Murata Electronics North America 2410M Modular 2.4 GHz Transceiver User Manual Integration Guide

Murata Electronics North America Modular 2.4 GHz Transceiver Integration Guide

Integration Guide

WIT24102.4GHz Spread SpectrumWireless Industrial TransceiverIntegration GuideJune 15, 1999One Meca WayNorcross, Georgia 30093www.digital-wireless.com (770) 564-5540
Note: This device has not been authorizedas required by the rules of the FederalCommunications Commission. This deviceis not, and may not be, offered for sale orlease, or sold or leased, until authorizationis obtained.About This ManualThis manual is designed to allow integration of the Digital Wireless Corporation WIT2410 OEMmodule into complete products. Care has been taken to try and make sure all of the informationin this manual is accurate. However, specifications can change over time and Digital Wirelesscannot guarantee the accuracy of this information. If you have any questions on any informationin this manual, please contact Digital Wireless Technical Support at (770) 564-5540.
TABLE OF CONTENTS1. INTRODUCTION..................................................................................................................................11.1 Why Spread Spectrum?.....................................................................................................................11.2 Frequency Hopping vs. Direct Sequence.........................................................................................22. RADIO OPERATION............................................................................................................................42.1. Synchronization and Registration ...................................................................................................42.2. Data Transmission...........................................................................................................................52.2.1. Point-to-Point ........................................................................................................................52.2.2. Point-to-Multipoint................................................................................................................62.2.3. TDMA Mode.........................................................................................................................62.2.4. CSMA Mode .........................................................................................................................82.2.5. Full Duplex Communication.................................................................................................82.2.6. Error-free Packet Transmission Using ARQ.........................................................................82.3. Modes of Operation.........................................................................................................................92.3.1. Control and Data Modes........................................................................................................92.3.2. Sleep Mode..........................................................................................................................102.3.3. Low Power Mode and Duty Cycling...................................................................................103. PROTOCOL MODES..........................................................................................................................113.1. Packet Formats..............................................................................................................................123.1.1. Data Packet..........................................................................................................................133.1.3. Connect Packet....................................................................................................................133.1.4. Disconnect Packet (base only, receive only)......................................................................134. MODEM INTERFACE........................................................................................................................144.1. Interfacing to 5 Volt Systems........................................................................................................155. MODEM COMMANDS......................................................................................................................165.1. Serial Commands ..........................................................................................................................165.2. Network Commands......................................................................................................................175.3. Protocol Commands......................................................................................................................195.4. Status Commands..........................................................................................................................215.5. Memory Commands......................................................................................................................225.6. Modem Command Summary........................................................................................................236. WIT2410 DEVELOPER’S KIT...........................................................................................................246.1. COM24..........................................................................................................................................246.2. Demonstration Procedure..............................................................................................................256.3. Troubleshooting ............................................................................................................................267. APPENDICES......................................................................................................................................287.1. Technical Specifications ...............................................................................................................287.1.1. Power Specifications ...........................................................................................................287.1.2. RF Specifications.................................................................................................................287.2.2. Mechanical Specifications...................................................................................................287.3. Serial Connector Pinouts...............................................................................................................297.4. Approved Antennas.......................................................................................................................297.5. Technical Support .........................................................................................................................297.6. Mechanical Drawing .....................................................................................................................307.7. Warranty........................................................................................................................................31
© 1999 Digital Wireless Corporation 16/15/991. INTRODUCTIONThe WIT2410 radio transceiver provides reliable wireless connectivity for eitherpoint-to-point or multipoint applications. Frequency hopping spread spectrum technologyensures maximum resistance to noise and multipath fading and robustness in the presence ofinterfering signals, while operation in the 2.4 GHz ISM band allows license-free use andworldwide compliance. A simple serial interface supports asynchronous data up to 230400bps. An on-board 3 KB buffer and an error-correcting over-the-air protocol provide smoothdata flow and simplify the task of integration with existing applications.- Multipath fading imperviousfrequency hopping technologywith 75 frequency channels(2401-2475 MHz).- Supports point-to-point ormultipoint applications.- Meets FCC rules 15.247 and ETS300.328 for worldwide license-free operation.- Superior range to 802.11 wirelessLAN devices.- Transparent ARQ protocolw/3KB buffer ensures dataintegrity.- Digital addressing supports up to32 networks, with 62 remotes pernetwork.- Low power 3.3v CMOS signals- Simple serial interface handles bothdata and control at up to 230400bps. - Fast acquisition typically locks tohopping pattern in 5 seconds or less.- Selectable 10 mW or 100 mWtransmit power.- Support for diversity antenna.- Built-in data scrambling reducespossibility of eavesdropping.- Nonvolatile memory storesconfiguration when powered off.- Smart power management featuresfor low current consumption.- Dynamic TDMA slot assignmentthat maximizes throughput.1.1 Why Spread Spectrum?The radio transmission channel is very hostile, corrupted by noise, path loss andinterfering transmissions from other radios. Even in a pure interference-freeenvironment, radio performance faces serious degradation through a phenomenonknown as multipath fading. Multipath fading results when two or more reflected rays ofthe transmitted signal arrive at the receiving antenna with opposing phase, therebypartially or completely canceling the desired signal. This is a problem particularlyprevalent in indoor installations. In the frequency domain, a multipath fade can bedescribed as a frequency-selective notch that shifts in location and intensity over time asreflections change due to motion of the radio or objects within its range. At any giventime, multipath fades will typically occupy 1% - 2% of the 2.4 GHz band. This meansthat from a probabilistic viewpoint, a conventional radio system faces a 1% - 2% chanceof signal impairment at any given time due to multipath.
© 1999 Digital Wireless Corporation 26/15/99Spread spectrum reduces the vulnerability of a radio system to both interference fromjammers and multipath fading by distributing the transmitted signal over a larger regionof the frequency band than would otherwise be necessary to send the information. Thisallows the signal to be reconstructed even though part of it may be lost or corrupted intransit.Figure 1Narrowband vs. spread spectrum in the presence of interference1.2 Frequency Hopping vs. Direct SequenceThe two primary approaches to spread spectrum are direct sequence (DS) and frequencyhopping (FH), either of which can generally be adapted to a given application. Directsequence spread spectrum is produced by multiplying the transmitted data stream by amuch faster, noise-like repeating pattern. The ratio by which this modulating patternexceeds the bit rate of the baseband data is called the processing gain, and is equal to theamount of rejection the system affords against narrowband interference from multipathand jammers. Transmitting the data signal as usual, but varying the carrier frequencyrapidly according to a pseudo-random pattern over a broad range of channels produces afrequency hopping spectrum system.
© 1999 Digital Wireless Corporation 36/15/99Figure 2Forms of spread spectrumOne disadvantage of direct sequence systems is that due to spectrum constraints and thedesign difficulties of broadband receivers, they generally employ only a minimal amountof spreading (typically no more than the minimum required by the regulating agencies).For this reason, the ability of DS systems to overcome fading and in-band jammers isrelatively weak. By contrast, FH systems are capable of probing the entire band ifnecessary to find a channel free of interference. Essentially, this means that a FHsystem will degrade gracefully as the channel gets noisier while a DS system mayexhibit uneven coverage or work well until a certain point and then give out completely.Because it offers greater immunity to interfering signals, FH is often the preferredchoice for co-located systems. Since direct sequence signals are very wide, they tend tooffer few non-overlapping channels, whereas multiple hoppers may interleave with lessinterference. Frequency hopping does carry some disadvantage in that as the transmittercycles through the hopping pattern it is nearly certain to visit a few blocked channelswhere no data can be sent. If these channels are the same from trip to trip, they can bememorized and avoided; unfortunately, this is generally not the case, as it may takeseveral seconds to completely cover the hop sequence during which time the multipathdelay profile may have changed substantially. To ensure seamless operation throughoutthese outages, a hopping radio must be capable of buffering its data until a clear channelcan be found. A second consideration of frequency hopping systems is that they requirean initial acquisition period during which the receiver must lock on to the moving carrierof the transmitter before any data can be sent, which typically takes several seconds. Insummary, frequency hopping systems generally feature greater coverage and channelutilization than comparable direct sequence systems. Of course, other implementationfactors such as size, cost, power consumption and ease of implementation must also beconsidered before a final radio design choice can be made.As an additional benefit, RF spectrum has been set aside at 2.4 GHz in most countries(including the U.S.) for the purpose of allowing compliant spread spectrum systems tooperate freely without the requirement of a site license. This regulatory conveniencealone has been a large motivation for the industry-wide move toward spread spectrum.
© 1999 Digital Wireless Corporation 46/15/992. RADIO OPERATION2.1. Synchronization and RegistrationAs discussed above, frequency hopping radios periodically change the frequency at whichthey transmit. In order for the other radios in the network to receive the transmission, theymust be listening to the frequency over which the current transmission is being sent. To dothis, all the radios in the net must be synchronized and must be set to the same hoppingpattern. All radios in a net must be set to the same hopping pattern before attempting tocommunicate.In point-to-point or point-to-multipoint arrangements, one radio module is designated as thebase station. All other radios are designated remotes. One of the responsibilities of the basestation is to transmit a synchronization signal to the remotes to allow them to synchronizewith the base station. Since the remotes know the hopping pattern, once they aresynchronized with the base station, they know which frequency to hop to and when. Everytime the base station hops to a different frequency, it immediately transmits a synchronizingsignal.When a remote is powered on, it rapidly scans the frequency band for the synchronizingsignal. Since the base station is transmitting over 75 frequencies and the remote is scanning75 frequencies, it can take several seconds for a remote to synch up with the base station.Once a remote has synchronized with the base station, it must request registration from thebase station. The registration process identifies to the base station the remotes from whichtransmissions will be received and not discarded. Registration also allows tracking ofremotes entering and leaving the network. The base station builds a table of serial numbersof registered remotes. To improve efficiency, the 24-bit remote serial number is assigned a6-bit “handle” number. Two of these are reserved for system use, thus each base station canregister 62 separate remotes. This handle is how user applications will know the remotes. Ifnecessary, the automatic handle assignment can be overridden to explicitly tie certain handlesto certain remotes. See the section on Network Commands for details on the Set DefaultHandle command.To detect if a remote has gone offline or out of range, the registration must be “renewed”once every 256 hops. Registration is completely automatic and requires no user applicationintervention. When the remote is registered, it will receive several network parameters fromthe base. This allows the base to automatically update these network parameters in theremotes over the air. Once a parameter has been changed in the base, it is automaticallychanged in the remotes. The parameters automatically changed are hop duration, the dutycycle and the multiple access mode, i.e., TDMA or CSMA.At the beginning of each hop, the base station transmits a synchronizing signal. After thesynchronizing signal has been sent, the base will transmit any data in its buffer unless packettransmit delay has been set. The packet transmit delay parameter allows for the transmissionof groups of continuous data in transparent mode (protocol mode 0). In TDMA mode the
© 1999 Digital Wireless Corporation 56/15/99amount of data that the base station can transmit per hop is determined by the hop durationand the number of remotes registered with the base. In CSMA mode, the maximum amountof data sent is determined by maximum data length. In any event, the maximum amount ofdata sent by a base station or remote per hop is 127 bytes. If there is no data to be sent, thebase station will not transmit until the next frequency.The operation of the remotes depends on whether the remote is set up for TDMA mode orCSMA mode. In TDMA mode, the operation of the remotes is the same as the base stationwithout the synchronization signal.In CSMA mode, remotes compete on an ad hoc basis for transmission time. The likelihoodthat a remote with will attempt to transmit immediately is affected by the persistenceparameter. If a collision is detected with another radio, the remote will wait a random periodof time before trying to retransmit. The backoff parameter controls the maximum time aremote will wait before attempting to retransmit. Unregistered remotes can requestregistration any time after the base station transmission. Refer to the section ProtocolCommands for details on the persistence and backoff parameters.Except for the registration process which occurs only when a remote logs onto the network,the whole procedure is repeated on every frequency hop. Refer to the section on ModemCommands for complete details on parameters affecting the transmission of data.2.2. Data TransmissionThe WIT2410 supports two network configurations: point-to-point and point-to-multipoint.In a point-to-point network, one radio is set up as the base station and the other radio is set upas a remote. In a point-to-multipoint network, a star topology is used with the radio set up asa base station acting as the central communications point and all other radios in the networkset up as remotes. In this configuration, all communications take place between the basestation and any one of the remotes. Remotes cannot communicate directly with each other.It should be noted that point-to-point mode is a subset of point-to-multipoint mode andtherefore there is no need to specify one mode or the other.2.2.1. Point-to-PointIn point-to-point mode, unless packet transmit delay has been set, the base station willtransmit whatever data is in its buffer limited to 127 bytes or by the length of the base slotsize. If the base station has more data than can be sent on one hop, the remaining data will besent on subsequent hops. In addition to the data, the base station adds some information tothe transmission over the RF link. It adds the address of the remote to which it istransmitting, even though in a point-to-point mode there is only one remote. It also adds asequence number to identify the transmission to the remote. This is needed in the case ofacknowledging successful packets and retransmitting errored packets. Also added is a 24-bitCRC to allow the base to check the received transmission for errors. When the remotereceives the transmission, it will acknowledge the transmission if it was received without
© 1999 Digital Wireless Corporation 66/15/99errors. If no acknowledgment is received, the base station will retransmit the same packet onthe next frequency hop.In point-to-point mode, a remote will transmit whatever data is in its buffer up to the limit ofits maximum packet length. If desired, a minimum packet length can also be set, which forcesthe remote to wait until a certain amount of data is available or the specified packet transmitdelay is exceeded before transmitting. If the remote has more data than can be sent on onehop, it will send as much data as possible as a packet, adding its own address, a packetsequence number and 24-bit CRC. These additional bytes are transparent to the userapplication if the protocol mode is 00 (which is the default). In the event a remote has moredata to send, the data will be sent on subsequent hops. If the packet is received by the basestation without errors, the base station will acknowledge the packet. If the remote does notreceive an acknowledgment, it will retransmit the packet on the next frequency hop. To theuser application, acknowledgments and retransmissions all take place behind the sceneswithout the need for user intervention.2.2.2. Point-to-MultipointIn point-to-multipoint mode, data sent from the user application to the base station must bepacketized by the user application. This is necessary to identify the remote to which the basestation should send data. When the user packet is received by the remote, if the remote is intransparent mode (protocol mode 0), the packetization bytes are stripped by the remote. Inthis instance the remote host receives just data. If the remote is not in transparent mode, theremote host will receive the appropriate packet header as specified by the remote’s protocolmode. Refer to the section Protocol Modes for details on the various packet formats.When a remote sends data to a base station in point-to-multipoint mode, the remote host doesnot need to perform any packetization of the data. The remote will add address, sequenceand CRC bytes as in the point-to-point mode. When the base station receives the data, thebase station will add packetization header bytes according to its protocol mode setting.2.2.3. TDMA ModeFor applications needing guaranteed bandwidth availability, the TDMA mode of theWIT2410 can meet this requirement. This is the default mode of the WIT2410. In TDMAmode, each remote has an assigned time slot during which it can transmit. The base stationtime slot is set independently of the remote time slots through the Set Base Slot Sizecommand. The base station assigns each remote a time slot and informs the remotes of thesize of the time slot. All remote time slots are the same size which is determined by thenumber of remotes registered with the base station. The slot size is a dynamic variable thatchanges as the number of registered remotes changes. The remotes are continually updatedwith the time slot size. This approach continually maximizes the data throughput. The basestation divides the amount of time available per hop by the number of registered remotes upto a maximum of 16 times slots per hop. If the number of registered remotes is greater than16, the time slots will be spread across the required number of hops. For networks with more
© 1999 Digital Wireless Corporation 76/15/99than 16 possible remotes, the Set Duty Cycle command must be used to specify a duty cycle -- the number of hops over which the time slots must be spread. For 1 to 16 remotes, no dutycycle is required; for 17 to 32 remotes a duty cycle of at least ½ is required; and for 33 to 62remotes a duty cycle of ¼ or more is necessary. An added benefit of using the power savemode to set a duty cycle is improved average current consumption efficiency. Refer to theStatus Commands section for details of this command.When setting up a TDMA network, keep in mind that time slot length, maximum packet sizeand hop duration are all interrelated. The hop duration parameter will determine the timeslot size and the maximum amount of data that can be transmitted per hop by the remotes.There is a hard limit of the absolute maximum amount of data that can be sent on any givenhop of 212 bytes regardless of any parameters. The base station requires 1.7 ms overhead fortuning, the synchronization signal and parameter updating, as well as a guard time of 500 usbetween each remote slot. Thus the amount of time allocated per remote slot is roughly:hop duration – base slot – 1.7ms - ( # of registered remotes-1)·500us( # of registered remotes)Take for example a network comprised of a base station and 10 remotes. A hop duration of15 ms is chosen. We decide that the base station needs to be able to send up to 32 bytes eachhop (equivalent to a capacity for the base of ~ 21 kbps). Counting the 1.7 ms overhead forthe base packet and making use of the fact that our RF rate is 460.8 kbps, we determine thatthe base slot requires approximately:Each remote time slot will be:15 ms – 2.3 ms – (9)·0.5 ms 10From our RF data rate of 460.8kbps we see that it takes 17.36 µs to send a byte of data, soeach remote will be able to send up to = 47 bytes of data per hop.Note that the 47 bytes is the actual number of data bytes that can be sent. If the WIT2410 isusing a protocol mode, the packet overhead does not need to be considered. So in thisexample, the total capacity per remote would be:If we figure a minimum margin of safety for lost packets and retransmissions of about 20%,we see that this would be more than sufficient to support 19.2 kbps of continuous data perremote. It is also useful to remember that the asynchronous data input to the WIT2410 is = 0.82 ms0.82 ms17.36µs32·8460.8kbps+ 1.7 ms = 2.3 ms47 bytes15 ms = 25 kbps
© 1999 Digital Wireless Corporation 86/15/99stripped of its start and stop bits during transmission by the radio, yielding a "bonus" of 10/8or 25% in additional capacity.The above calculations are provided as a means of estimating the capacity of a multipointWIT2410 network. To determine the precise amount of capacity, you can actually set up theradio system and then query the maximum packet length from one of the remotes in controlmode to discover its exact setting. Divide this number by the hop duration as above to getthe remote's exact capacity.2.2.4. CSMA ModeCSMA mode is not currently available for the WIT2410.2.2.5. Full Duplex CommunicationFrom an application perspective, the WIT2410 communicates in full duplex. That is, boththe user application and the remote terminal can be transmitting data without waiting for theother to finish. At the radio level, the base station and remotes do not actually transmit at thesame time. If they did, the transmissions would collide. As discussed earlier, the basestation transmits a synchronization signal at the beginning of each hop followed by up tothree packets of data. After the base station transmission, the remotes will transmit. Eachbase station and remote transmission may be just part of a complete transmission from theuser application or the remote terminal. Thus, from an application perspective, the radios arecommunicating in full duplex mode since the base station will receive data from a remotebefore completing a transmission to the remote.2.2.6. Error-free Packet Transmission Using ARQThe radio medium is a hostile environment for data transmission. In a typical office orfactory environment, 1% - 2% of the 2.4 GHz frequency band may be unusable at any giventime at any given station due to noise, interference or multipath fading. For narrowbandradio systems (and also many spread spectrum radio systems which use direct sequencespreading), this would imply a loss of contact on average of over 30 seconds per hour perstation. The WIT2410 overcomes this problem by hopping rapidly throughout the band in apseudo-random pattern. If a message fails to get through on a particular channel, theWIT2410 simply tries again on the next channel. Even if two thirds of the band areunusable, the WIT2410 can still communicate reliably.Data input to the WIT2410 is broken up by the radio into packets. A 24-bit checksum isattached to each packet to verify that it was correctly received. If the packet is receivedcorrectly, the receiving station sends an acknowledgment, or ACK, back to the transmittingstation. If the transmitter doesn't receive an ACK, at the next frequency hop it will attempt to
© 1999 Digital Wireless Corporation 96/15/99send the packet again. When ARQ is enabled, the transmitting radio will attempt to send apacket packet attempts limit times before discarding the packet. A value of 00H disablesARQ. When it is disabled, it is the responsibility of the user application to track errored ormissing packets. A second parameter, ARQ Mode, allows the choice between using ARQ toresend errored packets or always sending a packet packet attempts limit times regardless ofthe success or failure of any given transmission.All of this error detection and correction is transparent to the user application. All the userapplication sees is non-errored data from the modem. However, if the ARQ mode isdisabled, error detection and correction will be the responsibility of the user application.Refer to the Protocol Commands section for complete details.2.3. Modes of Operation2.3.1. Control and Data ModesThe WIT2410 has two modes of operation: Control mode and Data mode. When in ControlMode, the various radio and modem parameters can be modified. When in Data Mode, onlydata can be transmitted. The default mode is Data Mode. There are two ways to enterControl Mode. The first way is to assert the Configure (CFG) pin on the modem. Uponentering Control Mode, the modem will respond with a > prompt. After each command isentered, the modem will again respond with a > prompt. As long as the CFG pin is asserted,data sent to the modem will be interpreted as command data. Once the CFG pin isdeasserted, the modem will return to Data Mode.The second method for entering Control Mode is to send the escape sequence :wit2410 (alllower case) followed by a carriage return. In the default mode, the escape sequence is onlyvalid immediately after power up or after deassertion of the Sleep pin on the modem. Themodem will respond in the same way with a > prompt. To return to Data Mode, enter theExit Modem Control Mode command, z>, or assert and deassert the Sleep pin. There arethree modes for the escape sequence, controlled by the Set Escape Sequence Mode comand,zc:zc=0 Escape sequence disabledzc=1 Escape sequence available once at startup (default setting)zc=2 Escape sequence available at any timeThe zc2 mode setting is useful if the user application has a need to change the modemsettings "on the fly". In this mode the escape sequence is always and may be sent at any timeafter a pause of at least 20ms. The modem will respond in the same way as when in thedefault mode. It is necessary to issue the Exit Modem Control Mode command, z>, beforeresuming data transmission. The escape sequence must be interpreted as data until the lastcharacter is received and as such may be transmitted by the modem to any listening modems.
© 1999 Digital Wireless Corporation 10 6/15/992.3.2. Sleep ModeTo save power consumption for intermittent transmit applications, the WIT2410 supports aSleep Mode. Sleep Mode is entered by asserting the Sleep pin on the modem interface.While in Sleep Mode, the modem consumes less than 50µA. This mode allows the radio tobe powered off while the terminal device remains powered. After leaving Sleep Mode, theradio must re-synchronize with the base station and re-register.2.3.3. Low Power Mode and Duty CyclingTo conserve power, WIT2410 remotes power down the receiver and transmitter betweenhops when not in use. Base stations must remain active all the time to handle anytransmission from any remote. Remotes can save even more power by enabling the dutycycle feature. This feature causes a remote to power down for 2N frequency hops where 1/2Nis the duty cycle. Rather than attempting to transmit on every frequency hop when data is inthe transmit buffer, a remote will attempt to transmit only every 2N hops. Roughly speaking,this will proportionately reduce the average power consumption while increasing averagelatency. When there are more than 16 remotes being operated in TDMA mode, duty cyclingmust be enabled since a maximum of 16 time slots are available per hop.
© 1999 Digital Wireless Corporation 11 6/15/993. PROTOCOL MODESIn point-to-point applications, it is generally desired that the radios operate in a transparentmode. That is, raw unformatted data is sent from the host to the radio and is received as rawdata from the receiving end. The addressing and error detection and correction is stillperformed by the radios, but it is transparent to the user application. To set up a point-to-point network, one radio has to be set up as a base station. When the radios are powered on,the base station will send out the synchronization signal at the beginning of each hop. Theremote will synchronize with the base and automatically request registration. Once theremote is registered, the radios can transmit data. Protocol mode operation is available inpoint-to-point mode if desired.In point-to-multipoint mode, the data sent to the base station by the user application mustadhere to a packet format. This allows transmissions from the base station to be directed to aspecific remote. Data received by a base station from a remote is similarly formatted toidentify to the user application the remote that sent the transmission. The remotes may stilluse transparent mode without formatting to send data to the base, if desired. The WIT2410supports 12 protocol formats which are described in detail below. The protocol format isselected through the Set Protocol Mode command.mode 00 Transparent mode used for point-to-point networks ormultipoint remotes; does not support any packet types.mode 01 This is the simplest protocol mode supporting Data andCommand packets only. No CONNECT orDISCONNECT packets are supported and no sequencenumbers are provided.packet types supported: Datamode 02 This mode includes notification when remotes areregistered or dropped through CONNECT andDISCONNECT packets that are sent to the userapplication at the base station and at the remote. Nosequence numbers are provided.packet types supported: DataCONNECTDISCONNECTmode 04 This is the packet format used by the WIT2400. Thisallows legacy software to operate the WIT2410. Notehowever, that since different air data rates are used,WIT2410s and WIT2400s cannot be mixed in anetwork.packet types supported: 2400 data format(addresses must be limited to 0..62)
© 1999 Digital Wireless Corporation 12 6/15/99 modes 05 – 08 reserved for future use.mode 09 This mode sends the protocol mode 01 packets duringtransmit but receives data transparently.mode 0A This mode sends the protocol mode 02 packets duringtransmit but receives data transparently.mode 0C This mode sends the protocol mode 04 packet duringtransmit but receives data transparently. modes 0D – 0F reserved for future use.mode 11 This mode sends data transparently but supportsprotocol mode 1 during reception.mode 12 This mode sends data transparently but supportsprotocol mode 2 during reception.mode 14 This mode sends data transparently but supportsprotocol mode 4 during reception.3.1. Packet FormatsThe byte formats for each packet type are shown in the table below. Packet fields areorganized to fall on byte boundaries. In the case of bit-level fields, most-significant bits areon the left.WIT2400 packet type (mode 04):DATA 0000 0010 00HH HHHH 0LLL LLLL <0-127 bytes data> 0000 0011MRTP (WIT2410) packet types (modes 01-03):Transmit and Receive:DATA 1110 1001 00HH HHHH 0LLL LLLL <0-127 bytes data>Receive only:CONNECT 1110 1001 10HH HHHH RRRR TTTT 00NN NNNN <3 byte remote ID>DISCONNECT 1110 1001 11HH HHHH 0111 1111H: handle number (0-63)L : data length (0-127)N: remote's previous network number (if roamed)R: receive sequence number (from previous cell)T: transmit sequence number (from previous cell)
© 1999 Digital Wireless Corporation 13 6/15/993.1.1. Data PacketModes 01 & 02: 1110 1001 00HH HHHH 0LLL LLLL <0-127 bytes data>Mode 04 (WIT2400): 0000 0010 00HH HHHH 0LLL LLLL <0-127 bytes data> 0000 0011H: handle number (0-63)L : data length (0-127)This packet carries user data. The handle number is the handle of the sending or receivingremote, depending on whether the data is going to or coming from the base. Up to 127 bytesof user data may be carried per data packet.Handle 63 is reserved for broadcast packets from the base to all remotes. Acknowledgmentrequests are not supported for broadcasts. For this reason, it is a good idea to send broadcastmessages several times to increase the odds of reaching all remotes.3.1.3. Connect Packet1110 1001 10HH HHHH RRRR TTTT 00NN NNNN <3-byte remote ID> (base, receive only)H: handle number (0-62)R: receive sequence number (from previous cell)T: transmit sequence number (from previous cell)N: network number of the previous base (if roamed)1110 1001 10HH HHHH RRRR TTTT 00NN NNNN <3-byte base ID> (remote, receive only)H: handle number (0-62)R: receive sequence numberT: transmit sequence numberN: network number of baseRemotes must go through an automatic registration process when roaming from one base toanother, after loss of contact, or when acquiring a base signal for the first time after powerup. The base then assigns the remote a handle value, may or may not assign it a dedicatedtime slice depending on the user settings, and notifies the user application of the new remotewith a connect packet.The network number of the last base the remote was connected to is given to aid usersoftware in resending orphan packets that may have been sent to the remote's previous cell.If the remote has been powered up for the first time and this is the first base contacted, thelast base ID will be reported as FFH.3.1.4. Disconnect Packet (base only, receive only)1110 1001 10HH HHHH 0111 1111H: handle number (1-62)When a remote goes out of range or roams to another cell, the base issues a disconnect packetto indicate that the remote is no longer available.
© 1999 Digital Wireless Corporation 14 6/15/994. MODEM INTERFACEElectrical connection to the WIT2410 is made through a 16-pin male header on the modemmodule. The signals are 3.3 volt signals and form an RS-232 style asynchronous serialinterface. The table below provides the connector pinout.Pin Signal Type Description1 GND - Signal and chassis ground2 TXD Input Transmit data. Input for serial data to be transmitted. In ControlMode also used to transmit modem commands to the modem.3 RXD Output Receive data. Output for received serial data. In Control Mode, alsocarries receive modem status from the modem.4 Input Configuration selector. Used to switch between Control and DataModes. Normally, CFG will be set for Data Mode. An internal 10Kpull-up enables Data Mode if this signal is left unconnected. ControlMode is also accessible by transmitting an escape sequenceimmediately after wake up or power up.(0v) 1 = Control Mode(3.3v) 0 = Data Mode5 Input Request to send. Gates the flow of receive data from the radio tothe user on or off. In normal operation this signal should beasserted. When negated, the WIT2410 buffers receive data untilRTS is asserted.(0v) 1 = Receive data (RxD) enabled(3.3v) 0 = Receive data (RxD) disabled.6SLEEP Input Sleeps/wakes radio transceiver. In sleep mode all radio functionsare disabled consuming less than 50µA. At wake up, any userprogrammed configuration settings are refreshed from non-volatilememory, clearing any temporary settings that may have been set.(3.3v) 1 = Sleep Radio(0v) 0 = Wake Radio7 Output Data carrier detect. For remotes, indicates the remote hassuccessfully acquired the hopping pattern of the base station.(0v) 1 = Carrier detected (synchronized)(3.3v) 0 = No carrier detected (not synchronized)8 Output Clear to send. Used to control transmit flow from the user to theradio.(0v) 1 = Transmit buffer not full, continue transmitting(3.3v) 0 = Transmit buffer full, stop transmitting 9-15 - - Reserved for future use. Do not connect.16 VCC - Positive supply. Min 3.3 v, 5.0 v nominal, 10.0 v max.RTSDCDCTSCFG
© 1999 Digital Wireless Corporation 15 6/15/994.1. Interfacing to 5 Volt SystemsThe modem interface signals on the WIT2410 are 3.3 volt signals. To interface to 5 voltsignals, the resistor divider network shown below must be placed between the 5 volt signaloutputs and the WIT2410 signal inputs. The output voltage swing of the WIT2410 3.3 voltsignals is sufficient to drive 5 volt logic inputs.10 kΩ15 kΩFrom 5vOutput To 3.3v Input
© 1999 Digital Wireless Corporation 16 6/15/995. MODEM COMMANDSThe WIT2410 is configured and controlled through a series of commands. These commandsare sent to the modem directly when the modem is in Control Mode or through CommandPackets when the modem is in Data Mode. The command syntax is the same for eithermethod, a one- or two-letter command followed by one or more parameters. The modemwill respond with a two-byte message that indicates the new modem parameter value. Thecommands are loosely grouped into five different categories: Serial commands, Networkcommands, Protocol commands, Status commands and Memory commands. Each commandis described in detail below. In the descriptions, brackets ([,]) are used to denote a set ofoptional arguments. Vertical slashes (|) separate selections. For example, given the stringwn[?|0..3f], some legal commands are wn?, wn0, wn3 and wna. Most commands which seta parameter also have a ? option which causes the modem to respond with the currentparameter setting, e.g., wn?5.1. Serial CommandsThese commands affect the serial interface between the modem and the host. The defaultsettings are 9600 bps and protocol mode 0.Command Descriptionsd[?|00..FF] Set Data Rate DivisorData Rate Divisor (hex)1200 bps = BF2400 bps = 5F9600 bps = 1714400 bps = 0F19200 bps = 0B28800 bps = 0738400 bps = 0557600 bps = 03115200 bps = 01230400 bps =00sp[?|00..14] Set Protocol Mode00 = point-to-point transparent mode01 = basic command and data only02 = command, data and connection notification04 =WIT2400 protocol mode05 – 08 =reserved for future use09 = mode 01 during transmit, transparent receive0A = mode 02 during transmit, transparent receive0C = mode 04 during transmit, transparent receive0D – 10 =reserved for future use11 = transparent transmit, mode 01 during receive12 = transparent transmit, mode 02 during receive14 = transparent transmit, mode 04 during receive
© 1999 Digital Wireless Corporation 17 6/15/99Set Data Rate DivisorSets the serial bit rate between the modem and the host. This command takes effectimmediately and will require adjusting the host serial rate to agree. Nonstandard rates maybe programmed by entering a data rate divisor computed with the following formula:DIVISOR = (230400/RATE)-1Round all non-integer values down.Set Protocol ModeEnables the base station to operate in a multipoint network. Depending on the userapplication, more or less acknowledgment may be desired by the application. Remotes canoperate in transparent mode even though the base station is operating in one of thenontransparent modes.When using a protocol mode, make sure to count in packet overhead when calculatingnetwork performance. Refer to the section on Protocol Modes for details on each format.5.2. Network CommandsNetwork commands are used to set up a WIT2410 network and to set radio addressing andconfiguration.Command Descriptionwb[?|0|1] Set Transceiver Mode0 = remote (default)1 = base stationwd[?|0-3f] Set Default HandleUsed to override automatic handle assignment by the base station30 = defaultwg[?|0|1] Enable Global Network Mode0 = Link only to hop pattern specified by wn parameter (default)1 =Link to any hop pattern, regardless of wn parameterwn[?|0-1f] Set Hopping Pattern (Network Number)0 = defaultwp[?|0|1] Set Transmit Power0 = 10mW1 = 100mW (default)wr? Read Receive Signal StrengthSet Transceiver ModeSets modem operation as either base station or remote. Default is remote.Set Default HandleSets handle number between 1 and 62 inclusive for a remote. This handle will override theautomatic handle assignment by the base station. This command can be used in applicationswhere it is desired to have specific modems have specific handles.
© 1999 Digital Wireless Corporation 18 6/15/99When specified for the base, the default handle determines which remote it will address whentransparent protocol mode is in effect.Enable Global Network ModeFor networks with multiple base stations, remotes are ordinarily only able to link to one basestation, set by the hopping pattern. Enable the global mode if you wish to allow remotes tolink to any base station it can hear, acquiring whatever hop pattern is required.Set Hopping PatternThe WIT2410 has 32 preprogrammed hopping patterns (also referred to as networknumbers). By using different hopping patterns, nearby or co-located networks can avoidinterfering with each other’s transmissions. Even if both networks tried to use the samefrequency, on the next hop they would be at different frequencies.Set Transmit PowerThe WIT2410 has two preset transmit power levels, 10mW (10dBm) and 100mW (20dBm).Control of the transmit power is provided through this command. Default is 100mW.Read Receive Signal Strength Indicator (RSSI)This command reports the relative signal strength averaged over the last 10 hops. Thiscommand returns a two-digit hexadecimal value and can range from 00 to FF. This isavailable only at the remotes as the base station is the only source that transmits on a regularbasis. Plus, in a point-to-multipoint network the base will receive a different signal strengthfrom each remote.
© 1999 Digital Wireless Corporation 19 6/15/995.3. Protocol CommandsThese commands can be used to tune the transceiver for optimum transmission of data acrossthe RF link. For most applications, the default values are adequate.Command Descriptionpe[?|0-3] Set Alternative Frequency Band0 = FCC operation. (default)1 = France (ETSI)2 = Spain3 = Japanph[?|00-ff] (base only) Set Hop Duration90H = defaultpk[?|00-d0] Set Minimum Data Length0 = defaultpl? Get Maximum Data LengthD4 = defaultpr[?|00-ff] Set Packet Attempts Limit10H = defaultpt[?|00-ff] Set Packet Transmit Delay00H = defaultpw[?|00-30] (base only) Set Base Slot Size04H = defaultpx[?|0|1] Set ARQ mode.0 = ARQ enabled (default)1 = ARQ disabled (redundant transmission)Note: Incorrect setting of these parameters may result in reduced throughput or loss of data packets.Set Alternative Frequency BandWhen set to 1, limits the operating RF channel set to the 2448 to 2480 MHz frequency bandfor compliance with European ETSI or French regulatory standards. When set to 2, setsappropriate operation for Spain. When set to 3, sets appropriate operation for Japan. Thissetting should be set to 0, for FCC-compliant operation in the US (this is the default).Set Hop DurationSets the length of time the transceiver spends on each frequency channel. A smaller valuewill allow the remote to lock on to the base signal faster at system startup, and will generallydecrease packet latency. A larger value increases network capacity, due to decreasedoverhead in channel switching. The hop duration is specified in 69.4µs increments. Thedefault value of 90H corresponds to a duration of 10ms. The maximum value of FFH is17.7ms. For best results, do not specify a duration of less than 3 ms. This value only needsto be set in the base which broadcasts the parameter to all remotes. However, link time canbe reduced if this value is also programmed into the remotes, which use it as a starting valuewhen scanning for the base.
© 1999 Digital Wireless Corporation 20 6/15/99Get Maximum Data Length (read only)This parameter indicates the largest number of bytes that a remote will transmit per hop,based on the size of the slot it has been allocated by the base. In general more remotes meanless data can be transmitted per remote. By reading this parameter and dividing by the hopduration, the remote's data rate capacity can be determined.Set Minimum Data LengthThis sets the minimum threshold number of bytes required to form a packet in transparentmode. The radio will wait until the packet transmit delay elapses before sending a datapacket with less than this number of bytes. Can be used to keep short, intermittenttransmissions contiguous.Set Packet Attempts LimitSets the number of times the radio will attempt to send an errored packet before discarding itif ARQ Mode is set to 0. If ARQ Mode is set to 1, it is the number of times every packet willbe sent, regardless of success or failure of a given attempt.Set Packet Transmit DelayWhen used in conjunction with the minimum data length parameter, this ets the amount oftime from the receipt of a first byte of data from the host until the radio will transmit intransparent mode. Default is 00H which causes transmission to occur without any delay.When a host is sending a group of data that needs to be sent together, setting this parameterwill provide time for the group of data to be sent by the host before the radio transmits. If thelength of data to be sent together is longer than the time slot can send, the data will not besent together but will be broken up over multiple hops. Incremented in 69.4µs steps with amaximum value FFH or 17.7ms.Set Base Slot Size (base station only)Sets the amount of time allocated for transmission on each hop for the base station time slotin 69.4µs increments, corresponding to 4 bytes per unit. Maximum value is 30H whichcorresponds to 192 bytes.Set ARQ ModeSets ARQ mode when set to 0 which is the default. In this mode the radio will resend anerrored packet until either successful or packet attempt limit attempts have been made. Whenset to 1 selects redundant transmit mode that will send every packet packet attempt limittimes regardless of success or failure of any given attempt.
© 1999 Digital Wireless Corporation 21 6/15/995.4. Status CommandsThese commands deal with general interface aspects of the operation of the WIT2410.Command Descriptionzb[?|0|1] Banner Display Disable0 = disabled1 = enabled (default)zc[?|0..2] Set Escape Sequence Mode0 = disabled1 = once after reset (default)2 = unlimited timeszh? Read factory serial number high byte.zm? Read factory serial number middle byte.zl? Read factory serial number low byte.zp[?|0-5] Set the duty cycle at which the modem will wake up to send and receive data.Duty cycle equals 1/2N where the argument of the command equals N.z> Exit Modem Control ModeBanner Display DisableEnables or disables display of the banner string and revision code automatically at power-up.May be disabled to avoid being mistaken for data by the host.Set Escape Sequence ModeEnables or disables the the ability to use the in-data-stream escape sequence method ofaccessing Control Mode by transmitting the string ":wit2410". When this mode is set to 1,the escape sequence only works immediately after reset (this is the default). When set to 2,the escape sequence may be used at any time in the data stream when preceded by a pause of20 ms. For backwards compatibility with the WIT2400, the string ":wit2410" is alsoaccepted for entering Control Mode. Note that the escape sequence must be interpreted asdata by the radio until the last character is received, and as such will be generally betransmitted to a receiving radio station, if any.Read Factory Serial Number High, Middle and Low Bytes.These read only commands return one of the three bytes of the unique factory-set serialnumber, which are also visible in the startup banner.Set Duty CycleAllows reduced power consumption by having a remote wake up only every 2N hops toreceive and transmit. Power consumption is roughly proportional to the duty cycle selected.For example, if N=2, the remote will wake up every fourth hop. Power consumption will beroughly ¼ the consumption as when N=0. This parameter must be set to the appropriatevalue when TDMA mode is being used with more than 16 remotes.
© 1999 Digital Wireless Corporation 22 6/15/995.5. Memory CommandsThe WIT2410 allows the user to store a configuration in nonvolatile memory, which isloaded during the initialization period every time the radio is powered up. Command Descriptionm0 Recall Factory Defaultsm< Recall Memorym> Store MemoryRecall Factory DefaultsResets the WIT2400 to its factory default state. This is useful for testing purposes or if thereis a problem in operation of the system and the configuration is suspect. Use the StoreMemory command afterwards if you wish the factory default settings to be remembered thenext time you cycle power or reset the radio.Recall MemoryUseful for restoring the power-on settings after experimenting with temporary changes todata rate, protocol or network parameters, etc.Store MemoryThis command is necessary after any command to change the data rate, transceiver address,or other radio setting that you wish to make permanent.
© 1999 Digital Wireless Corporation 23 6/15/995.6. Modem Command SummarySerial Commandssd[?|00..ff] Set Data Rate Divisorsp[?|00..14] Set Protocol ModeNetwork Commandswb[?|0|1] Set Transceiver Modewd[?|0..3f] Set Default Handlewn[?|00..3f] Set Hopping Patternwg[?|0|1] Enable Global Network Modewp[?|0|1] Set Transmit Powerwr? Read Receive Signal Strength (remote only)Protocol Commandspe[?|0..3] Set Alternative Frequency Bandph[?|00..ff] Set Hop Duration (base only)pl? Get Maximum Data Lengthpk[?|00..d4] Set Minimum Data Lengthpr[?|00..ff] Set Packet Attempts Limitpt[?|00..ff] Set Packet Transmit Delay (remote only)pw[?|00..20] Set Base Slot Size (base only)px[?|0|1] Set ARQ ModeStatus Commandszb[?|0|1] Banner Display Disablezc[?|0..2] Set Escape Sequence Modezh? Read Factory Serial Number High Bytezm? Read Factory Serial Number Middle Bytezl? Read Factory Serial Number Low Bytezp[?|0..4] Set Duty Cyclez> Exit Modem Control ModeMemory Commandsm0 Recall Factory Defaultsm< Recall Memorym> Store MemoryNote: Brackets ([,]) as used here denote a set of optional arguments. Vertical slashes separate selections. Forexample, given the string wn[?|00..3f], legal commands would be wn?,wn0, wn3, and wn2a. Mostcommands which set a parameter also have a ? option which displays the current parameter setting; e.g., wn?.
© 1999 Digital Wireless Corporation 24 6/15/996. WIT2410 DEVELOPER’S KITThe WIT2410 Developer’s Kit contains two self-contained wireless modems built around theWIT2410M OEM module. In addition, two WIT2410 OEM modules are included in the kit.The self-contained units allow developers to get up and running quickly using standard RS-232 interfaces without having to build a CMOS level serial interface. In addition, the self-contained modems include status LEDs to provide modem status information visually. Thebuilt-in battery pack allows the developer to use the modems without being tethered to apower source. This provides a simple way to test the range of the radios. Other than the trueRS-232 signals of the serial interface, the self-contained modems operate exactly as the OEMmodules.Connection is made to the modems through a standard DB-9 connector. The modems are setup as DCE devices requiring the use of a straight-through cable to connect to DTE devices.The pinout is provided in Section 7.3. The modems can be used with just a three wireconnection. Transmit data, receive data and ground are the three required connections. Notethat in this configuration, no flow control is available as the WIT2410 does not supportsoftware flow control.When the developer’s kit is shipped from the factory, one modem is set up as a base stationand the other is set up as a remote. The interface rate for both modems is set at 9600 bps.The default setting for the network key allows the modems to communicate without changingany settings. The modems are set up to operate in TDMA mode. As a quick test, separatethe two modems by about 5 feet, plug in the power and turn the modems on. Do not connectthe modems to any device. The Carrier Detect (CD) LED on the base station will come onimmediately. After a few seconds, the CD LED on the remote will come on. This indicatesthat the modems have synchronized and have established a communications link.An important point to remember is that if the base station is in Sleep mode, nocommunications can take place until (1) the base station is taken out of sleep mode and (2)the remote has synchronized with the base station. As the Sleep signal is brought out on thepin usually occupied by DTR, connecting the base station to a PC serial port with DTR de-asserted will put the modem into sleep mode. Some communications programs will attemptto communicate immediately after asserting DTR. The base station will transmit this data,but the remote will not be synchronized with the base station and will not receive thetransmission. In this instance, do not connect the Sleep signal to DTR of the serial port.6.1. COM24Provided with the developer’s kit is a simple communications program designed especiallyfor the WIT2410. This program provides a simple command interface to the modems alongwith function key control for manipulating the serial port control lines and baud rates. Thisprogram is designed to run under DOS although it will also work in the DOS box under mostversions of Windows. However, due to the limitations Windows puts on programsinterfacing directly to hardware, COM24 may not work under Windows 98 without bootingdirectly to DOS.
© 1999 Digital Wireless Corporation 25 6/15/99COM24 defaults to com1: and 9600 bps. The port and baud rate can be changed through theinvocation of the program. The invocation syntax is shown below:COM24 <data rate> <port number>Note that the data rate applies to the serial port of the computer. This parameter has no effecton the modem. If the modem is set for 9600bps but COM24 is invoked to run at 19.2kbps,the computer and the modem will be unable to communicate. When the modems are used forthe first time, if they are connected to serial port 1, the program can be invoked without datarate or port number parameters.The following function keys on the PC have the following functions in COM24:F1 Toggles state of DTR (Sleep). State is shown in status line.F2 Toggles state of RTS. State is shown in status line.F3 Transmits “:wit2400”. Used to enter control mode.F5 Toggles local echo. If you are transmitting characters through one modem toanother WIT2410, this allows you to see what you are typing.F6 Toggles stream mode. Causes COM24 to transmit a repeating pattern ofcharacters. Useful for testing.F8 Toggles binary mode. Displays extended ASCII and control characters.Useful for testing.PgUp Sets data rate of PC serial port to next higher value. Value is displayed instatus line. Useful when COM24 is used to change the WIT2410 interfacedata rate. COM24 can communicate at new data rate without having to exitand re-enter COM24.PgDn Sets data rate of PC serial port to next lower value. Value is displayed instatus line.The values of DTR (Sleep), RTS, DSR, CTS, DCD and the PC serial port rate are displayedin the status line at the bottom of the display.6.2. Demonstration ProcedureThe procedure below provides a quick demonstration of the WIT2410.1. Attach a transceiver to each computer, preferably between 5' and 30' apart forconvenience. 2. Start COM24 running on both computers by typing "COM24". If you are connected to aserial port other than COM1:, use "COM24 9600 <port number>" to start the program;e.g., for COM2:, use "COM24 9600 2". If you prefer, almost any other serialcommunications program such as Procomm or QModem set for 9600 bps will also work.3. Turn the radios on and use the function keys to set DTR and RTS to 1 (if you are using aterminal program other than COM24, these are typically set automatically). The radioshould respond by setting both DSR and CTS to 1, and transmit a short sign-on message
© 1999 Digital Wireless Corporation 26 6/15/99including the firmware version and whether the unit is configured as a base or remote.Watch the states of the hardware control lines on the status bar as you do this. The DCDindicator should be lit on the base station. After a few seconds, the remote unit willacquire the base station's signal and also assert its DCD signal.4. Access modem control mode for each unit. To access modem control mode, use the F1key to toggle DTR to 0 and back to 1 and then press the F3 key, which sends the":wit2400" escape sequence. If you are not using COM24, simply turn the radio off andback on and then type ":wit2400" (must be lower case, no backspace characters). Thetransceiver should echo back “>” to indicate that you have entered modem control mode.Check the remote unit's hopping pattern by entering "wn?" at the prompt. The remoteshould respond with "0", the default setting. Check that the base station's hopping patternmatches this by entering "wn?" at the base station.5. Exit control mode by entering "z>". Do this for both radios. At this point, you should beable to type characters into either radio and see them appear at the other side. If you areusing COM24, you can press the F6 key to transmit a repeating test pattern.6. For a range test, disconnect the remote station from the computer and power supply. TheDCD indicator should remain lit as long as the base station is in range.. 7. Exit COM24 by pressing the ESC key.6.3. TroubleshootingRadio is not responding.Make sure DTR is asserted to bring the radio out of sleep mode. DSR should be on toindicate the radio is ready.Can’t enter modem control mode.Make sure the host data rate is correct. The WIT2410 defaults to 9600 bps asynchronous.Evaluation units do not have external access to the CFG_SEL signal; you must use the:wit2410 power-on escape sequence to access modem control mode. The first characterstyped after the radio wakes up should be the escape sequence. Make sure you type the colon(:) and enter the letters in lower case; the characters following the colon echo to show youhave typed them correctly. If using the “on-the-fly” escape sequence command, make sure apause of at least 20ms precedes the escape sequence.Remote never detects carrier.Check that the base station is running, and that the remote is programmed to the samehopping pattern. Also check that the hop duration for base and remote are the same, and thatthe remote has a non-zero link margin.Carrier is detected, but no data appears to be received.Make sure that RTS is asserted to enable receive character flow. In a point-to-pointapplication, if a remote is not receiving data, check that the base's deefault handle is the sameas the remote's. In a multipoint application, check that the remote is not configured forprotocol mode and that the base is using the correct protocol format and destination handle.
© 1999 Digital Wireless Corporation 27 6/15/99Radio is interfering with other nearby circuits.It is possible for the RF energy envelope to be rectified by nearby circuits that are notshielded for RFI, manifesting as a lower frequency noise signal. If possible, place theantenna at least 1 foot away from the transceiver module, and 3 feet from other circuit boardsand obstructions. Place sensitive circuits in a grounded metal casing to keep out RFI.Sign-on banner or modem control mode prompt is unreadable.If the problem is repeatable, check whether the data rates between host and transceivermatch.Range is extremely limited.This is usually a sign of poor antenna coupling. Check that the antenna is firmly connected.If possible, remove any obstructions in the near field of the antenna (~3' radius).Transmitting terminal flashes CTS occasionally.This indicates that the transmitter is unable to reliably get its data across. This may be theresult of an interfering signal, but most often is caused by overloading of the network.Adjusting the protocol parameters may increase the network efficiency.Receiving terminal drops characters periodically.Set the number of retries to a high number and send a few characters. Check that thetransmitted data can get through under these conditions. Sometimes this symptom is causedby an application that is explicitly dependent on the timing of the received data stream. Thenature of the packetized RF channel imposes a degree of unpredictability in the end-to-endtransmission delay.
© 1999 Digital Wireless Corporation 28 6/15/997. APPENDICES7.1. Technical Specifications7.1.1. Power SpecificationsVcc Input Range: 3.3v to 10.0vVcc Ripple: <1%Operating Temperature Range: -20C to +70CCurrent Consumption (Max transmit power, 230.4Kbps I/O)Mode Remote Base StationSleep 50µA N/AStandby 20mA N/ATypical 50mA 120mAPeak (Tx) 200mA 200mA7.1.2. RF SpecificationsFCC Certification Part 15.247, no license requiredETSI (European) Certification brETSI 300.328, no license requiredRated RF Power +18 dBm (+20 dBm effective radiated)Line-of-site Range approx. 6/10 of a mileFrequency Range 2401 – 2480MHzNumber of Channels 75 (France: 33, Spain & Japan: 25)Receiver Sensitivity -93dBmChannel Data Rate 460KbpsIF Adjacent Channel Rejection >55dB7.2.2. Mechanical SpecificationsWeight 35gDimensions (including shield) 80.2 x 46.5 x 8.6mm(refer to section 7.6 for mechanical drawing)RF Connector:WIT Huber/Suhner: 85 MMCX 50-0-1Mating Huber/Suhner: 11 MMCX-50-2-3 (straight)Huber/Suhner: 16 MMCX-50-2-2 (rt. angle)Data/Power Connector:WIT Samtec: DIS5-108-51-L-DMating Samtec: FFSD-08 (IDC cable) Samtec: CLP-108-02-G-D (PCB mount)
© 1999 Digital Wireless Corporation 29 6/15/997.3. Serial Connector PinoutsSignal WIT2410MOEM Pinout WIT2410EDB9 PinoutGND 1 5TXD 2 3RXD 3 2CFG 4 -RTS 5 7SLEEP 6 4DCD 7 1CTS 8 8The WIT2410E is wired as a DTE device and as such can be connected to DTE devices suchas PCs with a straight-through cable. When connecting a WIT2410E to a DCE device, a“null modem” cable is required. To effect a null modem cable, cross-wire TXD and RXDand connect ground. The WIT2410E can operate with just these three wires connected.However, as the WIT2410 does not support software flow control, there will be no flowcontrol in this mode. If the DCE device fails to respond, connect DCD from the WIT2410Eto the DTR and RTS inputs to activate the DCE device whenever the WIT2410 assertscarrier.When connecting to the WIT2410M, make sure that all of the inputs (TXD, CFG, RTS andSLEEP) are terminated for proper operation.7.4. Approved AntennasThe WIT2410M is designed to ensure that no antenna other than the one fitted shall be usedwith the device. The end user must permanently affix the antenna by using an adhesive onthe coupling such as Loctite, or ensure the antenna has a unique coupling. The table belowlists the antennas which can be purchased directly from Digital Wireless Corporation.Contact DWC Technical Support with any questions.Description Gain Part Number CouplingYD24/15 Yagi Directional 14 dB YAGI2415 NOm24/9 Omnidirectional 9 dB OMNI249 NDWC Patch 6 dB PA2400 MMCXDipole 2 dB RWA249R Reverse SMA7.5. Technical SupportFor technical support call Digital Wireless Corporation at (770) 564-5540 between the hoursof 8:30AM and 5:30PM Eastern Time.
© 1999 Digital Wireless Corporation 30 6/15/997.6. Mechanical Drawing
© 1999 Digital Wireless Corporation 31 6/15/997.7. WarrantySeller warrants solely to Buyer that the goods delivered hereunder shall be free from defectsin materials and workmanship, when given normal, proper and intended usage, for twelve (12)months from the date of delivery to Buyer. Seller agrees to repair or replace at its option andwithout cost to Buyer all defective goods sold hereunder, provided that Buyer has given Sellerwritten notice of such warranty claim within such warranty period. All goods returned toSeller for repair or replacement must be sent freight prepaid to Seller’s plant, provided thatBuyer first obtain from Seller a Return Goods Authorization before any such return. Sellershall have no obligation to make repairs or replacements which are required by normal wearand tear, or which result, in whole or in part, from catastrophe, fault or negligence of Buyer,or from improper or unauthorized use of the goods, or use of the goods in a manner for whichthey are not designed, or by causes external to the goods such as, but not limited to, powerfailure. No suit or action shall be brought against Seller more than twelve (12) months afterthe related cause of action has occurred. Buyer has not relied and shall not rely on any oralrepresentation regarding the goods sold hereunder, and any oral representation shall not bindSeller and shall not be a part of any warranty.THE PROVISIONS OF THE FOREGOING WARRANTY ARE IN LIEU OF ANYOTHER WARRANTY, WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL(INCLUDING ANY WARRANTY OR MERCHANT ABILITY OR FITNESS FOR APARTICULAR PURPOSE). SELLER’S LIABILITY ARISING OUT OF THEMANUFACTURE, SALE OR SUPPLYING OF THE GOODS OR THEIR USE ORDISPOSITION, WHETHER BASED UPON WARRANTY, CONTRACT, TORT OROTHERWISE, SHALL NOT EXCEED THE ACTUAL PURCHASE PRICE PAID BYBUYER FOR THE GOODS. IN NO EVENT SHALL SELLER BE LIABLE TOBUYER OR ANY OTHER PERSON OR ENTITY FOR SPECIAL, INCIDENTAL ORCONSEQUENTIAL DAMAGES, INCLUDING, BUT NOT LIMITED TO, LOSS OFPROFITS, LOSS OF DATA OR LOSS OF USE DAMAGES ARISING OUT OF THEMANUFACTURE, SALE OR SUPPLYING OF THE GOODS. THE FOREGOINGWARRANTY EXTENDS TO BUYER ONLY AND SHALL NOT BE APPLICABLETO ANY OTHER PERSON OR ENTITY INCLUDING, WITHOUT LIMITATION,CUSTOMERS OF BUYERS.

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