Designing the Next-Generation of Handheld Devices
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The document outlines key considerations in the design of next-generation handheld devices, focusing on hardware, software, and mechanical challenges. It emphasizes the importance of form factor and battery life, while identifying opportunities in mass and vertical markets. Design engineers must navigate a variety of factors including user requirements, component selection, and energy efficiency to create effective handheld solutions.
Designing the Next-Generation of Handheld Devices
- 1. Designing the NextDesigning the Next--Generation of Handheld DevicesGeneration of Handheld Devices Class 445Class 445 Thursday, September 18th, 2003Thursday, September 18th, 2003 Andrew GirsonAndrew Girson 240240--558558--20142014 agirsonagirson@inhandelectronics.com@inhandelectronics.com www.inhandelectronics.comwww.inhandelectronics.com
- 2. 2 Presentation FocusPresentation Focus A survey of the significant issues in theA survey of the significant issues in the development of system hardware anddevelopment of system hardware and system software for programmablesystem software for programmable handheld devices, based on 32handheld devices, based on 32--bitbit CPUs and operating systemsCPUs and operating systems
- 3. 3 Presentation OverviewPresentation Overview Market Opportunity & Design ChallengesMarket Opportunity & Design Challenges How Handheld Design is DifferentHow Handheld Design is Different Designing a HandheldDesigning a Handheld
- 4. 4 HandheldsHandhelds -- A Growing MarketA Growing Market Over 400M ARM CPUs shipped in 2001Over 400M ARM CPUs shipped in 2001 –– majority of these CPUs in cellular telephones,majority of these CPUs in cellular telephones, PDAs, and other wireless devicesPDAs, and other wireless devices Yet, cellular telephone penetration wasYet, cellular telephone penetration was just 6% in China in 2000just 6% in China in 2000 –– US penetration 41%US penetration 41% –– Worldwide penetration 12%Worldwide penetration 12%
- 5. 5 OpportunityOpportunity Mass MarketsMass Markets –– Merging multiple handhelds into oneMerging multiple handhelds into one –– Bringing handhelds to everybodyBringing handhelds to everybody Vertical marketsVertical markets –– Bringing smart handhelds to new segmentsBringing smart handhelds to new segments –– Upgrading “fixedUpgrading “fixed--function” handheldsfunction” handhelds All MarketsAll Markets –– Leveraging new technologiesLeveraging new technologies
- 6. 6 What This Means for EngineersWhat This Means for Engineers OpportunityOpportunity Volatility & InnovationVolatility & Innovation Design ChallengesDesign Challenges “make it smaller”“make it smaller” ““ruggedizeruggedize it”it” “make it run for weeks on a single charge”“make it run for weeks on a single charge” “make it hands“make it hands--free”free” “add location“add location--based services”based services” “use this new wireless technology”“use this new wireless technology”
- 7. 7 How Handheld Design is DifferentHow Handheld Design is Different Designers of handheld devices mustDesigners of handheld devices must overcome all of the challenges ofovercome all of the challenges of traditional embedded design, yet theytraditional embedded design, yet they must also…must also… …make it fit…make it fit …make it last…make it last
- 8. 8 How Handheld Design is DifferentHow Handheld Design is Different It all comes down to...It all comes down to... “Form Factor” & “Battery Life”“Form Factor” & “Battery Life”
- 9. 9 Designing a HandheldDesigning a Handheld Define user requirementsDefine user requirements Select a Form FactorSelect a Form Factor Select a DisplaySelect a Display Select BatteriesSelect Batteries Select a CPU & OSSelect a CPU & OS Design system hardware platformDesign system hardware platform Develop system software platformDevelop system software platform
- 10. 10 Define User RequirementsDefine User Requirements Will it be used outside?Will it be used outside? What types of data will be displayed?What types of data will be displayed? How will the user input data?How will the user input data? Is it likely to be dropped on a hard surface?Is it likely to be dropped on a hard surface? Could it get wet?Could it get wet? Will the user have ready access to AC power?Will the user have ready access to AC power? How will the user talk to the network?How will the user talk to the network?
- 11. 11 Select a Form FactorSelect a Form Factor PDAPDA Cell phoneCell phone SmartphoneSmartphone Web TabletWeb Tablet Wearable ComputerWearable Computer Wireless TerminalWireless Terminal
- 12. 12 Select a Form FactorSelect a Form Factor Develop mechanical specificationsDevelop mechanical specifications –– Package form factor and materialsPackage form factor and materials –– Display, battery, electronics, and input integrationDisplay, battery, electronics, and input integration –– Manufacturability and assembly issuesManufacturability and assembly issues –– Environmental and ruggedization issuesEnvironmental and ruggedization issues
- 13. 13 Select a DisplaySelect a Display Based on form factorBased on form factor Based on user interface requirementsBased on user interface requirements Based on ambient environmentBased on ambient environment indoor, outdoor, readable in sunlight, readableindoor, outdoor, readable in sunlight, readable in low light, viewing angle, orientationin low light, viewing angle, orientation
- 14. 14 Select a DisplaySelect a Display Different TechnologiesDifferent Technologies STN, TFT, OLEDSTN, TFT, OLED reflective, transmissive, transflectivereflective, transmissive, transflective BacklightsBacklights -- CCFT, EL, LED (watch out forCCFT, EL, LED (watch out for power consumption and noise)power consumption and noise) Always get:Always get: a demo of the working display in thea demo of the working display in the environment in which it will be usedenvironment in which it will be used a power measurement with and withouta power measurement with and without backlightingbacklighting
- 15. 15 Select BatteriesSelect Batteries Two Types of BatteriesTwo Types of Batteries –– PrimaryPrimary –– RechargeableRechargeable Each has advantages and disadvantagesEach has advantages and disadvantages Make sure you estimate battery life forMake sure you estimate battery life for “likely” user scenarios“likely” user scenarios
- 16. 16 Characteristics of Primary BatteriesCharacteristics of Primary Batteries Primary batteries have higher energyPrimary batteries have higher energy density thandensity than rechargeablesrechargeables CarbonCarbon--Zinc and Alkaline are commodityZinc and Alkaline are commodity “drugstore” batteries“drugstore” batteries Lithium batteries are best allLithium batteries are best all--aroundaround performers with very flat discharge curves,performers with very flat discharge curves, high energy density, and excellent shelfhigh energy density, and excellent shelf life and lowlife and low--temperature capacitytemperature capacity
- 17. 17 Comparison of Primary BatteryComparison of Primary Battery TypesTypes Chemistry Cell Voltage (V) Cell Capacity (mAh) Gravimetric Energy Density (WHr/kg) Volumetric Energy Density (WHr/l) Capacity loss per YEAR (@ 20C) Carbon- Zinc 1.5 10-5000 105-195 100-180 5% Alkaline 1.5 10-5000 125-225 150-440 4% Silver Oxide 1.5 5-200 155-285 250-500 3% Zinc Air 1.4 30-1000 245-455 470-1450 5% (sealed) Lithium 1.5, 3.0 10-3000 32-260 340-500 1%
- 18. 18 Characteristics of RechargeableCharacteristics of Rechargeable BatteriesBatteries Rechargeable batteries are reusable, reducingRechargeable batteries are reusable, reducing cost and environmental issuescost and environmental issues LiLi--Ion batteries are best performers, but areIon batteries are best performers, but are costly and require tight control of chargingcostly and require tight control of charging algorithmsalgorithms NiMH and LiNiMH and Li--Ion can be dangerous ifIon can be dangerous if overchargedovercharged NiCad is simpler with better overchargingNiCad is simpler with better overcharging tolerance, but lower performingtolerance, but lower performing
- 19. 19 Comparison of RechargeableComparison of Rechargeable Battery TypesBattery Types Chemistry Cell Voltage (V) Cell Capacity (mAh) Gravimetric Energy Density (WHr/kg) Volumetric Energy Density (WHr/l) Capacity loss per MONTH (@ 20C) NiCad 1.2 50-5000 55 170 10% NiMH 1.2 10-5000 70 250 15% Li-Ion 3.6 25-1600 120 350 3%
- 20. 20 Battery Life Estimates for CommonBattery Life Estimates for Common ScenariosScenarios PDAPDA -- 900mW on; 200mW idle; 5mW900mW on; 200mW idle; 5mW sleep; 1% on time; 3% idle timesleep; 1% on time; 3% idle time –– 3 AAA Alkaline cells (Energizer): ~200 hours3 AAA Alkaline cells (Energizer): ~200 hours –– 1 Li1 Li--Ion cell (iPAQ): ~200 hoursIon cell (iPAQ): ~200 hours Smart sensorSmart sensor -- 50mW on; 0.5mW sleep;50mW on; 0.5mW sleep; 2% on time2% on time –– 3 AAA Alkaline cells (Energizer): ~2700 hours3 AAA Alkaline cells (Energizer): ~2700 hours –– 1 Li1 Li--Ion cell (iPAQ): ~2900 hoursIon cell (iPAQ): ~2900 hours
- 21. 21 Select a CPUSelect a CPU ARM architecture is entrenchedARM architecture is entrenched –– Pocket PC now is only on ARMPocket PC now is only on ARM –– PalmOSPalmOS is now based on ARMis now based on ARM –– Intel, TI, Samsung, Sharp,Intel, TI, Samsung, Sharp, AtmelAtmel, Philips, and Motorola, Philips, and Motorola all have ARM CPUs specifically targeted at handheldsall have ARM CPUs specifically targeted at handhelds MIPsMIPs and x86 have intriguing optionsand x86 have intriguing options –– AMD (Alchemy and Geode)AMD (Alchemy and Geode)
- 22. 22 Select a CPUSelect a CPU Important featuresImportant features –– Power modes (run, idle, sleep, and more…)Power modes (run, idle, sleep, and more…) –– Voltage and clock scalingVoltage and clock scaling –– Lots of peripheral integration and I/OLots of peripheral integration and I/O –– OnOn--chip memorychip memory –– “Stacked” memory“Stacked” memory
- 23. 23 Select an Operating SystemSelect an Operating System Palm OS is market leaderPalm OS is market leader Will licensing restrictions loosen?Will licensing restrictions loosen? Microsoft’s Pocket PC is coming on strongMicrosoft’s Pocket PC is coming on strong Will it overtake Palm?Will it overtake Palm? SymbianSymbian Strong in cellular (Java)Strong in cellular (Java) LinuxLinux Will embedded growth translate to handhelds?Will embedded growth translate to handhelds?
- 24. 24 Hardware PlatformHardware Platform Power SupplyPower Supply Test & DebugTest & Debug MemoryMemory User InputUser Input LCDLCD AudioAudio CommunicationsCommunications ExpansionExpansion
- 25. 25 Hardware PlatformHardware Platform -- Power SupplyPower Supply RegulatorsRegulators LinearLinear –– Cheap & simple, low noiseCheap & simple, low noise SwitchedSwitched--ModeMode –– High efficiencyHigh efficiency Boost SuppliesBoost Supplies Allow operation from fewer/smaller batteriesAllow operation from fewer/smaller batteries Watch out for current transientsWatch out for current transients Segment the power systemSegment the power system
- 26. 26 Hardware PlatformHardware Platform -- Test & DebugTest & Debug Small boards limit test pointsSmall boards limit test points Small boards limit debug connectorsSmall boards limit debug connectors OptionsOptions Single debug connector with all debug hardware onSingle debug connector with all debug hardware on daughterboarddaughterboard Large board for development; respin in productionLarge board for development; respin in production
- 27. 27 Hardware PlatformHardware Platform -- MemoryMemory NonNon--volatilevolatile –– Linear NOR FlashLinear NOR Flash –– allows XIP, can reduce DRAM requirementsallows XIP, can reduce DRAM requirements –– Linear NAND FlashLinear NAND Flash –– reduces cost, scalable to large densitiesreduces cost, scalable to large densities –– Peripheral Flash Storage DevicesPeripheral Flash Storage Devices –– can be less expensive, straightforward parameter storagecan be less expensive, straightforward parameter storage Volatile/SDRAMVolatile/SDRAM –– Must have battery backupMust have battery backup –– New CPUs supporting 2.5V (and lower) partsNew CPUs supporting 2.5V (and lower) parts
- 28. 28 Hardware PlatformHardware Platform -- User InputUser Input Very dependent on user environmentVery dependent on user environment –– Keypads, buttons, andKeypads, buttons, and touchpadstouchpads imply largerimply larger devicedevice –– TouchscreensTouchscreens allow smaller device, but can beallow smaller device, but can be fragile and noisyfragile and noisy –– Speech input allows small device, but ambientSpeech input allows small device, but ambient and audio subsystem noise are issuesand audio subsystem noise are issues
- 29. 29 Hardware PlatformHardware Platform -- LCDLCD Very dependent on user environmentVery dependent on user environment –– Affects device sizeAffects device size –– Affects device battery lifeAffects device battery life –– Different “lighting” techniquesDifferent “lighting” techniques –– Watch out for touchscreen pointingWatch out for touchscreen pointing accuracy (noise) with large displaysaccuracy (noise) with large displays –– Be careful with connector placementBe careful with connector placement
- 30. 30 Hardware PlatformHardware Platform -- AudioAudio Can greatly impact battery lifeCan greatly impact battery life Audio component placement affectsAudio component placement affects sound input and output qualitysound input and output quality
- 31. 31 Hardware PlatformHardware Platform -- CommsComms Wireless Data and VoiceWireless Data and Voice 802.11 is power802.11 is power--hungryhungry Bluetooth is not ubiquitousBluetooth is not ubiquitous New technologies (e.g., UWB, Zigbee) areNew technologies (e.g., UWB, Zigbee) are intriguingintriguing Location (GPS)Location (GPS) Component placement affects qualityComponent placement affects quality Many manufacturers are opting for offMany manufacturers are opting for off-- thethe--shelf, plugshelf, plug--in solutionsin solutions
- 32. 32 Hardware PlatformHardware Platform -- ExpansionExpansion Standard connectors are flexible, butStandard connectors are flexible, but drive device sizedrive device size Daughtercard connectors provide optionalDaughtercard connectors provide optional followfollow--on developmenton development New peripherals requiring higher speedNew peripherals requiring higher speed busses (USB 2.0, Firewire, GB Ethernet)busses (USB 2.0, Firewire, GB Ethernet) Make sure peripheral is off or in “sleep”Make sure peripheral is off or in “sleep” when not in usewhen not in use
- 33. 33 System SoftwareSystem Software Power ModesPower Modes Frequency/Voltage AdjustmentFrequency/Voltage Adjustment Interrupt ReductionInterrupt Reduction Intelligent WaitingIntelligent Waiting
- 34. 34 System SoftwareSystem Software Power ModesPower Modes CPU Power ModesCPU Power Modes Run, Idle, Doze, Sleep, OffRun, Idle, Doze, Sleep, Off Prepare memory for battery backupPrepare memory for battery backup Allow instantAllow instant--onon Set I/O pins properly in SleepSet I/O pins properly in Sleep Peripheral Power ModesPeripheral Power Modes Many peripherals have themMany peripherals have them Usage can double or triple battery lifeUsage can double or triple battery life
- 35. 35 System SoftwareSystem Software Frequency/Voltage AdjustmentFrequency/Voltage Adjustment Power consumption linearly proportionalPower consumption linearly proportional to CPU core frequencyto CPU core frequency Power consumption proportional toPower consumption proportional to square of CPU core voltagesquare of CPU core voltage Analyze your software for periods whenAnalyze your software for periods when performance is independent of CPUperformance is independent of CPU core frequency and adjust accordinglycore frequency and adjust accordingly
- 36. 36 System SoftwareSystem Software Interrupt ReductionInterrupt Reduction Make interrupt buffers largerMake interrupt buffers larger Use DMA whenever possibleUse DMA whenever possible Allows CPU to remain in IdleAllows CPU to remain in Idle Reduces interrupt countReduces interrupt count Reduces computational bandwidth requirementsReduces computational bandwidth requirements
- 37. 37 System SoftwareSystem Software Intelligent WaitingIntelligent Waiting Avoid “spinning”Avoid “spinning” -- try to go to Idletry to go to Idle If “spinning” is unavoidable, can clockIf “spinning” is unavoidable, can clock frequency and voltage be reduced?frequency and voltage be reduced?
- 38. 38 SummarySummary Hardware, software, & mechanicalHardware, software, & mechanical design teams must interactdesign teams must interact mechanical, electrical, and softwaremechanical, electrical, and software engineering matters are highly intertwinedengineering matters are highly intertwined Design challengesDesign challenges Form factorForm factor Battery lifeBattery life