Designing the Next- Designing the Next -Generation of Handheld - - PowerPoint PPT Presentation

Designing the Next Designing the Next-

• Generation of Handheld Devices

Generation of Handheld Devices

Class 445 Class 445 Thursday, September 18th, 2003 Thursday, September 18th, 2003

Andrew Girson Andrew Girson

240 240-

• 558

558-

• 2014

2014 agirson agirson@inhandelectronics.com @inhandelectronics.com www.inhandelectronics.com www.inhandelectronics.com

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Presentation Focus Presentation Focus

A survey of the significant issues in the A survey of the significant issues in the development of system hardware and development of system hardware and system software for programmable system software for programmable handheld devices, based on 32 handheld devices, based on 32-

• bit

bit CPUs and operating systems CPUs and operating systems

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Presentation Overview Presentation Overview

• Market Opportunity & Design Challenges

Market Opportunity & Design Challenges

• How Handheld Design is Different

How Handheld Design is Different

• Designing a Handheld

Designing a Handheld

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Handhelds Handhelds -

• A Growing Market

A Growing Market

• Over 400M ARM CPUs shipped in 2001

Over 400M ARM CPUs shipped in 2001

– – majority of these CPUs in cellular telephones, majority of these CPUs in cellular telephones, PDAs, and other wireless devices PDAs, and other wireless devices

• Yet, cellular telephone penetration was

Yet, cellular telephone penetration was just 6% in China in 2000 just 6% in China in 2000

– – US penetration 41% US penetration 41% – – Worldwide penetration 12% Worldwide penetration 12%

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Opportunity Opportunity

• Mass Markets

Mass Markets

– – Merging multiple handhelds into one Merging multiple handhelds into one – – Bringing handhelds to everybody Bringing handhelds to everybody

• Vertical markets

Vertical markets

– – Bringing smart handhelds to new segments Bringing smart handhelds to new segments – – Upgrading “fixed Upgrading “fixed-

• function” handhelds

function” handhelds

• All Markets

All Markets

– – Leveraging new technologies Leveraging new technologies

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What This Means for Engineers What This Means for Engineers

Opportunity Opportunity

• Volatility & Innovation

Volatility & Innovation

• Design Challenges

Design Challenges

“make it smaller” “make it smaller” “ “ruggedize ruggedize 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”

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How Handheld Design is Different How Handheld Design is Different

• Designers of handheld devices must

Designers of handheld devices must

• vercome all of the challenges of
• vercome all of the challenges of

traditional embedded design, yet they traditional embedded design, yet they must also… must also…

• …make it fit

…make it fit

• …make it last

…make it last

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How Handheld Design is Different How Handheld Design is Different

It all comes down to... It all comes down to... “Form Factor” & “Battery Life” “Form Factor” & “Battery Life”

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Designing a Handheld Designing a Handheld

• Define user requirements

Define user requirements

• Select a Form Factor

Select a Form Factor

• Select a Display

Select a Display

• Select Batteries

Select Batteries

• Select a CPU & OS

Select a CPU & OS

• Design system hardware platform

Design system hardware platform

• Develop system software platform

Develop system software platform

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Define User Requirements Define 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?

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Select a Form Factor Select a Form Factor

• PDA

PDA

• Cell phone

Cell phone

• Smartphone

Smartphone

• Web Tablet

Web Tablet

• Wearable Computer

Wearable Computer

• Wireless Terminal

Wireless Terminal

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Select a Form Factor Select a Form Factor

• Develop mechanical specifications

Develop mechanical specifications

– – Package form factor and materials Package form factor and materials – – Display, battery, electronics, and input integration Display, battery, electronics, and input integration – – Manufacturability and assembly issues Manufacturability and assembly issues – – Environmental and ruggedization issues Environmental and ruggedization issues

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Select a Display Select a Display

• Based on form factor

Based on form factor

• Based on user interface requirements

Based on user interface requirements

• Based on ambient environment

Based on ambient environment

• indoor, outdoor, readable in sunlight, readable

indoor, outdoor, readable in sunlight, readable in low light, viewing angle, orientation in low light, viewing angle, orientation

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Select a Display Select a Display

• Different Technologies

Different Technologies

• STN, TFT, OLED

STN, TFT, OLED

• reflective, transmissive, transflective

reflective, transmissive, transflective

• Backlights

Backlights -

• CCFT, EL, LED (watch out for

CCFT, EL, LED (watch out for power consumption and noise) power consumption and noise)

• Always get:

Always get:

• a demo of the working display in the

a demo of the working display in the environment in which it will be used environment in which it will be used

• a power measurement with and without

a power measurement with and without backlighting backlighting

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Select Batteries Select Batteries

• Two Types of Batteries

Two Types of Batteries

– – Primary Primary – – Rechargeable Rechargeable

• Each has advantages and disadvantages

Each has advantages and disadvantages

• Make sure you estimate battery life for

Make sure you estimate battery life for “likely” user scenarios “likely” user scenarios

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Characteristics of Primary Batteries Characteristics of Primary Batteries

• Primary batteries have higher energy

Primary batteries have higher energy density than density than rechargeables rechargeables

• Carbon

Carbon-

• Zinc and Alkaline are commodity

Zinc and Alkaline are commodity “drugstore” batteries “drugstore” batteries

• Lithium batteries are best all

Lithium batteries are best all-

• around

around performers with very flat discharge curves, performers with very flat discharge curves, high energy density, and excellent shelf high energy density, and excellent shelf life and low life and low-

• temperature capacity

temperature capacity

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Comparison of Primary Battery Comparison of Primary Battery Types Types

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% S ilver 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%

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Characteristics of Rechargeable Characteristics of Rechargeable Batteries Batteries

• Rechargeable batteries are reusable, reducing

Rechargeable batteries are reusable, reducing cost and environmental issues cost and environmental issues

• Li

Li-

• Ion batteries are best performers, but are

Ion batteries are best performers, but are costly and require tight control of charging costly and require tight control of charging algorithms algorithms

• NiMH and Li

NiMH and Li-

• Ion can be dangerous if

Ion can be dangerous if

• vercharged
• vercharged
• NiCad is simpler with better overcharging

NiCad is simpler with better overcharging tolerance, but lower performing tolerance, but lower performing

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Comparison of Rechargeable Comparison of Rechargeable Battery Types Battery 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%

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Battery Life Estimates for Common Battery Life Estimates for Common Scenarios Scenarios

• PDA

PDA -

• 900mW on; 200mW idle; 5mW

900mW on; 200mW idle; 5mW sleep; 1% on time; 3% idle time sleep; 1% on time; 3% idle time

– – 3 AAA Alkaline cells (Energizer): ~ 200 hours 3 AAA Alkaline cells (Energizer): ~ 200 hours – – 1 Li 1 Li-

• Ion cell (iPAQ): ~ 200 hours

Ion cell (iPAQ): ~ 200 hours

• Smart sensor

Smart sensor -

• 50mW on; 0.5mW sleep;

50mW on; 0.5mW sleep; 2% on time 2% on time

– – 3 AAA Alkaline cells (Energizer): ~ 2700 hours 3 AAA Alkaline cells (Energizer): ~ 2700 hours – – 1 Li 1 Li-

• Ion cell (iPAQ): ~ 2900 hours

Ion cell (iPAQ): ~ 2900 hours

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Select a CPU Select a CPU

• ARM architecture is entrenched

ARM architecture is entrenched

– – Pocket PC now is only on ARM Pocket PC now is only on ARM – – PalmOS PalmOS is now based on ARM is now based on ARM – – Intel, TI, Samsung, Sharp, Intel, TI, Samsung, Sharp, Atmel Atmel, Philips, and Motorola , Philips, and Motorola all have ARM CPUs specifically targeted at handhelds all have ARM CPUs specifically targeted at handhelds

• MIPs

MIPs and x86 have intriguing options and x86 have intriguing options

– – AMD (Alchemy and Geode) AMD (Alchemy and Geode)

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Select a CPU Select a CPU

• Important features

Important features

– – Power modes (run, idle, sleep, and more…) Power modes (run, idle, sleep, and more…) – – Voltage and clock scaling Voltage and clock scaling – – Lots of peripheral integration and I/O Lots of peripheral integration and I/O – – On On-

• chip memory

chip memory – – “Stacked” memory “Stacked” memory

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Select an Operating System Select an Operating System

• Palm OS is market leader

Palm OS is market leader

• Will licensing restrictions loosen?

Will licensing restrictions loosen?

• Microsoft’s Pocket PC is coming on strong

Microsoft’s Pocket PC is coming on strong

• Will it overtake Palm?

Will it overtake Palm?

• Symbian

Symbian

• Strong in cellular (Java)

Strong in cellular (Java)

• Linux

Linux

• Will embedded growth translate to handhelds?

Will embedded growth translate to handhelds?

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Hardware Platform Hardware Platform

• Power Supply

Power Supply

• Test & Debug

Test & Debug

• Memory

Memory

• User Input

User Input

• LCD

LCD

• Audio

Audio

• Communications

Communications

• Expansion

Expansion

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Hardware Platform Hardware Platform -

• Power Supply

Power Supply

• Regulators

Regulators

• Linear

Linear

– – Cheap & simple, low noise Cheap & simple, low noise

• Switched

Switched-

• Mode

Mode

– – High efficiency High efficiency

• Boost Supplies

Boost Supplies

• Allow operation from fewer/smaller batteries

Allow operation from fewer/smaller batteries

• Watch out for current transients

Watch out for current transients

• Segment the power system

Segment the power system

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Hardware Platform Hardware Platform -

• Test & Debug

Test & Debug

• Small boards limit test points

Small boards limit test points

• Small boards limit debug connectors

Small boards limit debug connectors

• Options

Options

• Single debug connector with all debug hardware on

Single debug connector with all debug hardware on daughterboard daughterboard

• Large board for development; respin in production

Large board for development; respin in production

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Hardware Platform Hardware Platform -

• Memory

Memory

• Non

Non-

• volatile

volatile

– – Linear NOR Flash Linear NOR Flash

– – allows XIP, can reduce DRAM requirements allows XIP, can reduce DRAM requirements

– – Linear NAND Flash Linear NAND Flash

– – reduces cost, scalable to large densities reduces cost, scalable to large densities

– – Peripheral Flash Storage Devices Peripheral Flash Storage Devices

– – can be less expensive, straightforward parameter storage can be less expensive, straightforward parameter storage

• Volatile/SDRAM

Volatile/SDRAM

– – Must have battery backup Must have battery backup – – New CPUs supporting 2.5V (and lower) parts New CPUs supporting 2.5V (and lower) parts

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Hardware Platform Hardware Platform -

• User Input

User Input

• Very dependent on user environment

Very dependent on user environment

– – Keypads, buttons, and Keypads, buttons, and touchpads touchpads imply larger imply larger device device – – Touchscreens Touchscreens allow smaller device, but can be allow smaller device, but can be fragile and noisy fragile and noisy – – Speech input allows small device, but ambient Speech input allows small device, but ambient and audio subsystem noise are issues and audio subsystem noise are issues

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Hardware Platform Hardware Platform -

• LCD

LCD

• Very dependent on user environment

Very dependent on user environment

– – Affects device size Affects device size – – Affects device battery life Affects device battery life – – Different “lighting” techniques Different “lighting” techniques – – Watch out for touchscreen pointing Watch out for touchscreen pointing accuracy (noise) with large displays accuracy (noise) with large displays – – Be careful with connector placement Be careful with connector placement

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Hardware Platform Hardware Platform -

• Audio

Audio

• Can greatly impact battery life

Can greatly impact battery life

• Audio component placement affects

Audio component placement affects sound input and output quality sound input and output quality

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Hardware Platform Hardware Platform -

• Comms

Comms

• Wireless Data and Voice

Wireless Data and Voice

• 802.11 is power

802.11 is power-

• hungry

hungry

• Bluetooth is not ubiquitous

Bluetooth is not ubiquitous

• New technologies (e.g., UWB, Zigbee) are

New technologies (e.g., UWB, Zigbee) are intriguing intriguing

• Location (GPS)

Location (GPS)

• Component placement affects quality

Component placement affects quality

• Many manufacturers are opting for off

Many manufacturers are opting for off-

• the

the-

• shelf, plug

shelf, plug-

• in solutions

in solutions

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Hardware Platform Hardware Platform -

• Expansion

Expansion

• Standard connectors are flexible, but

Standard connectors are flexible, but drive device size drive device size

• Daughtercard connectors provide optional

Daughtercard connectors provide optional follow follow-

• on development
• n development
• New peripherals requiring higher speed

New 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 use when not in use

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System Software System Software

• Power Modes

Power Modes

• Frequency/Voltage Adjustment

Frequency/Voltage Adjustment

• Interrupt Reduction

Interrupt Reduction

• Intelligent Waiting

Intelligent Waiting

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System Software System Software

Power Modes Power Modes

• CPU Power Modes

CPU Power Modes

• Run, Idle, Doze, Sleep, Off

Run, Idle, Doze, Sleep, Off

• Prepare memory for battery backup

Prepare memory for battery backup

• Allow instant

Allow instant-

• on
• n
• Set I/O pins properly in Sleep

Set I/O pins properly in Sleep

• Peripheral Power Modes

Peripheral Power Modes

• Many peripherals have them

Many peripherals have them

• Usage can double or triple battery life

Usage can double or triple battery life

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System Software System Software

Frequency/Voltage Adjustment Frequency/Voltage Adjustment

• Power consumption linearly proportional

Power consumption linearly proportional to CPU core frequency to CPU core frequency

• Power consumption proportional to

Power consumption proportional to square of CPU core voltage square of CPU core voltage

• Analyze your software for periods when

Analyze your software for periods when performance is independent of CPU performance is independent of CPU core frequency and adjust accordingly core frequency and adjust accordingly

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System Software System Software

Interrupt Reduction Interrupt Reduction

• Make interrupt buffers larger

Make interrupt buffers larger

• Use DMA whenever possible

Use DMA whenever possible

• Allows CPU to remain in Idle

Allows CPU to remain in Idle

• Reduces interrupt count

Reduces interrupt count

• Reduces computational bandwidth requirements

Reduces computational bandwidth requirements

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System Software System Software

Intelligent Waiting Intelligent Waiting

• Avoid “spinning”

Avoid “spinning” -

• try to go to Idle

try to go to Idle

• If “spinning” is unavoidable, can clock

If “spinning” is unavoidable, can clock frequency and voltage be reduced? frequency and voltage be reduced?

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Summary Summary

• Hardware, software, & mechanical

Hardware, software, & mechanical design teams must interact design teams must interact

• mechanical, electrical, and software

mechanical, electrical, and software engineering matters are highly intertwined engineering matters are highly intertwined

• Design challenges

Design challenges

• Form factor

Form factor

• Battery life

Battery life