Definition: Embedded Systems
“Embedded systems are information processing systems embedded into a larger product” - Peter Marwedel
Definition: Cyber-Physical Systems
“Cy-Phy Systems are integrations of computation with physical processes” - Edward Lee
Cyberphysical system (CPS) = Embedded System + physical environment
Definition: Ubiquitous Computing
Information anytime, anywhere
Characteristics: Dependability (5)
CPS & ES must be dependable:
- Reliability R(t) = Probability of a system working correctly (works at t=0)
- Maintainability M(d) = Probabilty system works d time units after error occured
- Availability A(t) = Probabily of system working at time t
- Saftey = no harm causing
- Security = Confidential and authentic communication
Characteristics: Efficiency (5)
CPS & ES must be efficient:
- code-size efficient
- run-time efficient
- weight efficient
- cost efficient
- energy efficient
Characteristics: Real-time constraints (hard, soft)
CPS & ES must meet Real-time constraints:
- reaction of ES in time interval dictated by environment
- “a real time constraint is called hard, if not meeting the constraint could result in a catastrophe.” (Kopetz 1997.)
- all other time constraints are called soft
Characteristics: Reactive System
- “A reactive system is one which is in continual interaction with its environment and executes at a pace determined by that environment”.
Characteristics: Hybrid System
“System with analog and digital parts”
Characteristics: Dedicated Systems
- dedicated to a certain application (minimize resources and maximize robustness)
What are the major characteristics of CPS & ES and what alternative definition follows for an ES?
- Dependability
- Efficiency
- Real-time constraints
- System Type (hybrid, dedicated, reactive)
- Security
Not every CPS & ES has ALL of the above characteristics :
Def. “Information processing systems having most of the above characteristics are called embedded systems”.
Challenges in Embedded System Design? (hardware/software)
- Implementation in hardware: lack of flexibility, expensive mask cost for specialized integrated circuits
- Implementation in software: knowledge of many areas must be available (not only software),testing and validation of specifications
- Software Complexity: code size and development cost (i.e. >70% for development cost of car electronics)
Hypothetical Design flow in Embedded Systems?
- Application Knowledge
- Specification
- ES-Hardware
- System Software
(reoccuring) :
5. Evaluation & Validation (energy, cost, performance)
6. Application mapping
7. Optimization
- Test
