DEVELOPMENT KIT
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900 MHz Frequency Hopping Spread Spectrum Transceiver
Point-to-Point and Point-to-Multipoint Network Topologies
Transmitter Power Configurable from 1 mW to 1 W
RF Data Rate Configurable from 38.4 to 500 kb/s
Serial Port Rate up to 460.8 kb/s for Streaming Applications
128-Bit AES Encryption
Separate Serial Port for Diagnostics
Analog and Digital I/O for Sensor Applications
FCC and Canadian IC Certified for Unlicensed Operation
DNT900
Low Cost
900 MHz FHSS
Transceiver
Module with
I/O
The DNT900 FHSS transceiver module is a low cost, high-power solution for point-to-
point and point-to-multipoint wireless systems in the 900 MHz ISM band. The RF output
power of the DNT900 can be set from 1 mW to 1 W, and the RF data rate can be set
from 38.4 to 500 kb/s. The DNT900 receiver includes a low-noise preamplifier protected
by two SAW filters, providing an excellent combination of receiver sensitivity and out-of-
band interference rejection. The DNT900 module includes analog, digital and serial I/O,
providing the flexibility and versatility to serve applications ranging from cable replace-
ments to sensor networks. The DNT900 transceiver module is easy to integrate and pro-
vides robust wireless communications up to 40 miles in line-of-sight installations.
DNT900 Absolute Maximum Ratings
Rating
All Input/Output Pins
Non-Operating Ambient Temperature Range
DNT900 Electrical Characteristics
Characteristic
Operating Frequency Range
Hop Dwell Time
Number of RF Channels
Modulation
RF Data Transmission Rates
Receiver Sensitivity:
10
-5
BER @ 38.4 kb/s
10
-5
BER @ 200 kb/s
10
-5
BER @ 500 kb/s
Transmitter RF Output Power Levels
Optimum Antenna Impedance
RF Connection
Network Topologies
Access Schemes
1
-98
1
Sym
Notes
Minimum
902.75
5
Value
-0.5 to +3.3
-40 to +85
Units
V
o
Shown with Shield Removed
C
Typical
Maximum
927.25
200
50
Units
MHz
ms
FSK
38.4, 115.2, 200 and 500
kb/s
-108
dBm
dBm
-94
1, 10, 100, 250, 500, 1000 at 38.4 to 200 kb/s
1, 10, 85 at 500 kb/s
50
DNT900P - U.FL Coaxial Connector
DNT900C - U.FL Connector or PCB Pad
Point-to-Point, Point-to-Multipoint
CSMA and TDMA
dBm
mW
W
www.RFM.com E-mail: info@rfm.com
©2008-2009 by RF Monolithics, Inc.
Page 1 of 7
DNT900 - 06/11/09
DNT900 Electrical Characteristics
Characteristic
Number of Network Nodes:
TDMA Mode
CSMA Mode
ADC Input Range
ADC Input Resolution
ADC Sample Rate
Signal Source Impedance for ADC Reading
PWM (DAC) Output Range
PWM (DAC) Output Resolution
PWM Output Period
Primary Serial Port Baud Rates
Diagnostic Serial Port Baud Rate
Digital I/O:
Logic Low Input Level
Logic High Input Level
Logic Input Internal Pull-up Resistor
Logic Input Internal Pull-down Resistor
Power Supply Voltage Range
Power Supply Voltage Ripple
Peak Transmit Mode Current, 1 W Output
Average Operating Receive Current:
Base
Remote, No Data Transmission
Remote, 9.6 kb/s Continuous Data Stream
Remote, 115.2 kb/s Continuous Data Stream
Sleep Current
DNT900C Mounting
DNT900P Mounting
Operating Temperature Range
Operating Relative Humidity Range, Non-condensing
Notes:
1. The DNT900 achieves regulatory certification under FHSS rules at air data rates of 38.4, 115.2 and 200 kb/s. At 500 kb/s,
the DNT900 achieves regulatory certification under “digital modulation” or DTS rules. The DNT900 still employs frequency
hopping at 500 kb/s to mitigate the effects of interference and multipath fading, but hops on fewer, more widely spaced
frequencies than at lower data rates. Maximum RF power at 500 kb/s is 85 mW.
2. PWM is set with an 8-bit value. DAC resolution is limited to 7 bits by residual ripple at output of low-pass filter.
3. Maximum sleep current occurs at +85
o
C.
-40
10
3
105
35
40
53
50
Reflow Soldering
Socket
85
90
o
Sym
Notes
Minimum
Typical
Maximum
Units
16
unlimited
0
10
10
10
0
2
20
1.2, 2.4, 4.8, 9.6, 19.2, 28.8, 38.4, 57.6, 76.8,
115.2, 230.4, 460.8
3.3
V
bits
ms
KW
V
bits
µs
kb/s
kb/s
3.3
8
38.4
-0.5
2
50
50
V
CC
+3.3
0.8
3.3
200
180
+5.5
10
1200
V
V
KW
KW
Vdc
mV
P-P
mA
mA
mA
mA
mA
225
µA
C
%
CAUTION: Electrostatic Sensitive Device. Observe precautions when handling.
www.RFM.com E-mail: info@rfm.com
©2008-2009 by RF Monolithics, Inc.
Page 2 of 7
DNT900 - 06/11/09
D N T 9 0 0 B lo c k D ia g r a m
P K T _ D E T
1
2
3
4
5
6
7
8
9
1 0
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
2 0
F ilte r
F ilte r
C L K
S I
S O
P W R
R S V D
A D C _ R E F
R S S I
G P IO 0
G P IO 1
G P IO 2
G P IO 3
P W M 0
P W M 1
S L E E P
A D C 2
A D C 1
A D C 0
R S V D
D IA G _ T X
D IA G _ R X
/C F G
V C C
G N D
3 .3 V
M ic r o c o n tr o lle r
C S n
IN T
P K T D E T
R F
T r a n s c e iv e r
4 3
T /R
T /R
F ilte r
4 2
4 1
P R E
R F IO
R e g
3 .6 V
R e g
2 1
2 2
2 3
2 4
2 5
2 6
2 7
2 8
2 9
3 0
3 1
3 2
3 3
3 4
3 5
3 6
3 7
3 8
3 9
4 0
/H O S T _ R T S
R S V D
R S V D
G N D
R S V D
R S V D
R A D IO _ T X D
G P IO 4
A C T
/D C D
G N D
R S V D
R S V D
/H O S T _ C T S
G P IO 5
/R E S E T
R S V D
V M O D
R A D IO _ R X D
R S V D
Figure 1
DNT900 Hardware
The major components of the DNT900 include a 900 MHz
FHSS transceiver and a low current 32-bit microcontroller.
The DNT900 operates in the 902 to 928 MHz ISM band.
There are a number of selectable hopping patterns includ-
ing patterns compatible with frequency allocations in the
US, Canada, South America, Israel, Australia and New
Zealand. The DNT900 has six selectable RF output power
levels: 1, 10, 100, 250 and 500 mW plus 1 W. Also, there
are four selectable RF transmission rates: 38.4, 115.2,
200 and 500 kb/s.
The DNT900 includes a low-noise preamplifier protected
by two SAW filters, providing an excellent blend of receiver
sensitivity and out-of-band interference rejection that is
especially important in outdoor applications.
The DNT900 provides a variety of hardware interfaces.
There are two UART serial ports, one for data and a sec-
ond for diagnostics. The data port supports standard baud
rates from 1.2 to 460.8 kb/s and the diagnostic port is fixed
at 38.4 kb/s. Also included are three 10-bit ADC inputs,
two 8-bit PWM outputs, and six general-purpose digital I/O
ports. Four of the digital I/O ports support an optional inter-
rupt-from-sleep mode when configured as inputs. The
radio is available in two mounting configurations. The
DNT900C is designed for solder reflow mounting. The
DNT900P is designed for plug-in connector mounting.
DNT900 Firmware
The DNT900 firmware can operate using either TDMA or
CSMA channel access modes. TDMA supports up to 16
remotes with rapid, deterministic channel latency. CSMA
provides carrier-sense managed channel access for an
unlimited number of low-traffic remotes. DNT900 firmware
will operate “out of the box” using its point-to-point trans-
parent serial mode, with point-to-multipoint supported by
the firmware’s protocol mode. DNT900 firmware provides
the user with a rich set of configuration options including a
choice of hopping patterns, hopping dwell times, RF data
transmission rates, serial port data rates and RF power
levels, plus configurable analog and digital I/O lines. Data
integrity is protected by 24-bit error detection, with optional
ACK and automatic transmission retries or redundant
transmissions. 128-bit AES encryption provides a high
level of data security for sensitive applications. Sensor net-
works can take advantage of timer or event-based data
reporting and remote node sleep cycling for extended
battery life.
www.RFM.com E-mail: info@rfm.com
©2008-2009 by RF Monolithics, Inc.
Page 3 of 7
DNT900 - 06/11/09
DNT900 I/O Descriptions
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Name
PKT_DET
RSVD
ADC_REF
RSVD
GPIO0
GPIO1
GPIO2
GPIO3
PWM0
PWM1
SLEEP/DTR
ADC2
ADC1
ADC0
RSVD
DIAG_TX
DIAG_RX
/CFG
VCC
GND
GND
GPIO4
GPIO5
GND
ACT
/DCD
RSVD
RSVD
RSVD
I/O
O
-
I
-
I/O
I/O
I/O
I/O
O
O
I
I
I
I
-
O
I
I
I
-
-
I/O
I/O
-
O
O
-
-
-
Description
Packet detect output. Signal switches logic high at the end of the start-of-packet symbol and switches logic
low at the end of the end-of-packet symbol on both received and transmitted packets. PKT_DET provides a
timing reference for external use in network timing evaluations, etc.
Reserved pin. Leave unconnected.
ADC supply and external full scale reference voltage input. Voltage range is 2.4 to 3.3 Vdc. Connect pad 34 to
this input to reference the ADC full scale reading to the module’s 3.3 V regulated supply.
Reserved pin. Leave unconnected.
Configurable digital I/O port 0. When configured as an input, an internal pull-up resistor can be selected and
interrupt from sleep can be invoked. When configured as an output, the power-on state is configurable. The
sleep mode direction and state are also configurable.
Configurable digital I/O port 1. Same configuration options as GPIO0.
Configurable digital I/O port 2. Same configuration options as GPIO0.
Configurable digital I/O port 3. Same configuration options as GPIO0.
8-bit pulse-width modulated output 0 with internal low-pass filter. Filter is first-order, with a159 Hz 3 dB
bandwidth.
8-bit pulse-width modulated output 1 with internal low-pass filter. Filter is first-order, with a 159 Hz 3 dB
bandwidth.
Active high module sleep input (active low DTR). When switched low after sleep, the module executes a
power on-reset. Usually connected to host DTR. Connect to ground if SLEEP/DTR function not used.
10-bit ADC input 0. Full scale reading is referenced to the ADC_REF input.
10-bit ADC input 1. Full scale reading is referenced to the ADC_REF input.
10-bit ADC input 2. Full scale reading is referenced to the ADC_REF input.
Reserved pad. Leave unconnected.
Diagnostic UART transmitter output.
Diagnostic UART receiver input.
Protocol selection input. Leave unconnected when using software commands to select transparent/protocol
mode (default is transparent mode). Logic low selects protocol mode, logic high selects transparent mode.
Power supply input, +3.3 to +5.5 Vdc.
Power supply and signal ground. Connect to the host circuit board ground.
Power supply and signal ground. Connect to the host circuit board ground.
Configurable digital I/O port 4. When configured as an input, an internal pull-up resistor can be selected.
When configured as an output, the power-on state is configurable.
Configurable digital I/O port 5. Same configuration options as GPIO4.
Logic ground.
Data activity output, logic high when data is being transmitted or received.
Default functionality is data carrier detect output, logic low on a remote when the module is locked to FHSS
hopping pattern and logic low on a base station when at least one remote is connected to it. The sleep mode
state of this pin and /HOST_CTS is jointly configurable.
Reserved pin. Leave unconnected.
Reserved pin. Leave unconnected.
Reserved pin. Leave unconnected.
www.RFM.com E-mail: info@rfm.com
©2008-2009 by RF Monolithics, Inc.
Page 4 of 7
DNT900 - 06/11/09
Pin
30
31
32
33
Name
/HOST_RTS
RADIO_TXD
RADIO_RXD
/HOST_CTS
I/O
I
O
I
O
Description
UART flow control input. The host sets this line low to allow data to flow from the DNT900 on the RADIO_TXD
pin. When the host sets this line high, the DNT900 will stop sending data to the host.
UART transmitter output. The DNT900 sends serial data to the host on this pin. The sleep mode state of this
pin is configurable.
UART receiver input. The DNT900 receives serial data from the host on this pin.
UART flow control output. The DNT900 sets this line low to indicate it is ready to accept data from the host on
the RADIO_RXD input. When the DNT900 sets this line high, the host must stop sending data. The sleep
mode state of this pin and /DCD is jointly configurable.
Module’s +3.3 V regulated supply. Connect to pad 3 to support 3.3 V full scale and/or ratiometric ADC read-
ings, etc. Current drain on this output should be no greater than 5 mA.
Reserved pin. Leave unconnected.
Reserved pin. Leave unconnected.
Reserved pin. Leave unconnected.
Reserved pin. Leave unconnected.
Active low module hardware reset.
Reserved pin. Leave unconnected.
RF ground for the DNT900C only. Connect to the host circuit board ground plane.
Alternate RF port for the DNT900C only. The antenna can be connected to this port with a 50 ohm stripline or
coaxial cable. Leave unconnected when using the U.FL connector.
RF ground for the DNT900C only. Connect to the host circuit board ground plane.
34
35
36
37
38
39
40
41
42
43
VMOD
RSVD
RSVD
RSVD
RSVD
/RESET
RSVD
GND
RFIO
GND
O
-
-
-
-
I
-
-
I/O
-
D N T 9 0 0 C O u tlin e a n d M o u n tin g D im e n s io n s
2 .0 1 0
0 .0 4 0
0 .0 4 0
0 .1 0 0
1
1 .2 6 0
0 .5 9 5
4 0
0 .1 8 0
D im e n s io n s in in c h e s
Figure 2
www.RFM.com E-mail: info@rfm.com
©2008-2009 by RF Monolithics, Inc.
Page 5 of 7
DNT900 - 06/11/09
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