Instruction Manual

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Page36
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GNAV540UserManual
7430‐0808‐01Rev.B
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I/OPortInterface
ThefollowingportsareaccessiblethroughtheJ1connector.RefertoJ1—I/OConnectoronpage35forthepinout
listing.
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NOTE:TheGNAV540canbepurchasedwithadeveloper’skit:acableisprovidedwitha37pinconnectoronone
end,andfiveconnectorsontheotherendtoconnecttoexternaldevices.Thiscableisdesignedonlyfor
laboratoryuse.See
Figure31onpage126.
PortA:User(computer),RS422serialdatainterface
ThisserialinterfaceisstandardRS‐422,9600,19200,38400,or57600baud,8databits,1startbit,1stopbit,no
parity,andnoflowcontrolandwilloutputatauserconfigurableoutputrate.Thesesettingsallowinteractionviaa
standardPCserialport
PortB:ExternalGPS,RS422serialinterface
ThisserialinterfaceisstandardRS‐422,whichconnectstotheexternalGPS.GNAV540supportsaGPS‐ICD‐153C
compliantGPSreceiver.
PortC:ExternalMagnetometer,RS422serialinterface
ThisserialinterfaceisstandardRS‐422.Thesettingsforanexternalmagnetometerare38400baud,8databit,
1startbid,1stopbit,noparity,noflowcontrol.
CableFieldRequirements
CAUTION:TheGNAV540isshippedwithanEMIfilterattachedtotheAmphenol(MIL‐DTL‐38999‐III),TVP02R
Receptacle,37pinscircularconnector.Thisconnectormustremaininplacetoensurepropershieldingfrom
EMIinterference.Thecablesentwiththeunitisintendedtoprovidetheuserwiththeabilitytotesttheunit
rightoutofthebox,andwillnotprovideadequateshieldingforallenvironments.
Forfielduse,thecablemustbeusedwiththeshieldconnectedtotheI/Oconnectorshelltoprovidetherequired
EMIprotection.CasegroundmustbeusedtoprovidefullEMIprotection;Ensurethecableshieldisgroundedon
onlyoneendofthecable.
Signals
HardwareBITErrorOutput
ThehardwareBITerroroutputpinistheultimateindicationofsystemfailure.Thisindicationisavailableinmost
softwareoutputpacketsasthemasterFailflag.ItisthelogicalANDofthehardwareError,comError,and
softwareErrorflagsmonitoredbythesystem.Intheeventofacommunicationfailure,thehardwareBITerrorpin
maybeusedtodetectamasterFailassertion.Thispinisopen‐collectorandrequiresa1kto10kohmpull‐up
resister.Thesystemwilldrivethispinlowtoassertasystemfailure.
1PPSInputInterface
The1PPSinputsignalallowstheuseroftheGNAV540toforcesynchronizationofsensordatacollectiontoa1Hz
rising‐edgesignal.Thesignalmustmaintain0.0‐0.2Vzerologicand3.0‐5.0voltshighlogicandstaywithin100ms
oftheinternalsystem1secondtiming.Sendingthissignaltothesystemwillalignthesensordatacollectionand
algorithmprocessingtoitsrisingedgeand10msboundariesthereafter.Whenthesystemissynchronizedto1PPS,
thehardwareStatusÆunlocked1PPSflagwillbe
zero;otherwise,theflagwillbeone.