Embedded Systems Interfacing for Engineers using the Freescale HCS08 Microcontroller II: Digital and Analog Hardware Interfacing

139 Pages·2009·1.73 MB·English

by  Douglas Summerville

Embedded Systems Interfacing for
Engineers using the
Freescale HCS08 Microcontroller
II: Digital and Analog Hardware
Interfacing

Synthesis Lectures on
Digital Circuits and Systems
Editor
MitchellA.Thornton,SouthernMethodistUniversity
EmbeddedSystemsInterfacingforEngineersusingtheFreescaleHCS08Microcontroller
II:DigitalandAnalogHardwareInterfacing
DouglasH.Summerville
2009
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Copyright© 2009byMorgan&Claypool
Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmittedin
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EmbeddedSystemsInterfacingforEngineersusingtheFreescaleHCS08MicrocontrollerII:
DigitalandAnalogInterfacing
DouglasH.Summerville
www.morganclaypool.com
ISBN:9781608450084 paperback
ISBN:9781608450091 ebook
DOI10.2200/S00199ED1V01Y200906DCS022
APublicationintheMorgan&ClaypoolPublishersseries
SYNTHESISLECTURESONDIGITALCIRCUITSANDSYSTEMS
Lecture#22
SeriesEditor:MitchellA.Thornton,SouthernMethodistUniversity
SeriesISSN
SynthesisLecturesonDigitalCircuitsandSystems
Print1932-3166 Electronic1932-3174
Embedded Systems Interfacing for
Engineers using the
Freescale HCS08 Microcontroller
II: Digital and Analog Hardware
Interfacing
Douglas H.Summerville
StateUniversityofNewYorkatBinghamton
SYNTHESISLECTURESONDIGITALCIRCUITSANDSYSTEMS#22
M
&C Morgan &cLaypool publishers
ABSTRACT
The vast majority of computers in use today are encapsulated within other systems.In contrast to
general-purposecomputersthatrunanendlessselectionofsoftware,theseembeddedcomputersare
often programmed for a very specific,low-level and often mundane purpose.Low-end microcon-
trollers,costingaslittleasonedollar,areoftenemployedbyengineersindesignsthatutilizeonlya
smallfractionoftheprocessingcapabilityofthedevicebecauseitiseithermorecost-effectivethan
selecting an application-specific part or because programmability offers custom functionality not
otherwiseavailable.EmbeddedSystemsInterfacingforEngineersusingtheFreescaleHCS08Microcon-
troller isatwo-partbookintendedtoprovideanintroductiontohardwareandsoftwareinterfacing
for engineers. Building from a comprehensive introduction of fundamental computing concepts,
thebooksuitableforafirstcourseincomputerorganizationforelectricalorcomputerengineering
students with a minimal background in digital logic and programming.In addition,this book can
be valuable as a reference for engineers new to the Freescale HCS08 family of microcontrollers.
TheHCS08processorarchitectureusedinthebookisrelativelysimpletolearn,powerfulenough
toapplytowardsawide-rangeofinterfacingtasks,andaccommodatesbreadboardprototypingina
laboratoryusingfreelyavailableandlow-costtools.
InPartII:DigitalandAnalogHardwareInterfacing,hardwareandsoftwareinterfacingconcepts
are introduced.The emphasis of this work is on good hardware and software engineering design
principles.Devicedriversaredevelopedillustratingtheuseofgeneral-purposeandspecial-purpose
digitalI/Ointerfaces,analoginterfaces,serialinterfacesandreal-timeI/Oprocessing.Thehardware
sideofeachinterfaceisdescribedandelectricalspecificationsandrelatedissuesareconsidered.The
firstpartofthebookprovidestheprogrammingskillsnecessarytoimplementthesoftwareinthis
part.
KEYWORDS
microcontrollers, embedded computers, computer engineering, digital systems,
FreescaleHCS08,devicedrivers,hardware/softwareinterfacing
ix
Contents
Acknowledgments...............................................................xiii
1 IntroductiontotheMC9S08QG4/8Hardware......................................1
1.1 Input/OutputBasics........................................................1
1.1.1 PinDiagrams 1
1.1.2 Memory-MappedI/O 2
1.1.3 I/OSynchronization 4
1.1.4 DeviceDrivers 5
1.2 AMC9S08QG4/8SkeletonProgram ........................................6
1.2.1 SystemConfigurationRegisters 6
1.2.2 ComputerOperatingProperly(COP)Watchdog 7
1.2.3 InterruptVectorTable 8
1.2.4 HCS08ModesofOperation 9
1.2.5 ProgramSkeletonfortheMC9S08QG4/8 10
1.3 General-PurposeDigitalI/O...............................................13
1.3.1 GeneralPurposeI/OontheMC9S08QG4/8 14
1.3.2 ElectricalSpecifications 17
1.3.3 SwitchInputInterface 21
1.3.4 SwitchBounce 24
1.3.5 LEDIndicators 26
1.3.6 EmulationofOpen-DrainandTri-StateOutputs 32
1.4 InterruptSynchronization..................................................34
1.4.1 HCS08CPUInterruptProcessing 34
1.4.2 IRQInterruptPin 35
1.4.3 KeyboardInterrupt 38
1.5 ChapterProblems.........................................................41
x CONTENTS
2 AnalogInput....................................................................47
2.1 AnalogtoDigitalConversion...............................................47
2.1.1 ADCBasics 47
2.1.2 ConvertingADCOutputtoFixed-Point 48
2.2 ADContheMC9S08QG4/8..............................................50
2.2.1 MC9S08QG4/8ADCI/OInterfaceRegisters 51
2.3 DriverExamplesfortheMC9S08QG4/8ADC..............................54
2.3.1 Basic8-BitSingle-PinPolledI/ODriver 56
2.3.2 Basic10-BitSingleConversionwithSoftwareSelectablePin 58
2.3.3 Interrupt-Based8-BitDriver 58
2.3.4 MultipleADCPinScanningusingInterrupt-BasedDriver 61
2.3.5 8-BitPolledDriverwithCompareFunction 63
2.3.6 8-BitInterrupt-BasedDriverwithCompareFunction 64
2.3.7 8-BitInterrupt-BasedDriverwithHysteresis 65
2.4 AnalogComparator .......................................................66
2.5 AnalogComparatorontheMC9S08QG4/8.................................70
2.6 AnalogComparatorDriverExamples .......................................71
2.6.1 DCVoltageMonitoring 71
2.6.2 AnalogSignaltoDigitalWaveformGeneration 72
2.6.3 HardwareSwitchDebouncingUsingtheAnalogComparator 73
2.7 ChapterProblems.........................................................75
3 SerialCommunication...........................................................77
3.1 SerialCommunicationInterface ............................................77
3.1.1 MC9S08QG8SCI 79
3.1.2 SCIDriverExamples 84
3.1.3 Polled-I/OFull-DuplexSCIDriver 85
3.1.4 Interrupt-BasedRing-BufferedSCISimplex(Receive-Only)Driver
87
3.1.5 Interrupt-BasedRing-BufferedSCISimplex(Transmit)Driver 91
3.2 SerialPeripheralInterface(SPI) ............................................94
3.2.1 MC9S08GQ8SPI 95