departmentsww.38jjj.com

EasingembeddedLinuxsoftwaredevelopmentforSBCsMostprogrammerstodayleavingcollegewithElectricalEngineeringorComputerSciencedegreesarefairlywellversedinprogrammingonaLinuxdesktopplatform.
WhentheseprogrammersneedtotaketheleaptoprogrammingembeddedLinuxsystems,theyareoftensurprisedandbewilderedthattheprogramtheywroteontheirdesktopwillnotruntheirLinuxembeddedsystem.
Toalleviatethisproblem,someprogrammerschoosetouseversionsofdesktopsystemsinembeddedapplications.
Thisisgenerallynotagoodfitasdesktopsystemstypicallyhavefansandharddrives,whicharefailurepoints.
Abiggerobstacleisfastchange;theneedtohavethefastest,newesttechnologyobsoletesdesktopsystemsinaslittleassixmonths.
Designingalong-lifeembeddedproductaroundaplatformwithnolongevityisarecipefordisaster.
Evenifdesktopplatformscouldbeguaranteedtobearoundfiveyearsfromnow,theLinuxkernelandassociateddistributionsaremovingtargets.
Thekernelandstandardlibrariesareconstantlyevolving,anddistributionsarefightingtokeeppace.
Kernelpatchesandlibraryupdatescanrenderauser'sprograminoperable.
Thissituationisexacerbatedwhenengineersarerequiredtoupdatedevelopmentmachinesduetoasecurityholeorotherissue.
Awaytoabstracttheembeddeddevelopmentenvironmentfromthestandarddesktopenvironmentisneeded.
Thekeyisnotonlytofindalong-lifeembeddedLinuxhardwareplatform,butalsoalong-lifeembeddedLinuxsoftwareplatform.
AccomplishedembeddedLinuxprogrammersoftencancreateanembeddeddevelopmentplatformbygatheringthecorrectlibrariesandtoolversions,andmodifyingtheMakefileappropriately.
Evenwhensuccessful,it'sasuboptimumdevelopmentenvironment.
Ideally,compilersshouldnotrelyonthelibrariesandkernelsoftheirhost,butinsteadonthetoolchainofthemorestatictarget.
Thesoftwareplatformshouldbecompatiblewithotherplatforms,otherOperatingSystems(OSs),andotherlanguages.
TheSoftwareDevelopmentKit(SDK)shouldbebasedontoolchainswithbroadcommunitysupportsothatevenifoneoftheorganizationsdrivingtheSDKstopssupportingit,itsurvivesontheshouldersoftherest.
EnterEclipseEclipseisanopensource,redistributable,cross-platform,frameworkforcodedevelopment.
ItnativelysupportsJava,andC/C++withitsCDTplug-in.
ItprovidesmanyofthesamefunctionsthathavebeenreinventedoverandoverbythecommercialIntegratedDevelopmentEnvironments(IDEs)(syntaxhighlighting,languageawaresearches,codecompletion,andsoon)butdoesn'trelyonanyoneparticularsetoftoolstoaccomplishit(seeFigure1).
Printedfrom:http://www.
embedded-computing.
com/departments/eclipse/2006/11/ByNathanGustavsonEMAC,Inc.
andEricRossiEMAC,Inc.
Page1of5Printedfromembedded-computing.
comFigure1(clicktozoom)TheflexibilityofthissolutionledEMACandotherembeddedsoftwarecompaniestobuilddevelopmentplatformsinanEclipseenvironment.
Thiscommercialadoptionhascreateddefactostandardizationforembeddedcodedevelopers.
OEMscanwriteEclipseplug-insandprojectsthatworkwithGNUtoolchainswhileprovidingcompatibilitywithnumerouscommercialplatformsrunningbothWindowsandLinux.
EmbeddedJavaEMAC'soriginalEclipseenvironmentwasdevelopedfortheSoM-400Mmodule,usingaDS400TINIprocessorfromDallas/Maxim.
Thisprocessor'sfirmwarecontainsaproprietaryembeddedJRE.
BuildingJavacodeforthesystemiscompletedbycompilingclassesforanormalJREenvironment,replacingthecorejarswithTINIspecificjarsandthenconvertingtheresultingclassesintoTINIexecutables.
TodothisdeveloperstookadvantageofEclipse'snativeAntsupport,whichcanbeusedtocreateakindofadvancedJavaMakefileinXMLformat.
AntthenbuildstargetsbyusingEclipse'sJDTcompileradaptorclass,whichmakestheinternalcompileravailabletoAnt'stasks.
TheSourceforgeTiniAntextensionthenperformsthefinalconversionfromJavaclasstoTINIexecutable.
Allthecomplexdeclarationsrequiredtodothisarehiddeninatop-levelbuild.
propertiesfile,vastlyreducingthecomplexityofcompilationfortheSoM-400Mtosimple,standardAnttasks.
Cross-compiledCTheEclipsetoolsprojectprovidesanopen,redistributableCdevelopmentplug-incalledtheCDT.
Itprovides,amongotherthings:SyntaxhighlightingCodecompletionOn-the-flybuildsDebuggerintegration(usingGDB'sMIinterface)Itdoesnotprovidetheactualcompiler,linker,anddebuggerbinaries.
Thesearespecifictothetargetbeingbuiltforandmustbeprovidedfromanexternalsource.
TheycanthenbeintegratedintoEclipsebywritinganEclipseplug-in,or,moresimply,byusing"standard"makeprojectsandspecifyingthecompilerintheMakefile.
TheMakefileinListing1willcompileasimpleHelloWorldexampleprojectintheEMACEclipseenvironment.
Page2of5Printedfromembedded-computing.
comLiketheembeddedJavaenvironment,complexcompiler/linkerflagscommontoallprojectsarehiddeninahigher-levelfile,whichisthenincludedbyallMakefilesintheSDK.
EMACprovidescross-compilersforallitsboardsbybuildingfreelyavailableGNUcross-compilersagainstthelibrariesofthetargetdevelopmentOS.
OnLinuxtheselibrariesarenative;onWindowstheCygwinlibraryisused.
Wethen"hide"theactualEclipseexecutableandreplaceitwithabatchfilethattemporarilyaddstherequiredpathstosupporttheGNUtoolchainswhenEclipseisstarted.
DebuggingDebuggingtakesplaceusingGDBandGDBServertofacilitatearemotedebuggingenvironment.
Toaccomplishthis,thecompiledexecutableisuploadedtotheSBCandaGDBServersessionisinitiatedlisteningonaspecificportorserialterminal.
TheEclipseDebuggingperspectiveallowstheusertothendebugtheapplicationbyspecifyingtheconnectionparameterstouseaswellastheversionofGDBbuiltforthetargetarchitecture.
TheDebuggingperspectivedisplaysthesourcecodeoftheprogramtobedebuggedandthegeneratedassemblycode.
Itiseasytomanageandmonitorbreakpointsandvariables,aswellassingle-stepthroughtheprogramlinebyline.
Thecurrentpositioninthesourcecodeisautomaticallyhighlighted.
Eclipseprovidesagraphicaldebuggingenvironmentthatgreatlysimplifiestheprocessofremotetargetdebugging.
TargetcommunicationWhendevelopingforanembeddedenvironment,itwillbenecessarytoestablishaconnectionwiththetargetboard,eitherbyaserialterminalprogramorthroughTCPusingaTelnet,SSH,orothersimilarconnection.
Whenthisisdonethroughthecommandlineinterfaceoragraphicalfrontend,theprogrammerisforcedtoconstantlyswitchbetweenwindowstomonitortheconnectionandtheIDEsimultaneously.
EMACeliminatesthisproblembyintegratingEclipseplug-insthatallowforSSH,Telnet,andTerminalconnectionsallwithinEclipse.
ThisallowstheprogrammertomonitortheembeddedtargetboardasifitwerealocalfilesystemandissuecommandsdirectlywithouthavingtoleavetheEclipseenvironment.
CVSEclipseprovidesapowerfulCVSnatively.
BysettingupaCVSloginandprovidingpasswordstocustomers,developerscaninsuretheyalwayshaveaccesstothemostrecentversionsofcodeandbugfixesforproducts.
SDKBASE=.
.
/.
.
/CROSS=$(SDKBASE)gcc-4.
0.
0-i486-D/bin/i486-linux-CC=$(CROSS)gccLIBFLAGS=-lc#VERBOSE=-vCFLAGS=-gOFLAGS=-WlTARGET=helloCFILES=hello.
call:$(TARGET)$(TARGET):objects$(CC)$(VERBOSE)*.
o$(OFLAGS)$(SLIBS)-o$(TARGET)$(LIBFLAGS)objects:$(CFILES)$(CC)$(VERBOSE)$(CFLAGS)-c$(CFILES)clean:$(RM)*.
o*.
gdb$(TARGET)TARGET_IP=192.
168.
0.
1LOGIN=someuserPASSWORD=somepasswordupload:wput$(TARGET)ftp://$(LOGIN):$(PASSWORD)@$(TARGET_IP)/.
.
/.
.
/tmp/$(TARGET)"Withalittleintegration,anOEMcancreatearobust,cross-platformdevelopmentplatformfortheirboardsthatwillrunonthesameplatformadoptedbymanycommercialsoftwarevendors.
"Page3of5Printedfromembedded-computing.
comUploadingsoftwarepatchesandentirelynewcomponentsforSDKsontoaCVSserverprovidesup-to-the-minutesoftwaresupporttocustomers,whocangraphicallyviewdifferencesinfilesandpatchtheirownSDKwithsome,all,ornoneofwhathasbeenuploaded.
DocumentationEclipseprovidesitsownnativebrowser,whichisbeneficialforcreatingHTMLlinkeddocumentationrightintheworkspace.
Inthisway,customerscanbrowsethroughHTMLdocumentation(similartothatgeneratedbyDoxygenandJavadoc).
Context-sensitivehelpisalsointegratedinEclipse(seeFigure2),allowingnewuserstobemoreproductive.
Figure2(clicktozoom)Thisdocumentationcanlinkrightbacktothesoftwaredeveloper'swebsiteaswell,allowinguserdocumentationtobeaddeddynamically.
Userscanswitchrightfromcodetodocumentationwithatab,ratherthannavigatingseveralwindowsatonce.
Integratedtools,betterdevelopmentEclipseprovidesanenvironmentwhereGNUtoolsandcommercialtoolscanplaytogether.
Withalittleintegration,anOEMcancreatearobust,cross-platformdevelopmentplatformfortheirboardsthatwillrunonthesameplatformadoptedbymanycommercialsoftwarevendors.
WithintheEclipseframework,EMACusescross-compilationtoalleviatetheproblemofabstractingtheembeddeddevelopmentenvironmentfromthestandarddesktopenvironment.
DebuggingisaccomplishedusingGDBwithEclipsewindowsforthedebugger'sinputandoutput.
CommunicationwiththetargetisalsointegratedintoEclipsethroughTelnet,FTP,Terminal,andSSHplug-ins.
CVSversioncontrolandHTMLdocumentationarebothaccomplishedwithintheEclipseenvironmentaswell.
AlloftheaforementioneddevelopmentcapabilitiesrolledupintoastandardIDEmakeforapowerful,efficientdevelopmentplatformthatcanbeusedwithasmall8-bitJava-basedcontrolleranda32-bitLinuxserverprogrammedinC.
ThisisthepowerofEclipse.
NathanZ.
GustavsonisaseniorsystemsengineeratEMAC,Inc.
specializinginLinuxandreal-timecontrol.
HeholdsaBSinElectricalEngineeringandiscurrentlypursingaMSatSouthernIllinoisUniversity.
EricRossiisaseniormanageratEMAC,Inc.
whereheisresponsiblefornewproductdevelopmentandcustomengineeringmanagement.
Erichasmorethan25yearsofexperienceinembeddedsystemdesignandholdsaBSinElectricalEngineeringTechnologyaswellasaBSandMSinComputerScience.
Tolearnmore,contactNathanorEricat:EMAC,Inc.
2390EMACWayCarbondale,IL62902Page4of5Printedfromembedded-computing.
com618-529-4525Nathan:ngustavson@emacinc.
comEric:erossi@emacinc.
comwww.
emacinc.
comMMVIIEmbeddedComputingDesign.
AnOpenSystemsPublishing,LLCpublication.
Page5of5Printedfromembedded-computing.
com