Lecture 13
Introduction to
Embedded Systems
Graduate Computer Architecture
Fall 2005
Shih-Hao Hung
Dept. of Computer Science and
Information Engineering
National Taiwan University
Computing Systems
• Desktop
– PC, Workstations, Laptops
• Servers
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Tier-0: network appliance
Tier-1: webserver
Tier-2: application/database server
File servers, Storage-area-network
• Embedded Systems
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–
–
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PDA
Cellphone
Routers
Microcontrollers
Embedded?
• Computing system embedded within
electronic devices.
• Combination of computer hardware and
software designed to performance a
specific function.
• Any computing system that is not a
desktop computer nor a server.
Area of Applications
• General purpose
– PDA
• Control systems
– Electronics, Automotive
• Signal processing
– Media player, Camera
• Communication
– Cellphone, switch
Market
• Average household uses ~225 embedded
processors; about 35 for automobile
• Estimated 5 billion embedded processors
in use
– 94% share of world market
– 6%: Pentium, PowerPC, etc.
[Source: World Semiconductor Trade Statistics Bluebook]
Key Issues
User’s Point of View
• Single function/application
– Dedicated to specific type of tasks
• Tight constraints
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Size
Power
Cost
Time-to-market
• Real-time
– Respond to environment in real time
• Safety/Reliability
– Failure can result in critical damages
Key Issues
Developer’s Point of View
• Concurrent development of HW and SW,
i.e. HW/SW codesign
• Wide selection of uP’s.
• Wide selection of OS, mostly real time
(RTOS)
• Few system resources
• Specialized development tools
• Debugging skills important
• Robust HW/SW
Example
Elements
Trends
• High level of integration
– System-on-chip (SoC)
– Multiprocessor System-on-Chip (MPSoC)
• HW/SW co-design
– Concurrent development
– Optimization
• Design flow
– Design tools
– Experiences
Microcontroller
• Usually a simple uP plus
peripheral support devices
integrated in a single
package
SoC
• A uP plus peripheral
support devices
integrated in a single
chip
• E.g. Intel StrongARM
• SoC vs uController?
SoC Design
• Intellectual Property (IP)
– Circuits or cores pre-deisgned/pre-verified for
certain functions
– Implications:
• Lower design cost
• Fast time-to-market
Requirements
• Functional
– Functions
– I/O
• Non-functional
– Performance
– Cost
– Power consumption
– Size/weight
Architecture
• How to implement the specifications
– Components
– System structure
– Hardware/software partitioning
• HW/SW work together to solve a problem
• Partitioning decided by
– Performance
– Flexibility
– Cost
Architecture Design
Designing An Embedded
System
• Understand the big picture
• Understand the details
• Design SW with
– Real time constraints
– Low power
– Small code size
• Domain-specific knowledge