often
suffice). With typical microcontrollers and uarts, direct connection is possible.
3a DWA3 is compatible with the TDi2 interface board (which provides a MAX232 type buffer, 9 way D
connector, 5v voltage regulator and support circuits) provided the SMA RF connector is not fitted. This
board is 61mm x 33mm in size.
4. Rx_busy pin goes high when valid data is present in the receive buffer.
5. The DWA3 provides a half duplex link, but provided no two devices attempt to transmit at one time
(a 'low' on RX_busy may be used as a primitive 'CTS' indication) no further restrictions on data
transmission need be made, as all transmit timing, valid data identification and datastream buffering
is conducted by the unit. There is no 'transmit enable' pin.
Sync and framing words in the packet prevent the receiver outputting garbage in the absence of signal
or presence of interference.
6. A simple addressing structure is included in the datastream. Units may be programmed onto one of
eight addresses (all units are supplied set to default addr=0)
7. DWA3 uses a BiM3 series transceiver module (e.g. BiM3A-914-64, BiM3B-869-64) and the cpu
circuitry of the TDL3F
8. This unit is programmed exactly as a TDL2A, with the channel select commands being ignored.
Radiometrix Ltd
DWA3 Data Sheet
page 2
Serial interface – modem operation
To connect to a true RS232 device, inverting RS232-CMOS level shifters must be used. Maxim MAX232
or equivalent are ideal, but simple NPN transistor switches with pull-ups often suffice. With typical
microcontrollers and UARTs, direct connection is possible.
The Radio / data stream interface
A 32 byte software FIFO is implemented in both the transmit and receive sub-routine. At the
transmitting end this is used to allow for the transmitter start up time (about 4mS), while on receiving
end it buffers arriving packets to the constant output data rate. All timing and data formatting tasks
are handled by the internal firmware. The user need not worry about keying the transmitter before
sending data as the link is entirely transparent.
For transmission across the radio link data is formatted into packets, each comprising 3 bytes of data
and a sync code. If less than 3 bytes are in the transmit end FIFO then a packet is still sent, but idle
codes replaces the unused bytes. When the transmit end FIFO is completely emptied, then the
transmitter is keyed off.
Operation: Radio interface.
Raw data is not fed to the radios. A coding operation in the transmit sub-routine, and decoding in the
receiver, isolate the AC coupled, potentially noisy baseband radio environment from the datastream.
The radio link is fed a continuous tone by the modem. As in bi-phase codes, information is coded by
varying the duration consecutive half-cycles of this tone. In our case half cycles of 62.5us and 31.25us
are used. In idle (or 'preamble') state, a sequence of the longer cycles is sent (resembling an 8KHz tone).
A packet comprises the Synchronising (or address) part, followed by the Data part, made up of twelve
Groups (of four half cycles duration). Each Group encodes 2 data bits, so one byte is encoded by 4
Radiometrix Ltd
DWA3 Data Sheet
page 3
Programming the DWA3
In order to use all the functions embedded in the DWA3, the user must be aware of the
setup/programming facility, which allow different addresses and frequency channels to be set up, and if
necessary accesses diagnostic test modes.
The DWA3 is programmed through the same RS232 port that is used for sending/receiving data. An
RS232 terminal emulator (such as Aterm or HyperTerminal) is an ideal tool.
To enter program mode, the SETUP pin must be pulled low. In this mode the radio link is disabled,
but characters sent (at 9600 baud, as normal) to the unit are echoed back on the RXD pin.
The unit will only respond to certain command strings:
ADDR0 to ADDR7 <CR>:
These commands set up one of 8 unique addresses.
A DWA3 will only communicate with a unit set to the same address.
Address and channel numbers are stored in volatile memory. On power-up the DWA3 reverts to the
default in EEPROM (as supplied this is always address 0)
Writes the current address and current channel into EEPROM as the
new default.
A tilda character (~, ascii 126dec) sent by the unit indicates end of
EEPROM write sequence
(these commands are normally only used for factory diagnostics)
Transmit unmodulated carrier
Transmit carrier modulated with 8KHz squarewave
Transmit carrier modulated with 16KHz squarewave
# <CR>:
Transmitter off
A Carriage Return ‘<CR>’ (00Dhex) should be entered after each command sequence to execute it.
Releasing the SETUP pin to high state returns the DWA3 to normal operation.
Interfacing a microcontroller to DWA3
Figure 5: DWA3 interfaced directly to a microcontroller
DWA3 can be directly interfaced to any microcontrollers. If the microcontroller has a built-in UART, it
can concentrate on its main task and leave the packet formatting, bit balancing and error checking of
serial data to DWA3.
Radiometrix Ltd
DWA3 Data Sheet
page 4
Serial data should be in the following format:
1 start bit, 8 data bits, no parity, 1 or 2 stop bits
0V=low, 5V=high
STATUS pin can be connected to one of the port pins which can generate an interrupt on low-to-high
transition (e.g. RB0/INT pin in the PIC). This can be used to enter a receive sub-routine to download
data received from remote DWA3. Therefore, the host does not need to wait in a loop for a packet.
Range test and site survey can be carried out by connecting an LED on the STATUS pin. Every time,
DWA3 is within range to receive valid data, the LED will flicker.
Interfacing DWA3 to an RS232 port
Figure 6: DWA3 interfaced to an RS232 port via an RS232 line driver/receiver
STATUS pin in this can be connected to CTS, DSR and DCD pin to simulate a flow control signal.
DWA3 is capable of continuously streaming data at 9600bps. Therefore, STATUS pin is not asserted to
stop the Host from sending data as in normal RTS/CTS flow control method, but merely to warn the
host that there is already data in the receive buffer which need to be downloaded before sending any
more data.
Some DTE hosts assert DTR signal when they are active and this can be used via RS232 line receiver to
enable DWA3. Otherwise the ENABLE must be physically pulled-low to activate the DWA3.
An interface board (with MAX232 type buffer, 9 way D connector, 5V voltage regulator and SMA RF
connector) is available. This board is 61mm x 33mm in size.
Radiometrix Ltd
DWA3 Data Sheet
page 5
Condensed specifications
868.30MHz or 869.85MHz (Europe)
914.5MHz (North America)
Frequency stability
Channel width
Number of channels
Supply Voltage
Current Transmit
Operating temperature
Spurious radiations
40mA @ 868.30MHz, 18mA @ 869.85MHz, 12mA @ 914.5MHz
-20 °C to +70 °C (Storage -30 °C to +70 °C)
Compliant with ETSI EN 300 220-3 and EN 301 489-3 and FCC
Part 15
9pin 0.1" pitch molex (pin 6 absent)
Phycomp 431111900087 wideband ceramic antenna
56 x 23 x 10mm
Output power
TX on switching time
Modulation type
FM peak deviation
TX spurious
25mW @ 868.30MHz
5mW @ 869.85MHz
-1dBm (0.75mW) @ 914.5MHz
1% @ 868.30MHz
100% @ 869.85MHz
100% @ 914.5MHz
16kbps bi-phase FSK
+/-40KHz (typ.)
spurious / adjacent channel
LO re-radiation
-106dBm for 1% BER
<-100dBm typ.
Data rate
Flow control
9600baud, Half duplex
1 start, 8 data, 1 stop, no parity
5V CMOS (inverted RS232. Mark = 5V = idle)
32 byte FIFO
None (‘RX busy’ pin provided)
1 of 8, user programmed
Data latency
14ms (first byte into TX, to first byte out of RX)
Duty cycle limit
Ordering information
The DWA3 radio modem is manufactured in the following variants as standard:
Part Number
Radiometrix Ltd
Frequency band
869.85 MHz
868.30 MHz
914.50 MHz
RF power (typ.)
DWA3 Data Sheet
Baud rate
page 6
Radiometrix Ltd
Hartcran House
231 Kenton Lane
Harrow, Middlesex
Tel: +44 (0) 20 8909 9595
Fax: +44 (0) 20 8909 2233
[email protected]
Copyright notice
This product data sheet is the original work and copyrighted property of Radiometrix Ltd. Reproduction in whole or
in part must give clear acknowledgement to the copyright owner.
Limitation of liability
The information furnished by Radiometrix Ltd is believed to be accurate and reliable. Radiometrix Ltd reserves the
right to make changes or improvements in the design, specification or manufacture of its subassembly products
without notice. Radiometrix Ltd does not assume any liability arising from the application or use of any product or
circuit described herein, nor for any infringements of patents or other rights of third parties which may result from
the use of its products. This data sheet neither states nor implies warranty of any kind, including fitness for any
particular application. These radio devices may be subject to radio interference and may not function as intended if
interference is present. We do NOT recommend their use for life critical applications.
The Intrastat commodity code for all our modules is: 8542 6000.
R&TTE Directive
After 7 April 2001 the manufacturer can only place finished product on the market under the provisions of the
R&TTE Directive. Equipment within the scope of the R&TTE Directive may demonstrate compliance to the
essential requirements specified in Article 3 of the Directive, as appropriate to the particular equipment.
Further details are available on The Office of Communications (Ofcom) web site:
Information Requests
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2a Southwark Bridge Road
London SE1 9HA
Tel: +44 (0)845 456 3000 or 020 7981 3040
Fax: +44 (0)20 7783 4033
[email protected]
European Radiocommunications Office (ERO)
Nansensgade 19
DK 1366 Copenhagen
Tel. +45 33896300
Fax +45 33896330
[email protected]