
GPS-PS1E-DataSheet u-bloxag
GPS.G1-PS1-00002-B Page9
5 OPERATING MODES
GPS-PS1Ecanbeoperatedindifferentoperatingmodes.
5.1 Normal Operation
InNormalMode,themoduleiscontinuouslyrunningaslongastheoperatingvoltageVccissupplied.Position
fixesaregeneratedatthemaximumupdaterate.Anexternalbackupbatterymustbeconnectedtoenablethe
moduletokeeptheinternalRealTimeClockrunningandtoholdtheSRAMdata(ephemerisandalmanacdata)
duringpowersupplyinterruption.Useofanexternalbackupbatteryis recommended to reducethesystem's
startuptime.However,undergoodvisibilityconditionscold-andwarmstarttimesdonotdiffersignificantly.
5.2 TricklePowerTM Operation
In TricklePowerTM Mode, Vcc is continuously supplied to the module. A software configurable internal timer
periodicallyforcesthemoduletoacquireapositionfix.Betweenthefixes,themoduleremainsinanultra-low
power sleep mode. This mode is recommended for applications where lowest power consumption and a
periodicalpositionup-dateareofprimaryconcern.Abackupbatterymustbeconnectedtoenablethemodule
to reduce startup times when recovering from a Vcc supply interruption. The GPS-PS1E supports a new
enhanced TricklePowerTM Mode. This enables to shut off the CPU independently from the RF part. So in
TricklePowerTM Mode operation there are 3 Modes: Track Mode (RFand CPU on),CPU Mode (CPU on) and
StandbyMode(RFoff,CPUinstand-by).
State Current (typ.)1
TrackMode 140mA
CPUMode 34mA
StandbyMode 0.25mA
Table 3 : TricklePowerTM Mode states
The RF on time (Track Mode) depends on the length of the up-date period. TheCPU on time (CPU Mode)
dependsalsoonthenumberofsatellitesinview.(SeeLow Power Mode Application Noteformoredetails).
ThecurrentsduringthedifferentstatesaregiveninTable3.Thismeansthatthepowersupplymustbecapable
of delivering at least 140mA at 5V, regardless of the average current drawn by the module in TricklePowerTM
Mode.
DuringtheTricklePowerTMmodethefirmwareperiodicallyschedulesephemeriscollectionandRTCcalibrationto
insurethatuseabledataisalwaysavailable.Ephemeriscollectionoccursoncewithina30minutesperiodand
wheneveranewsatelliterisesabovethehorizon.Collectingephemerisdataevery30minutesfor18secondsis
equivalenttorunningthefullreceiver(140mA)foranextra10msataonesecondup-daterate.
Thepower-onscenarioinTricklePowerTMModediffersfromtheoneincontinuousMode.Ifthemodulefailsto
acquire3satelliteswithinagiventime(duetobadvisibilityorverylowsignallevels)themodulegoesintoan
extendedsleepphase.Thelengthofthissleepphaseisdefinedbythedutycycle(up-daterate).Afterthisperiod
themodulewakesupandtriestoacquireapositionfixagain.
FormoredetailedinformationonTricklePowerTMModepleasechecktheLow Power Mode Application Note.
5.3 Customized Operation
TheHitachiSH-7020RISC-CPUprovidesenoughcomputationalpowertoallowtheimplementationofadditional
customerspecificsoftwareintothemodule.Inordertoimplementsoftwareontheon-boardprocessorthe
SoftwareCustomizationKit(GPS-SCK)isrequired.TheSoftwareCustomizationKitincludesadevelopment
platform(compiler)andasub-licenseofthefirmwareonthereceiver.Contactu-bloxforadetaileddiscussionof
thefeasibilityofimplementingaparticularapplication.
1ExcludingAntennaPower(dependsonthetypeofactiveantenna)