EE185Lab
Basics:ConditionalStatements
Conditionalstatementsaretheheartofdecision-makinginprogramming.
SuggestedPrerequisites
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ProgrammingIntro
SetupandPreparation
ListofMaterials
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TIMSP430G2LaunchPad
Breadboard
M/FJumperWires(4)
M/MJumperWires(4)
Pushbuttons(2)
Resistorsofsmallvalue(~1kΩ)(4)
Preparethecircuit
Designthefollowingcircuit(Figure1).
Figure1:ConditionalLabCircuit
Program1:ifstatement
Createanduploadthefollowingprogram(Figure2)totheLaunchPad.
Figure2:ifstatement
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Youcanuseavoltmetertoexaminethevoltageacrossthebuttonwhenitgetspressed.
TheSerialMonitorcanbeusedtoexaminethevaluesofpinState,buttonIsPressed,
andLEDstate(You’llneedtorevisethecodetoenablethis).
ThereisarelationshipbetweenthevaluesofpinStateandthevoltageacrossthebutton.
ConsiderwhytheNOToperator!wasincludedinthisprogram.
Considerhowfastthisprogramisrepeatingthecodeintheloop()function.
Program2:NestedIfstatements
Createanduploadthefollowingprogram(Figure3)totheLaunchPad.
Figure3:Nestedifstatements
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Considerthegeneraleffectofnestingifstatements.
Youcananalyzetheprogrambyexaminingthe3variablesbutton1IsPressed,
button2IsPressed,andLEDstate,usingtheSerialMonitor.
Thisprogramcanbeimplementedwithasingleifstatement,usingBooleanoperators.
InformationaboutBooleanoperatorscanbefoundatthefollowinglink:
o http://energia.nu/reference/
Program3:Ifstatementsinsequence
Createanduploadthefollowingprogram(Figure4)totheLaunchPad.
Figure4:Ifstatementsinsequence
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Considerthegeneraleffectofputtingifstatementsinsequencethatdothesamethingbutare
activatedbydifferentconditionalstatements.
Youcananalyzetheprogrambyexaminingthe3variablesbutton1IsPressed,
button2IsPressed,REDstate,andGREENstateusingtheSerialMonitor.
ThisprogramcanbeimplementedwithasingleifstatementusingBooleanoperators.
InformationaboutBooleanoperatorscanbefoundatthefollowinglink:
o http://energia.nu/reference/
Program4:elseifstatements
Createanduploadthefollowingprogram(Figure5)totheLaunchPad.
Figure5:elseifstatement
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Unlikeifstatementsinsequence,elseifstatementsarelinkedtotheirprecedingifstatement,
andexecutionismutuallyexclusive.Youcandeterminewhichconditionalstatementhas
precedenceintheeventthattheyarebothtrue.
Youcananalyzetheprogrambyexaminingthe3variablesbutton1IsPressed,
button2IsPressed,REDstate,andGREENstateusingtheSerialMonitor.
Youcantrytoexplainthelogicalflowoftheif…elseifcodestructurewithablockdiagram.
Program5:elsestatements
Createanduploadthefollowingprogram(Figure6)totheLaunchPad.
Figure6:elsestatement
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Similartoelseifstatements,elsestatementsarelinkedtotheprecedingifstatement.
Noticethattheelsestatementdoesnotcontainanyconditionalstatement.
Youcananalyzetheprogrambyexaminingthe3variablesbuttonIsPressed,REDstate,
andGREENstateusingtheSerialMonitor.
Youcantrytoexplainthelogicalflowoftheif…elsecodestructurewithablockdiagram.
Itisalsocommontoputanelsestatementafteranif…elseifcodestructure.
Informationaboutifstatementsandtheirvariationscanbefoundatthefollowinglink:
o http://energia.nu/reference/else/
Review
Afterthislab,youshouldhaveagoodunderstandingofthefollowingtopics.Ifyou’renotsureabout
someofthem,gobackthroughthelabandtrytoafindagoodplacetoexplorethetopic.
Youshouldbeabletodothefollowing
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Createprogramsthatuseifstatementsanditsvariantstoexecutecodeconditionally.
Explainthelogicalflowofanifstatementsanditsvariantswithblockdiagrams.
UseNOT,AND,andORBooleanoperatorstomakemoresophisticatedconditionalstatements.
UsethevoltmeterandSerialMonitortoanalyzeandtroubleshootacircuitorprogram.
Application
Tryapplyingtheskillsyoulearnedfromthislab.Youcancomeupwithyourownprojectideaortryone
fromtheflowchart.