This document discusses embedded systems and provides an overview of the embedded system design process. It defines embedded systems and gives examples. Key steps in the design process are discussed such as defining requirements, creating specifications, designing the architecture, and integrating system components. Challenges in embedded system design such as meeting deadlines, minimizing power consumption, and testing are also covered.

1. 임베디드 ( 내장형 ) 시스템
교과서
Computers as components
Morgan Kaufmann by Wayne Wolf
www.mkp.com/embed
Surviving the SoC revolution
KAP by Henry Chang et Al.
평가 :
시험 60%, H.W. 20%, 실습 20%
Homepage: http://vada.skku.ac.kr

2. 임베디드 시스템 개요
임베디드 시스템
특정 목적으로 구성된 하드웨어 위에 소프트웨어
를 내장하여 최적화시킨 시스템
임베디드 소프트웨어
임베디드 시스템에 탑재되는 시스템 소프트웨어 ,
미들웨어 , 응용 소프트웨어를 총칭
임베디드 시스템 온 칩
논리 회로와 메모리 , 프로세서등을 집적하여 기
본적인 처리 기능에 입출력 , 저장 기능을 포함시
켜 시스템을 칩으로 구현한 것 .

3. 임베디드 소프트웨어 산업의 발전 동향
1970 1990 2000 2010이전
마이크로
프로세서 등장
1980
제어
기기
정보
단말
에듀테인먼트
및
가전기기
통신
장비
Transistor기반
제어시스템
이동통신지원
통신시스템
모니터기반
제어시스템
고기능
제어시스템
Intelligent
제어시스템
라우터,
게이트웨이
전자식
교환기
기계식
교환기
정보가전,
Playstation2, X-Box
백색가전,
TV부착형게임기
아날로그
휴대폰
이동지능정보단말
디지털
휴대폰
고급 RT OS
등장

4. 내장형시스템 설계
강의일정
1. Embedded computing
2. Instruction sets
3. CPUs
4. Embedded computing platform
5. Program design and analysis
6. Processes and operating system
7. Hardware Accelerators
8. Networks
9. System design techniques

5. SoC 설계
강의일정
Moving to SOC design
1. Overview of the SOC design process
2. Integration platforms and SOC design
3. Function-architecture co-design
4. Designing communications networks
5. Network on Chip
6. Low Power SoC designs

6. 1. Embedded Computing
1.1 Introduction
1.2 Complex system and microprocessors
1.3 Embedded system design process
1.4 Formalisms for system designs
1.5 Design example: model train controller

7. 1. Introduction
What are embedded systems?
Challenges in embedded computing
system design.
Design methodologies.

8. Definition
Embedded system: any device that
includes a programmable computer but is
not itself a general-purpose computer.
Take advantage of application
characteristics to optimize the design:
don’t need all the general-purpose bells and
whistles.

9. Embedding a computer
CPU
mem
input
output analog
analog
embedded
computer

10. Examples
Personal digital assistant (PDA).
Printer.
Cell phone.
Automobile: engine, brakes, dash, etc.
Television.
Household appliances.
PC keyboard (scans keys).

11. Early history
Late 1940’s: MIT Whirlwind computer was
designed for real-time operations.
Originally designed to control an aircraft
simulator.
First microprocessor was Intel 4004 in
early 1970’s.
HP-35 calculator used several chips to
implement a microprocessor in 1972.

12. Early history, cont’d.
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.

13. Microprocessor varieties
Microcontroller: includes I/O devices, on-
board memory.
Digital signal processor (DSP):
microprocessor optimized for digital signal
processing.
Typical embedded word sizes: 8-bit, 16-
bit, 32-bit.

14. Application examples
Simple control: front panel of microwave
oven, etc.
Canon EOS 3 has three microprocessors.
32-bit RISC CPU runs autofocus and eye
control systems.
Analog TV: channel selection, etc.
Digital TV: programmable CPUs +
hardwired logic.

15. Automotive embedded
systems
Today’s high-end automobile may have
100 microprocessors:
4-bit microcontroller checks seat belt;
microcontrollers run dashboard devices;
16/32-bit microprocessor controls engine.

16. BMW 850i brake and
stability control system
Anti-lock brake system (ABS): pumps
brakes to reduce skidding.
Automatic stability control (ASC+T):
controls engine to improve stability.
ABS and ASC+T communicate.
ABS was introduced first---needed to
interface to existing ABS module.

17. BMW 850i, cont’d.
brake
sensor
brake
sensor
brake
sensor
brake
sensor
ABS
hydraulic
pump

18. Characteristics of
embedded systems
Sophisticated functionality.
Real-time operation.
Low manufacturing cost.
Low power.
Designed to tight deadlines by small
teams.

19. Functional complexity
Often have to run sophisticated algorithms
or multiple algorithms.
Cell phone, laser printer.
Often provide sophisticated user
interfaces.

20. Real-time operation
Must finish operations by deadlines.
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 rates.

21. Non-functional
requirements
Many embedded systems are mass-
market items that must have low
manufacturing costs.
Limited memory, microprocessor power, etc.
Power consumption is critical in battery-
powered devices.
Excessive power consumption increases
system cost even in wall-powered devices.

22. Design teams
Often designed by a small team of
designers.
Often must meet tight deadlines.
6 month market window is common.
Can’t miss back-to-school window for
calculator.

23. Why use microprocessors?
Alternatives: field-programmable gate
arrays (FPGAs), custom logic, etc.
Microprocessors are often very efficient:
can use same logic to perform many
different functions.
Microprocessors simplify the design of
families of products.

24. The performance paradox
Microprocessors use much more logic to
implement a function than does custom
logic.
But microprocessors are often at least as
fast:
heavily pipelined;
large design teams;
aggressive VLSI technology.

25. Power
Custom logic is a clear winner for low
power devices.
Modern microprocessors offer features to
help control power consumption.
Software design techniques can help
reduce power consumption.

26. Challenges in embedded
system design
How much hardware do we need?
How big is the CPU? Memory?
How do we meet our deadlines?
Faster hardware or cleverer software?
How do we minimize power?
Turn off unnecessary logic? Reduce memory
accesses?

27. Challenges, etc.
Does it really work?
Is the specification correct?
Does the implementation meet the spec?
Reliability in safety-critical systems

28. Challenges
How do we work on the system?
Complex testing
How do we test for real-time characteristics?
How do we test on real data?
Limited observability and controllability
Restricted development environments
What is our development platform?

29. Design methodologies
A procedure for designing a system.
Understanding your methodology helps
you ensure you didn’t skip anything.
Compilers, software engineering tools,
computer-aided design (CAD) tools, etc.,
can be used to:
help automate methodology steps;
keep track of the methodology itself.

30. Design goals
Performance.
Overall speed, deadlines.
Functionality and user interface.
Manufacturing cost.
Power consumption.
Other requirements (physical size, etc.)

31. Levels of abstraction
requirements
specification
architecture
component
design
system
integration

32. Top-down vs. bottom-up
Top-down design:
start from most abstract description;
work to most detailed.
Bottom-up design:
work from small components to big system.
Real design uses both techniques.

33. Stepwise refinement
At each level of abstraction, we must:
analyze the design to determine
characteristics of the current state of the
design;
refine the design to add detail.

34. Requirements
Plain language description of what the
user wants and expects to get.
May be developed in several ways:
talking directly to customers;
talking to marketing representatives;
providing prototypes to users for comment.

35. Functional vs. non-
functional requirements
Functional requirements:
output as a function of input.
Non-functional requirements:
time required to compute output;
size, weight, etc.;
power consumption;
reliability;
etc.

36. Our requirements form
name
purpose
inputs
outputs
functions
performance
manufacturing cost
power
physical size/weight

37. Example: GPS moving map
requirements
Moving map
obtains position
from GPS, paints
map from local
database.
lat: 40 13 lon: 32 19
I-78
ScotchRoad

38. GPS moving map needs
Functionality: For automotive use. Show
major roads and landmarks.
User interface: At least 400 x 600 pixel
screen. Three buttons max. Pop-up menu.
Performance: Map should scroll smoothly.
No more than 1 sec power-up. Lock onto
GPS within 15 seconds.
Cost: $500 street price = approx. $100
cost of goods sold.

39. GPS moving map needs,
cont’d.
Physical size/weight: Should fit in hand.
Power consumption: Should run for 8
hours on four AA batteries.

40. GPS moving map
requirements form
name GPS moving map
purpose consumer-grade
moving map for driving
inputs power button, two
control buttons
outputs back-lit LCD 400 X 600
functions 5-receiver GPS; three
resolutions; displays
current lat/lon
performance updates screen within
0.25 sec of movement
manufacturing cost $100 cost-of-goods-
sold
power 100 mW
physical size/weight no more than 2: X 6:,
12 oz.

41. Specification
A more precise description of the system:
should not imply a particular architecture;
provides input to the architecture design
process.
May include functional and non-functional
elements.
May be executable or may be in
mathematical form for proofs.

42. GPS specification
Should include:
What is received from GPS;
map data;
user interface;
operations required to satisfy user requests;
background operations needed to keep the
system running.

43. Architecture design
What major components go satisfying the
specification?
Hardware components:
CPUs, peripherals, etc.
Software components:
major programs and their operations.
Must take into account functional and
non-functional specifications.

44. GPS moving map block
diagram
GPS
receiver
search
engine
renderer
user
interfacedatabase
display

45. GPS moving map hardware
architecture
GPS
receiver
CPU
panel I/O
display frame
buffer
memory

46. GPS moving map software
architecture
position database
search
renderer
timer
user
interface
pixels

47. Designing hardware and
software components
Must spend time architecting the system
before you start coding.
Some components are ready-made,
some can be modified from existing
designs, others must be designed from
scratch.

48. System integration
Put together the components.
Many bugs appear only at this stage.
Have a plan for integrating components to
uncover bugs quickly, test as much
functionality as early as possible.

49. Summary
Embedded computers are all around us.
Many systems have complex embedded
hardware and software.
Embedded systems pose many design
challenges: design time, deadlines,
power, etc.
Design methodologies help us manage
the design process.