Murata Electronics North America DNT2400 2.4GHz Transceiver Module User Manual 09 0199 Exhibit Cover

Murata Electronics North America 2.4GHz Transceiver Module 09 0199 Exhibit Cover

UserManual.wiki >

Murata Electronics North America >

DNT2400 User Manual HTML Version

Manual

5015 B.U. Bowman Drive Buford, GA 30518 USA Voice: 770-831-8048 Fax: 770-831-8598

Certification Exhibit

FCC ID: HSW-DNT2400

IC: 4492A-DNT2400

FCC Rule Part: 15.247

IC Radio Standards Specification: RSS-210

ACS Report Number 09-0199-15C

Manufacturer: RFM / Cirronet Inc.

Model(s): DNT2400C, DNT2400P

Manual

www.RFM.com Technical support +1.678.684.2000 Page 1 of 81

DNT2400 Series

2.4 GHz Spread Spectrum

Wireless Transceivers

Integration Guide

www.RFM.com Technical support +1.678.684.2000 Page 2 of 81

Important Regulatory Information

RFM Product FCC ID: HSW-DNT2400

IC 4492A-DNT2400

Note: This unit 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 when the equipment is operated in a commercial environment. This equipment generates,

uses, and can radiate radio frequency energy and, if not installed and used in accordance with the in-

struction manual, may cause harmful interference to radio communications. Operation of this equipment

in a residential area is likely to cause harmful interference in which case the user will be required to

correct the interference at their expense.

FCC Antenna Gain Restriction:

The DNT2400 has been designed to operate with any dipole antenna of up to 9 dBi of gain, or any patch

of up to 6 dBi gain.

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.

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

9 dB. Antennas not included in this list or having a gain greater than 9 dB are strictly prohibited for use

with this device. The required antenna impedance is 50 ohms:

RFM OMNI249 Omnidirectional Dipole Antenna, 9 dB

RFM PA2400 Patch Antenna, 6 dB

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 3.10 of this manual for regulatory notices and labeling requirements. Changes or modifica-

tions to a DNT2400 not expressly approved by RFM may void the user’s authority to operate the module.

www.RFM.com Technical support +1.678.684.2000 Page 3 of 81

Table of Contents

1.0 Introduction ......................................................................................................................................... 5

1.1 Why Spread Spectrum?................................................................................................................... 5

1.2 Frequency Hopping versus Direct Sequence..................................................................................6

2.0 DNT2400 Radio Operation ................................................................................................................. 7

2.1 Network Synchronization and Registration...................................................................................... 7

2.2 Authentication .................................................................................................................................. 8

2.3 Transparent and Protocol Serial Port Modes .................................................................................. 9

2.4 RF Data Communications................................................................................................................ 9

2.5 RF Transmission Error Control........................................................................................................ 9

2.6 Transmitter Power Management ................................................................................................... 10

2.7 Network Configurations ................................................................................................................. 10

2.7.1 Point-to-Point Network Operation............................................................................................... 10

2.7.2 Point-to-Multipoint Network Operation ....................................................................................... 11

2.7.3 Peer-to-Peer Network Operation................................................................................................ 11

2.8 Full-Duplex Serial Data Communications...................................................................................... 11

2.9 Channel Access............................................................................................................................. 12

2.9.1 Polling Mode............................................................................................................................... 12

2.9.2 CSMA Mode ............................................................................................................................... 13

2.9.3 TDMA Modes.............................................................................................................................. 14

2.10 Transmission Configuration Planning............................................................................................ 14

2.10.1 TDMA Throughput...................................................................................................................... 15

2.10.2 Polling Throughput ..................................................................................................................... 15

2.10.3 CSMA Throughput...................................................................................................................... 16

2.10.4 Latency ....................................................................................................................................... 16

2.10.5 Configuration Validation ............................................................................................................. 17

2.11 Serial Port Operation .................................................................................................................. 19

2.12 Sleep Modes.................................................................................................................................. 20

2.13 Encryption...................................................................................................................................... 22

2.14 Synchronizing Co-located Bases................................................................................................... 22

3.0 DNT2400 Hardware .......................................................................................................................... 24

3.1 Specifications................................................................................................................................. 25

3.2 Module Interface ............................................................................................................................ 26

3.3 DNT2400C RFIO Stripline ............................................................................................................. 27

3.4 DNT2400 Antenna Connector ....................................................................................................... 28

3.5 Input Voltages................................................................................................................................ 28

3.6 ESD and Transient Protection ....................................................................................................... 28

3.7 Interfacing to 5 V Logic Systems ................................................................................................... 29

3.8 Power-On Reset Requirements..................................................................................................... 29

3.9 Mounting and Enclosures .............................................................................................................. 29

3.10 Labeling and Notices ..................................................................................................................... 29

4.0 Protocol Messages............................................................................................................................ 31

4.1 Protocol Message Formats............................................................................................................ 31

4.1.1 Message Types .......................................................................................................................... 31

4.1.2 Message Format Details............................................................................................................. 32

4.1.3 /CFG Select Pin.......................................................................................................................... 33

4.1.4 Flow Control ............................................................................................................................... 33

4.1.5 Protocol Mode Data Message Example ..................................................................................... 34

www.RFM.com Technical support +1.678.684.2000 Page 4 of 81

4.2 Configuration Registers ................................................................................................................. 34

4.2.1 Bank 0 - Transceiver Setup........................................................................................................ 34

4.2.2 Bank 1 - System Settings ........................................................................................................... 36

4.2.3 Bank 2 - Status Registers........................................................................................................... 39

4.2.4 Bank 3 - Serial ............................................................................................................................ 41

4.2.5 Bank 4 - Host Protocol Settings ................................................................................................. 42

4.2.6 Bank 5 - I/O Peripheral Registers............................................................................................... 43

4.2.7 Bank 6 - I/O Setup ...................................................................................................................... 43

4.2.8 Bank 7 - Authentication List........................................................................................................ 45

4.2.9 Bank FF - Special Functions ...................................................................................................... 46

4.2.10 Protocol Mode Configuration Message Example ....................................................................... 46

4.2.11 Protocol Mode Sensor Message Example ................................................................................. 47

4.2.12 Protocol Mode Event Message Example ................................................................................... 47

5.0 DNT2400DK Developer’s Kit ............................................................................................................ 48

5.1 DNT2400DK Kit Contents.............................................................................................................. 48

5.2 Additional Items Needed................................................................................................................ 48

5.3 Developer’s Kit Operational Notes................................................................................................. 48

5.4 Developer’s Kit Default Operating Configuration........................................................................... 49

5.5 Developer’s Kit Hardware Assembly ............................................................................................. 49

5.6 DNT2400 Demo Utility Program .................................................................................................... 51

5.6.1 Initial Kit Operation ..................................................................................................................... 52

5.6.2 Serial Communication and Radio Configuration ........................................................................ 55

5.7 DNT2400 Wizard Utility Program................................................................................................... 60

5.8 DNT2400 Interface Board Features .............................................................................................. 68

6.0 Demonstration Procedure ................................................................................................................. 71

7.0 Troubleshooting ................................................................................................................................ 72

7.1 Diagnostic Port Commands........................................................................................................... 72

8.0 Appendices ....................................................................................................................................... 75

8.1 Ordering Information...................................................................................................................... 75

8.2 Technical Support.......................................................................................................................... 75

8.3 DNT2400 Mechanical Specifications............................................................................................. 76

8.4 DNT2400 Development Board Schematic..................................................................................... 79

9.0 Warranty............................................................................................................................................ 81

www.RFM.com Technical support +1.678.684.2000 Page 5 of 81

1.0 Introduction

The DNT2400 series transceivers provide highly reliable wireless connectivity for point-to-point, point-to-

multipoint and peer-to-peer applications. Frequency hopping spread spectrum (FHSS) technology en-

sures maximum resistance to multipath fading and robustness in the presence of interfering signals, while

operation in the 2.4 GHz ISM band allows license-free use world wide. The DNT2400 supports all stan-

dard serial data rates for host communications from 1.2 to 460.8 kb/s. On-board data buffering and an

error correcting radio protocol provide smooth data flow and simplify the task of integration with existing

applications. Key DNT2400 features include:

• Multipath fading resistant frequency hop-

ping technology with up to 37 frequency

channels per subband

• Dynamic TDMA slot assignment that maxi-

mizes throughput and CSMA modes that

maximizes network size

• Support for point-to-point or point-to-

multipoint applications

• AES encryption provides protection from

eavesdropping

• FCC 15.247, IC and ETSI certified for

license-free operation

• Nonvolatile memory stores DNT2400 con-

figuration when powered off

• 10 mile plus range with omnidirectional

antennas (antenna height dependent)

• Selectable 1, 10 and 63 mW transmit power

levels

• Transparent ARQ protocol with data

buffering ensures data integrity

• Selectable RF data rates of 38.4, 155.2, 200

and 500 kb/s

• Analog and digital I/O simplifies wireless

sensing

• Auto-reporting I/O mode simplifies applica-

tion development

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 do-

main, 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 frequency band than would otherwise be necessary to

send the information. This allows a signal to be reconstructed even though part of it may be lost or cor-

rupted in transmission.

www.RFM.com Technical support +1.678.684.2000 Page 6 of 81

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 applica-

tion. 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 chan-

nels produces a frequency hopping spread spectrum system.

Forms of spread spectrum - direct sequence and frequency hopping

Figure 1.1.2

www.RFM.com Technical support +1.678.684.2000 Page 7 of 81

One disadvantage of direct sequence systems is that due to design issues related to broadband transmit-

ters 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 chan-

nels, whereas multiple hoppers can interleave, minimizing interference. Frequency hopping does carry

some disadvantage, in that it requires 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 sec-

onds. 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 DNT2400 Radio Operation

2.1 Network Synchronization and Registration

As discussed above, frequency hopping spread spectrum radios such as the DNT2400 periodically

change the frequency at which they transmit. In order for the other radios in the network to receive the

transmission, they must be listening to the frequency on which the current transmission is being sent. To

do this, all the radios in the network must be synchronized to the same hopping pattern.

In point-to-point or point-to-multipoint networks, one radio module is designated as the base. All other

radios are designated as remotes. One of the responsibilities of the base is to transmit a synchronization

signal (beacon) to the remotes to allow them to synchronize with the base. Since the remotes know the

hopping pattern, once they are synchronized with the base, they know which frequency to hop to and

when. Every time the base hops to a different frequency, it immediately transmits a synchronizing signal.

When a remote is powered on, it rapidly scans the frequency band for the synchronizing signal. Since the

base is transmitting on up to 37 frequencies and the remote is scanning up to 37 frequencies, it can take

several seconds for a remote to synchronize with the base.

Once a remote has synchronized with the base, it will request registration information to allow it to join the

network. Registration is handled automatically by the base. When a remote is registered, it receives

several network parameters from the base, including HopDuration, InitialNwkID, FrequencyBand and

Nwk_Key (see Section 4.2 for parameter details). Note that if a registration parameter is changed at the

base, it will update the parameter in the remotes over the air.

Among other things, registration allows the tracking of remotes entering and leaving a network, up to a

limit of 254 remotes. The base builds a table of serial numbers of registered remotes using their three-

byte serial numbers (MAC addresses). To detect if a remote has gone offline or out of range, the registra-

tion is “leased” must be “renewed” once every 250 hops. Any transmission from a remote running on a

leased registration renews the lease with the base. Note that more remotes can join the network but their

www.RFM.com Technical support +1.678.684.2000 Page 8 of 81

entering and leaving the network cannot be tracked by the base radio. The DNT2400 base can be config-

ured to send join announcements to a host application for an unlimited number of remotes. The applica-

tion can then verify the continued presence of remotes in the network through periodic polling of each

remote.

In addition, the DNT2400 supports a RemoteLeave command that allows a host application to cause a

remote to leave the network. This is useful to remove any rogue remotes that may have joined when

authentication is not being used. It is also useful to remove remotes from the network once they have

been serviced by the application. In this manner, the base can use the lease times to keep track of re-

motes that have not yet been serviced thereby allowing networks of more than 254 remotes to be tracked.

The RemoteLeave command includes the amount of time the remote must leave the network which can

be set from 2 seconds to more than 36 hours. In addition, a remote can be told to leave and not rejoin

until it has been power-cycled or reset.

2.2 Authentication

In many applications it is desirable to control which remote devices may join the network. This provides

security from rogue nodes joining the network and simplifies network segregation for co-located networks.

Network registration of remotes is controlled by the AuthMode parameter in the base. The AuthMode

parameter can be set to one of four values, 0..3. The default value is 0, which allows any remote to regis-

ter with a base.

When the AuthMode parameter is set to 1, a remote’s address must be listed in Parameter Bank 7 before

it will be allowed to register with the base. This is referred to as base authentication. Bank 7 must be

preloaded with the addresses of the authorized remotes before using base authentication. If a remote

whose MAC address is not in Bank 7 attempts to join the network the base radio will deny the registration

request. A maximum of 16 remotes can be entered into Bank 7. To support larger networks, mode 2 must

be used.

When the AuthMode parameter is set to 2, the address of a remote attempting to register with the base is

sent to the host for authentication in a JoinRequest message. The host application determines if the

remote should be allowed to register and returns a JoinReply message to the base containing a Permit-

Status parameter that allows or blocks the remote from registering. The host application has 30 seconds

in which to respond, after which time the base denies registration to the remote. Up to 16 join requests

can be pending at any one time. If more than 16 remotes are asking to join, the first 16 will be serviced

and additional remotes will be serviced after the earlier requests are handled. The RegDenialDelay pa-

rameter controls how often a remote will request registration after it has been denied. If it is anticipated

that more than 16 remotes will request registration before the application can service the first 16, this

parameter should be set to the time it will take the application to service four requests as this will speed

the authentication process by freeing the base from issuing multiple denials to the same remotes.

When the AuthMode parameter is set to 3, authentication is locked to the addresses of the remotes

currently registered with the base. Mode 3 is typically used in conjunction with Mode 0 during a commis-

sioning process. AuthMode is set to 0, remotes are turned on and allowed to register with the base, and

AuthMode is then switched to 3 to lock the network membership.

www.RFM.com Technical support +1.678.684.2000 Page 9 of 81

2.3 Transparent and Protocol Serial Port Modes

DNT2400 radios can work in two serial port data modes: transparent and packet protocol. Transparent

mode formatting is simply the raw user data. Protocol mode formatting includes a start-of-packet framing

character, length byte, addressing, command bytes, etc. Transparent mode operation is especially useful

in point-to-point systems that act as simple cable replacements. In point-to-multipoint systems where the

base needs to send data specifically to each remote, protocol formatting must be used unless the data

being sent includes addressing information that the devices connected to the remote radios can use to

determine the intended destination of the broadcast data. Protocol formatting is also required for configu-

ration commands and responses, and sensor I/O commands and responses. Protocol mode can be used

at the base radio while transparent mode is used at the remotes. The one caution about protocol mode is

that the length of a protocol mode message cannot exceed the BaseSlotSize or RemoteSlotSize or the

packet will be discarded. Protocol formatting details are covered in Section 4.

The DNT2400 provides two ways to switch between transparent and protocol modes. If /CFG input Pin 18

on the DNT2400 is switched from logic high to low, protocol mode is invoked. Or if the EnterProtocolMode

command is sent, the DNT2400 will switch to the protocol mode. When input Pin 18 is switched from logic

low to high, or an ExitProtocolMode command is sent to the primary serial input, the DNT2400 will switch

to transparent operation. Note that it is possible that part of the EnterProtocolMode command will be sent

over the air as transparent data.

When operating in transparent mode, two configuration parameters control when a DNT2400 radio will

send the data in its transmit buffer. The MinPacketLength parameter sets the minimum number of bytes

that must be present in the transmit buffer to trigger a transmission. The TxTimeout parameter sets the

maximum time data in the transmit buffer will be held before transmitting it, even if the number of data

bytes is less than MinPacketLength. The default value for MinPacketLength parameter is one and the

TxTimeout parameter is zero, so that any bytes that arrive in the DNT2400 transmit buffer will be sent on

the next hop. As discussed in Section 2.7.2, it is useful to set these parameters to values greater than

their defaults in point-to-multipoint systems where some or all the remotes are in transparent mode.

2.4 RF Data Communications

At the beginning of each hop the base transmits a beacon, which always includes a synchronizing signal.

After synchronization is sent, the base will transmit any user data in its transmit buffer, unless in transpar-

ent mode the MinPacketLength and/or TxTimeout parameters have been set above their default values.

The maximum amount of user data bytes that the base can transmit per hop is limited by the BaseSlot-

Size parameter, as discussed in Section 2.7.1. If there is no user data or reception acknowledgements

(ACKs) to be sent on a hop, the base will only transmit the synchronization signal in the beacon.

The operation for remotes is similar to the base, but without a synchronizing signal. The RemoteSlotSize

parameter indicates the maximum number of user data bytes a remote can transmit on one hop and is a

read-only value. The RemoteSlotSize is determined by the HopDuration and BaseSlotSize parameters

and the number of registered remotes. The MinPacketLength and TxTimeout parameters operate in a

remote in the same manner as in the base.

2.5 RF Transmission Error Control

The DNT2400 supports two error control modes: automatic transmission repeats (ARQ), and redundant

transmissions for broadcast packets. In both modes, the radio will detect and discard any duplicates of

www.RFM.com Technical support +1.678.684.2000 Page 10 of 81

messages it receives so that the host application will only receive one copy of a given message. In the

redundant transmission mode, broadcast packets are repeated a fixed number of times based on the

value of the ARQ_AttemptLimit parameter. In ARQ mode, a packet is sent and an acknowledgement is

expected on the next hop. If an acknowledgement is not received, the packet is transmitted again on the

next available hop until either an ACK is received or the maximum number of attempts is exhausted. If the

ARQ_AttemptLimit parameter is set to its maximum value, a packet transmission will be retried without

limit until the packet is acknowledged. This is useful in some point-to-point cable replacement applications

where it is important that data truly be 100% error-free, even if the destination remote goes out of range

temporarily.

2.6 Transmitter Power Management

The DNT2400 includes provisions for setting the base transmit power level and the remote maximum

transmit power level with the TxPower parameter. DNT2400 networks covering a small area can be

adjusted to run at lower transmitter power levels, reducing potential interference to other nearby systems

such as 802.11 networks. Remotes that are located close to their base can be adjusted to run at lower

maximum power, further reducing potential interference. Base units transmit at the fixed power level set

by the TxPower parameter. Remotes automatically adjust their transmitter power to deliver packets to the

base at an adequate but not excessive signal level, while not transmitting more power than set by their

TxPower parameter. Remotes make transmitter power adjustments using the strength of the signals

received from the base and the base transmitter power setting, which is periodically transmitted by the

base. The remote automatic transmit power adjustment is enabled by default but can be disabled if so

desired. Refer to Section 4.2.1 for details.

2.7 Network Configurations

The DNT2400 supports three network configurations: point-to-point, point-to-multipoint, and peer-to-peer.

In a point-to-point network, one radio is set up as the base and the other radio is set up as a remote. In a

point-to-multipoint network, a star topology is used with the radio set up as a base acting as the central

communications point and all other radios in the network set up as remotes. In this configuration, each

communication takes place between the base and one of the remotes. Peer-to-peer communications

between remotes using the base as a relay is also supported, as discussed in Section 2.7.3.

2.7.1 Point-to-Point Network Operation

Most point-to-point networks act as serial cable replacements and both the base and the remote use

transparent mode. Unless the MinPacketLength and TxTimeout parameters have been set above their

default values, the base will send the data in its transmit buffer on each hop, up to a limit controlled by the

BaseSlotSize parameter. In transparent mode, if the base is buffering more data than can be sent on one

hop, the remaining data will be sent on subsequent hops. The base adds the address of the remote, a

packet sequence number and error checking bytes to the data when it is transmitted. These additional

bytes are not output at the remote in transparent mode. The sequence number is used in acknowledging

successful transmissions and in retransmitting corrupted transmissions. A two-byte CRC and a one-byte

checksum allow a received transmission to be checked for errors. When a transmission is received by the

remote, it will be acknowledged if it checks error free. If no acknowledgment is received, the base will

retransmit the same data on the next hop. Note that acknowledgements from remotes are suppressed on

broadcast packets from the base.

www.RFM.com Technical support +1.678.684.2000 Page 11 of 81

In point-to-point operation, by default a remote will send the data in its transmit buffer on each hop, up to

the limit controlled by its RemoteSlotSize parameter. If desired, the MinPacketLength and TxTimeout

parameters can be set above their default values, which configures the remote to wait until the specified

amount of data is available or the specified delay has expired before transmitting. In transparent mode, if

the remote is buffering more data than can be sent on one hop, it will send the remaining data in subse-

quent hops. The remote adds its own address, a packet sequence number and error checking bytes to

the data when it is transmitted. These additional bytes are not output at the base if the base is in trans-

parent mode. When a transmission is received by the base, it will be acknowledged if it checks error free.

If no acknowledgment is received, the remote will retransmit the same data on the next hop.

2.7.2 Point-to-Multipoint Network Operation

In a point-to-multipoint network, the base is usually configured for protocol formatting, unless the applica-

tions running on each remote can determine the data’s destination from the data itself. Protocol formatting

adds addressing and other overhead bytes to the user data. If the addressed remote is using transparent

formatting, the source (originator) address and the other overhead bytes are removed. If the remote is

using protocol formatting, the source address and the other overhead bytes are output with the user data.

A remote can operate in a point-to-multipoint network using either transparent or protocol formatting, as

the base is the destination by default. In transparent operation, a remote DNT2400 automatically adds

addressing, a packet sequence number and error checking bytes as in a point-to-point network. When the

base receives the transmission, it will format the data to its host according to its formatting configuration.

A remote running in transparent mode in a point-to-multipoint network can have the MinPacketLength and

TxTimeout parameters set to their default values to reduce latency, or above their default values to re-

duce the volume of small packet transmissions.

2.7.3 Peer-to-Peer Network Operation

After a remote has joined the network, it can communicate with another remote through peer-to-peer

messaging, where the base acts as an automatic message relay. In protocol mode, if a remote specifies a

destination address other than the base address, peer-to-peer messaging is enabled. In transparent

mode, the RmtTransDestAddr parameter sets the destination address. Changing RmtTransDestAddr from

the default base address to the address of another remote enables peer-to-peer messaging. The broad-

cast address can also be used as a peer-to-peer destination address. In this case, the message will be

unicast from the remote to the base (using ARQ) and then broadcast by the base (no ARQ). For peer-to-

peer broadcasts, no acknowledgement is sent and no TxDataReply packet is reported to the host.

2.8 Full-Duplex Serial Data Communications

From a host application’s perspective, DNT2400 serial communications appear full duplex. Both the base

host application and each remote host application can send and receive serial data at the same time. At

the radio level, the base and remotes do not actually transmit at the same time. If they did, the transmis-

sions would collide. As discussed earlier, the base transmits a beacon with a synchronization signal at the

beginning of each hop, followed by its user data. After the base transmission, the remotes can transmit.

Each base and remote transmission may contain all or part of a complete message from its host applica-

tion. From an application’s perspective, the radios are communicating in full duplex since the base can

receive data from a remote before it completes the transmission of a message to the remote and vice-

versa.

www.RFM.com Technical support +1.678.684.2000 Page 12 of 81

2.9 Channel Access

The DNT2400 provides five methods of channel access: one Polling, two CSMA and three TDMA, as

shown in the table and figure below. The channel access method is selected by the AccessMode parame-

ter in Bank 1. See section 4.2.2. The channel access setting is distributed to all remotes by the base, so

changing it at the base sets the entire network. Polling refers to an application sending a command from

the base to one or more remote devices where only one remote device will respond at a time. Polling is

suitable for both large and small networks where unsolicited or event reporting by remotes is not required.

Carrier Sense Multiple Access (CSMA) is very effective at handling packets with varying amounts of data

and/or packets sent at random times from a large number of remotes. Time Division Multiple Access

(TDMA) provides a scheduled time slot for each remote to transmit on each hop. The default DNT2400

access mode is TDMA dynamic mode.

Access Mode Description Max Number of Remotes

0 Polling unlimited

1 CSMA unlimited

2 TDMA dynamic slots up to 16

3 TDMA fixed slots up to 16

4 TDMA with PTT up to 16

Table 2.9.1

B a s e

R e m o t e # 1

R e m o t e # 2

R e m o t e # 3

T D M A

B a s e

R e m o t e # 1

R e m o t e # 2

R e m o t e # 3

C S M A

B a c k o f f

L i s t e n

B a s e

R e m o t e # 1

R e m o t e # 2

R e m o t e # 3

P O L L

Figure 2.9.1

2.9.1 Polling Mode

Polling channel access is used for point-to-point and point-to-multipoint systems where only one remote

will attempt to transmit data at a time, usually in response to a command from the base.

Polling (mode 0) is a special case of CSMA mode 1. The user can set the BaseSlotSize and CSMA_

RemtSlotSize parameters when using this mode. Since only one remote will attempt to transmit at a time,

www.RFM.com Technical support +1.678.684.2000 Page 13 of 81

to minimize latency, the CSMA_Predelay and CSMA_Backoff parameters are not used. Lease renewals

are also not used, again to minimize latency. Thus, when the base is operated in protocol mode with

Announce messages enabled, only join messages are generated. This mode provides high throughput

since there is no contention between remotes and the entire portion of the hop frame following the base

transmission is available for a remote to transmit. Applications where more than one remote may attempt

to transmit at a time, or where periodic reporting and/or event reporting are enabled should not use this

mode.

2.9.2 CSMA Mode

When using CSMA channel access, each remote with data to send listens to see if the channel is clear

and then transmits. If the channel is not clear, a remote will wait a random period of time and listen again.

CSMA works best when a large or variable number of remotes transmit infrequent bursts of data. There is

no absolute upper limit on the number of remote radios that can be supported in this mode - it depends

on message density. A maximum of 254 remotes can be supported if base join-leave tracking is required,

or an unlimited number of remotes if base join-leave tracking is not required or will be handled by the host

application.

There are two important parameters related to CSMA operation. The CSMA_Backoff parameter defines

the initial time that a remote will wait when it determines the channel is busy before again checking to see

if the channel is clear (back-off interval). If, after finding the channel busy and backing off, the radio finds

the channel busy a second time, the amount of time the remote will wait before checking the channel will

increase. It will continue to increase each subsequent time the channel is busy until the channel is finally

found idle. This is the classic CSMA technique that handles the situation where a number of remotes hold

data to send at the same time. The CSMA_ Predelay parameter controls the maximum time that a remote

will wait before first listening to see if the channel is clear for a transmission. This parameter is used to

make sure that all the remotes do not transmit immediately after the base finishes transmitting.

CSMA (mode 1) provides classical CSMA channel access, and gives the user control over both the

CSMA_Predelay and CSMA_Backoff parameters. This mode is well suited for large numbers of uncoordi-

nated remotes, and/or where periodic/event reporting is used. In addition to CSMA_ Predelay and

CSMA_ MaxBackoff, the user can set the BaseSlotSize and CSMA_RemtSlotSize parameters when

using this mode. The following guidelines are suggested for setting CSMA_Predelay:

• For lightly loaded CSMA contention networks, decrease CSMA_Predelay

to 0x20 or less to reduce latency.

• For heavily loaded CSMA contention networks, increase CSMA_Predelay

to 0x80 or more for better throughput.

As an option, CSMA mode allows the base to directly track remotes entering and leaving the network, for

up to 254 remotes. The base is operated in protocol mode and is configured to send Announce messages

to its host when a remote joins and when the remote’s registration lease expires.

While a base in a CSMA network can track a maximum of 254 remotes entering and leaving the network,

it can generate join Announce messages for an unlimited number of remotes. This allows the host appli-

cation to track remotes entering and leaving a CSMA network with more than 254 remotes by creating its

own table of MAC addresses and periodically sending a GetRemoteRegister command to each remote in

the table. Failure to answer a GetRemoteRegister command indicates the remote is no longer active in

the network.

www.RFM.com Technical support +1.678.684.2000 Page 14 of 81

CSMA modes work well in many applications, but CSMA has some limitations, as summarized below:

• Bandwidth is not guaranteed to any remote.

• Marginal RF links to some remotes can create a relatively high chance of

collisions in heavily loaded networks.

2.9.3 TDMA Modes

TDMA modes provide guaranteed bandwidth to some or all of the remotes in a network. Remotes that

channel access time slot assignment. TDMA registrations are always leased and must be renewed every

250 hops. The DNT2400 provides three TDMA access modes, as discussed below.

TDMA Dynamic Slots (mode 2) is used for general-purpose TDMA applications where scaling the capac-

ity per slot to the number of active remotes is automatic. Each remote that registers with the base

receives an equal time slice. As new remotes join, the size of the TDMA remote slots shrinks accordingly.

The number of slots, individual slot start times, and the RemoteSlotSize are computed automatically by

the DNT2400 network in this mode. The user should note that the bandwidth to each remote will change

immediately as remotes join or leave the network. When running in protocol mode on a remote, care must

be taken not to generate messages too long to be sent in a single hop due to automatic RemoteSlotSize

reduction.

TDMA Fixed Slots (mode 3) is used for applications that have fixed data throughput requirements, such

as isochronous voice or streaming telemetry. The slot start time and the RemoteSlotSize are computed

automatically by the DNT2400 network in this mode. The user must set the number of slots using the

MaxSlots parameter. The base radio will allocate remote slot sizes as if MaxSlots are linked with the

base, even when fewer remotes are actually linked. In this mode, the remote slot sizes are constant.

TDMA with PTT (mode 4) supports remotes with a "push-to-talk" feature, also referred to as "listen-

mostly" remotes. This mode uses fixed slot allocations. Remotes can be registered for all but the last slot.

The last slot is reserved for the group of remotes that are usually listening, but occasionally need to

transmit. In essence, the last slot is a shared channel for this group of remotes. When one of them has

data to send it keys its transmitter much like a walkie-talkie, hence the name push-to-talk (PTT).

The slot start time and the RemoteSlotSize are computed automatically by the DNT2400 network in mode

4. The user must specify the number of slots using the MaxSlots parameter. The last slot is reserved for

the PTT remotes. The user must configure PTT remotes individually to select mode 4 operation. The

user's application must ensure that only one PTT remote at a time is using the slot.

2.10 Transmission Configuration Planning

Because frequency hopping radios change frequency periodically, a single message may be sent in one

or more RF transmissions. The length of time the radio stays on a frequency, the hop duration, impacts

both latency and throughput. The longer the radio stays on a single frequency, the higher the throughput

since the radio is transmitting for a higher percentage of the time, but latency is also higher since radios

may have to wait longer to transmit. So latency and throughput trade off against one another. The

DNT2400 has several configuration parameters that allow latency and throughput to be optimally bal-

anced to the needs of an application.

www.RFM.com Technical support +1.678.684.2000 Page 15 of 81

2.10.1 TDMA Throughput

For TDMA channel access, throughput and latency are controlled by the RF data rate, the serial port

baud rate, the BaseSlotSize, the HopDuration, and the number of remotes. A wide range of throughput

and latency combinations can be obtained by adjusting these parameters. The throughput of a radio in a

TDMA network is simply:

Number of bytes per hop/Hop Duration

For the base, the number of byes per hop is controlled by the BaseSlotSize parameter so the throughput

of the base radio is:

BaseSlotSize/HopDuration

Note that if fewer bytes than the BaseSlotSize limit are sent to the base radio by its host during the hop

duration time in transparent mode, the observed throughput of the base radio will be reduced. If the base

is in protocol mode, it will wait until a protocol formatted message is completely received from its host

before transmitting it. If the message is not completely received by the time the base transmits, the base

will wait until the next hop to transmit the message. The throughput for each remote is:

RemoteSlotSize/HopDuration

In a TDMA mode, the RemoteSlotSize is set automatically based on the number of remotes and the

BaseSlotSize. Note that the base radio always reserves BaseSlotSize amount of time in each hop

whether or not the base has user data to send.

To help select appropriate parameter values, RFM provides the DNT2400 Throughput Calculator utility

program. This program is on the development kit CD. Enabling encryption (security) adds additional bytes

to the data to be sent but the Calculator has a mode to take this into account.

2.10.2 Polling Throughput

In polling mode, the application sends data from the base to a specific remote, which causes the remote

and/or its host to send data back to the application. The network operates like a point-to-point network in

this case. In polling, the HopDuration should be set just long enough to accommodate a base transmis-

sion up to the limit allowed by the BaseSlotSize parameter, plus one remote transmission up to the limit

allowed by the CSMA_RemtSlotSize parameter. These slot sizes and the hop duration set the polling

throughput as in TDMA channel access.

The throughput in Polling mode is also determined by the amount of time it takes for the remote host

device to respond to the poll. For example, consider the situation where a remote host device communi-

cates with the DNT2400 at 38.4 kb/s, receives a 16-byte poll command, and takes 1 ms to generate a 32-

byte response which it then sends to the DNT2400. Sixteen bytes over a UART port is 160 bits using

8,N,1 serial parameters. Sending 160 bits at 38.4 kb/s takes 4.2 ms. Add 1 ms for the host device to

process the command and begin sending the 32-byte response. The 32-byte response takes 8.4 ms to

send at 38.4 kb/s, for a total turnaround time of 13.6 ms. This amount of time could be added to the base

and remote slot times to allow the entire transaction to take place in a single hop. However, except at the

38.4 kb/s over-the-air data rate, this is likely to be much longer than the base and remote slot times.

Thus, in practice, lengthening the hop duration to complete the transaction in a single hop doesn’t really

affect the throughput. Nevertheless, it is important to note that the throughput for the remote in the exam-

ple above is substantially less than the remote slot size in bytes divided by the hop duration.

www.RFM.com Technical support +1.678.684.2000 Page 16 of 81

It is not a radio requirement that the complete application message be sent in a single hop, nor that the

remote response is returned in a single hop, when in transparent mode. If either transmission occurs over

more than one hop, then depending on the length of the data, the RF data rate and the serial port data

rate at the receiving end, there may be a gap in the serial data. Some protocols, such as Modbus RTU,

use gaps in data to determine packet boundaries.

2.10.3 CSMA Throughput

In CSMA mode, remote radios do not have a fixed throughput, which is why applications requiring guar-

anteed throughput should use polling or a TDMA mode. The reason that the throughput of a CSMA

remote is not fixed is because its ability to transmit at any given time depends on whether another radio is

already transmitting. The throughput of a remote is further affected by how many other remotes are

waiting for the channel to become clear so they can transmit. This is not a problem when remotes, even a

large numbers of remotes, only send data infrequently. The DNT2400 includes several configuration

parameters that can be used to optimize the performance of a CSMA network.

It is often desirable to limit the amount of data a CSMA remote can send in one transmission. This pre-

vents one remote from hogging network throughput. To accommodate this, the DNT2400 provides a

CSMA_RemtSlotSize parameter that is user configurable. When a remote has transmitted CSMA_

RemtSlotSize bytes on a given hop, it will stop transmitting until the next hop. Note that this remote will

have to contend for the channel on the next hop, so it is not guaranteed that it will be the first remote to

transmit on the next hop or that it will be able to transmit on the next hop at all. To allow multiple remotes

a chance to transmit on the same hop, the HopDuration parameter must be set long enough to support

the BaseSlotSize, plus the number of remotes to transmit per hop times CSMA_ RemtSlotSize, plus the

number of remotes to transmit per hop times the CSMA_Backoff. Because of the way CSMA channel

access works, this does not guarantee that the desired number of remotes to transmit on a hop will al-

ways be able to transmit on a single hop. This is due to the fact that when a remote with data to send

finds the channel busy a second time, it waits for a longer period to time before testing the channel again.

This time will continue to increase until the remote finds the channel clear. In practice this is unlikely to

present a problem, as CSMA networks are used with devices that infrequently have data to send.

The DNT2400 Throughput Calculator can be used to determine the HopDuration, but it will be necessary

to increase the number of slots to a value greater than the number of remotes to transmit on a single hop

to account for the backoffs. It is indeterminate how many backoffs may occur during a single hop, which is

why the number of remotes that transmit on a given hop cannot be guaranteed. Note that the CSMA_

Backoff parameter sets the length of time a remote will wait to recheck the channel when it has detected

that the channel is busy. The second time a remote detects that the channel is busy, it will increase the

amount of time it waits until it checks again. Every subsequent time it detects a busy channel it will in-

crease the amount of time it will wait in a geometric fashion. This continues until it detects an idle chan-

nel. So while a short CSMA_Backoff can decrease the time between when one remote transmits and the

next remote transmits, it can actually lead to a longer time between remote transmissions than a longer

backoff. This can occur when the remote checks the channel multiple times during the transmitting re-

mote’s transmission causing the back-off time to be increased.

2.10.4 Latency

The worst case latency for TDMA access, excluding retries, occurs when the radio receives data just after

its turn to transmit. In this instance, it will have to wait the length of time set by the HopDuration to begin

www.RFM.com Technical support +1.678.684.2000 Page 17 of 81

transmitting the data. If the radio is receiving data over its serial port at a rate higher than its throughput,

this will only occur at the beginning of a transmission that spans several hops.

In a polling application, latency is affected by how long the remote and/or its host takes to respond, and

when in the hop data is ready to be transmitted. Since a remote can begin transmitting at practically any

time during the hop after the base has transmitted, the latency can be less than HopDuration. However,

the remote transmission may extend over two hops if it starts late in the first hop.

Latency for any given remote in a CSMA network is particularly difficult to characterize. If many remotes

have data to send, the latency for the last remote to send will be the length of time it takes all the other

remotes to send. The CSMA scheme used in the DNT2400 is designed to allow each remote an equal

opportunity to transmit, so the concern is not that one remote is locked out, but just how long it will take a

number of remotes with data to sent to each gain access to the channel and send their data. The more

data that needs to be sent, the more time will be consumed checking the channel and backing off when

the channel is busy. Again, this is why CSMA networks are best used when there are a large number of

nodes that send data infrequently.

The other factor impacting latency is retries. This impact is not unique to frequency hopping radios but is

common among all wireless technologies. A radio only transmits data once per hop. It needs to wait until

the next hop to see if the transmission was received at the destination. If not, the radio will transmit the

data again and wait for the acknowledgement. This can happen up to ARQAttemptLimit number of times

which is equal to ARQAttemptLimit times HopDuration amount of time.

2.10.5 Configuration Validation

Although slot durations are automatically calculated by the DNT2400, the RF data rate, hop duration, etc.,

must be coordinated by the user to assure a valid operating configuration based on the following criteria:

1. Regardless of the RF data rate, the maximum DNT2400 hop duration is limited to 200 ms. A

DNT2400 network must be configured accordingly.

2. In protocol mode, the BaseSlotSize and RemoteSlotSize parameters must be large enough to

hold all the data bytes in the largest protocol formatted message being used. Protocol formatted

messages must be sent in a single transmission. Any protocol formatted messages too large for

the slot size setting will be discarded

3. In TDMA mode 2, the RemoteSlotSize may be reduced automatically when a new remote joins

the network. This can cause a network to suddenly malfunction if the hop duration is not set to

provide an adequately large remote slot allocation when fully loaded with remotes

4. When operating in polling mode 0, the CSMA_RemtSlotSize and HopDuration parameters are

usually set to accommodate the number of data bytes in a maximum size transmission. This con-

figuration provides low latency for polled messages.

5. When operating in CSMA mode 1, the CSMA_RemtSlotSize and HopDuration parameters are

usually set to accommodate three times the number of data bytes in one maximum size transmis-

sion, to allow time for more than one remote to attempt to transmit during a single hop.

www.RFM.com Technical support +1.678.684.2000 Page 18 of 81

Figure 2.10.5.1

The DNT Throughput Calculator utility program is shown in Figure 2.10.5.1. Decimal data is entered by

default. Hexadecimal data can also be entered using a 0x prefix, as shown in the Hop Duration Counts

text box. When using the DNT Throughput Calculator, parameter coordination depends on the operating

mode of a DNT2400 network, as outlined below:

Polling (mode 0) - the user can set and must coordinate the RF data rate, hop duration, base slot size

and remote slot size. First, set the BaseSlotSize to accommodate the maximum number of data bytes in a

base transmission. Next, set the CSMA_RemtSlotSize to accommodate the maximum number data bytes

in a remote transmission. Use these slot sizes, the RF data rate and the maximum operating range (20

miles is the default) as inputs to the Calculator program to determine minimum valid HopDuration.

CSMA contention (mode 1) - the same procedure as for polling is used, except that the CSMA_

RemtSlotSize typically should be set at three times the maximum number of data bytes. The default

values for CSMA pre-delay and back-off are assumed.

TDMA dynamic (mode 2) - this is the DNT2400’s default operating mode and the default settings are

optimized for point-to-point transparent operation. For other configurations the user must coordinate the

RF data rate, hop duration, base slot size and maximum number of remotes. Although the remote slot

size and remote slot time allocation are automatically set in mode 2, the user must predetermine these

values to assure a valid operating configuration. First, set the BaseSlotSize to accommodate the maxi-

mum number of data bytes in a base transmission. Next, determine the RemoteSlotSize required to

accommodate the maximum number of data bytes in a remote transmission. Use these slot sizes, the

maximum number of remotes that will be used in the network, the RF data rate and the maximum operat-

ing range as inputs to the Calculator to determine the minimum valid HopDuration time. Note that when

there are fewer remotes on the network than the maximum specified, the remotes will automatically be

configured with a bigger RemoteSlotSize parameter.

TDMA fixed (mode 3) - First, set the BaseSlotSize to accommodate the maximum number of data bytes in

a transmission. Next, determine the RemoteSlotSize required to accommodate the maximum number of

data bytes in a remote transmission. Then set the number of remote slots. Use the slot sizes, the number

of remotes, the RF data rate and maximum operating range as inputs to the Calculator to determine the

minimum valid hop duration.

www.RFM.com Technical support +1.678.684.2000 Page 19 of 81

TDMA PTT (mode 4) - use the same procedure as for TDMA fixed mode 3.

The DNT2400 base firmware can detect a significant number of invalid configurations and override the

HopDuration parameter to establish a valid configuration. To take advantage of this feature, configure a

DNT2400 network in the following order:

1. In all system radios, set the RF_DataRate parameter and save it. Then reset all radios to estab-

lish the new RF data rate.

2. Set the BaseSlotSize and TDMA_MaxSlots or CSMA_RemtSlotSize as needed. Use the default

maximum operating range unless links of more than 20 miles are planned.

3. Set the HopDuration parameter and then read it back. If the HopDuration parameter readout is

different than the value set, the firmware detected an invalid configuration and is overriding it.

2.11 Serial Port Operation

DNT2400 networks are often used for wireless communication of serial data. The DNT2400 supports

serial baud rates from 1.2 to 460.8 kb/s. Listed in Table 2.11.1 below are the supported data rates and

their related byte data rates and byte transmission times for an 8N1 serial port configuration:

Baud Rate kb/s Byte Data Rate kB/s Byte Transmission Time ms

1.2 0.12 8.3333

2.4 0.24 4.1667

4.8 0.48 2.0833

9.6 0.96 1.0417

19.2 1.92 0.5208

28.8 2.88 0.3472

38.4 3.84 0.2604

57.6 5.76 0.1736

76.8 7.68 0.1302

115.2 11.52 0.0868

230.4 23.04 0.0434

460.8 46.08 0.0217

Table 2.11.1

To support continuous full-duplex serial port data flow, an RF data rate higher than the serial port baud

rate is required for FHSS. Radios transmissions are half duplex, and there are overheads related to

hopping frequencies, assembling packets from the serial port data stream, transmitting them, sending

ACK’s to confirm error-free reception, and occasional transmission retries when errors occur.

For example, consider a TDMA mode 2 system with one remote operating up to 20 miles at 500 kb/s with

the BaseSlotSize parameter set to 64 bytes and the RemoteSlotSize parameter at 64 bytes. As shown in

Figure 2.11.1, the hop duration from the DNT Throughput Calculator program for this configuration is

4.70 ms

www.RFM.com Technical support +1.678.684.2000 Page 20 of 81

Figure 2.11.1

The average full-duplex serial port byte rate that can be supported under error free conditions is:

64 Bytes/4.70 ms = 13.62 kB/s, or 136.2 kb/s for 8N1

Continuous full-duplex serial port data streams at a baud rate of 115.2 k/bs can be supported by this

configuration, provided only occasional RF transmission errors occur. Plan on an average serial port data

flow of 90% of the calculated error-free capacity for general-purpose applications.

The DNT2400 transmit and receive buffers hold at least 1024 bytes and will accept brief bursts of data at

high baud rates, provided the average serial port data flow such as shown in the example above is not

exceeded. It is strongly recommended that the DNT2400 host use hardware flow control in applications

where the transmit buffer can become full. The host must send no more than 32 additional bytes to the

DNT2400 when the DNT2400 de-asserts the host’s CTS line. In turn, the DNT2400 will send no more

than one byte following the host de-asserting its RTS line. Three-wire serial port operation is allowed

through parameter configuration, as discussed in Section 4.2.4. However, data loss is possible under

adverse RF channel conditions when using three-wire serial operation due to buffer overruns.

2.12 Sleep Modes

To save power in applications where a remote transmits infrequently, the DNT2400 supports hardware

and firmware sleep modes. Hardware sleep mode is entered by switching SLEEP/DTR Pin 11 on the

DNT2400 from logic low to high. While in hardware sleep mode, the DNT2400 consumes less than 50 µA

at room temperature. This mode allows a DNT2400 to be powered off while its host device remains

powered. After leaving hardware sleep mode, the radio must re-synchronize with the base and re-

In addition to the sleep mode controlled by Pin 11, in CSMA mode the DNT2400 remotes support an

additional sleep mode to support battery-powered applications. When this mode is enabled, the DNT2400

is in a low-power state and only wakes up in response to the I/O report triggers. The following list explains

the rules that sleeping remotes follow:

www.RFM.com Technical support +1.678.684.2000 Page 21 of 81

• The DNT2400 will wake up when any of the enabled I/O report trigger conditions fire. When any

of the ADC triggers are enabled, the radio will also wake up every ADC_SampleIntvl long enough

to sample the ADCs, and then go back to sleep.

• When a sleeping radio wakes up, it must acquire and synchronize to its base before it can send

or receive any data. To prevent excessive battery use, if the remote is unable to acquire before

the WakeLinkTimeout elapses, it will cancel any pending event trigger(s) and go back to sleep.

• If a remote is linking for the first time or if its last attempt to acquire and synchronize was unsuc-

cessful, it will scan and record the entire broadcast system parameter list before it goes back to

sleep. Otherwise, in order to conserve battery life, a sleeping remote will update any values that it

may hear while it is awake, but is not required to listen to the entire list.

• If a remote is linking for the first time or if its last attempt to acquire and synchronize was unsuc-

cessful, it will send a registration request to the base, allowing it to announce its presence to the

host. Otherwise, in order to conserve battery life, a sleeping remote will not register each time it

reacquires link with its base on successive wakeups.

• After a remote has received an acknowledgement for its I/O report, a WakeResponseTime timer

is started before the remote goes back to sleep. This allows the base host time to send a mes-

sage to the remote. Note that the only notification that the base host application has that a remote

is awake is its report packet. In order to send it data, the base host must ensure that the message

is transmitted and received before the remote's WakeResponseTime window elapses. If this func-

tion is not needed, the WakeResponseTime can be set to zero to disabled it.

The lease renewal mechanism is not supported for sleeping remotes. In order to successfully use sleep-

ing remotes, the user must ensure that the system is configured for CSMA mode and that leases are

disabled. If these settings are not used, there is no guarantee that the remotes will be able to communi-

cate reliably. Because leases are not supported, there is no built-in mechanism for the base to detect or

announce to its host if a remote leaves the network.

To summarize, while a remote is awake, the following list of condition checks are used to determine if and

when it is allowed to go back to sleep:

• If the remote is linking for the first time or was unsuccessful linking on its last attempt, it will re-

main awake to record the beacon system parameter list.

• At wakeup, the WakeLinkTimeout timer is started. If the remote is unable to acquire link before

this elapses, it goes back to sleep.

• If the remote receives an acknowledgement for a data packet it has sent (typically an Event

packet, but in theory it could be any other type of message), it starts or resets the WakeRespon-

seTime timer to remain awake.

• So long as a GPIO for which I/O reporting is enabled for a level trigger remains in its triggered

state, the remote will remain awake.

• The remote will remain awake while it still has any ARQ attempts left for a queued transmit

packet of any type.

www.RFM.com Technical support +1.678.684.2000 Page 22 of 81

• The remote will remain awake while it is has serial characters in its buffer left to transmit to its lo-

cal host.

Sleep functions are controlled by the following registers (see Section 4.2):

• SleepMode - enables/disables sleep mode.

• WakeResponseTime - sets the amount of time that a remote will wait for a

response after sending an I/O report.

• WakeLinkTimeout - sets the maximum time that a remote will spend trying

to acquire it base before giving up.

Sleep is also affected by the following registers associated with I/O reporting: IO_ReportTrigger,

IO_ReportInterval, ADC_SampleIntvl, and GPIO_EdgeTrigger. The following table indicates how the

status and control pins function on sleeping remotes (see Table 2.12.1):

Pin Awake Sleep

/HOST_RTS Normal operation high impedance

/HOST_CTS Normal operation 0 V

/DCD Normal operation 0 V

ACT 3 V 0 V

DIVERSITY Normal operation 0 V

RADIO_TXD Normal operation Hi-Z

RADIO_RXD Normal operation 0 V

Table 2.12.1

Note that the ACT pin may be used by a local host to detect when a sleeping remote is awake. The

behavior of the GPIOs during sleep is governed by the GPIO_ SleepMode, GPIO_SleepDir, and

GPIO_SleepState configuration registers. Refer to the register definitions in Section 4.2.

2.13 Encryption

The DNT2400 supports 128-bit AES encryption of data and configuration packets. Encryption is enabled

by setting the EncryptionKey register to a value other than a string of NULL (0x00) bytes. A remote with-

out encryption enabled cannot link to an encrypted base, and an encrypted remote will not attempt to link

to an unencrypted base. A remote's encryption key must match that of the base before it can link. The

EncryptionKey register can be set over the air so it can be changed periodically if desired.

2.14 Synchronizing Co-located Bases

The EX_SYNC input (Pin 15) on the DNT2400 allows co-located bases to synchronize their transmissions

so they all transmit at the same time. This prevents the situation where one base is transmitting while

another nearby base is trying to hear a distant remote. Even though the base radios may be on different

frequencies, because of their close proximity, the transmitting base can reduce the receiving base’s ability

to hear distant remotes. The EX_SYNC input has the following characteristics:

www.RFM.com Technical support +1.678.684.2000 Page 23 of 81

1. Base radios trigger on the rising edge of the pulse applied to their EX_SYNC input.

2. All co-located bases must use the same hop duration and the period of the pulse train applied to

the EX_SYNC input must be within ±10 µs of this hop duration.

3. The co-located bases must use different network IDs but the same frequency subband, which as-

sures they are using different hopping patterns.

4. A “narrow” pulse of 50 to 800 µs triggers base beacon synchronization. A train of narrow pulses

as described above will synchronize a group of co-located base stations after a period of time.

5. An optional “wide” pulse of 1 to 2 ms triggers a hopping pattern reset. Note: a wide pulse

can only be used in ETSI applications. It is not allowed under FCC and Canadian IC

regulations. The benefit provided by the wide pulse is to keep co-located networks from ever be-

ing on the same frequency at the same time. When the wide pulse is not used, it is possible that

co-located networks may occasionally try to transmit on the same frequency at the same time.

This can slightly reduce the network throughput. Where a wide pulse can be used, it should be

sent to reset all base patterns to their first frequency following the reset or power-up of any of the

co-located bases. Thereafter a cycle of N -1 narrow pulses and then 1 wide pulse should be sent,

where N is the number of frequencies in the subband being used. For example, if the frequency

subband contains 15 frequencies, a repeating cycle containing 1 wide pulse followed by 14 nar-

row pulses should be used.

www.RFM.com Technical support +1.678.684.2000 Page 24 of 81

3.0 DNT2400 Hardware

2 3 2 4 2 5 2 6 2 7 2 82 22 1 2 9 3 0 3 1

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

D N T 2 4 0 0 B l o c k D i a g r a m

3 2 3 3 3 4 3 6

M i c r o c o n t r o l l e r

R e g

F i l t e r

V C C

P W M 0

P W M 1

G P I O 0

G P I O 1

G P I O 2

G P I O 3

G N D

4 2

R F

T r a n s c e i v e r

C L K

I N T

C S n R F I O

G N D

R A D I O _ T X D

R A D I O _ R X D

/ R E S E T

R S V D

T / R

P W R

P R E

F i l t e r

3 5

4 1

4 3

1 9

2 0

3 7 3 8 3 9 4 0

S I

S O

P K T D E T

R e g

3 . 3 V

3 . 6 V

P K T _ D E T

R S V D

A D C _ R E F

R S S I

S L E E P

A D C 2

A D C 1

A D C 0

E X _ S Y N C

D I A G _ T X

D I A G _ R X

/ C F G

/ H O S T _ R T S

/ H O S T _ C T S

G P I O 4

G P I O 5

G N D

A C T

/ D C D

R S V D

V M O D

R S V D

Figure 3.0.1

The major components of the DNT2400 include a 2.4 GHz FHSS transceiver and a low current 32-bit

microcontroller. The DNT2400 operates in the 2.4 GHz ISM band. The module includes nine frequency

subbands and 37 total frequency channels to support the various 2.4 GHz frequency allocations used

throughout the world. The DNT2400 has three selectable RF output power levels: 1, 10, and 63 mW.

Also, there are four selectable RF transmission rates: 38.4, 115.2, 200 and 500 kb/s. The DNT2400

includes a low-noise receiver preamplifier and a high efficiency transmitter amplifier, providing excellent

range in outdoor applications.

The DNT2400 provides a variety of hardware interfaces. There are two UART serial ports, one for data

and a second for diagnostics. The data port supports standard baud rates from 1.2 to 460.8 kb/s, with the

diagnostic port fixed at 38.4 kb/s. The module also includes 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 DNT2400C is designed for solder reflow mounting, and the DNT2400P is designed for plug-in con-

nector mounting.

www.RFM.com Technical support +1.678.684.2000 Page 25 of 81

3.1 DNT2400 Specifications

Characteristic Sym Minimum Typical Maximum Units

Operating Frequency Range 2409.3 2467.1 MHz

Hop Dwell Time 5 200 ms

Number of Frequency Hopping Subbands 9

Number of RF Channels in a Subband 15 37

Modulation FSK/MSK

RF Data Transmission Rates 38.4, 115.2, 200 and 500 kb/s

Receiver Sensitivity:

10-5 BER @ 38.4 kb/s -104 dBm

10-5 BER @ 200 kb/s -96 dBm

10-5 BER @ 500 kb/s -90 dBm

Transmitter RF Output Power Levels 1, 10, 63 mW

Optimum Antenna Impedance 50 Ω

RF Connection DNT2400P - U.FL Connector

DNT2400C - U.FL Connector or PCB Pad

Network Topologies Point-to-Point, Point-to-Multipoint

Access Schemes TDMA and CSMA

Number of Network Nodes:

TDMA 16

CSMA unlimited

ADC Input Range 0 3.3 V

ADC Input Resolution 10 bits

Signal Source Impedance for ADC Reading 10 KΩ

PWM (DAC) Output Range 0 3.3 V

PWM (DAC) Output Resolution 8 bits

PWM Output Period 20 µs

Primary Serial Port Baud Rates 1.2, 2.4, 4.8, 9.6, 19.2, 28.8, 38.4, 57.6, 76.8,

115.2, 230.4, 460.8 kb/s

Diagnostic Serial Port Baud Rate 38.4 kb/s

Digital I/O:

Logic Low Input Level -0.5 0.8 V

Logic High Input Level 2 3.3 V

Logic Input Internal Pull-up Resistor 50 200 KΩ

Logic Input Internal Pull-down Resistor 50 180 KΩ

Power Supply Voltage Range VCC +3.3 +5.5 Vdc

Power Supply Voltage Ripple 10 mVP-P

Peak Transmit Mode Current, 63 mW Output 300 mA

Average Operating Receive Current:

Base 105 mA

Remote, No Data Transmission 35 mA

Remote, 9.6 kb/s Continuous Data Stream 40 mA

Remote, 115.2 kb/s Continuous Data Stream 53 mA

Sleep Current 50 2251 µA

Operating Temperature Range -40 85 oC

Operating Relative Humidity Range (non condensing) 10 90 %

1. Maximum sleep current occurs at +85 oC Table 3.1.1

www.RFM.com Technical support +1.678.684.2000 Page 26 of 81

3.2 Module Interface

Electrical connections to the DNT2400C are made through the I/O pads and through the I/O pins on the

DNT2400P. The hardware I/O functions are detailed in the table below:

Pad Name I/O Description

1 PKT_DET O

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 use in network timing evaluations, etc.

2 RSVD - Reserved pad. Leave unconnected.

3 ADC_REF I 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.

4 RSVD - Reserved pad. Leave unconnected.

5 GPIO0 I/O

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 also configurable.

6 GPIO1 I/O Configurable digital I/O port 1. Same configuration options as GPIO0.

7 GPIO2 I/O Configurable digital I/O port 2. Same configuration options as GPIO0.

8 GPIO3 I/O Configurable digital I/O port 3. Same configuration options as GPIO0.

9 PWM0 O 8-bit pulse-width modulated output 0 with internal low-pass filter. Filter is 1st order, 159 Hz 3 dB BW.

10 PWM1 O 8-bit pulse-width modulated output 1 with internal low-pass filter. Filter is 1st order, 159 Hz 3 dB BW.

11 SLEEP/DTR I Default functionality is 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.

12 ADC2 I 10-bit ADC input 0. Full scale reading is referenced to the ADC_REF input.

13 ADC1 I 10-bit ADC input 1. Full scale reading is referenced to the ADC_REF input.

14 ADC0 I 10-bit ADC input 2. Full scale reading is referenced to the ADC_REF input.

15 EX_SYNC I

Rising-edge triggered input for synchronizing co-located bases. Synchronization pulse interval must

equal the hop dwell time ±10 µs. Pulse width must be in the range of 50 µs to 2 ms.

16 DIAG_TX O Diagnostic UART transmitter output.

17 DIAG_RX I Diagnostic UART receiver input.

18 /CFG I

Protocol selection input. Leave unconnected when using software commands to select transpar-

ent/protocol mode (default is transparent mode). Logic low selects protocol mode, logic high selects

transparent mode.

19 VCC I Power supply input, +3.3 to +5.5 Vdc.

20 GND - Power supply and signal ground. Connect to the host circuit board ground.

21 GND - Power supply and signal ground. Connect to the host circuit board ground.

22 GPIO4

I/O 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.

23 GPIO5 I/O Configurable digital I/O port 5. Same configuration options as GPIO4.

24 GND - Logic ground.

25 ACT O Data activity output, logic high when data is being transmitted or received.

26 /DCD O

Default functionality is data carrier detect output, which provides a logic low on a remote when the

module is locked to FHSS hopping pattern and logic low on a base when at least one remote is

connected to it.

www.RFM.com Technical support +1.678.684.2000 Page 27 of 81

Pad Name I/O Description

27 RSVD - Reserved pad. Leave unconnected.

28 RSVD - Reserved pad. Leave unconnected.

29 RSVD - Reserved pad. Leave unconnected.

30 /HOST_RTS I UART flow control input. The host sets this line low to allow data to flow from the DNT2400 on the

RADIO_TXD pin. When the host sets this line high, the DNT2400 will stop sending data.

31 RADIO_TXD O UART transmitter output. The DNT2400 sends serial data to the host on this pin.

32 RADIO_RXD I UART receiver input. The DNT2400 receives serial data from the host on this pin.

33 /HOST_CTS O

UART flow control output. The DNT2400 sets this line low to indicate it is ready to accept data from

the host on the RADIO_RXD input. When the DNT2400 sets this line high, the host must stop

sending data.

34 VMOD O Module’s +3.3 V regulated supply output. Connect to pad 3 to support 3.3 V full scale and/or

ratiometric ADC readings, etc. Current drain on this output should be no greater than 5 mA.

35 RSVD - Reserved pad. Leave unconnected.

36 RSVD - Reserved pad. Leave unconnected.

37 RSVD - Reserved pad. Leave unconnected.

38 RSVD - Reserved pad. Leave unconnected.

39 /RESET I Active low module hardware reset.

40 RSVD - Reserved pad. Leave unconnected.

41 GND - RF ground (DNT2400C only). Connect to the host circuit board ground plane.

42 RFIO

I/O Alternate RF port to the U.FL connector (DNT2400C 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.

43 GND - RF ground (DNT2400C only). Connect to the host circuit board ground plane.

Table 3.2.1

3.3 DNT2400C RFIO Stripline

C o p p e r

G r o u n d

P l a n e

C o p p e r

S t r i p l i n e

T r a c e

F R - 4 P C B

M a t e r i a l

C i r c u i t B o a r d S t r i p l i n e T r a c e D e t a i l

F o r 5 0 o h m i m p e d a n c e W = 1 . 7 5 * H

Figure 3.3.1

The DNT2400C has a U.FL coaxial connector mounted near pad 42 for antenna connection (see Antenna

Connector discussion below). It is also possible to connect an antenna using a stripline from pad 42. It is

www.RFM.com Technical support +1.678.684.2000 Page 28 of 81

important that this connection be implemented as a 50 ohm stripline. Referring to Figure 3.3.1, the width

of this stripline depends on the thickness of the circuit board between the stripline and the groundplane.

For FR-4 type circuit board materials (dielectric constant of 4.7), the width of the stripline is equal to 1.75

times the thickness of the circuit board. Note that other circuit board traces should be spaced away from

the stripline to prevent signal coupling, as shown in Table 3.3.1. The stripline trace should be kept short to

minimize its insertion loss.

Trace Separation from

50 ohm Microstrip

Length of Trace Run

Parallel to Microstrip

100 mil 125 mill

150 mil 200 mil

200 mil 290 mil

250 mil 450 mil

300 mil 650 mil

Table 3.3.1

3.4 DNT2400 Antenna Connector

A U.FL miniature coaxial connector is provided on both DNT2400 configurations for connection to the

RFIO port. A short U.FL coaxial cable can be used to connect the RFIO port directly to an antenna. In this

case the antenna should be mounted firmly to avoid stressing the U.FL coaxial cable due to antenna

mounting flexure. Alternately, a U.FL coaxial jumper cable can be used to connect the DNT2400 module

to a U.FL connector on the host circuit board. The connection between the host circuit board U.FL con-

nector and the antenna or antenna connector on the host circuit board should be implemented as a 50

ohm stripline. Referring to Figure 3.3.1, the width of this stripline depends on the thickness of the circuit

board between the stripline and the groundplane. For FR-4 type circuit board materials (dielectric con-

stant of 4.7), the width of the stripline is equal to 1.75 times the thickness of the circuit board. Note that

other circuit board traces should be spaced away from the stripline to prevent signal coupling, as shown

in Table 3.3.1. The stripline trace should be kept short to minimize its insertion loss.

3.5 Input Voltages

DNT2400 radio modules can operated from an unregulated DC input (Pad 19) in the range of 3.3 (trough)

to 5.5 V (peak) with a maximum ripple of 5% over the temperature range of -40 to 85 oC. Applying AC,

reverse DC, or a DC voltage outside the range given above can cause damage and/or create a fire and

safety hazard. Further, care must be taken so logic inputs applied to the radio stay within the voltage

range of 0 to 3.3 V. Signals applied to the analog inputs must be in the range of 0 to ADC_REF (Pad/Pin

3). Applying a voltage to a logic or analog input outside of its operating range can damage the DNT2400

module.

3.6 ESD and Transient Protection

The DNT2400C and DNT2400P circuit boards are electrostatic discharge (ESD) sensitive. ESD precau-

tions must be observed when handling and installing these components. Installations must be protected

from electrical transients on the power supply and I/O lines. This is especially important in outdoor instal-

lations, and/or where connections are made to sensors with long leads. Inadequate transient protection

can result in damage and/or create a fire and safety hazard.

www.RFM.com Technical support +1.678.684.2000 Page 29 of 81

3.7 Interfacing to 5 V Logic Systems

All logic signals including the serial ports on the DNT2400 are 3.3 V signals. To interface to 5 V signals,

the resistor divider network shown in Figure 3.5.1 below must be placed between the 5 V signal outputs

and the DNT2400 signal inputs. The output voltage swing of the DNT2400 3.3 V signals is sufficient to

drive 5 V logic inputs.

5 V

L o g i c D N T 5 0 0

2 . 2 K

4 . 3 K

Figure 3.7.1

3.8 Power-On Reset Requirements

When applying power to the DNT2400, the /RESET pin should be held low until the power supply voltage

reaches 3.3 volts for 100 milliseconds.

3.9 Mounting and Enclosures

DNT2400C radio modules are mounted by reflow soldering them to a host circuit board. DNT2400P

modules are mounted by plugging their pins into a set of mating connectors on the host circuit board.

Refer to Section 8.3 and/or the DNT2400 Data Sheet for DNT2400P connector details.

DNT2400 enclosures must be made of plastics or other materials with low RF attenuation to avoid com-

promising antenna performance where antennas are internal to the enclosure. Metal enclosures are not

suitable for use with internal antennas as they will block antenna radiation and reception. Outdoor enclo-

sures must be water tight, such as a NEMA 4X enclosure.

3.10 Labeling and Notices

DNT2400 FCC Certification - The DNT2400 hardware has been certified for operation under FCC Part 15

Rules, Section 15.247.

DNT2400 FCC Notice - This device complies with Part 15 of the FCC rules. 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.

DNT2400 FCC Label - A clearly visible label is required on the outside of the user’s (OEM) enclosure

stating ”Contains FCC ID: HSW-DNT2400.”

WARNING: This device operates under Part 15 of the FCC rules. Any modification to this device, not

expressly authorized by RFM, Inc., may void the user’s authority to operate this device.

DNT2400

www.RFM.com Technical support +1.678.684.2000 Page 30 of 81

Canadian Department of Communications Industry Notice - IC: 4492A-DNT2400

This apparatus complies with Health Canada’s Safety Code 6 / IC RSS-210.

IC RSS-210 Notice - Operation is subject to the following two conditions: (1) this device may not cause

interference, and (2) this device must accept any interference, including interference that may cause

undesired operation of the device.

Canadian ICES-003 - This digital apparatus does not exceed the Class B limits for radio noise emissions

from digital apparatus as set out in the radio interference regulations of Industry Canada.

Le present appareil numerique n’emet pas de bruits radioelectriques depassant les limites applicables

aux appareils numeriques de Classe B prescrites dans le reglement sur le brouillage radioelectrique

edicte par Industrie Canada.

www.RFM.com Technical support +1.678.684.2000 Page 31 of 81

4.0 Protocol Messages

4.1 Protocol Message Formats

The DNT2400 is configured and controlled through a series of protocol mode messages. All protocol

mode messages have a common header format:

0 1 2 3 …

SOP

Length PktType variable number of arguments …

Figure 4.1.1

The scale above is in bytes.

The Start-of-Packet (SOP) character, 0xFB, is used to distinguish the beginning of a message and to

assure synchronization in the event of a glitch on the serial port at startup.

The Length byte is defined as the length of the remainder of the message following the length byte itself

(or the length of the entire message - 2).

The Packet Type (PktType) byte specifies the type of message. It is a bitfield-oriented specifier, decoded

as follows:

Bits 7-6 Reserved for future use

Bit 5 Event - set to indicate this message is an event

Bit 4 Reply - set to indicates this message is a reply

Bits 3-0 Type - indicates the message type/command

As indicated, the lower 4 bits (3-0) specify a message type. Bit 4 is a modifier indicating that the message

is a command or a reply. A reply message has the original command type in bits 3:0, with bit 4 set to one.

Arguments vary in size and number depending on the type of message and whether it is a message sent

from the host or is a reply from the radio; see Table 4.1.2.1 below. Messages that are generated on the

serial interface by the user are referred to as host messages. Messages that are generated by the radio

are referred to as reply messages. For many message types, there is a reply message that corresponds

to a host message. For example, when the host sends a TxData message, the radio will reply to indicate

the status of the transmission, whether it succeeded or failed. Some message types are host-only or

reply-only; refer to Table 4.1.2.1 for specifics.

4.1.1 Message Types

Each message generally has two forms, a command from the host and a reply from the radio. Depending

on the direction, they have different arguments as shown in Table 4.1.2.1. Event messages from the radio

such as received data packets or status announcements make up a third category of messages. To assist

in interpreting the command-reply data flow, the direction is indicated by the high nibble in the message

type. For example, an EnterProtocolMode command from the host is a message type 0x00, and the

EnterProtocolModeReply from the radio is a message type 0x10. Event messages, including RxData,

RxEvent and Announce packets are indicated by 0x20 in the high nibble of the type byte. If multiple

arguments are to be provided, they are to be concatenated in the order shown. Little-Endian byte format

www.RFM.com Technical support +1.678.684.2000 Page 32 of 81

is used for all multi-byte arguments, where the lowest order byte is the left-most byte of the argument and

the highest order byte in the right-most byte of the argument.

4.1.2 Message Format Details

Com-

mand Reply Event Description Direction Arguments

0x00 - - EnterProtocolMode from Host DNT2400 (ASCII characters)

- 0x10 - EnterProtocolModeReply from Radio none

0x01 - - ExitProtocolMode from Host none

- 0x11 - ExitProtocolModeReply from Radio none

0x02 - - SoftwareReset from Host BootSelect

- 0x12 - SoftwareResetReply from Radio none

0x03 - - GetRegister from Host Reg, Bank, Span

- 0x13 - GetRegisterReply from Radio Reg, Bank, Span,Val

0x04 - - SetRegister from Host Reg, Bank, Span, Val

- 0x14 - SetRegisterReply from Radio none

0x05 - - TxData from Host Addr, Data

- 0x15 - TxDataReply from Radio TxStatus, Addr, RSSI

- - 0x26 RxData from Radio Addr, RSSI, Data

- - 0x27 Announce from Radio AnnStatus, additional fields

- - 0x28 RxEvent from Radio Addr, RSSI, Reg, Bank, Span,Val

0x0A - - GetRemoteRegister from Host Addr, Reg, Bank, Span

- 0x1A - GetRemoteRegisterReply from Radio

If command successful:

TxStatus, Addr, RSSI,

Reg, Bank, Span, Val

If command failed:

TxStatus, Addr

0x0B - - SetRemoteRegister from Host Addr, Reg, Bank, Span, Val

- 0x1B - SetRemoteRegisterReply from Radio TxStatus, Addr, RSSI

- - 0x2C JoinRequest from Radio Addr,3 Reserved Bytes ,

0x0C - - JoinReply from Host Addr, PermitStatus

0x0D - - RemoteLeave from Host Addr, BackOffTime

Table 4.1.2.1

Arguments:

Reg = Register location (1 byte)

Bank = Register bank, which provides logical isolation from other data regions (1 byte)

Span = Number of bytes of register data to get or set; must align to a parameter boundary (1 byte)

Val = Value to read/write to/from a register (see table 4.1.2.1 for size and acceptable range).

Data = User data (must fit within the slot size allocation)

Addr = the MAC address of the destination node in a command, the MAC address of a node sending a

reply or event message, or the MAC address of the originating node in an RxData message (3 bytes)

TxStatus = Result of last TxData operation (1 byte)

0 = Acknowledgement received

1 = No acknowledgement received

2 = Not linked (remote)

3 = No ACK due to recipient holding for flow control

www.RFM.com Technical support +1.678.684.2000 Page 33 of 81

RSSI = 2’s complement value in dBm, with a range of -128 (0x80) to +125 (0x7D) dBm (1 byte);

large positive RSSI values will not occur under ordinary circumstances. RSSI values 126 (0x7E)

and 127 (0x7F) have special meaning:

0x7F = No RSSI measured because no ACK was received

0x7E = reserved for future use

NwkID = Network identifier of network joined (1 byte).

BaseMacAddr = MAC address of base that the remote joined (3 bytes).

AnnStatus = Status announcement (1 byte). Additional fields are also reported

depending on the status code:

Status code Additional fields

A0 = Radio has completed startup initialization none

A2 = Base: a remote has joined the network Addr, reserved, Range

A3 = Remote: joined a network, ready for data NwkID, BaseMacAddr, Range

A4 = Remote: exited network (base is out of range) NwkID

A7 = Base: remote has left the network. Addr

Status codes for error conditions Additional fields

E0 = Protocol error - invalid message type none

E1 = Protocol error - invalid argument none

E2 = Protocol error - general error none

E3 = Protocol error - parser timeout none

E4 = Protocol error - register is read-only none

E8 = UART receive buffer overflow none

E9 = UART receive overrun none

EA = UART framing error none

Range = Range measurement of joining radio (1 byte). Each count equals 0.29 miles.

BootSelect = Code indicating whether to do a normal reset or a reset to the bootloader (1 byte)

(0 = normal reset, 1 = reset to bootloader)

PermitStatus = Permission for new node to join, 0x00 = denied, 0x01 = permitted (1 byte)

BackoffTime = Time that a node will avoid trying to join a network, in seconds (2 bytes)

(0xFFFF = back off until reset or power cycled)

4.1.3 /CFG Select Pin

A falling edge on the /CFG pin is the equivalent of the EnterProtocolMode command. A rising edge on the

/CFG pin is the equivalent to sending the ExitProtocolMode command. The input to the /CFG pin is de-

bounced to make it compatible with a mechanical switch or jumper.

4.1.4 Flow Control

There are two flow control signals between the radio and the host, /HOST_RTS and /HOST_CTS. See

Section 2.11 for flow control details.

www.RFM.com Technical support +1.678.684.2000 Page 34 of 81

4.1.5 Protocol Mode Data Message Example

In this example, ASCII text Hello World is sent from the base to a remote using a TxData command. The

MAC address of the remote is 0x000102. The protocol formatting for the host message is:

0xFB 0x0F 0x05 0x02 0x01 0x00 0x48 0x65 0x6C 0x6C 0x6F 0x20 0x57 0x6F 0x72 0x6C 0x64

There are 15 bytes following the length byte, so the length byte is set to 0x0F. Note that the 0x000102

MAC address is entered in Little-Endian byte order 0x02 0x01 0x00.

When an ACK to this message is received from the remote, the base outputs a TxDataReply message to

its host:

0xFB 0x06 0x15 0x00 0x02 0x01 0x00 0xC4

The 0x00 TxStatus byte value indicates the ACK reception from the remote. The RSSI value of the re-

ceived ACK is 0xC4 (-60 dBm).

If the remote is in protocol mode, the message is output in the following format:

0xFB 0x10 0x26 0x00 0x00 0x00 0xC4 0x48 0x65 0x6C 0x6C 0x6F 0x20 0x57 0x6F 0x72 0x6C 0x64

The message is output as an 0x26 event. The address field contains the base (originator) address. Note

that the RSSI value 0xC4 is inserted between the base MAC address and the Hello World user data.

4.2 Configuration Registers

The configuration registers supported by the DNT2400 are described below. Registers are sorted into

banks according to similar functions. Default register values are in bold. All changes to parameters are

temporary and will not persist through power cycling until 0x01 has been written to the MermorySave

parameter in Bank FF. Writing 0x00 to the MemorySave parameter will reload the factory default values

which also require writing 0x01 to the MemorySave location. Also note that some parameter changes do

not take effect until they are saved and the module is reset or power cycled. Modules can be reset by

writing 0x00 to the UcReset parameter in Bank FF.

4.2.1 Bank 0 - Transceiver Setup

Size in

Bank Loc'n Name R/W bytes Range Default, Options

00 00 DeviceMode R/W 1 0..2 0 = Remote, 1= Base, 2 = PTT Remote

00 01 RF_DataRate R/W 1 0..4 0 = 500, 1 = 200, 2 = 115.2, 3 = 38.4 kb/s,

0XFF = auto

00 02 HopDuration R/W 2 4..4000 10 ms (0x00C8)

00 04 InitialNwkID R/W 1 0..255 0xFF = join any network

00 05 SecurityKey R/W 16 0..2128 all null bytes (0x00) = security disabled

00 15 SleepMode R/W 1 0..1 0 = off, 1 = timer, 2 = interrupt

00 16 WakeResponseTime R/W 1 0..255 1 = 50 ms, 0 to disable

00 17 WakeLinkTimeout R/W 1 0..255 5 s

00 18 TxPower R/W 1 0..2 0 = 1 mW; 1 = 10 mW, 2 = 63 mW

00 19 ExtSyncEnable R/W 1 0..1 0 = off; 1 = enable

00 1A DiversityMode R/W 1 0..2 0 = 0 V, 1 = 3.3 V, 2 = toggle

00 1B Reserved 1

00 1C UserTag R/W 16 "DNT2400"

00 2C RegDenialDelay R/W 2 10 s

00 2E RmtTransDestAddr R/W 3 0x000000 (Base)

Note: These settings are individual to each module.

www.RFM.com Technical support +1.678.684.2000 Page 35 of 81

DeviceMode - selects the operating mode for the radio: remote, base, or PTT remote (listen mostly

remote). Note that changing this setting does not take effect immediately. It must be followed by a Mem-

orySave command (See Section 4.2.9) and then a hardware reset.

RF_DataRate - this sets the over-the-air data rate. DNT2400’s with different RF data rates cannot inter-

communicate. The following codes are defined:

0x00 = 500 kb/s (default)

0x01 = 200 kb/s

0x02 = 115.2 kb/s

0x03 = 38.4 kb/s

0xff = auto

The auto setting will cause a remote to try all four over-the-air rates when scanning for a network to join.

Setting the RF_DataRate to a fixed value on the remotes will allow a network to link much faster than

using the auto setting. However, if the base RF_DataRate is changed when the remotes are set to a fixed

rate, the network will not link. Note that changing this setting does not take effect immediately. It must be

followed by a MemorySave command (See Section 4.2.9) and then a hardware reset.

HopDuration - this sets the duration of the hop frame. The duration is set as a 12-bit value,

0.05 ms/count. Changing the hop duration must be followed by a MemorySave command to allow the

change to persist through a reset or power cycle. A HopDuration change takes effect immediately. Re-

motes will re-link following a HopDuration parameter change.

InitialNwkID - selects the initial network ID that the radio will start (if a base) or join (if a remote). A value

of 0xFF instructs a remote to operate in 'promiscuous mode' and join any network it finds (if set for a

base, this will select the default network ID of 0x00.) The network ID also sets the base frequency at

which the hopping pattern starts, as illustrated by the following equation:

FrequencyIndex[n] = HoppingPattern[n + NetworkID mod 32]

This allows the user to coordinate frequency spacing of co-located networks to maintain a constant sepa-

ration as they hop. The InitialNwkID values of co-located networks should be two apart (0, 2, 4 … or 1, 3,

5 …) for best results.

SecurityKey - this sets the 128-bit AES encryption key to be used. To protect the key, this is a write-only

parameter for the user (always reads back as 0x2A). Refer to the Section 2.13 for further information.

SleepMode - this parameter enables sleep mode, which may be used in conjunction with the automatic

I/O reporting feature to wake up on specified triggers. Sleep mode is only available for remotes, and the

channel access mode for the network must be one of the CSMA modes.

WakeResponseTime - this parameter sets the length of time that a remote in sleep mode will wait for a

response after sending an I/O report before going back to sleep, from a minimum of 10 ms to a maximum

of 2.5 seconds in 10 ms units. This time interval is set to allow the base host application to respond to a

remote with a packet before the remote returns to sleep. If this parameter is set to 0, the remote will stay

awake indefinitely after sending an I/O report. This allows the application as much time as needs for any

initial configuration after which it can cause the remote to re-enter sleep by setting this to the operating

value.

www.RFM.com Technical support +1.678.684.2000 Page 36 of 81

WakeLinkTimeout - this parameter sets the maximum length of time that a remote in sleep mode will

spend trying to acquire a link to its base before going back to sleep, from a minimum of 100 ms to 25.5 s

in 100 ms units. If this value is set to 0, the remote will stay awake and continue trying to link to its base

indefinitely.

TxPower - this parameter sets the transmit power level used by the base (fixed), and the maximum trans-

mit power level used by a remote. A remote may automatically adjust its power below the TxPower set-

tings based on the signal strength it receives from the base plus the TxPower setting being used by the

base. The default 1 mW TxPower setting is useful for desktop testing. TxPower is usually set to a higher

level to increase operating range in actual applications. Setting bit 4 (0001xxxx) disables the remote

automatic transmit power function.

0x00 = 0 dBm or 1 mW (default)

0x01 = 10 dBm or 10 mW

0x02 = 18 dBm or 63 mW

ExtSyncEnable - this parameter enables or disables the hardware EX_SYNC function on Pin 15. When

enabled, a pulse train can be input on Pin 15 to synchronize the transmission of co-located bases. Dis-

abled by default.

DiversityMode - the following diversity antenna switching options are supported as an output on GPIO5:

0 = 0 V output (default)

1 = 3.3 V output

2 = hop-by-hop toggle between 0 and 3.3 V

UserTag - this is a user definable field intended for use as a location description or other identifying tag

such as a “friendly name”.

RegDenialDelay - when a remote has been removed from a network through a RemoteLeave, the Reg-

DenialDelay parameter sets the length of time the remote will wait before considering that network a

candidate for joining again. Units are in seconds; the default is 10 s.

RmtTransDestAddr - this parameter sets the destination address that a remote will send packets to when

configured to use transparent mode. The default destination is the base (0x000000). If this field is set to

another remote's MAC address or to the broadcast address, a peer-to-peer packet will be sent. Note that

peer-to-peer packets have higher latency than direct packets between base and remote. This setting has

no effect on the base.

4.2.2 Bank 1 - System Settings

Size in

Bank Loc'n Name R/W bytes Range Default; Options

01 00 FrequencyBand R/W 1 0..FF 0x00 to 0x08 = general purpose,

0x04,

0x05 & 0x07 = France, 0xFF = auto

01 01 AccessMode R/W 1 0..4 2 = TDMA Dynamic Slots

01 02 BaseSlotSize R/W 1 6..233 50 bytes

01 03 LeasePeriod R/W 1 0..250 5 s (0 to disable)

01 04 ARQ_Mode R/W 1 0..3 1 = redundant broadcast to ARQ_AttemptLimit,

ARQAttemptLimit pass to remotes enabled

01 05 ARQ_AttemptLimit R/W 1 0..63 8 attempts

01 06 MaxSlots R/W 1 0..15 16 slots

01 07 CSMA_Predelaty R/W 1 0..255 0x03

01 08 CSMA_Backoff R/W 1 0..255 0x0A

01 09 MaxPropDelay R/W 1 0..255 0x45 (20 mi, 32.18 km)

01 0A LinkDropThreshold R/W 1 0..255 0x0C

www.RFM.com Technical support +1.678.684.2000 Page 37 of 81

01 0B CSMA_RemtSlotSize R/W 1 1..255 50

01 0C CSMA_BusyThreshold R/W 1 1..255 20

01 0D RangingInterval R/W 1 0..255 0 = disable

01 0E AuthMode R/W 1 0..3 0 = authentication disabled

01 0F PeerReplyTimeout R/W 1 8 hops

Bank 1 holds configuration parameters to be input to the base only. The base passes these parameters to

the remotes as needed. The exception is the ARQ_AttemptLimit parameter. If ARQ_Mode bit 1 is set to 1

at the base, the ARQ_AttemptLimit parameter can be set in the remotes and used.

FrequencyBand - this parameter selects the frequency hopping subband. Nine subbands are available,

as shown below. Note that operation in France is limited to subbands 0x04, 0x05 and 0x07.

Subband Channels Frequency Range(s) Notes

0x00 37 2409.3-2467.1 MHz General purpose 37 channel subband

0x01 17 2441.1-2467.1 MHz 17 channel subband, avoids 802.11b/g channels 1-4

0x02 17 2409.3-2416.6 MHz, 2451.2-2467.1 MHz 17 channel subband, avoids 802.11b/g channels 5-6

0x03 17 2409.3-2426.7 MHz, 2461.3-2467.1 MHz 17 channel subband, avoids 802.11b/g channels 7-8

0x04 17 2409.3-2435.3 MHz 17 channel subband, avoids 802.11b/g channels 9-10,

also for use in France

0x05 21 2409.3-2441.1 MHz 21 channel subband, avoids 802.11b/g channels

11-13, also for use in France

0x06 21 2428.1-2461.3 MHz 21 channel subband, avoids 802.11 b/g channel 1

0x07 15 2409.3-2432.4 MHz 15 channel subband, avoids 802.11b/g channels

8-13, also for use in France

0x08 15 2433.9-2455.6 MHz 15 channel subband, avoids 802.11b/g channels

1-2 and 13

0xFF 15 to 37 Auto Autoscan for remote to match base

AccessMode - this sets the channel access mode that remotes will use to communicate with the base:

Access Mode Description Max # of Remotes Remote Slot Size

0 Polling unlimited manual

1 CSMA unlimited manual

2 (default) TDMA dynamic slots up to 16 automatic

3 TDMA fixed slots up to 16 automatic

4 TDMA with PTT up to 16 automatic

BaseSlotSize - This parameter set the maximum number of user data bytes that the base can send on a

single hop. This value must be set by the user for all access modes. The default value is 50 bytes.

LeasePeriod - this sets the duration in seconds for leases that remotes receive from the base. If a period

of zero is specified, then lease functions are disabled. The minimum valid lease period is two seconds.

Remotes will attempt to renew their leases at an interval equal to half the lease period. For example, if the

lease period is set to four seconds, remotes will renew their leases every two seconds.

ARQ_Mode - this sets the ARQ mode for delivery of application messages. In ARQ mode, an ACK is

expected from the receiving radio for each message addressed and sent to it. If no ACK is received, up to

ARQ_AttemptLimit, attempts to send the data will be made, after which the message is discarded. In

redundant broadcast mode, each broadcast message is sent exactly ARQ_AttemptLimit times. No ACKS

are sent or expected. The following bit options control this function:

bits 7..2 Not used

bit 1 If set to 0, the base can pass a new ARQ_AttemptLimit to the remotes

If set to 1, the remotes use their own ARQ_AttemptLimit in Bank 1

bit 0 If set to 1, ARQ mode is enabled for Protocol mode; the base will send broadcast packets ARQ_AttemptLimit

times instead of once. If set to 0, broadcast packets are sent once

www.RFM.com Technical support +1.678.684.2000 Page 38 of 81

ARQ_AttemptLimit - this sets the maximum number of attempts that will be made to send a data packet

on the RF link. Setting this parameter to the maximum value of 63 is a flag value indicating that there

should be no limit to the number of attempts to send each packet (infinite number of attempts). This mode

is intended for point-to-point networks in serial data cable replacement applications where absolutely no

packets can be lost. Note - if this mode is used in a multipoint network, one remote that has lost link will

shut down the entire network if the base is trying to send it data.

MaxNumSlots - in TDMA access modes, this sets the number of slots that are allowed. In fixed slot mode,

this allocates the number of slots directly. In dynamic slot mode, this sets the maximum number of slots

that may be generated regardless of the number of remotes that attempt to link with the base. Any re-

motes requesting registration after this limit is reached will be denied registration by the base.

CSMA_Predelay - in CSMA mode 1, this parameter sets the maximum delay between when the base

transmission has finished and when a remote checks for a clear channel. Refer to Section 2.9.2 for more

information.

CSMA_Backoff - in a CSMA mode 1, this sets the length of time that a remote will back off after it detects

a busy channel. Refer to Section 2.9.2 for more information.

MaxPropDelay - this is the maximum propagation delay that the base and the remotes will use in their slot

timing calculations, in units of 3.1 µs. This is used to increase the amount of time dedicated to the regis-

tration slot. Increasing this value will subtract slightly from the overall slot time available to remotes for

sending data. Note that the free-space round trip propagation delay for one mile is 10.72 µs. Each incre-

ment of MaxPropDelay thus corresponds to a maximum radius from the remote to the base of 0.29 mi

(0.46 km). The default setting provides enough time to handle remotes up to 20 miles away. It is recom-

mended to use the default setting unless a path greater than 20 miles is planned at start up. Once linked

to the base, remotes will periodically update their timing based on ranging information from the base,

except in Polling Mode. The frequency with which this value is updated is set by the RangingInterval

parameter discussed below. The current range information is available in the CurrPropDelay parameter.

LinkDropThreshold - this is the number of consecutive beacons missed by a remote that causes the

remote to restart a link acquisition search. Please contact RFM technical support before making changes

to the parameter.

CSMA_RemtSlotSize - this sets the maximum size for a remote data transmission in polling or CSMA

channel access modes. Setting this parameter to a large value allows a remote to send more data in a

single hop, but can result in fewer remotes having time to send on a given hop. The default is 50 bytes.

CSMA_BusyThreshold - this sets the RSSI energy detection threshold that remotes use to determine

whether the channel is occupied. The factory default should be sufficient for most applications and it is

recommended that this value not be changed.

RangingInterval - this sets the period at which remotes will reassess their range to the base. Polling

(mode 0) disables the ranging interval mechanism, so remotes receive ranging information only once

each time they join a network. The RangingInterval timer does not advance while a remote is sleeping.

AuthMode - this parameter is valid on the base only. It controls how remotes are permitted to join the

network. Permitted values are:

www.RFM.com Technical support +1.678.684.2000 Page 39 of 81

0 = Any remote may join

1 = Authentication by base radio permission table

2 = Authentication by request to host application

3 = Lock authentication to permit only currently registered remotes

PeerReplyTimeout - This sets the reply timeout for peer-to-peer packets sent from one remote to another.

Because each leg of the journey from one remote to another and back may take multiple transmit at-

tempts, the length of time to confirm receipt and issue a TxDataReply is subject to more variation than a

normal transmission between base and remote. The PeerReplyTimeout parameter specifies the maxi-

mum number of hops that a remote will wait for a reply from its recipient. If a reply returns sooner than the

timeout, the remote will send a TxDataReply indicating success to its host as soon as it is received and

cancel the timeout. If a reply does not come back before the timeout expires, the remote will send a

TxDataReply to its host indicating failure. If a reply should come back after the timeout expires the remote

will ignore it, as a TxDataReply has already been sent. Units are in hops; the default is 8 hops.

4.2.3 Bank 2 - Status Registers

Size in

Bank Loc'n Name R/W bytes Range Default

02 00 MacAddress R 3 0..0x0ffffff fixed value

02 03 Reserved R 1 0..255 reserved

02 04 CurrNwkID R 1 0..255 as set

02 05 CurrRF_DataRate R 1 0..4 as set

02 06 CurrFreqBand R 1 0..1 as set

02 07 LinkStatus R 1 0..1 current status

02 08 RemoteSlotSize R 1 0..243 as set

02 09 TDMA_NumSlots R 1 0..16 as set

02 0A Reserved R 1 0..255 reserved

02 0B TDMA_CurrSlot R 1 0..16 current slot

02 0C HardwareVersion R 1 0..255 0x00 = DNT2400 rev A

02 0D FirmwareVersion R 1 0..255 current firmware load

02 0E FirmwareBuildNum R 2 0..216 current firmware load

02 10 Reserved R 1 0..255 reserved

02 11 SuperframeCount R 1 0..255 current value

02 12 RSSI_Idle R 1 0..255 as set

02 13 RSSI_Last R 1 0..255 as set

02 14 CurrTxPower R 1 0..255 as set

02 15 CurrAttemptLimit R 1 0..255 as set

02 16 CurrRangeDelay R 1 0..255 as set

02 17 FirmwareBuildDate R 8 ASCII as set

02 1F FirmwareBuildTime R 8 ASCII as set

02 27 ModelNumber R 1 0..255 0x02

MacAddress - returns the radio's unique 24-bit MAC address.

CurrNwkID - This returns the network ID of the network that the radio is currently assigned to or con-

nected to. A value of 0xFF means the radio is scanning for a network but has not yet joined one.

CurrRF_DataRate - this returns the RF data rate of the network that the radio is currently assigned to or

connected to. A value of 0xFF means the radio is scanning for a network but has not yet joined one.

CurrFreqBand - this returns the frequency band of the network that the radio is currently assigned to or

connected to. A value of 0xFF means the radio is scanning for a network but has not yet joined one.

www.RFM.com Technical support +1.678.684.2000 Page 40 of 81

LinkStatus - this returns the radio's current connection status to the network. The following codes are

defined:

LinkStatus Remote Status Base Status

0 initializing initializing

1 unlinked, scanning for a network not used

2 linked, acquiring network parameters not used

3 linked, registering with the base not used

4 linked and registered ready for data transfer

RemoteSlotSize - returns the current remote slot size, defined as the maximum number of bytes a remote

can send on a single hop. When using protocol mode, the entire packet, including overhead bytes must

be less than or equal to this value or the packet will be discarded. In the three TDMA modes the remote

slot size is automatically computed, and this value is read-only. In polling and CSMA modes, the remote

slot size must be set by the user. The parameter to set this is CSMA_RemtSlotSize in Bank 1.

TDMA_NumSlots - in TDMA access modes, this returns the number of slots currently allocated.

TDMA_CurrSlot - returns the current TDMA slot number assigned to the remote in modes where the slot

position is automatically computed. In modes where this number is not applicable, it is read as 0xFF.

HardwareVersion - returns an identifier indicating the type of radio. A value of 0x41 is defined for the

DNT2400 Rev A hardware.

FirmwareVersion - returns the firmware version of the radio in 2-digit BCD format.

FirmwareBuildNum - returns the firmware build number, in binary format.

SuperframeCount - returns the current superframe count. The count increments every 64 hops.

RSSI_Idle - returns the last measurement of RSSI made during a time when the RF channel was idle.

Can be used to assess the noise floor or detect interferers.

RSSI_Last - returns the last measurement of RSSI made during the receipt of an RF packet with a valid

CRC. Can be used for network commissioning and diagnostic purposes.

CurrTxPower - returns the current transmitter power setting, allowing the automatic power setting to be

tracked. This parameter is the nominal output power setting in dBm, and is a 2’s complement value.

CurrAttemptLimit - this returns the value of ARQ_AttemptLimit currently in use (depending on the selected

ARQ_Mode, it may not always match the local EEPROM value).

CurrRangeDelay - returns the current propagation delay for this remote as measured from the base

(applies to remote nodes only).

FirmwareBuildDate - date of firmware build in MM/DD/YY format.

FirmwareBuildTime - time of firmware build in HH:MM:SS format.

ModelNumber - DNT model number parameter, 0x01 = DNT900, 0x02 = DNT2400.

www.RFM.com Technical support +1.678.684.2000 Page 41 of 81

4.2.4 Bank 3 - Serial

Size in

Bank Loc'n Name R/W bytes Range Default

03 00 SerialRate R/W 2 0..216 9.6 kb/s (0x0030)

03 01 SerialParams R/W 1 0..7 8N1

03 03 SerialControls R/W 1 0..7 0x07

SerialRate - sets the serial rate divisor according to the following formula:

Serial rate in b/s = 460800/SerialRate

Serial rate division settings for commonly used baud rates are:

Setting Serial rate

0x0000 460.8 kb/s

0x0001 460.8 kb/s

0x0002 230.4 kb/s

0x0004 115.2 kb/s

0x0006 76.8 kb/s

0x0008 57.6 kb/s

0x000C 38.4 kb/s

0x0010 28.8 kb/s

0x0018 19.2 kb/s

0x0030 9.6 kb/s (default)

0x0060 4.8 kb/s

0x00C0 2.4 kb/s

0x0180 1.2 kb/s

Note that if a value of 0x0000 is specified, the maximum data rate of 460.8 kb/s will be selected.

SerialParams - sets the serial mode options for parity and stop bits:

Setting Mode

0x00 No parity, 8 data bits, 1 stop bit (default)

0x01 No parity, 8 data bits, 2 stop bits

0x02 Reserved

0x03 Reserved

0x04 Even parity, 8 data bits, 1 stop bit

0x05 Even parity, 8 data bits, 2 stop bits

0x06 Odd parity, 8 data bits, 1 stop bit

0x07 Odd parity, 8 data bits, 2 stop bits

Note that 8-bit data with no parity is capable of carrying 7-bit data with parity for compatibility without loss

of generality for legacy applications that may require it.

SerialControls - this parameter affects the way the radio responds to the various serial control lines.

Enabling or disabling response to some serial control signals can facilitate communicating with devices

that support only a reduced serial interface. The parameter is defined as a bitmask, with the following

options:

bits 7..3 Reserved

bit 2 Base /DCD mode:

1 = The base will only assert /DCD when at least one remote is registered (default).

0 = The base always asserts /DCD, regardless of whether any remotes are attached.

bit 1 /HOST_RTS enable:

1 = Radio will respond to changes on the /HOST_RTS control line (default).

0 = Radio ignores the /HOST_RTS pin and assumes flow control is always asserted.

bit 0 SLEEP/DTR enable.

1 = Radio will respond to changes on the SLEEP Pin (default)

0 = Radio ignores the SLEEP Pin and is always in the awake state.

www.RFM.com Technical support +1.678.684.2000 Page 42 of 81

4.2.5 Bank 4 - Host Protocol Settings

Size in

Bank Loc'n Name R/W bytes Range Default; Options

04 00 ProtocolMode R/W 1 0..1 0 = transparent; 1 = protocol

04 01 ProtocolOptions R/W 1 0..255 0x05

04 02 TxTimeout R/W 1 0..255 0 ms

04 03 MinPacketLength R/W 1 1..255 1 byte

04 04 AnnounceOptions R/W 1 0..7 0x07 all enabled

04 05 TransLinkAnnEn R/W 1 0..1 0 = disabled; 1 = <LINK> announce

04 06 ProtocolSequenceEn R/W 1 0..2 0 = disabled; 1 = startup, 2 = anytime

04 07 TransPtToPtMode R/W 1 0..1 0 = multipoint, 1 = point-to-point

ProtocolMode - this parameter selects the host protocol mode. The default is 0, which is transparent

mode, meaning the radio conveys whatever characters that are sent to it transparently, without requiring

the host to understand or conform to the DNT2400's built-in protocol. This setting is recommended for

point-to-point applications for legacy applications such as wire replacements where another serial proto-

col may already exist. Setting this parameter to 1 enables the DNT2400 host protocol, which is recom-

mended for point-to-multipoint applications and is preferred for new designs. It is not necessary to define

the same protocol mode for all radios in a network. For example, it is frequently useful to configure all the

remotes for transparent mode and the base for protocol mode. Note that it is possible for the host to

switch the radio from transparent mode to protocol mode and back if desired by transmitting an EnterPro-

tocolMode command.

ProtocolOptions - this is a bitmask that selects various options for the protocol mode. The default is 0x05.

bits 7..3 Reserved

bit 2 Enable output of TxReply packets

bit 1 Reserved

bit 0 Enable output of Announce packets

AnnounceOptions - this is a bitmask that enables/disables different types of Announce packets:

bit 7..3 Reserved

bit 2 Enable bit for Announce types E0-EA (error notification)

bit 1 Enable bit for Announce types A1-A7 (<LINK> notifications)

bit 0 Enable bit for Announce types A0 (initialization)

TxTimeout - this parameter is the transmit timeout used for determining message boundaries in transpar-

ent data mode. Units are in milliseconds. A message boundary is determined whenever a gap between

consecutive characters is equal to or greater than the TxTimeout value, or the number of bytes reaches

the MinPacketLength. Either condition will trigger a transmission. The default TxTimeout value is 0 ms.

MinPacketLength - sets the minimum message length used for determining packet boundaries in trans-

parent data mode. The default is one byte. A transmission is triggered when either the number of bytes

reaches MinPacketLength or a gap is detected between consecutive characters greater than TxTimout.

TransLinkAnnEn - enables a link announcement function for transparent mode. Whenever link is acquired

or dropped, the strings "<LINK>" or "<DROP>" are sent to the local host.

ProtocolSequenceEn - enables or disables the EnterProtocolMode ASCII command string to switch from

transparent mode to protocol mode. Valid settings are 0 = disabled, 1 = one time at startup, 2 = enabled

at any time. The default is enabled at anytime.

TransPtToPtMode- controls the behavior for addressing packets in transparent mode. When this setting is

zero (default), in transparent mode the base will direct packets to the broadcast address. This is useful for

www.RFM.com Technical support +1.678.684.2000 Page 43 of 81

point-to-multipoint where the base is sending data to multiple remotes, for instance in applications where

a wireless link is replacing an RS-485 serial bus. When this setting is one, in transparent mode the base

will direct packets to the last remote that registered with it. This is useful for point-to-point networks where

there are only two endpoints, for instance in applications where a simple serial cable is being replaced.

4.2.6 Bank 5 - I/O Peripheral Registers

Size in Range

Bank Loc'n Name R/W bytes in bits Default

05 00 GPIO0 R/W 1 1 0

05 01 GPIO1 R/W 1 1 0

05 02 GPIO2 R/W 1 1 0

05 03 GPIO3 R/W 1 1 0

05 04 GPIO4 R/W 1 1 0

05 05 GPIO5 R/W 1 1 0

05 06 ADC0 R 2 10 N/A

05 08 ADC1 R 2 10 N/A

05 0A ADC2 R 2 10 N/A

05 0C Event Flags R 2 10 N/A

05 0E PWM0 R/W 2 9 0

05 10 PWM1 R/W 2 9 0

GPIO0..5 - writing to these registers sets the corresponding driver for pins that are enabled outputs.

Writing to pins that are enabled as inputs enables or disables the internal pull-up. Reading these registers

returns the current level detected on the corresponding pins.

ADC0..2 - read-only, returns the current 10-bit ADC reading for the selected register. See the discussion

of the ADC_SampleIntvl parameter below.

EventFlags - used with the automatic I/O reporting feature, this parameter indicates which I/O events

have been triggered since the last report message:

bits 15..8 Reserved

bit 7 ADC2 high/low threshold excursion

bit 6 ADC1 high/low threshold excursion

bit 5 ADC0 high/low threshold excursion

bit 4 Periodic timer report

bit 3 GPIO3 edge transition

bit 2 GPIO2 edge transition

bit 1 GPIO1 edge transition

bit 0 GPIO0 edge transition

PWM0..1 - sets the PWM (DAC) outputs. The DC voltage derived from the integrated low-pass filters on

the PWM output provides an effective DAC resolution of 7 bits (8 bits achievable with external filtering).

The range of this parameter is 0x0000 to 0x00FF.

4.2.7 Bank 6 - I/O setup

Size in Range

Bank Loc'n Name R/W bytes in bits Default; Options

06 00 GPIO_Dir R/W 1 6 0 (all inputs)

06 01 GPIO_Init R/W 1 6 0 (all zeros)

06 02 GPIO_Alt R/W 1 6 0x08 = use GPIO3 for RS485 enable

06 03 GPIO_Edge Trigger R/W 1 8 0x00

06 04 GPIO_SleepMode R/W 1 1 0 = off; 1 = use sleep I/O states

06 05 GPIO_SleepDir R/W 1 6 0 (all inputs)

06 06 GPIO_SleepState R/W 1 6 0 (all zeros)

06 07 PWM0_Init R/W 2 10 0x0000

06 09 PWM1_Init R/W 2 10 0x0000

06 0B ADC_SampleIntvl R/W 2 16 0x0001 (10 ms)

06 0D ADC0 ThresholdLo R/W 2 10 0x0000

06 0F ADC0_ThresholdHi R/W 2 10 0x03FF

www.RFM.com Technical support +1.678.684.2000 Page 44 of 81

06 11 ADC1_ThresholdLo R/W 2 10 0x0000

06 13 ADC1_ThresholdHi R/W 2 10 0x03FF

06 15 ADC2_ThresholdLo R/W 2 10 0x0000

06 17 ADC2_ThresholdHi R/W 2 10 0x03FF

06 19 IO_ReportTrigger R/W 1 0..1 0x01 (GPIO0)

06 1A IO_ReportInterval R/W 4 32 0x00000BB8 (every 30 seconds)

GPIO_Dir - this parameter is a bitmask that sets whether the GPIOs are inputs (0) or outputs (1). The

default is all inputs.

GPIO_Init - this parameter is a bitmask that sets the initial value for any GPIOs which are enabled as

outputs. For GPIOs enabled as inputs, this sets the initial pull-up setting.

GPIO_Alt - provides and alternate function for GPIO3 as an RS-485 driver enable.

GPIO_EdgeTrigger - when GPIO triggers are enabled for automatic I/O reporting, this function controls

the trigger behavior:

bits 7..6 GPIO3 edge function

bits 5..4 GPIO2 edge function

bits 3..2 GPIO1 edge function

bits 1..0 GPIO0 edge function

The bit values for each GPIO map to the following settings:

Value GPIO edge behavior

11 Rising edge trigger, neither level keeps remote awake

10 Bidirectional edge trigger, neither level keeps remote awake

01 Rising edge trigger, holding high keeps remote awake

00 Falling edge trigger, holding low keeps remote awake

GPIO_SleepMode - when set to 1, this parameter enables setting of GPIOs to the designated direction

and state whenever a device is asleep.

GPIO_SleepDir - when GPIO_SleepMode is enabled, this parameter functions as a secondary GPIO_Dir

to set the direction of the GPIOs during a device’s sleep period. This enables the user to provide alternate

configurations during sleep that will help minimize current consumption. Bits 0..5 correspond to

GPIO0..GPIO5. Set a GPIO_SleepDir bit to 1 to specify an output, or to 0 to specify an input.

GPIO_SleepState - when GPIO_SleepMode is enabled, this parameter functions as a bitmask to control

the states of the GPIOs, the RADIO_TXD output, and the /HOST_CTS and /DCD outputs during a de-

vice’s sleep period. This allows the user to set alternate configurations during sleep to minimize current

consumption. Bits 0..5 correspond to GPIO0..GPIO5 respectively. Bit 6 sets the state of RADIO_TXD,

and bit 7 sets the states of /HOST_CTS and /DCD. A sleep state bit is set to 1 to specify a high output or

an internal pull-up on an input, or to 0 to specify a low output or no internal pull-up on an input. Bit 6 must

be set low in order to achieve minimum sleep current (high impedance load assumed), and the other bits

may need to be set low or high depending on their external loads. When bit 6 is set low, expect a serial

“break” condition to occur as the module wakes from sleep. The serial break condition can be eliminated

by setting bit 6 high, but sleep current will be increased.

PWM0_Init - this parameter sets the initial value for PWM0 at startup.

PWM1_Init - this parameter sets the initial value for PWM1 at startup.

www.RFM.com Technical support +1.678.684.2000 Page 45 of 81

ADC_SampleIntvl - this parameter sets the interval between the beginning of one ADC read cycle and the

next ADC read cycle. The three ADC inputs are read on each ADC read cycle. Each ADC_SampleIntvl

count equals 10 ms. This interval will be the worst-case latency for ADC generated interrupts. This inter-

val is independent of the IO_ReportInterval as the ADCs will be read again on that interval.

ADC0..2_ThresholdLo/Hi - these values define thresholds to trigger an I/O report based on ADC meas-

urements. If I/O reporting is enabled, a single EVENT report containing the contents of the I/O bank is

generated when a threshold is crossed. Reporting is "edge-triggered" with respect to threshold bounda-

ries, not "level-triggered"; i.e., if the measurement remains there, additional reports are not triggered until

the value crosses the threshold again. The thresholds are met whenever one of the following inequalities

are satisfied:

ADCx < ADCx_ThresholdLo

ADCx > ADCx_ThresholdHi

IO_ReportTrigger - when a selected trigger source is enabled, a trigger event will cause the remote to

send an EVENT message to its base containing the entire current values of the I/O Register Bank from

GPIO0 up to and including the EventFlags, but not the PWM settings which are output-only.

bit 7 ADC2 high/low thresholds

bit 6 ADC1 high/low thresholds

bit 5 ADC0 high/low thresholds

bit 4 Periodic report timer

bit 3 GPIO3 edge

bit 2 GPIO2 edge

bit 1 GPIO1 edge

bit 0 GPIO0 edge

I/O reporting is supported for remotes only, not the base.

IO_ReportInterval - when periodic I/O reporting is enabled, this parameter sets the interval between

reports. Units are 10 ms increments, and the default report interval is every 30 seconds but can be set as

long as 497 days.

4.2.8 Bank 7 - Authentication List

Size in

Bank Loc'n Name R/W bytes

07 00 ApprovedAddr0 R/W 3

07 03 ApprovedAddr1 R/W 3

07 06 ApprovedAddr2 R/W 3

07 09 ApprovedAddr3 R/W 3

07 0C ApprovedAddr4 R/W 3

07 0F ApprovedAddr5 R/W 3

07 12 ApprovedAddr6 R/W 3

07 15 ApprovedAddr7 R/W 3

07 18 ApprovedAddr8 R/W 3

07 1B ApprovedAddr9 R/W 3

07 1E ApprovedAddr10 R/W 3

07 21 ApprovedAddr11 R/W 3

07 24 ApprovedAddr12 R/W 3

07 27 ApprovedAddr13 R/W 3

07 2A ApprovedAddr14 R/W 3

07 2D ApprovedAddr15 R/W 3

ApprovedAdd0..15 - the three-byte parameters in Bank 7 are the MAC addresses of the remotes author-

ized to join the network. The addresses are entered in little-endian format such that a radio with MAC

address 012345 would be entered 0x452301.

www.RFM.com Technical support +1.678.684.2000 Page 46 of 81

4.2.9 Bank FF - Special Functions

This bank contains three user functions, UcReset, SleepModeOverride and MemorySave:

Bank Loc'n Name R/W bytes Range Description

FF 00 UcReset W 1 0..90 0x00 = reset, 0x5A = reset with factory defaults,

FF 0C SleepModeOverride R/W 1 0..2 0 = inactive, 1 = stay awake, 2 = cancel stay awake

FF FF MemorySave W 1 0..1 0 = load factory defaults, 1 = save settings

to EEPROM

UcReset - writing a value of 0x00 to this location forces a software reset of the microcontroller. This will

enable those changes which require a reset. If this is written to before 0x01 is written to the MemorySave

parameter, the last parameter values saved before the reset will be in effect. A reply packet, either local

or over-the-air, may not be received when writing a value to this register. Writing 0x5A to this location will

reset the radio and load the factory default settings. This is equivalent to writing 0x00 to UcReset followed

by writing 0x00 to MemorySave. Note that 0x01 must be written to MemorySave to save the retrieved

factory defaults.

SleepModeOverride - when remotes are operating in sleep mode, writing 0x01 to the location will cause

the remotes to say awake. Writing 0x00 to this location causes the remotes to resume sleeping in 10 sec-

onds. Writing 0x02 to this location causes the remotes to resume sleeping immediately (subject to their

configuration).

MemorySave - writing a 0x00 to this location clears all registers back to factory defaults. Writing 0x01 to

this location commits the current register settings to EEPROM. When programming registers, all changes

are considered temporary until this command is executed.

4.2.10 Protocol Mode Configuration Example

In this example, the host configures the base to transmit 10 dBm (10 mW) of RF power using the SetReg-

ister command, 0x04. The TxPower parameter is stored in bank 0x00, register 0x18. A one-byte parame-

ter value of 0x01 selects the 10 dBm (10 mW) power level. The protocol formatting for the command is:

0xFB 0x05 0x04 0x18 0x00 0x01 0x01

Note the order of the bytes in the command argument: register, bank, span, parameter value. When the

base receives the command it updates the parameter setting and return a SetRegisterReply message as

follows:

0xFB 0x01 0x14

In order for this new RF power setting to persist through a base power down, MemorySave must be

invoked. This is done by setting a one-byte parameter in register 0xFF of bank 0xFF to 0x01 with another

SetRegister command:

0xFB 0x05 0x04 0xFF 0xFF 0x01 0x01

The base will write the current parameter values to EEPROM and return a

SetRegisterReply message:

0xFB 0x01 0x14

www.RFM.com Technical support +1.678.684.2000 Page 47 of 81

4.2.11 Protocol Mode Sensor Message Example

In this example, the base host requests an ADC1 reading from a remote using the GetRemoteRegister

command, 0x0A. The MAC address of the remote is 0x000102. The current ADC1 measurement is read

from register 0x08 in bank 0x05. The ADC reading spans two bytes. The protocol formatting for this

command is:

0xFB 0x07 0x0A 0x02 0x01 0x00 0x08 0x05 0x02

Note the remote MAC address 0x000102 is entered in Little-Endian byte order, 0x02 0x01 0x00. The

ADC reading is returned in a GetRemoteRegisterReply message:

0xFB 0x0B 0x1A 0x00 0x02 0x01 0x00 0xC4 0x08 0x05 0x02 0xFF 0x02

Substantial information is returned in the message. The last two byes of the message give the ADC

reading in Little-Endian format, 0xFF 0x02. The ADC reading is thus 0x02FF. The RSSI value is the byte

following the address, 0xC4 (-60 dBm). The TxStatus byte to the right of the GetRemoteRegisterReply

Packet Type is 0x00, showing the packet was acknowledged on the RF channel.

4.2.12 Protocol Mode Event Message Example

In this example, the IO_ReportInterval is set to 10 seconds and the periodic report timer bit in the

IO_ReportTrigger parameter is set on the remote, with MAC address 0x123456. This causes event mes-

sages to be sent from this remote every 10 seconds. The IO_ReportInterval and the IO_ReportTrigger

parameters are loaded using SetRemoteRegister commands. The command to set the IO_ReportInterval

to 10 seconds is:

0xFB 0x0B 0x0B 0x56 0x34 0x12 0x1A 0x06 0x04 0xE8 0x03 0x00 0x00

The IO_ReportInterval parameter starts in location 0x1A of bank 0x06. The report interval is set in 10 ms

units, so a 10 second report interval is 1000 units or 0x000003E8 (Little-Endian format E8 03 00 00). The

IO_ReportInterval parameter is updated and SetRemoteRegisterReply is returned:

0xFB 0x06 0x1B 0x00 0x56 0x34 0x12 0xC4

The command to set the periodic report timer bit in IO_ReportTrigger to is:

0xFB 0x08 0x0B 0x56 0x34 0x12 0x19 0x06 0x01 0x10

The periodic report timer bit in IO_ReportTrigger is located in bit position four (00010000b) or 0x10. The

IO_ReportTrigger parameter is updated and SetRemoteRegisterReply is returned:

0xFB 0x06 0x1B 0x00 0x56 0x34 0x12 0xC4

The remote will start sending event messages on 10 second intervals as shown in the log records below:

FB 16 28 56 34 12 CB 00 05 0E 01 00 00 00 01 01 F9 01 DF 01 C9 01 10 00

FB 16 28 56 34 12 B6 00 05 0E 01 00 00 00 01 01 F8 01 DF 01 CC 01 10 00

FB 16 28 56 34 12 B3 00 05 0E 01 00 00 00 01 01 F8 01 E0 01 CC 01 10 00

FB 16 28 56 34 12 B1 00 05 0E 01 00 00 00 01 01 F9 01 DF 01 C9 01 10 00

FB 16 28 56 34 12 AE 00 05 0E 01 00 00 00 01 01 F9 01 DF 01 C8 01 10 00

FB 16 28 56 34 12 AD 00 05 0E 01 00 00 00 01 01 F9 01 E1 01 CF 01 10 00

IO_ReportTrigger generates RxEvent messages (PktType 0x28). The message payload consists of the

first 14 bytes in Bank 5, including the state of GPIO0 through GPIO5, the input voltages measured by

ADC0 through ADC2, and the state of the event flags. Note the ADC readings and the event flags are

presented in Little-Endian order.

www.RFM.com Technical support +1.678.684.2000 Page 48 of 81

5.0 DNT2400DK Developer’s Kit

Figure 5.0.1 shows the main contents of a DNT2400DK Developer’s kit:

Figure 5.0.1

5.1 DNT2400DK Kit Contents

• Two DNT2400P radios installed in DNT2400 interface boards (labeled Base and Remote)

• Two 2 dBi dipole antennas with two U.FL coaxial jumper cables

• Two 9 V wall-plug power suppliers, 120/240 VAC, plus two 9 V batteries (not show above)

• Two RJ-45/DB-9F cable assemblies, one RJ-11/DB-9F cable assembly, two A/B USB cables

• One DNT2400DK documentation and software CD

5.2 Additional Items Needed

To operate the kit, the following additional items are needed:

• One PC with Microsoft Windows XP or Vista Operating System. The PC must be equipped with a

USB port or a serial port capable of operation at 9.6 kb/s.

5.3 Developer’s Kit Operational Notes:

DNT2400DK kits are preconfigured to run at a 500 kb/s RF data rate with 1 mW of RF transmitter power.

Due to the high sensitivity of the DNT2400 radio module which provides its exceptional range, if the RF

transmit power is increased from the default 1 mW, the DNT2400 nodes must be separated by a

minimum of 6 feet for 10 mW or 25 feet at 63 mW in order to reliably link.

www.RFM.com Technical support +1.678.684.2000 Page 49 of 81

5.4 Developer’s Kit Default Operating Configuration

The default operating configuration of the DNT2400DK developer’s kit is TDMA Mode 2, point-to-point,

with transparent serial data at 9.6 kb/s, 8N1. One DNT2400P is preconfigured as a base and the other as

a remote. Labels on the bottom of the interface boards specify Base or Remote. The defaults can be

overridden to test other operating configurations using the DNT Demo utility discussed in Section 5.5. The

default RF power setting is 0 dBm (1 mW), which is suitable for operation at a spacing of about 1.5 to 2 m

(4 to 6 ft). The RF power level should be set higher as needed for longer range operation. Note that

setting the RF power to a high level when doing testing at 2 m can overload the DNT2400P receiver and

cause erratic operation. See Section 5.3.

5.5 Developer’s Kit Hardware Assembly

Observe ESD precautions when handling the kit circuit boards. The components that make up a devel-

opment board are shown in Figure 5.5.1, and are shipped with the DNT2400P radios and U.FL coax

jumper cables installed in the interface board. If a DNT2400P radio and/or the U.FL jumper cable has

been unplugged after receipt, confirm the DNT2400P is correctly plugged into its interface board with the

radio oriented so that its U.FL connector is next to the U.FL connector on the interface board, as shown in

Figure 5.5.2. Also check the radio’s alignment in the socket on the interface board. No pins should be

hanging out over the ends of the connector. Next, install the dipole antennas.

Figure 5.5.1 Figure 5.5.2

www.RFM.com Technical support +1.678.684.2000 Page 50 of 81

As shown in Figure 5.5.3, there is a jumper on pins J14. This jumper can be removed and a current meter

connected across J14 to measure just the DNT2400’s current consumption during operation.

Figure 5.5.3

www.RFM.com Technical support +1.678.684.2000 Page 51 of 81

There are three serial connectors on the interface boards, as shown in Figure 5.5.4. The RJ-45 connector

provides a high-speed RS232 interface to the DNT2400P’s main serial port. The USB connector provides

an optional interface to the radio’s main serial port. The RJ-11 connector provides a high-speed RS232

interface to the radio’s diagnostic port. The DNT Demo utility program runs on the radio’s main port.

Figure 5.5.4

Many desktop PCs have a built-in serial port capable of operation at 9.6 kb/s. The kit can be run satisfac-

torily at the 9.6 kb/s data rate, but not at its fastest throughput. Use the RJ-45 to DB-9F cable assemblies

for serial port operation.

Optionally, the kit development boards can be run from USB ports. Plugging in the USB cable automati-

cally switches operation from the RJ-45 connector. The USB interface is based on an FT232RL serial-to-

USB converter IC manufactured by FTDI. The FT232RL driver files are located in the i386 and AMD64

folders on the kit CD, and the latest version of the drivers can downloaded from the FTDI website,

www.ftdichip.com. The drivers create a virtual COM port on the PC. Power the Base using one of the

supplied wall-plug power supplies. Next connect the Base to the PC with a USB cable. The PC will find

the new USB hardware and open a driver installation dialog box. Enter the letter of the drive holding the

kit CD and click Continue. The installation dialog will run twice to complete the FT232R driver installation.

5.6 DNT Demo Utility Program

The DNT Demo utility requires only one PC for initial kit operation and sensor applications (ADC, PWM

and digital I/O). Two serial/USB ports are required for bidirectional serial communications. Section 5.6.1

below covers using the DNT Demo utility for initial kit operation and familiarization. Section 5.6.2 covers

serial message communication and radio configuration.

www.RFM.com Technical support +1.678.684.2000 Page 52 of 81

5.6.1 Initial Kit Operation

Create a file folder on the PC and copy the contents of the kit CD into the folder.

The DNT Demo utility program runs on the radio’s main port. The preferred PC interface is a serial port

capable of operating at 9.6 kb/s or faster. As discussed above, the USB interface can also be used,

Connect the Base to the PC and power up the Base and the Remote development boards with the

supplied wall-plug power supplies.

The DNT Demo utility program is located in the PC Programs folder. The DNT Demo requires no

installation and can be simply copied to the PC and run. Start the DNT Demo on the PC. The start-up

window is shown in Figure 5.6.1.1.

Figure 5.6.1.1

www.RFM.com Technical support +1.678.684.2000 Page 53 of 81

Click on Connect to open the Select Comm Port Settings dialog box, as shown in Figure 5.6.1.2. Set the

baud rate to 9600 (9.6 kb/s). Set the CommPort to match the serial port connected to the Base, either the

hardware port or the USB virtual serial port. Then click OK to activate the serial connection.

Figure 5.6.1.2

At this point the Demo will collect data from the Base, filling in data in the Local Radio column on the

Demo window as shown in Figure 5.6.1.3. The Status Window should also show that the Remote has

joined the Base. Click on the drop-down box at the top of the Radio 1 column and select the MAC

Address for the Remote. Next press the Start button using the default 1 second Refresh Delay.

Figure 5.6.1.3

www.RFM.com Technical support +1.678.684.2000 Page 54 of 81

The Demo will display updated data on the Remote in the Radio 1 column, including bar graphs of RSSI

signal strength in dBm and percent packet success rate, as shown in Figure 5.6.1.4. Adjusting the large

pot on the Remote can be observed on the Potentiometer (ADC1) row.

Figure 5.6.1.4

To perform serial data loop back testing with the kit, move the two jumpers on the Remote board labeled

Ext_TX and Ext_RX to connect the center and right header pins. This disconnects the module's TX and

RX pins from the USB and RS-232C circuits. Use a banana clip or other short jumper to connect together

the two pins on the header labeled Ext_MICRO. See Figure 5.6.1.5. Attempting loop back testing by

connecting Pins 2 and 3 of the DB9 serial connector can cause erratic behavior due to noise coupling

from the serial TX and RX lines into the weakly pulled up flow control lines on the board.

M o v e E x t _ T X

a n d E x t _ R X

J u m p e r s t o R i g h t

I n s t a l l J u m p e r

o n E x t _ M I C R O

Figure 5.6.1.5

www.RFM.com Technical support +1.678.684.2000 Page 55 of 81

In order to turn off the DCD LED (D4) on the development board in sleep mode, the GPIO_ SleepState

parameter in the DNT2400P has been set to 0xC0 rather than the factory default value of 0x00. If the

DNT2400P is reset to its factory defaults, the DCD LED with remain on in sleep mode until the GPIO_

SleepState is set to 0xC0. See Section 4.2.7 for additional information on the GPIO_SleepState

parameter.

If any difficulty is encountered in setting up the DNT2400DK development kit, contact RFM’s module

technical support group. The phone number is +1.678.684.2000. Phone support is available from 8:30 AM

to 5:30 PM US Eastern Time Zone, Monday through Friday. The E-mail address is tech_sup@rfm.com.

5.6.2 Serial Communication and Radio Configuration

Connect PCs to both the Base and the Remote for serial communication testing. Click the Stop button

under the Refresh Delay label on the I/O Tools tab and move to the Transmit Tools tab, as shown in

Figure 5.6.2.1.

Figure 5.6.2.1

Pressing the Transmit button on this screen sends the message in the Data to Transmit text box to the

selected MAC Address. Data sent to the local radio is displayed in the Received Data text box. Received

data can be displayed as ASCII (default) or in Hexadecimal format by checking the Hex Mode check box.

When the Transmit Interval is set to zero, Data to Transmit is sent once when the Transmit button is

clicked. When the Transmit Interval is set to a positive number, Pressing the Transmit button once will

cause a transmission each transmit interval (seconds) until the button is pressed again.

www.RFM.com Technical support +1.678.684.2000 Page 56 of 81

Returning to the I/O Tools tab, the multi-tab Configuration window for each radio can be accessed by

clicking on its Config button. The data presented on the first six tabs corresponds to configuration register

Banks 0 through 5 as discussed in Section 4.2 above, with the data on the last two tabs corresponding to

configuration register Bank 6.

Figure 5.6.2.2

The Transceiver Setup Tab is shown in Figure 5.6.2.2 and corresponds to Bank 0. The current values of

each Bank 0 parameter are displayed and can be updated by selecting from the drop-down menus or

entering data from the keyboard, and then pressing the Apply Changes button. Note that data is

displayed and entered in Big-Endian order. The Demo automatically reorders multi-byte data to and from

Little-Endian order when building or interpreting messages.

Figure 5.6.2.3

Figure 5.6.2.3 shows the System tab contents, corresponding to Bank 1. The current values of each

parameter are displayed and can be updated by selecting from the drop-down menus or entering data

www.RFM.com Technical support +1.678.684.2000 Page 57 of 81

from the keyboard, and then pressing the Apply Changes button. Note that Bank 1 holds configuration

parameters for the base only except for ARQ_Mode, which applies to both the base and the remotes.

Figure 5.6.2.4

Figure 5.6.2.4 shows the Status tab contents, corresponding to Bank 2. Note the Status tab contains

read-only parameters.

Figure 5.6.2.5

Figure 5.6.2.5 shows the Serial tab contents corresponding to Bank 3. The values shown are the defaults

for serial port operation.

www.RFM.com Technical support +1.678.684.2000 Page 58 of 81

Figure 5.6.2.6

Figure 5.6.2.6 shows the Protocol tab contents, corresponding to Bank 4. Transparent data serial com-

munication is currently chosen.

Figure 5.6.2.7

Figure 5.6.2.7 shows the I/O Peripherals tab contents, corresponding to Bank 5. GPIO ports 1, 3, 4 and 5

are logic high, GPIO port 1 and 2 are logic low. The 10-bit ADC input readings and PWM output settings

are given in Big-Endian byte order. Event flags are presented on the right side of the window.

www.RFM.com Technical support +1.678.684.2000 Page 59 of 81

Figure 5.6.2.8

Figure 5.6.2.8 shows the first I/O Setup tab contents, corresponding to Bank 6 GPIO parameters. This tab

allows the direction of the GPIO ports to be set both for active and sleep modes, and in the case of GPIO

outputs, the initial power up states and sleep mode states to be set. When GPIO ports 0 - 3 are config-

ured as inputs, event interrupts can be set for them with check boxes. The type of interrupt trigger is

selected from the drop-down boxes to the right of the check boxes. GPIO alternate function, periodic I/O

reporting, reporting interval and enable/disable sleep I/O states can also be specified under this tab.

Figure 5.6.2.9

Figure 5.6.2.9 shows the second I/O Setup tab contents, corresponding to Bank 6 ADC input and PWM

output parameters. The ADC sampling interval, high and low thresholds for event reporting and event

reporting triggers on each ADC channel can be set, along with the start-up output values for each PWM

(DAC) channel.

www.RFM.com Technical support +1.678.684.2000 Page 60 of 81

5.7 DNT Wizard Utility Program

The DNT Wizard is a complementary program to the DNT Demo that emphasizes the details of serial

communication between a DNT2400 and its host computer. The DNT Wizard start-up window is shown in

Figure 5.7.1.

Figure 5.7.1

The DNT Wizard uses three Function keys:

F1 toggles the SLEEP/DTR input to the DNT2400 on and off. This allows the DNT2400 to be reset.

F2 toggles the RTS input to the DNT2400 on and off, providing manual flow control.

F6 toggles test transmissions on and off. The test message is “This is a test”.

The DNT Wizard also includes the ability to log messages to and from the DNT2400. This feature is

especially useful in confirming the format of protocol command and reply messages. Control of the log file

is under the View menu. Logging is enabled by default. The log file created is logfile.dat, and is in ASCII

text format. An example log is shown at the end of this section.

www.RFM.com Technical support +1.678.684.2000 Page 61 of 81

Click on Connect to open the Select Comm Port Settings dialog box, as shown in Figure 5.7.2. Set the

baud rate to 9600 (9.6 kb/s). Set the CommPort to match the serial port connected to the Base, either the

hardware port or the USB virtual serial port. Then click OK to activate the serial connection.

Figure 5.7.2

At this point the Wizard will collect data from the Base, filling in data under Current Settings as shown in

Figure 5.7.3. The Status Window should also show that the Remote has joined the Base.

Figure 5.7.3

www.RFM.com Technical support +1.678.684.2000 Page 62 of 81

There are three tabs on the DNT Wizard main window: Receive Data, Transmit Data and Wincom.

Figure 5.7.4

Received messages are displayed in the Receive Data tab, along with the MAC address of the sender

and the RSSI (signal strength) of the received message in dBm. See Figure 5.7.4.

www.RFM.com Technical support +1.678.684.2000 Page 63 of 81

Figure 5.7.5

The Transmit Data tab is shown in Figure 5.7.5. The message to send is input in the Data to Transmit text

box. The address to send the message can be chosen or input in the MAC Addr drop-down box. Note

that the address for the base is always 0x000000. If the Transmit Interval is set to 0, the message is sent

once each time the Transmit button is clicked. When the Transmit Interval is set to an integer greater than

zero, the message will sent at the beginning of each interval until the Stop button (was Transmit button) is

clicked. The status of each transmission is shown below TX Data Reply. Figure 5.7.5 shows that the

transmitted message was ACKed, with the received signal strength of the ACK -66 dBm.

www.RFM.com Technical support +1.678.684.2000 Page 64 of 81

Figure 5.7.6

As shown in Figure 5.7.6, the Wincom tab provides the basic functionality of a serial terminal program.

Messages typed in are sent, and messages received are appended to the bottom of the on-screen text.

www.RFM.com Technical support +1.678.684.2000 Page 65 of 81

The multi-tab Configuration window is accessed by clicking on its Config button. The data presented on

the first six tabs corresponds to configuration register Banks 0 through 5 as discussed in Section 4.2

above, with the data on the last two tabs corresponding to configuration register Bank 6.

Figure 5.7.7

The Configuration window in the DNT Wizard is identical the Configuration window in the DNT Demo. See

Figures 5.6.2.2 through 5.6.2.9 for Configuration window details.

www.RFM.com Technical support +1.678.684.2000 Page 66 of 81

Details of the File, View and Tools menus are shown in Figure 5.7.8.

Figure 5.7.8

The Tools menu contains two very useful items. Packet Builder opens the window shown in Figure 5.7.9.

On the left, the Packet Type drop-down box provides a selection of all packet types used in the DNT2400

protocol. On the right, the reply packet types are presented.

Figure 5.7.9

Figure 5.7.10

www.RFM.com Technical support +1.678.684.2000 Page 67 of 81

Figure 5.7.10 shows the Raw Packet and Raw Packet Reply tabs. Components of the protocol messages

are shown in hexadecimal format.

Log Data controls the log file. Logging is enabled by default. The log file created is logfile.dat, and is in

ASCII text format. An example log is shown below:

New Data------------------------------------------

12/7/2008 | 7:05:39 AM

DNT Wizard Version 0.92

Sent Data : FB 07 00 44 4E 54 35 30 30 (Enter Protocol Mode)

Recv Data : FB 01 10 (Enter Protocol Mode Reply)

Sent Data : FB 04 03 00 00 2C (Get Register)

Recv Data : FB 30 13 00 00 2C 01 FF 68 01 05 2A 2A 2A 2A 2A 2A 2A 2A 2A 2A 2A 2A 2A 2A 2A 2A

00 05 32 00 00 02 02 44 4E 54 39 30 30 00 00 00 00 00 00 00 00 00 00 (Get Register Reply)

Sent Data : FB 04 03 00 01 0E (Get Register)

Recv Data : FB 12 13 00 01 0E 00 03 D2 05 00 05 08 03 0A 0E 0C 30 14 00 (Get Register Reply)

Sent Data : FB 04 03 00 02 27 (Get Register)

Recv Data : FB 2B 13 00 02 27 02 CD FB 00 05 00 00 04 47 08 00 FF 42 14 49 01 18 00 A9 00 00

05 00 31 31 2F 31 38 2F 30 38 31 36 3A 30 30 3A 35 30 (Get Register Reply)

Sent Data : FB 04 03 00 03 04 (Get Register)

Recv Data : FB 08 13 00 03 04 04 00 00 07 (Get Register Reply)

Sent Data : FB 04 03 00 04 08 (Get Register)

Recv Data : FB 0C 13 00 04 08 00 05 05 01 07 00 02 00 (Get Register Reply)

Sent Data : FB 04 03 00 05 12 (Get Register)

Recv Data : FB 16 13 00 05 12 01 00 00 00 01 01 F5 01 FD 01 DA 01 00 00 00 00 00 00 (Get

Sent Data : FB 04 03 00 06 1E (Get Register)

Recv Data : FB 22 13 00 06 1E 00 00 00 01 00 00 00 00 00 00 00 01 00 00 00 FF 03 00 00 FF 03

00 00 FF 03 01 B8 0B 00 00 (Get Register Reply)

Recv Data : FB 07 27 A2 01 CD FB 01 01 (Announce)