u-blox ANTARIS 4 - Migration from TIM-ST to TIM-4 x

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D.6 Migration from TIM-ST to TIM-4x
MigratingaTIM-STdesigntooneoftheTIM-4xGPSreceiversisusuallyaneasy,straightforwardprocedure.This
sectionsummarizesmostimportantdifferences.
NMEA Protocol
TIM-STandTIM-LxoutputNMEAdata(GGA,GLL,GSA,GSV,RMC,VTGandZDAmessages)onport1.
TIM-ST TIM-4x (ANTARIS
®
4) Remarks
NMEAV2.2 NMEAV2.3 MostNMEAparsersshouldbeabletohandleV2.2andV2.3.Shouldyour
parserstrugglewithV2.3,configureTIM-4xtooutputNMEAV2.1bysending
anUBX-CFG-NMEAmessage.

12channels 16channels ANTARIS
®
4isabletotrackupto16satellitesinparallel.SinceoneGSV
messagecontainsonlyupto4satellites,ANTARISmaysendupto4GSV
messageswhereasTIM-STonlyoutput3.Ifthiscausesproblem,reducethe
NMEAoutputofANTARISto12satellitesbysendingaCFG-NMEA
message
LatandLongareoutputin LatandLongareonly ANTARIS 4canbereconfiguredtooutputLatandLongincaseofinvalidfixes
caseofinvalidfixes outputforvalidfixes
®
bysendinganUBX-CFG-NMEAmessage.
Acceptspositionuptoa Acceptspositionuptoa ANTARIS
PDOPof50 PDOPof25 conservativeapproachwithaPDOP of25worksusuallyfine.However,it’s
possibletoconfigureTIIM-LxtoacceptpositionwithahigherPDOPbysendin
®
4receiversaremoresensitivethanTIM-ST.Hencethemore
g
aUBX-CFG-NAV2message
LatandLongareoutput
with4,thetimewith3
LatandLongareoutput
with5,thetimewith2
TheNMEAspecificationisfairlyopenandallowsminorvariationsinthe
implementation(e.g.numberofpositionafterdecimalpoint,etc.)
butitalways
numberofdigitsfortheindividualmessagefields.Itwillevenbeable
tohandle
emptyfields",,".Besidethecommas,a goodparsershouldbeablethehandle

no
T
positionafterdecimalpoint positionafterdecimalpoint
requestscommasbetweenasaseparatorbetweenNMEAdatafields.One
shouldthereforewriteaparserthatsearchesforcommasandextracts
everythingbetweentwocommas.Thisway,theparserisindependentofthe
thevalidflagscorrectly.Dataareonlyvalidifthevalidflagissettovalid.Ifit’s
settoinvalid,theNMEAparsershouldrejectdataoutputbythereceiver.By
meansshould
itforwardittotheapplication.
StartingwithFirmware5.0,it’spossibletoconfigureANTARIS
®
4tooutputLA
&LONwith4digits etc.
SupportsproprietaryNMEA SupportsproprietaryNMEA TheNMEAspecificationdoesnotincludeinputmessages.ThisiswhyGPS
messages(PSRF) messages(PUBX) manufacturersintroduceproprietaryNMEAmessages.IfPSRFmessageshave
beenusedwithTIM-ST,migratethemtoeitherPUBXorevenbettertoUBX-
CFG-xxxmessages.Thelatterispreferred
andit’seasysinceANTARISisableto
handletoprotocolsonthesameport(4.3).
Binary Protocol
TIM-ST supports SiRF binary protocol whereas TIM-4x supports UBX protocol. These two protocols are not
TIM-ST does not have a built-in antenna supervisor whereas all TIM-4x modules have a built-in short-circuit

compatible.ItisnecessarytomigratethehostsoftwaretoUBXprotocolifSiRFbinarywasusedbefore.
Antenna and Antenna Supervisor
detection.
TIM-STdesignswithexternalactiveantennasupervisorwillnotworkwithoutminormodificationsto
thecircuitry.
Power Supply
TIM-4xreceiversconsumeapproximately120mAlesscurrent,whichisusuallynotaproblem.

TIM-ST TIM-4x (ANTARIS
®
4) Remarks
Vcc 2.75–3.45 2.7–3.3V
CurrentConsumption <160mA  Approx36–40mA TIM-4xcurrentconsumptiondependsonTIM-4xvariant
PowerSavingMode TPM,Push-2-fix FixNOW Inmostcases,it’snotnecessarytouse FixNOWmodedueto
muchlowercurrentconsumptionofTIM-4x
the
 Note: MakesuretherippleonVccisbelow50mV.
GPSModules-SystemIntegrationManual(SIM)(incl.ReferenceDesign) MigrationtoANTARISP®P4receivers
GPS.G4-MS4-05007-A1
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