book

Mastering the Raspberry Pi

by Warren W. Gay

August 2014

Beginner

504 pages

11h 2m

English

Apress

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Who Needs This Book?This Book Is Primarily AboutLearning ApproachOrganization of This BookSoftware in This BookFinal Words

ModelsHardware in CommonWhich Model?
Static IP AddressUsing SSHVNCDisplay NumberGeometryDepthPixel FormatPassword SetupServer StartupVNC ViewersStopping VNC ServerPrototype StationAdafruit Pi CobblerGertboardBare Metal
Calculating PowerCurrent RequirementPeripheral PowerModel B Input PowerModel A Input Power3.3 Volt PowerPowered USB HubsPower AdaptersAn Unsuitable SupplyE-book AdaptersBest Power SourceVoltage TestBattery PowerRequirementsHeadroomLM7805 RegulationDC-DC Buck ConverterSigns of Insufficient PowerNo Power
Status LEDsOK or ACT LEDPWR LEDFDX LEDLNK LED10M or 10/100 LEDHeader P1Safe ModeLogic LevelsGPIO Configuration at Reset1-Wire DriverHeader P5Reset
/proc/meminfoMemTotalMemFreeBuffersCachedSwapCachedActiveInactiveActive(anon)Inactive(anon)Active(file)Inactive(file)UnevictableMlockedSwapTotalSwapFreeDirtyWritebackAnonPagesMappedShmemSlabSReclaimableSUnreclaimKernelStackPageTablesNFS_UnstableBounceWritebackTmpCommitLimitCommitted_ASVmallocTotalVmallocUsedVmallocChunkPhysical MemoryMemory MappingAddressLengthProtectionFlagsFile DescriptorOffsetReturn ValueVolatileVirtual MemoryFinal Thoughts on SDRAM
IdentificationOverclockingExecutionThreadspthread Headerspthread Error Handlingpthread_create(3)pthread_attr_tpthread_join(3)pthread_detach(3)pthread_self(3)pthread_kill(3)Mutexespthread_mutex_create(3)pthread_mutex_destroy(3)pthread_mutex_lock(3)pthread_mutex_unlock(3)Condition Variablespthread_cond_init(3)pthread_cond_destroy(3)pthread_cond_wait(3)pthread_cond_signal(3)pthread_cond_broadcast(3)
PowerPowered HubsUSB API SupportlibusbInclude Files
Wired Ethernet/etc/network/interfacesChanging to Static IPTest Static IP AddressUSB Adapters/etc/hosts FileWireless EthernetConfiguration
SD Card MediaSD Card InterfaceSD Card BasicsRaspbian Block SizeDisk CacheCapacities and PerformanceTransfer ModesSPI Bus Mode1-bit SD Mode4-bit SD ModeWear Leveling
RS-232 ConverterDTE or DCERS-232Start BitData BitsParity BitStop Bit(s)Baud RateBreakFlow ControlRaspberry Pi UARTsARM PL011 UARTRTS/CTS AccessPL011 UART FeaturesExclusive Serial Line UseProcedureVerificationSerial APIHeader Filesopen(2)struct termiostcgetattr(3)tcsetattr(3)tcsendbreak(3)tcdrain(3)tcflush(3)tcflow(3)cfmakeraw(3)cfgetispeed(3)cfgetospeed(3)cfsetispeed(3)cfsetospeed(3)cfsetspeed(3)read(2)write(2)readv(2) and writev(2)Error EINTR
Pins and DesignationsConfiguration After ResetPull-up ResistorsConfiguring Pull-up ResistorsTesting Pull-up StateLogic LevelsDrive StrengthInput PinsOutput PinsDriving Bi-color LEDsTesting Drive StrengthGPIO Current BudgetConfigurationAlternate Function SelectOutput PinsInput PinsAlternate FunctionSysfs GPIO AccessexportunexportgpioXChip LevelGPIO TesterGPIO Input TestFloating PotentialsReading EventsTest RunDirect Register Accessgpio_init( )gpio_config( )gpio_write( )gpio_read( )gpio_io.cGPIO Transistor DriverDriver DesignSubstitutionInductive LoadsDriver SummaryUtility gpioDisplaying GPIO SettingsReading GPIOWriting GPIOModify Drive Levels
1-Wire Line and PowerLine DrivingMaster and SlaveProtocolResetData I/OSlave SupportReading TemperatureBus MasterSlave DevicesReading the Temperature1-Wire GPIO Pin
I2C OverviewSDA and SCLMultimaster and ArbitrationBus SignalingData BitsMessage FormatsWhich I2C Bus?I2C Bus SpeedToolsI2C APIKernel Module SupportHeader Filesopen(2)ioctl(2,I2C_FUNC)ioctl(2,I2C_RDWR)
SPI BasicsSPI ModeSignalingSlave SelectionDriver SupportSPI APIHeader FilesOpen DeviceSPI Mode MacrosBits per WordClock RateData I/OCloseWriteReadSPI Testing
Booting ARM LinuxBoot SequenceBoot Filesconfig.txtComposite Video SettingsHigh-Definition VideoOverscan VideoFrame Buffer SettingsGeneral Video OptionsLicensed CodecsTestingMemoryBoot OptionsOverclockingWarranty and OverclockingVoltage Settingscmdline.txtSerial console=Virtual console=kgdboc=root=rootfstype=elevator=rootwait=nfsroot=ip=Emergency Kernel
Run Levels/etc/inittabinittab Action initdefaultGeneral Startup Sequenceinittab Action waitinittab Action onceinittab Action respawnChanging Run LevelstelinitChange of Run LevelSingle-User ModeHalt and RebootCreating a New Service
vcgencmd CommandsOption measure_clockOption measure_voltsOption measure_tempOption codec_enabledOption versionOption get_lcd_infoOption get_config
Available ConsolesSerial Console
TerminologyOperating SystemHost, Guest, Build, and TargetPlatform LimitationsWithout VirtualBox (Native)Using VirtualBox (Ubuntu/Linux)Planning Your Cross-Development EnvironmentBuilding the Cross-CompilerDownload crosstool-NGStaging DirectoryUnpack the TarballCreate /opt/x-toolsInstall Package DependenciesConfigure crosstools-NGmake crosstool-ngmake installPATHCross-Compiler ConfigurationPaths and Misc OptionsTarget OptionsOperating SystemBinary UtilitiesC CompilerSave ConfigurationBuild Cross-CompilerTroubleshooting
Image ToolsDownload KernelEdit Makefilemake mrproperKernel Configmake menuconfigmakePrepare Kernel ImageInstall Kernel ImageBoot FailureModulesFirmwareVirtualBox Mount of SD Card
CharacteristicsCircuitProtocolOverall ProtocolData BitsData FormatSoftwareChosen ApproachExample RunSource Code
DC CharacteristicsGPIO Output CurrentGPIO InputsStandby CurrentInput Logic LevelsOutput Logic LevelsReset TimingCircuitI2C BusWiring and TestingSoftware ConfigurationGeneral ConfigurationMain ProgramModule i2c_funcs.cModule sysgpio.cExample RunResponse Times
Project OverviewNunchuk FeaturesConnector PinoutTesting the ConnectionNunchuk I2C ProtocolEncryptionRead Sensor DataLinux uinput InterfaceWorking with Header FilesOpening the Device NodeConfiguring EventsCreating the NodePosting EV_KEY EventsPosting EV_REL EventsPosting EV_SYN EventsClosing uinputX-WindowInput UtilitiesTesting the NunchukTesting ./nunchukUtility lsinputsUtility input-eventsThe Program
DS1307 OverviewPins X1 and X2Pin SQW/OUTPower3-Volt CompatibilityLogic LevelsTiny RTC ModificationsChecking for Pull-up ResistorsDS1307 Bus SpeedRTC and RAM Address MapReading Date and TimeI2C CommunicationWiringRunning the ExamplesThe Ultimate TestThe Startup Script
Operating ParametersPinoutVS1838B CircuitThe IR ReceiverSoftwareSignal ComponentsCode OrganizationCommand-Line Options
Floppy-Disk Stepper MotorYour Junk-Box Motor?Driver CircuitDarlington PairDriving the DriverInput LevelsPower-on Reset/BootModes of OperationWave Drive (Mode 0)Full-Step Drive (Mode 1)Half-Step Drive (Mode 2)SoftwareTesting
The L298 DriverSensing ResistorEnable A and BInputs In1 and In2Protection DiodesL298 PCBDriving from GPIOThe DMM CheckBipolar Stepper ModesOne-Phase-On ModeTwo-Phase-On ModeHalf-Step ModeChoosing Driving GPIOsProject SchematicJunk-Box MotorsProgram OperationProgram Internals
Switched InputsThe CD4013Testing the Flip-FlopThe LEDØMQPerforming InstallationCompiling and LinkingSensing Station DesignSensing Station ProgramConsole ProgramConsole CommandsSensor Source CodeConsole Source Code
Introduction to PWMPWM ParametersPWM Hardware PeripheralPWM SoftwareMeter Circuitpwm ProgramHardware PWM Set CommandHardware Based CPU Percent-Busy DisplaySoftware PWM ProgramHow Many PWMs?Running the Software PWM CommandSoftware Based CPU Percent-Busy Display
Ohm’s LawPowerUnits
List Available PackagesList Installed PackagesList Files for PackagePerform Package SearchInstall a PackageRemove a PackageInstall UpdatesUpgradeObtain Kernel Sources

Content preview from Mastering the Raspberry Pi

CHAPTER 30

Pulse-Width Modulation

This chapter explores pulse-width modulation (PWM) using the Raspberry Pi. PWM is applied in motor control, light dimming, and servo controls, to name a few examples. To keep the hardware simple and the software small enough to read, we’re going to apply PWM to driving an analog meter in this chapter.

While the CPU percent-busy calculation used here is a bit cheesy, it is simple and effective for our demonstration. The meter deflection will indicate how busy your Raspberry Pi’s CPU is. We’ll demonstrate this using a hardware and software PWM solution.

Introduction to PWM

The GPIO output signal is a digital signal ...