Murata Electronics North America DNT90 manual pt a
Preliminary
DNT90 Series
900 MHz Spread Spectrum
Wireless Transceivers
Integration Guide
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Preliminary
Important Regulatory Information
RFM Product FCC ID: HSW-DNT90
IC 4492A-DNT90
Note: This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses
and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct the interference by one or more
of the following measures:
1) Re-orientate or relocate the receiving antenna,
2) Increase the separation between the equipment and the radiator,
3) Connect the equipment to an outlet on a circuit different from that to which the receiver is connected,
4) Consult the dealer or an experienced radio/TV technician for help.
FCC Antenna Gain Restriction and MPE Statement:
The DNT90 has been designed to operate with any dipole antenna of up to 5.1 dBi of gain, any Yagi of up
to 6.1 dBi gain, or chip antenna JTI-0915AT43A0026.
The antenna(s) used for this transmitter must be installed to provide a separation distance of at least
20 cm from all persons and must not be co-located or operating in conjunction with any other antenna or
transmitter.
Industry Canada Specific Statements:
The term “IC:” before the radio certification number only signifies that Industry Canada technical specifications were met.
This Class B digital apparatus meets all requirements of the Canadian Interference Causing Equipment
Regulations. Operation is subject to the following two conditions: (1) this device may not cause harmful
interference, and (2) this device must accept any interference received, including interference that may
cause undesired operation.
Cet appareillage numérique de la classe B répond à toutes les exigences de l'interférence canadienne
causant des règlements d'équipement. L'opération est sujette aux deux conditions suivantes: (1) ce dispositif peut ne pas causer l'interférence nocive, et (2) ce dispositif doit accepter n'importe quelle interférence reçue, y compris l'interférence qui peut causer l'opération peu désirée.
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Preliminary
IC RSS-210 Detachable Antenna Gain Restriction:
This device has been designed to operate with the antennas listed below, and having a maximum gain of
6.1 dB. Antennas not included in this list or having a gain greater than 6.1 dB are strictly prohibited for
use with this device. The required antenna impedance is 50 ohms:
RFM RWA092R Omnidirectional Dipole Antenna, 2 dBi
RFM OMNI095 Omnidirectional Dipole Antenna, 5 dBi
RFM YAGI099 Directional Antenna, 6.1 dBi
Chip Antenna JTI-0915AT43A0026, -1 dBi
To reduce potential radio interference to other users, the antenna type and its gain should be so chosen
that the equivalent isotropically radiated power (e.i.r.p.) is not more than that permitted for successful
communication.
See Section 6.8 of this manual for regulatory notices and labeling requirements. Changes or modifications to a DNT90 not expressly approved by RFM may void the user’s authority to operate the module.
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Preliminary
Table of Contents
1.0 DNT90 Introduction .......................................................................................................................... 6
1.1 Why Spread Spectrum? ............................................................................................................ 6
1.2 Frequency Hopping versus Direct Sequence ............................................................................ 7
2.0 DNT90 System Overview ................................................................................................................. 8
2.1 Point-to-Point Systems .............................................................................................................. 8
2.2 Point-to-Multipoint Systems ....................................................................................................... 9
2.3 Store-and-Forward Systems ...................................................................................................... 9
2.4 RF Channel Access ................................................................................................................. 10
2.5 DNT90 Addressing .................................................................................................................. 11
2.6 Network Linking and Slot Registration .................................................................................... 11
2.6.1 Fast Linking Techniques ................................................................................................... 12
2.7 Transparent and Protocol-formatted Serial Data ..................................................................... 12
3.0 DNT90 Application Interfaces ........................................................................................................ 13
3.1 Serial Ports .............................................................................................................................. 13
3.2 SPI Port ................................................................................................................................... 13
3.3 Digital I/O ................................................................................................................................. 16
3.4 Analog I/O ................................................................................................................................ 16
3.5 I/O Event Reporting and I/O Binding ....................................................................................... 17
4.0 DNT90 System Configuration ........................................................................................................ 18
4.1 Configuration Parameters ........................................................................................................ 18
4.2 Configuring a Basic Point-to-Point System ............................................................................. 18
4.3 Configuring a Basic Point-to-Multipoint System ...................................................................... 18
4.4 Configuring a Customized Point-to-Point or Point-to-Multipoint System ................................. 19
4.5 Configuring a Store-and-Forward System ............................................................................... 20
4.6 Slot Buffer Sizes, Number of Slots, Messages per Hop and Hop Duration ............................ 21
5.0 DNT90 Application Interface Configuration.................................................................................... 23
5.1 Configuring the Serial Port ...................................................................................................... 23
5.2 Configuring the SPI Port .......................................................................................................... 24
5.3 Configuring Digital I/O ............................................................................................................. 24
5.4 Configuring Analog I/O ............................................................................................................ 24
5.5 Configuring I/O Event Reporting and I/O Binding .................................................................... 25
5.6 Configuring Sleep Mode .......................................................................................................... 26
6.0 DNT90 Hardware ........................................................................................................................... 27
6.1 Electrical Specifications ........................................................................................................... 28
6.2 Module Pin Out ........................................................................................................................ 29
6.3 Antenna Connector .................................................................................................................. 30
6.4 Power Supply and Input Voltages ........................................................................................... 31
6.5 ESD and Transient Protection ................................................................................................. 31
6.6 Interfacing to 5 V Logic Systems ............................................................................................. 31
6.7 Mounting and Enclosures ........................................................................................................ 31
6.8 Labeling and Notices ............................................................................................................... 32
7.0 DNT90 Protocol-formatted Messages ............................................................................................ 33
7.1 Protocol Formats ..................................................................................................................... 33
7.2 Message Types ....................................................................................................................... 33
7.3 Message Format Details .......................................................................................................... 34
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Preliminary
7.4 Configuration Parameter Registers ......................................................................................... 41
7.4.1 Bank 0x00 - Transceiver Setup ......................................................................................... 41
7.4.2 Bank 0x01 - System Settings ............................................................................................ 44
7.4.3 Bank 0x02 - Status Parameters ........................................................................................ 45
7.4.4 Bank 0x03 - Serial and SPI Settings ................................................................................. 47
7.4.5 Bank 0x04 - Host Protocol Settings .................................................................................. 48
7.4.6 Bank 0x05 - I/O Parameters ............................................................................................. 49
7.4.7 Bank 0x06 - I/O Settings ................................................................................................... 50
7.4.8 Bank 0x0FF - Special Functions ....................................................................................... 55
7.5 Protocol-formatted Message Examples .................................................................................. 56
7.5. 1 Data Message ................................................................................................................... 56
7.5.2 Configuration Message ..................................................................................................... 57
7.5.3 Sensor Message ............................................................................................................... 57
7.5.4 Event Message ................................................................................................................. 58
8.0 DNT90DK Developer’s Kit ............................................................................................................. 59
8.1 DNT90DK Kit Contents ............................................................................................................ 59
8.2 Additional Items Needed ......................................................................................................... 59
8.3 Developer’s Kit Default Operating Configuration ..................................................................... 59
8.4 Developer’s Kit Hardware Assembly ....................................................................................... 60
8.5 DNT90 Utility Program ............................................................................................................. 61
8.6 Initial Kit Operation .................................................................................................................. 62
8.6.1 Serial Communication and Radio Configuration ............................................................... 65
8.7 DNT90 Interface Board Features ............................................................................................ 71
9.0 Troubleshooting ............................................................................................................................. 73
9.1 Diagnostic Port Commands ..................................................................................................... 73
10.0 Appendices .................................................................................................................................... 74
10.1 Ordering Information ................................................................................................................ 74
10.2 Technical Support .................................................................................................................... 74
10.3 DNT90 Mechanical Specifications ........................................................................................... 75
10.4 DNT90 Development Board Schematic .................................................................................. 77
11.0 Warranty ......................................................................................................................................... 80
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Preliminary
1.0 DNT90 Introduction
DNT90 transceivers provide highly-reliable wireless connectivity for point-to-point, point-to-multipoint and
store-and-forward radio applications. Frequency hopping spread spectrum (FHSS) technology ensures
maximum resistance to multipath fading and robustness in the presence of interfering signals, while operation in the 900 MHz ISM band allows license-free use in North America, South America and Australia.
The DNT90 supports serial data rates for host communications from 1.2 to 250 kbps, plus three SPI data
rates from 125 to 500 kbps. On-board data buffering plus an error-correcting radio protocol provide
smooth data flow and simplify the task of integration with existing applications. Key DNT90 features include:
Multipath fading resistant frequency hopping
technology with up to 52 frequency channels, 902.76 to 927.24 MHz
Receiver protected by low-loss SAW filter,
providing excellent receiver sensitivity and
interference rejection important in outdoor
applications
Ad Hoc TDMA operating mode supports a
large number of remotes with low latency
for burst data streaming
Simple interface handles both data and con-
trol at up to 250 kbps on the serial port or
500 kbps on the SPI port
Support for point-to-point, point-to-multipoint,
peer-to-peer and store & forward networks
FCC 15.247 and IC RSS-210 certified for
license-free operation
Five mile plus range with omnidirectional
antennas (antenna height dependent)
Transparent ARQ protocol with data
buffering ensures data integrity
Analog and Digital I/O supports wireless
sensing applications
AES encryption provides protection from
eavesdropping
Nonvolatile memory stores DNT90 configura-
tion when powered off
Selectable +16 dBm (40 mW) or +22 dBm
(158 mW) transmit power levels
Automatic I/O event reporting mode simplifies
application development
I/O binding mode provides wireless transmis-
sion of analog and digital values
1.1 Why Spread Spectrum?
A radio channel can be very hostile, corrupted by noise, path loss and interfering transmissions from other radios. Even in an interference-free environment, radio performance faces serious degradation from a
phenomenon known as multipath fading. Multipath fading results when two or more reflected rays of the
transmitted signal arrive at the receiving antenna with opposing phases, thereby partially or completely
canceling the signal. This problem is particularly prevalent in indoor installations. In the frequency domain, a multipath fade can be described as a frequency-selective notch that shifts in location and intensity
over time as reflections change due to motion of the radio or objects within its range. At any given time,
multipath fades will typically occupy 1% - 2% of the band. From a probabilistic viewpoint, a conventional
radio system faces a 1% - 2% chance of signal impairment at any given time due to multipath fading.
Spread spectrum reduces the vulnerability of a radio system to both multipath fading and jammers by distributing the transmitted signal over a larger region of the frequency band than would otherwise be necessary to send the information. This allows the signal to be reconstructed even though part of it may be lost
or corrupted in transmission.
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Narrow-band versus spread spectrum transmission
Figure 1.1.1
1.2 Frequency Hopping versus Direct Sequence
The two primary approaches to spread spectrum are direct sequence spread spectrum (DSSS) and frequency hopping spread spectrum (FHSS), either of which can generally be adapted to a given application. Direct sequence spread spectrum is produced by multiplying the transmitted data stream by a much
faster, noise-like repeating pattern. The ratio by which this modulating pattern exceeds the bit rate of the
base-band data is called the processing gain, and is equal to the amount of rejection the system affords
against narrow-band interference from multipath and jammers. Transmitting the data signal as usual, but
varying the carrier frequency rapidly according to a pseudo-random pattern over a broad range of channels produces a frequency hopping spectrum system.
Forms of spread spectrum - direct sequence and frequency hopping
Figure 1.1.2
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One disadvantage of direct sequence systems is that due to design issues related to broadband transmitters and receivers, they generally employ only a minimal amount of spreading, often no more than the
minimum required by the regulating agencies. For this reason, the ability of DSSS systems to overcome
fading and in-band jammers is relatively weak. By contrast, FHSS systems are capable of hopping
throughout the entire band, statistically reducing the chances that a transmission will be affected by fading or interference. This means that a FHSS system will degrade gracefully as the band gets noisier,
while a DSSS system may exhibit uneven coverage or work well until a certain point and then give out
completely.
Because it offers greater immunity to interfering signals, FHSS is often the preferred choice for co-located
systems. Since direct sequence signals are very wide, they can offer only a few non-overlapping channels, whereas multiple hoppers can interleave, minimizing interference. Frequency hopping systems do
carry some disadvantages, in that they require an initial acquisition period during which the receiver must
lock on to the moving carrier of the transmitter before any data can be sent, which typically takes several
seconds. In summary, frequency hopping systems generally feature greater coverage and channel utilization than comparable direct sequence systems. Of course, other implementation factors such as size,
cost, power consumption and ease of implementation must also be considered before a final radio design
choice can be made.
2.0 DNT90 System Overview
A DNT90 radio can be configured to operate in one of three modes - base, remote or router. A base controls a DNT90 system, and interfaces to an application host such as a PC or Internet gateway. A remote
functions to transmit or receive serial, digital (state) and analog data. A router alternates between functioning as a remote on one hop and a network base on the next hop. When acting as a remote, the router
stores messages it receives from its parent, and then repeats the messages to its child radios when acting as a network base. Likewise, a router will store messages received from its child radios when acting
as a base, and repeat them to its parent when acting as a remote. Any message addressed directly to a
router is processed by the router rather than being repeated.
2.1 Point-to-Point Systems
A DNT90 system contains at least one network. The simplest DNT90 topology is a point-to-point system,
as shown in Figure 2.1.1. This system consists of a base and one remote forming a single network. Pointto-point systems are often used to replace wired serial connections. Point-to-point systems are also used
to transmit switch positions or analog signals from one location to another.
Figure 2.1.1
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2.2 Point-to-Multipoint Systems
Figure 2.2.1 shows the topology of a point-to-multipoint (star) system, which consists of a base and more
than one remote in a single network. Point-to-multipoint systems are typically used for data, sensor and
alarm systems. While most traffic in a point-to-multipoint system is between the base and the remotes,
DNT90 technology also allows for peer-to-peer communication from one remote to another.
Figure 2.2.1
2.3 Store-and-Forward Systems
Figure 2.3.1 shows the topology of a store-and-forward system, which consists of a base, one or more
routers, one or more remotes, and two or more networks. Networks in a store-and-forward system form
around the base and each router. The base and the routers are referred to as the parents of the networks
they form. The rest of the radios in each network are referred to as child radios. Note that a router is a
child of the base or another router while being the parent of its own network. Each network parent transmits beacons to allow child radios to synchronize with its hopping pattern and join its network. Different
frequency hopping patterns are used by the parent radios in a system, minimizing interference between
networks.
Store-and-forward systems are used to cover larger areas than is possible with point-to-point or point tomultipoint systems. The trade-off in store-and-forward systems is longer delivery times due to receiving
and retransmitting a message several times. Store-and-forward systems are especially useful in applications such as agriculture where data is only collected periodically.
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2.4 RF Channel Access
The time a DNT90 network stays on each frequency in its hopping pattern is called the hop duration or
dwell time, which can be configured from 8 to 100 ms. Radio communication during each dwell is orga-
nized as a time division multiple access (TDMA) frame. A DNT90 frame begins with a base-mode beacon,
followed by 1 to 8 time slots used by the network children to transmit to their parent, as shown in Figure
2.4.1. A base-mode beacon can include up to 8 messages addressed to one or more child radios. The
number of slots is chosen accommodate the number of children that need to send messages each hop.
E x a m p l e D N T 9 0 C o m m u n i c a t i o n F r a m e
Figure 2.3.1
S y s t e m / N e t w o r k
C o n t r o l
B a s e - M o d e
B e a c o n
M e s s a g e s t o
N e t w o r k C h i l d r e n
O p e n
S l o t
Figure 2.4.1
Each beacon includes the status of all slots - either registered (assigned) or open. When a child radio has
information to transmit to its parent, it randomly selects one of the open slots and transmits all or the first
part of its data. If the parent successfully receives the transmission, it includes the child’s MAC address in
the next beacon. This signals the child radio that the slot is temporarily registered to it, allowing the child
to efficiently stream any remaining data to the base hop-by-hop until it is all sent.
If a child radio does not see its address in the next beacon following its transmission, it again randomly
selects an open slot and retransmits its data. During times when there are no open slots, a child radio
M e s s a g e s
f r o m C h i l d
A s s i g n e d
S l o t
O p e n
S l o t
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keeps its data queued and continues to look for an open slot in each beacon until at least one slot becomes available. The access method the DNT90 uses is referred to as Ad Hoc TDMA.
2.5 DNT90 Addressing
Each DNT90 has a unique MAC address. The MAC address can be read or bar-code scanned from the
label on top of each radio. A DNT90 radio in any mode (base/router/remote) can be addressed using its
MAC address. A DNT90 base can be addressed using either its MAC address or address 0x000000. A
DNT90 can send a message to all other DNT90’s in its system by using the broadcast address
0xFFFFFF.
The base and all routers (parents) hold base-mode network IDs, which are transmitted in every beacon.
All routers and remotes hold parent network IDs and optionally alternate parent network IDs to compare
against the base-mode network IDs in the beacons they receive. A child router or remote is allowed to
join a parent if its parent network ID or alternate parent network ID matches the parent’s base-mode net-
work ID, or with any parent when its parent network ID is set to 0xFF (wildcard).
In a point-to-point or point-to-multipoint system, the default base-mode network ID of 0xFF (wildcard) can
be used. In a store-and-forward system, however, the base-mode network IDs of all routers must be set
to different values between 0x00 to 0x3F. If the base-mode network ID of 0x00 is assigned to a router, the
base must be assigned an unused base-mode network ID between 0x01 and 0x3F. Leaving all parent
network IDs in a store-and-forward system set to the default value of 0xFF allows networks to automatically form, and self-repair if a parent router fails. Enabling the alternate parent network ID also provides
self-repairing message routing.
All DNT90 radios hold a system ID that can be used to distinguish systems that physically overlap. In a
DNT90 system, the system ID must be different from those used by overlapping systems to provide message filtering. Also, using different base-mode network IDs for all networks in overlapping systems helps
reduce hopping pattern collisions.
The store-and-forward path between the base and any other radio in a system can be determined by
reading the radio’s ParentMacAddress parameter. If this address is not the base, then reading the
ParentMacAddress parameter of its parent, grandparent, etc., in succession reveals the complete path to
the base. Path determination is useful in optimizing and troubleshooting systems during commissioning
and maintenance.
2.6 Network Linking and Slot Registration
When first turned on, a DNT90 router or remote rapidly scans all frequency channels in its operating band
to acquire synchronization and link to a parent based on a system ID match plus a base-mode network ID
to parent network ID/alternate parent network ID match (or by using a wildcard (0xFF) parent network ID).
In addition to the slot status and the MAC addresses of child radios holding slot registrations, each basemode beacon includes one of a number of cycled control parameters. The cycled parameters are collect-
ed by child radios, allowing them to register with a parent, and to later follow any control parameter
changes. When a router or remote has collected a full set of cycled parameters, it can issue an optional
initial heartbeat message and then optional periodic heartbeat messages which allow an application to
maintain the status of all routers and remotes in its DNT90 system.
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When a router/remote has data to send to its parent, it picks an open slot at random and transmits. It then
looks for its MAC address in the next beacon. If its MAC address is present in the beacon, it is temporarily
registered to the slot and continues to use it until all current data is sent, or its MAC address drops off the
beacon.
2.6.1 Fast Linking Techniques
Minimizing linking time is important in certain applications. For example, when the remotes in a system
are battery powered and wake from sleep occasionally to report data. Minimizing linking time increases
the operating battery life of the remotes. The basic techniques to reduce linking time include:
- use no more hop duration (dwell time) than necessary
- use no more slots than necessary for the application
- use no larger base slot size (BSS) than necessary
- transmit only dynamic cycle parameters once system nodes have static parameters
Once a complete set of cycled parameters has been receive by all routers and remotes in a system and
stored in memory, it is not necessary to send all of them again during a re-linking, as long as the system
configuration remains stable.
As discussed in Section 7.4.1, the base station in a DNT90 system can be configured to transmit “fast
beacons” for a period of time when powered up, reset or triggered with the FastBeaconTrig parameter.
Fast beacons are sent using a very short hop dwell time, facilitating fast system linking.
2.7 Transparent and Protocol-formatted Serial Data
A DNT90 remote can directly input and output data bytes and data strings on its serial port. This is referred to as transparent serial port operation. In a point-to-point system, the base can also be configured
for transparent serial port operation.
In all other cases, serial data must be protocol formatted:
- configuration commands and replies
- I/O event messages
Protocol-formatted messages are discussed in detail in Section 7. Briefly, protocol-formatted messages
include a start-of-messages character, message length and message type information, the destination
address of the message, and the message payload.
Transparent data is routed using a remote transparent destination address. In a remote, this address defaults to the base, 0x000000, and in the base this address defaults to broadcast, 0xFFFFFF. These defaults can be overridden with specific radio addresses. For example, it is possible to set up transparent
peer-to-peer routing between two remotes in a point-to-multipoint or store-and-forward system by loading
specific MAC addresses in each radio’s remote transparent destination address.
- announcement messages including heartbeats
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