1. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 1 Embedded Systems Kris Hermans November 10, 1999

2. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 2 Overview uDefinitions uExamples uDesign dimensions uDealing with time uReliability uSystem software uCosts involved uConclusion

3. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 3 Definitions (1) uBroad domain: single definition does not exist (or remains general) (wristwatches, microwave ovens, factory automation, nuclear power plant, …) (4/8 bit microcontrollers, 32/64 bit multiprocessors, networked clusters, …) uReal-Time System: “Any system in which the time at which output is produced is significant.[…] The lag from input to output time must be sufficiently small for acceptable timeliness.” (Oxford dictionary of Computing)

4. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 4 Definitions (2) uEmbedded = computer integrated into some product uOften no awareness of a computer system uBut software = added value uReal-time and Embedded go hand in hand (mixed terminology) uThere are differences !

5. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 5 Examples (1) uDish washer wone specific task wlimited functionality wlimited flexibility wcheap, mass production uMail sorting machine wone specific task wextensive but manageable functionality

6. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 6 Examples (2) uCar communication system wcomplex system wcheap wreal-time constraints wreliable wlow power consumption wflexible, open implementation uMPEG-4 decoder wcomplex system whigh speed wlow power consumption

7. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 7 Examples (3) uPatient ventilator wcomplex system wreal-time constraints wreliable wsafety critical

8. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 8 Design dimensions (1) uReal-time and high speed ulow power ucheap (decrease production costs) utime-to-market

9. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 9 Design dimensions (2) uReliable: despite disturbances uFault tolerant uSafety uinteraction with environment (control loop) Computer System Measure behavior desired behavior

10. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 10 Dealing with time uCorrectness = F(time, …) uTypes: wHard: too late  incorrect  system failure wSoft: average response time wFirm: shorter soft + longer hard requirement uDerived from bounds on performance

11. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 11 Reliability (1) uReliable system wR = M(specification, behaviour, t) uFailure wbehaviour is not according to specs uvery reliable = P(f)  0 uFailure caused by errors (internal) Error caused by faults (mechanics, algorithms)

12. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 12 Reliability (2) Failure modes Value domainTime domain ConstraintValue too early too late never

13. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 13 Reliability uTwo approaches for reliable sytems wfault prevention  hardware reliable components special techniques for composition avoid e.m. interference (package)  software formal specs good design methodology, tools high level languages (abstraction, modularity) wfault tolerance  necessary !  Complete FT  fail soft  fail safe uImportant: system has a failure mode

14. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 14 System software Real-time OS (RTOS) winterface to hardware wscheduling / pre-empting tasks wmemory management wcommon services (I/O) wscalable (microkernel architecture) wscheduling policies (priority based) wsupport for embedded / diskless target environment Kernel Device I/O File System Networking Debugging

15. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 15 Costs involved (1) uRecurring costs: per-shipped-item whardware production cost wperformance wmemory capacity wspecial handling (cooling etc.) uNon-recurring: design costs wTrend: recurring costs , design cost  Mostly an issue in consumer markets

16. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 16 Costs involved (2) uHardware vs. Software wperformance (H) wlow power (H) wdevelopment cost (H/S) wdevelopment time (H/S) wflexibility (S) wrobustness (S)

17. K ATHOLIEKE U NIVERSITEIT L EUVEN D EPT. OF C OMPUTER S CIENCE SEESCOA Kick-off Meeting 17 Conclusion uEmbedded / Real-Time systems: wcomplex wbut are ubiquitous approx. 50 systems per desktop PC wdevelopment costs play major role ua good development approach (re-use, components, UML, debugging, …) will bring a significant strategic advantage !