product manual - solarbotics
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Product Manual1134 - Switchable Voltage Divider
Phidgets 1134 - Product Manual
For Board Revision 0
© Phidgets Inc. 2010
Contents
4 Product Features
4 Applications
4 Connections
4 Type of Measurement
5 Getting Started
5 Checking the Contents
5 Connecting all the pieces
5 Testing Using Windows 2000/XP/Vista
7 Testing Using Mac OS X
7 Programming a Phidget
7 Code Samples
7 Coding for your Sensor
8 Technical Information
8 Formulas
8 ConfiguringtheVoltageDivider
9 Variable resistance sensors
9 OtherInterfacingAlternatives
9 Analog Input Cable Connectors
10 MechanicalDrawing
10 DeviceSpecifications
10 Product History
10 Support
41134_0_Product_Manual - March 29, 2010
Designedtoconnecttoa:
1018 - PhidgetInterfaceKit 8/8/8•
1019 - PhidgetInterfaceKit 8/8/8 w/6 Port Hub•
1070 - PhidgetSBC•
1202or1203-PhidgetTextLCD•
Product FeaturesApplications
Providesaninterfacetonon-Phidgetsvariableresistancesensorssuchas:ForceSensingResistors(FSR),light•sensors,thermistors(heatsensors),andbendsensors.
Precisionresistorsonthe1134allowstheapplicationtopreciselycalculatetheresistanceoftheattachedsensor.•
Possibletousemultipleresistorstoselectanequivalentresistanceforthe‘fixed’resistor•
Theinterfacetothevariableresistancesensorisaconvenientterminalblock.•
Connections
Type of MeasurementThesensorusesratiometricmeasurement.
51134_0_Product_Manual - March 29, 2010
ConnecttheSwitchableVoltageDividertoanAnalogInput1.on the PhidgetInterfaceKit 8/8/8 board using the sensor cable.
Connectthevariableresistancesensortotheterminal2.blockontheVoltageDivider.
Select an appropriate measurement range for your 3.applicationbytogglingthedesiredDIPswitch.Wearetogglingthe27.4Kswitch.Whentheswitchisdown,theassociatedmeasuringresistorisselected.Itispossibletohavemorethanoneswitchtoggledandhavetheresistorsinparallel.Forourpurposeonlytoggleoneswitch.
Connect the InterfaceKit board to your PC using the USB 4.cable.
Getting StartedChecking the Contents
In order to test your new Phidget you will also need:
A PhidgetInterfaceKit 8/8/8•
A USB Cable•
Avariableresistancesensororanyresistor(weareusinga27K•resistor)
You should have received:
ASwitchableVoltageDividerboard•
A Sensor Cable•
Connecting all the pieces
Testing Using Windows 2000/XP/VistaDownloading the Phidgets driversMakesurethatyouhavethecurrentversionofthePhidgetlibraryinstalledonyourPC.Ifyoudon’t,dothefollowing:
Gotowww.phidgets.com>>Drivers
DownloadandrunPhidget21Installer(32-bit,or64-bit,dependingonyourPC)
You should see the iconontherighthandcorneroftheTaskBar.
Running Phidgets Sample Program
Doubleclickingonthe icon loads the Phidget Control Panel; we will use this program to make sure that your newPhidgetworksproperly.Sincethesensorisconnectedtoa1018,thecomputerwillseeonlythe1018.ThesensorisprovidingdatathroughtheAnaloginputitisconnectedto.
The source code for the InterfaceKit-full sample program can be found under C# by clicking on www.phidgets.com >>Programming.
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61134_0_Product_Manual - March 29, 2010
DoubleClickonthe icontoactivatethePhidget Control Panel and make sure that the Phidget InterfaceKit 8/8/8 is properly attachedtoyourPC.
DoubleClickonPhidgetInterfaceKit1.8/8/8 in the Phidget Control Panel to bring up InterfaceKit-full and check that the box labelled Attached containsthewordTrue.
MakesurethattheRatiometricbox2.isTicked.
The Analog In box displays a number 3.correspondingtotheresistorvalue.
Youcanadjusttheinputsensitivity4.bymovingthesliderpointer.
Click on the Sensors button to bring 5.uptheAdvancedSensorForm.
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IntheAdvancedSensorForm,selectthe1.1134-SwitchableVoltageDividerfromthedropdownmenu.
Select the appropriate resistor from the 2.drop-down menu that has been selected withtheDIPswitchontheboard.
The resistance measured by the sensor is 3.shownhere.
Formulausedtoconverttheanaloginput4.SensorValueintoresistance.
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71134_0_Product_Manual - March 29, 2010
Testing Using Mac OS XClickonSystemPreferences>>Phidgets(underOther)toactivatethePreferencePane•
MakesurethatthePhidgetInterfaceKit8/8/8isproperlyattached.•
DoubleClickonPhidgetInterfaceKit8/8/8inthePhidgetPreferencePanetobringuptheInterfaceKit-Full•example.ThisexamplewillfunctioninasimilarwayastheWindowsversion,butnotethatitdoesnotincludeanAdvancedSensorDisplay.
Programming a Phidget
Phidgets’philosophyisthatyoudonothavetobeanelectricalengineerinordertodoprojectsthatusedeviceslikesensors,motors,motorcontrollers,andinterfaceboards.Allyouneedtoknowishowtoprogram.WehavedevelopedacompletesetofApplicationProgrammingInterfaces(API)thataresupportedforWindows,MacOSX,andLinux.Whenitcomestolanguages,wesupportVB6,VB.NET,C#.NET,C,C++,Flash9,Flex,Java,LabVIEW,Python,Max/MSP,andCocoa.
Code SamplesWehavewrittensampleprogramstoillustratehowtheAPIsareused.
Duetothelargenumberoflanguagesanddeviceswesupport,wecannotprovideexamplesineverylanguageforeveryPhidget.Someoftheexamplesareveryminimal,andotherexampleswillhaveafull-featuredGUIallowingallthefunctionalityofthedevicetobeexplored.Mostdevelopersstartbymodifyingexistingexamplesuntiltheyhaveanunderstandingofthearchitecture.
Go to www.phidgets.com>>Programming toseeiftherearecodesampleswrittenforyourdevice.Findthelanguageyouwanttouseandclickonthemagnifyingglassbesides“CodeSample”.Youwillgetalistofallthedevicesforwhichwewrotecodesamplesinthatlanguage.
IfthisisyourfirsttimewritingaprogramtocontrolaPhidget,youshouldreadtheGettingStartedGuideforthelanguageyouareplanningtouse.
Coding for your SensorPhidgetanalogsensorsdonothavetheirownAPI,butinsteadtheiroutputisavoltagethatisconvertedtoadigitalvalueandaccessedthroughtheSensorValuepropertiesandeventsonaPhidgetInterfaceKit.ItisnotpossibletoprogrammaticallyidentifywhichsensorisattachedtotheAnalogInput.YourapplicationwillneedtoapplyanyformulasfromthismanualtotheSensorValuetotranslateitintousabledata.
SeethePhidgetInterfaceKitproductmanualforanoverviewofitsAPIandadescriptionofourarchitecture.
81134_0_Product_Manual - March 29, 2010
Technical InformationThe1134SwitchableVoltageDividerisavoltagedividerwithswitches.Theswitchescanbeusedtocontrolwhichresistorsareusedinthevoltagedivider.Fromlefttoright,theresistancevalues(inOhms)are249,820,2.61K,8.45K,27.4K,91K,300Kand1M.Itispossibletohavemultipleswitchesflipped,puttingthecorrespondingresistorsinparallel.
FormulasTheFormulatotranslateSensorValueintoresistanceis:
Resistance(Ohms)=Req*(1000/SensorValue-1)
WhereReqistheequivalentresistanceoftheswitchesthatareflippedoninOhms.
TheSwitchableVoltageDividerhasaninternalbufferontheoutput.Thisallowstheoutputtobereadwithoutdistortioncausedbythedevicereadingthemeasurement,suchasthePhidgetInterfaceKit.
Configuring the Voltage DividerTooptimizethevoltagedividertomeetyourneeds,youhavetoadjusttheswitchable resistance to match the characteristicsofyourchosenvariableresistor.First,adjusttheresistancefornostimulionyoursensor,thenapplymaximum stimuli and make sure that the Sensor Value stays within a range that givesyouanacceptableresolution.Theformula is most accurate at a SensorValue of500,withanerrorof0.4%.At100and900,theerrorincreasestoapproximately1.1%andat50and950,itincreasesto2.1%.
Asageneralrule,iftheSensorValueisover900,alowerresistanceshouldbeswitchedin.IftheSensorValueisbelow100,ahigherswitchshouldbetoggled.Continue adjusting the switches until you findanacceptablerange.
Warning:Itispossibleforthe1134toapplyupto5Vtothevariableresistor.Iftheresistorcannothandlethisvoltage,itcanbedamaged.
The1134isaverysimplewayofmeasureresistance.Wheninterfacingtosensorswithsmallresistances(like100ohmRTDs,forinstance),largecurrentscanflow-upto30mA.Thislevelofcurrentmaycausesubstantialheatinginthevariableresistor,distortingthemeasurementorevenpossiblypermanentlydamagingit.
OUTPUT+5V
249
820
2.41
K
8.45
K
27.4K
91K
300K
1M
91134_0_Product_Manual - March 29, 2010
Variable resistance sensorsHerearesomeinterestingvariableresistancesensorsthatcouldbeusedwiththeVoltageDivider.
Sensor Type Manufacturer Example Digikey searchLight Sensors AdvancedPhotonics PDV-P9003-1 photocell
Force Sensors CUIInc. IESP-12 force sensor
Thermistors US Sensor 615-1037-ND thermistor radial
Bend Sensors imagesco.com FLX-01 n/a
Other Interfacing AlternativesIfyouwantmaximumaccuracy,youcanusetheRawSensorValueproperty.Tomodifytheformula,substitute(SensorValue)with(RawSensorValue/4.095)
IfthesensorisbeinginterfacedtoyourownAnalogtoDigitalConverter(notaPhidgetdevice),ourformulascanbemodifiedbyreplacing(SensorValue)with(Vin*200).ItisimportanttoconsiderthevoltagereferenceandinputvoltagerangeofyourADCforfullaccuracyandrange.
Analog Input Cable Connectors
EachAnalogInputusesa3-pin,0.100inchpitchlockingconnector.Picturedhereisaplugwiththeconnectionslabeled.Theconnectorsarecommonlyavailable-refertotheTablebelowformanufacturerpartnumbers.
Cable ConnectorsManufacturer Part Number Description
Molex 50-57-9403 3 Position Cable Connector
Molex 16-02-0102 Wire Crimp Insert for Cable Connector
Molex 70543-0002 3 Position Vertical PCB Connector
Molex 70553-0002 3PositionRight-AnglePCBConnector(Gold)
Molex 70553-0037 3PositionRight-AnglePCBConnector(Tin)
Molex 15-91-2035 3PositionRight-AnglePCBConnector-SurfaceMount
Note:Mostoftheabovecomponentscanbeboughtatwww.digikey.com
101134_0_Product_Manual - March 29, 2010
Mechanical Drawing
Device SpecificationsCharacteristic ValueMaximum Current Consumption 30 mA
Supply Voltage 3.0to5.25VDC
MaxSwitchableResistance 1M Ohms
MinSwitchableResistance 172 Ohms
VariableResistorRange Up to 50 MegaOhms
ResolutionbetweenSensorValue100-900 Less than ±1%ofvariableresistorperSensorValue
1:1scale
Product History
SupportCallthesupportdeskat1.403.282.73358:00AMto5:00PMMountainTime(US&Canada)-GMT-07:00
or
E-mailusat:[email protected]
Date Board Revision CommentMarch 2010 0 ProductRelease