Introduction to Embedded Systemsnyx.skku.ac.kr/wp-content/uploads/2019/09/1-intro.pdfICE3028: Embedded Systems Design, Fall 2019, Dongkun Shin ([email protected]) 18 Want More? •You

ICE3028: Embedded Systems Design, Fall 2019, Dongkun Shin ([email protected])

Introduction to Embedded Systems

Dongkun Shin ([email protected])

Embedded Software Laboratory

Sungkyunkwan University

http://nyx.skku.ac.kr/

mailto:[email protected]

http://nyx.skku.ac.kr/

ICE3028: Embedded Systems Design, Fall 2019, Dongkun Shin ([email protected]) 2

Embedded Systems Everywhere

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Definition

• Embedded System (ES):

any device that includes a programmable

computer but is not itself a general-purpose

computer.

– Take advantage of application characteristics to optimize

the design


Embedded Systems

• Features– Designed to perform a specific task or function– Invisible to end user– Defined by standard– Cyber-physical systems– Real-time– Low Power– Cost-sensitive

• Consumer devices– Internet-enabled TV, Blu-ray players, video game consoles,

streaming Internet TV devices, printers• Communications– Wifi router, ADSL modem, DSLAM, IP router• Control Systems– Motor controllers, actuators, sensors, PLCs, control panels


Where are the CPUs?

• Estimated 98% of 8 billion

CPUs produced in 2000

used for embedded

applications

• Smartphone shipments

(101M) surpass PCs

(2010Q4)

8.5B Parts per Year

Robots6%

Vehicles12%

Direct2%

Source: DARPA/Intel (Tennenhouse)


Embedded Processors

• Microcontroller (μC or MCU)

– A small computer on a single IC containing a

processor core, memory, and I/O peripherals

• Microprocessor

– A general-purpose CPU in a single chip

• SoC (System-on-a-Chip)

– More integration than MCU

– Mostly, require external memory

http://upload.wikimedia.org/wikipedia/commons/f/f0/KL_Intel_P8051.jpg

http://upload.wikimedia.org/wikipedia/en/f/f9/Apple-a4.jpg


Early History (1)

• Intel 4004 (1971)

– The first microprocessor (4-bit)

– Originally designed for use in a calculator

– The first complete CPU on one chip

– The first commercially available microprocessor

– 2300 transistors @ 108KHz


Early History (2)

• Automobiles used microprocessor-based engine

controllers starting in 1970’s

– Control fuel/air mixture, engine timing, etc.

– Multiple modes of operation: warm-up, cruise, hill

climbing, etc.

– Provides lower emissions, better fuel efficiency


Mouse


Hard Disk Drive


Digital Still Camera

Canon EOS3 uses three microprocessors for auto-focus, etc. (1998)


Digital TV

Programmable CPUs + hardwired logic for video/audio decode, etc.


iPhone 7

Apple A10 AP &

Samsung 2GB

LPDDR4 DRAM

Qualcomm

LTE Modem

Avago

PowerAmplifiers

SK Hynix

32GB Flash

Dialog & Qualcomm

Power Management ICs

Qualcomm

LTE Transceiver

Qualcomm

RF Transceiver

Bosch Barometric

Pressure Sensor

Apple/Cirrus Logic

Audio Codec

Cirrus Logic

Audio Amplifiers

NXP NFC

Controller

Murata Wi-Fi/Bluetooth

Module

Source: https://www.ifixit.com/Teardown/iPhone+7+Teardown/67382


Fitbit Flex

STMicroelectronics 32L151C6

Ultra Low Power ARM Cortex M3

Microcontroller

Nordic Semiconductor nRF8001

Bluetooth Low Energy IC

Charger IC: TI BQ24040

Accelerometer IC?

Source: https://www.ifixit.com/Teardown/Fitbit+Flex+Teardown/16050


DJI Phantom 2 Drone

Source: http://www.nytimes.com/2014/09/11/technology/personaltech/a-teardown-of-the-phantom-2-vision-plus-drone-from-dji.html


Automobile

• A high-end automobile

– > 100 microprocessors

– 4-bit microcontroller

checks seat belt

– Microcontrollers run

dashboard devices

– 16/32-bit

microprocessor

controls engine


Solid State Drive (SSD)


Want More?

• You name it!

And the list goes on and on …

Anti-lock brakes

Auto-focus cameras

Automatic teller machines

Automatic toll systems

Automatic transmission

Avionic systems

Battery chargers

Camcorders

Cell phones

Cell-phone base stations

Cordless phones

Cruise control

Curbside check-in systems

Digital cameras

Disk drives

Electronic card readers

Electronic instruments

Electronic toys/games

Factory control

Fax machines

Fingerprint identifiers

Home security systems

Life-support systems

Medical testing systems

Modems

MPEG decoders

Network cards

Network switches/routers

On-board navigation

Pagers

Photocopiers

Point-of-sale systems

Portable video games

Printers

Satellite phones

Scanners

Smart ovens/dishwashers

Speech recognizers

Stereo systems

Teleconferencing systems

Televisions

Temperature controllers

Theft tracking systems

TV set-top boxes

VCR’s, DVD players

Video game consoles

Video phones

Washers and dryers


ES Characteristics (1)

• Single-functioned

– Executes a single program, repeatedly

• Sophisticated functionality

– Often have to run sophisticated algorithms or multiple

algorithms

• Cell phone, laser printer, digital TV, etc.

– Often provide sophisticated user interfaces



• Reactive and real-time operation:

Must finish operations by deadlines

– Continually reacts to changes in the systems

environment

– Hard real-time: missing deadline causes failure

– Soft real-time: missing deadline results in degraded

performance

– Many systems are multi-rate:

Must handle operations at widely varying rate



• Low cost

– Manufacturing cost

• The monetary cost of manufacturing each copy

– NRE (Non-Recurring Engineering) cost

• The one-time monetary cost of designing the system

– Many embedded systems are mass-market items that

must have low manufacturing cost

– Limited memory, microprocessor power, etc.



• Low power

– Power consumption is critical in battery-powered

devices

– Excessive power consumption increases system cost

even in wall-powered devices



• Designed to tight deadlines by small teams

– Often designed by a small team of designers

– Often must meet tight deadlines

• 6-month time-to-market is common

• Can’t miss back-to-school window for calculator

– Many design alternatives

– Hard to develop and debug


Challenges in ES Design (1)

• How much hardware do we need?– Powerful CPU? Big memory?

• OS or Firmware?

• How do we meet our deadlines?– Faster hardware or cleverer software?

• How do we minimize power?– Turn off unnecessary logic? Reduce memory accesses?

• How do we design for upgradeability?– e.g. Evolution Kit in Samsung Digital TVs

• Time-to-market?



• Does it really work?

– Is the specification correct?

– Does the implementation meet the spec?

– How do we test for real-time characteristics?

– How do we test on real data?

– Does it work reliably?

• How do we work on the system?

– Limited observability and controllability

– Restricted development environments



• Optimizing design metrics

– Improving one may worsen others

– Expertise with both software and hardware is needed to

optimize design metrics

– A designer must be

comfortable with various

technologies in order to

choose the best for a given

application and constraints

SizePerformance

Power

NRE cost


Challenges for implementation ES

• Implementation in HW

– Lack of flexibility (changing standards).

– Mask cost for specialized HW becomes very expensive

• Trend towards implementation in Software

• Implementation in SW

– Exponential increase in software complexity

– In some areas code size is doubling every 9 months

–... > 70% of the development cost for complex systems such as automotive electronics and communication systems are due to software development


28

Processor technology

• The architecture of the computation engine used to implement a system’s desired functionality

• Processor does not have to be programmable– “Processor” not equal to general-purpose processor

Application-specific

Registers

Custom

ALU

DatapathController

Program memory

Assembly code

for:

total = 0

for i =1 to …

Control logic

and State

register

Data

memory

IR PC

Single-purpose (“hardware”)

DatapathController

Control

logic

State

register

Data

memory

index

total

+

IR PC

Register

file

General

ALU

DatapathController

Program memory

Assembly code

for:

total = 0

for i =1 to …

Control

logic and

State register

Data

memory

General-purpose (“software”)


29

Processor technology

• Processors vary in their customization for the problem at hand

total = 0

for i = 1 to N loop

total += M[i]

end loop

General-purpose

processor

Single-purpose

processor

Application-specific

processor

Desired

functionality


30

General-purpose processors

• Programmable device used in a variety of applications

– Also known as “microprocessor”

• Features– Program memory

– General datapath with large register file and general ALU

• User benefits– Low time-to-market and NRE costs

– High flexibility

• “ARM” the most well-known, but there are hundreds of others

IR PC

Register

file

General

ALU

DatapathController

Program

memory

Assembly code

for:

total = 0

for i =1 to …

Control

logic and

State register

Data

memory


31

Single-purpose processors

• Digital circuit designed to execute exactly

one program

– a.k.a. coprocessor, accelerator or peripheral

• Features

– Contains only the components needed to execute

a single program

– No program memory

• Benefits

– Fast

– Low power

– Small size

DatapathController

Control

logic

State

register

Data

memory

index

total

+


32

Application-specific processors

• Programmable processor optimized for a

particular class of applications having

common characteristics

– Compromise between general-purpose and

single-purpose processors

• Features

– Program memory

– Optimized datapath

– Special functional units

• Benefits

– Some flexibility, good performance, size and

power

IR PC

Registers

Custom

ALU

DatapathController

Program

memory

Assembly code

for:

total = 0

for i =1 to …

Control

logic and

State register

Data

memory


TI C62/C67 (High Performance DSP)

• Up to 8 instructions/cycle.

• 32 32-bit registers.

• Function units:– Two multipliers.

– Six ALUs.

• All instructions execute conditionally.

• Data operations– 8/16/32-bit arithmetic.

– 40-bit operations.

– Bit manipulation operations.


Freescale Starcore SC140

• DALU includes 4 ALUs, 1 register file.

• AGU includes 2 address arithmetic units (AAU), 1 address register file.

• Program sequencer and control unit (PSEQ).

• Performance:– 4 million MACs per

second per MHz clock.

– 10 RISC MIPS per MHz clock.

SC140 Core


SC140 Instruction format

• 16-bit instructions.

• Up to 6 instructions per cycle.

• Instructions are grouped to define allowable simultaneous operations.

• Allowable addressing modes:

– linear, modulo, multiple

– wrap-around modulo, and reverse-carry.

• Array addressing: base, offset, modifier registers.

1. The contents of the D0 and D1 registers are multiplied fractionally. The result is subtracted from the D7 data register. The final result is then rounded and stored in the D7 data register.2. The contents of the D4 and D5 registers are ANDed together. The result is stored in the D5 data register.3. The contents of the data memory location (pointed to by the R0 register) are moved into the R6 register.4. The address in the R0 register is incremented by the contents of the N0 register.5. The contents of R2 are added to the R3 register. This result is stored back in the R3 register.

Four SC140 Instructions in an Execution Set


Typical Smart Phone System Architecture

• SoC

– comprises a CPU and a bunch of

peripheral controllers all on the

same Integrated-Circuit (IC) die

• All other components on the

target's board are typically

connected in one way or

another to the SoC


Integrated Mobile Processor


System-on-Chip (SoC)• Multi-core

– The Linux kernel has supported symmetric multi-processing, so it can handle a multi-core SoC.

– Android stack itself doesn't contain any specific multi-core optimizations.

• Graphics Processing Unit (GPU)

– accelerating the rendering of graphics to the device's display

• RAM controller: Interfaces with the on-board RAM.

• DMA: Handles the automated transfers of data between the RAM and memory-mapped hardware.

• USB controller: Manages the hardware-side of the device's USB connections.

• DSP: Provides hardware acceleration for some signal processing, such as JPEG encoding.

• Display: Enables the SoC to drive various display types.

• Camera: Allows the SoC to interface with a camera.

• Storage: Manages I/O with the various types of storage that can be used with the SoC.

• Debug: Enables the SoC to be connected to hardware debugging tools through various types of mechanisms such as JTAG.

• Crypto and security functionality

– locking the device and denying the opportunity for unauthorized code to run.


Development Board


Development Setup• Serial connection (RS232)

– allows to interact with the board's bootloader, upload/download small files

– interact with the target when nothing else works.

– slow and for basic interaction

– Serial support is usually provided by the bootloader and the kernel board

• Ethernet

– transfer large amounts of data

– DHCP to retrieve its IP configuration,

– TFTP to load its kernel images

– NFS to mount root filesystem

– require a proper driver for the Ethernet chip used on your board

• USB (Android)

– connect to the target using ADB

– shelling into the target

– forwarding ports, updating filesystems

– you can configure ADB to run over IP

Documents

Introduction to Embedded Systemsnyx.skku.ac.kr/wp-content/uploads/2019/09/1-intro.pdfICE3028: Embedded Systems Design, Fall 2019, Dongkun Shin ([email protected]) 18 Want More? •You