1. Embedded Systems Design

2. 2 Objectives Introduction to embedded systemsIntroduction to embedded systems Embedded system componentsEmbedded system components HardwareHardware SoftwareSoftware Embedded system programmingEmbedded system programming

3. An embedded system is nearly any An embedded system is nearly any computing system other than a desktop, laptop, or mainframe computer. 3

4. 4 Definition for: embedded system Definition for: embedded system A combination of hardware and software which together form a component of a larger machine. A combination of hardware and software which together form a component of a larger machine. An example of an embedded system is a microprocessor that controls an automobile engine. An example of an embedded system is a microprocessor that controls an automobile engine. An embedded system is designed to run on its own without human intervention, and may be required to respond to events in real time. An embedded system is designed to run on its own without human intervention, and may be required to respond to events in real time. Source: www.computeruser.com/resources/dictionary Source: www.computeruser.com/resources/dictionary

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6. 6 Definition “ Any sort of device which includes a programmable computer but itself is not intended to be a general-purpose computer ” “ Any sort of device which includes a programmable computer but itself is not intended to be a general-purpose computer ” Wayne Wolf Wayne Wolf

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9. 9 More examples

10. 10 Introduction to Embedded Systems Setha Pan-ngum Slide credit Y Williams, GWU

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13. 13 Definition

14. 14 Embedded systems overview Computing systems are everywhere Computing systems are everywhere Most of us think of “desktop” computers Most of us think of “desktop” computers –PC’s –Laptops –Mainframes –Servers But there’s another type of computing system But there’s another type of computing system –Far more common...

15. 15 Embedded systems overview Embedded computing systems Embedded computing systems –Computing systems embedded within electronic devices –Hard to define. Nearly any computing system other than a desktop computer –Billions of units produced yearly, versus millions of desktop units –Perhaps 50 per household and per automobile Computers are in here... and here... and even here... Lots more of these, though they cost a lot less each.

16. 16 A “short list” of embedded systems 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

17. 17 How many do we use? Average middle-class American home has 40 to 50 embedded processors in it Average middle-class American home has 40 to 50 embedded processors in it –Microwave, washer, dryer, dishwasher, TV, VCR, stereo, hair dryer, coffee maker, remote control, humidifier, heater, toys, etc. Luxury cars have over 60 embedded processors Luxury cars have over 60 embedded processors –Brakes, steering, windows, locks, ignition, dashboard displays, transmission, mirrors, etc. Personal computers have over 10 embedded processors Personal computers have over 10 embedded processors –Graphics accelerator, mouse, keyboard, hard-drive, CD- ROM, bus interface, network card, etc. - Mike Schulte

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19. Characteristics of ES 19

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21. 21 Characteristics of Embedded Systems Application-specific functionality – specialized for one or one class of applications Application-specific functionality – specialized for one or one class of applications Deadline constrained operation – system may have to perform its function(s) within specific time periods to achieve successful results Deadline constrained operation – system may have to perform its function(s) within specific time periods to achieve successful results Resource challenged – systems typically are configured with a modest set of resources to meet the performance objectives Resource challenged – systems typically are configured with a modest set of resources to meet the performance objectives Power efficient – many systems are battery-powered and must conserve power to maximize the usable life of the system. Power efficient – many systems are battery-powered and must conserve power to maximize the usable life of the system. Form factor – many systems are light weight and low volume to be used as components in host systems Form factor – many systems are light weight and low volume to be used as components in host systems Manufacturable – usually small and inexpensive to manufacture based on the size and low complexity of the hardware. Manufacturable – usually small and inexpensive to manufacture based on the size and low complexity of the hardware. Slide credit Y William, GWU

22. 22 Types of Embedded Systems

23. 23 Types of Embedded Systems

24. 24 Typical Embedded Systems Are designed to observed (through sensors) and control something (through actuators) Are designed to observed (through sensors) and control something (through actuators) E.g. air condition senses room temperature and maintains it at set temperature via thermostat.

25. Design Challenges 25

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27. Design Metric Competition 27

28. Time to Market 28

29. 29 Embedded System Block Diagram Slide credit Y Williams, GWU Introduction to Embedded Systems Setha Pan-ngum Processor mem Observe (Input) Control (Output) Motor/Light Temperature Sensor System Bus

30. 30 Processors Microprocessors for PCs Microprocessors for PCs Embedded processors or Microcontrollers for embedded systems Embedded processors or Microcontrollers for embedded systems –Often with lower clock speeds –Integrated with memory and –I/O devices e.g. A/D D/A PWM CAN –Higher environmental specs Introduction to Embedded Systems Setha Pan-ngum

31. 31 Microcontrollers dominates processor market

32. 32 Types of Embedded Processors Computational micros (32- or 64-bit datapaths) Computational micros (32- or 64-bit datapaths) –CPU of workstations, PCs, or high-end portable devices (PDAs) –x86, PA-RISC, PowerPC, SPARC, etc. Embedded general purpose micros (32-bit datapaths) Embedded general purpose micros (32-bit datapaths) –Designed for a wide range of embedded applications –Often scaled-down version of computational micros –ARM, PowerPC, MIPS, x86, 68K, etc. Microcontrollers (4-, 8-, or 16-bit datapaths) Microcontrollers (4-, 8-, or 16-bit datapaths) –Integrate processing unit, memory, I/O buses, and peripherals –Often low-cost, high-volume devices Domain-specific processors (datapath size varies greatly) Domain-specific processors (datapath size varies greatly) –Designed for a particular application domain –Digital signal processors, multimedia processors, graphics processors, network processors, security processors, etc.

33. 33 Processor Sales Data

34. 34 Processor Market 2001 processor market by volume: 2001 processor market by volume: –Computational micros: 2% –Embedded general-purpose micros: 11% –DSPs: 10% –Microcontrollers: 80% 2001 processor market by revenue: 2001 processor market by revenue: –Computational micros: 51% –Embedded general-purpose micros: 8% –DSPs: 13% –Microcontrollers: 28% Higher growth expected for embedded micros, DSPs, and microcontrollers Higher growth expected for embedded micros, DSPs, and microcontrollers Slide credit - Mike Schulte

35. 35 Growing Demand Embedded processors account for Embedded processors account for –Over 97% of total processors sold –Over 60% of total sales from processors Sales expected to increase by roughly 15% each year Sales expected to increase by roughly 15% each year Slide credit - Mike Schulte Introduction to Embedded Systems Setha Pan-ngum

36. 36 Moore’s Law

37. Number of Transistors on Chips

38. 38 Graphical illustration of Moore’s law 19811984198719901993199619992002 Leading edge chip in 1981 10,000 transistors Leading edge chip in 2002 150,000,000 transistors

39. 39 Some common characteristics of embedded systems Single-functioned Single-functioned –Executes a single program, repeatedly Tightly-constrained Tightly-constrained –Low cost, low power, small, fast, etc. Reactive and real-time Reactive and real-time –Continually reacts to changes in the system’s environment –Must compute certain results in real-time without delay

40. 40 Design with focus on Application Slide credit – P Koopman, CMU Introduction to Embedded Systems Setha Pan-ngum

41. 41 Design Constraints Slide credit – P Koopman, CMU Introduction to Embedded Systems Setha Pan-ngum

42. 42 Design Challenges Does it really work? 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? How do we work on the system? How do we work on the system? –Observability, controllability? –What is our development platform? Slide credit – P Koopman, CMU More importantly – optimising design metrics!! More importantly – optimising design metrics!!

43. 43 Design Metrics Common metricsCommon metrics Unit cost: the monetary cost of manufacturing each copy of the system, excluding NRE costUnit cost: the monetary cost of manufacturing each copy of the system, excluding NRE cost NRE cost (Non-Recurring Engineering cost): The one-time monetary cost of designing the systemNRE cost (Non-Recurring Engineering cost): The one-time monetary cost of designing the system Size: the physical space required by the systemSize: the physical space required by the system Performance: the execution time or throughput of the systemPerformance: the execution time or throughput of the system Power: the amount of power consumed by the systemPower: the amount of power consumed by the system Flexibility: the ability to change the functionality of the system without incurring heavy NRE costFlexibility: the ability to change the functionality of the system without incurring heavy NRE cost

44. 44 Design Metrics Common metrics (continued)Common metrics (continued) Time-to-prototype: the time needed to build a working version of the systemTime-to-prototype: the time needed to build a working version of the system Time-to-market: the time required to develop a system to the point that it can be released and sold to customersTime-to-market: the time required to develop a system to the point that it can be released and sold to customers Maintainability: the ability to modify the system after its initial releaseMaintainability: the ability to modify the system after its initial release Correctness, safety, many moreCorrectness, safety, many more Slide credit Vahid/Givargis, Embedded Systems Design: A Unified Hardware/Software Introduction

45. 45 Trade-off in Design Metrics Expertise with both software and hardware is needed to optimize design metrics Expertise with both software and hardware is needed to optimize design metrics –Not just a hardware or software expert, as is common –A designer must be comfortable with various technologies in order to choose the best for a given application and constraints Slide credit Vahid/Givargis, Embedded Systems Design: A Unified Hardware/Software Introduction SizePerformance Power NRE cost

46. 46 Time-to-market: a demanding design metric Time required to develop a product to the point it can be sold to customers Time required to develop a product to the point it can be sold to customers Market window Market window –Period during which the product would have highest sales Average time-to-market constraint is about 8 months Average time-to-market constraint is about 8 months Delays can be costly Delays can be costly Slide credit Vahid/Givargis, Embedded Systems Design: A Unified Hardware/Software Introduction Revenues ($) Time (months)

47. 47 Losses due to delayed market entry Simplified revenue model Simplified revenue model –Product life = 2W, peak at W –Time of market entry defines a triangle, representing market penetration –Triangle area equals revenue Loss Loss –The difference between the on-time and delayed triangle areas Slide credit Vahid/Givargis, Embedded Systems Design: A Unified Hardware/Software Introduction On-time Delayed entry Peak revenue Peak revenue from delayed entry Market rise Market fall W2W Time D On-time Delayed Revenues ($)

48. 48 Other Design Considerations Dependability Dependability –Reliability: probability of system working correctly provided that it worked at time t=0 –Maintainability: probability of system working correctly d time units after error occurred. [Some systems require no maintenance throughout their operating lives (e.g. electric kettles, computer keyboards), while some may need it such as mobile phones and airplane flight control (software upgrade)]

49. 49 Other Design Considerations Dependability Dependability –Availability: probability of system working at time t –Safety –Security: in communication Basically, critical applications have to operate correctly at all time e.g. airplane flight control computer. This includes both hardware and software aspects.

50. 50 Example of System Fault

51. 51 Other Design Considerations Operating environment Operating environment Some engine Electronic Control Units (ECUs) in cars are located under the bonnets. So they have to work at high temperature, as well as dusty and wet environment. EMI (Electromagnetic Interference) EMI (Electromagnetic Interference)

52. 52 Real-Time Consideration Correct operation of real-time systems means: Correct operation of real-time systems means: –Working correctly (functionally correct) –Producing outputs in time! i.e. correct result at the right time i.e. correct result at the right time

53. 53 Hard Real-time System designed to meet all deadlines System designed to meet all deadlines A missed deadline is a design flaw A missed deadline is a design flaw For examples: ABS brake, nuclear reactor monitoring system For examples: ABS brake, nuclear reactor monitoring system System hardware (over) designed for worst- case performance System hardware (over) designed for worst- case performance System software rigorously tested System software rigorously tested Formal proofs used to guarantee timing correctness Formal proofs used to guarantee timing correctness Slide credit – T Givargis

54. 54 Firm Real-time System designed to meet all deadlines, but occasional missed deadline is allowed System designed to meet all deadlines, but occasional missed deadline is allowed –Sometimes statistically quantified (e.g. 5% misses) For examples: multimedia systems For examples: multimedia systems System hardware designed for average case performance System hardware designed for average case performance System software tested under average (ideal) conditions System software tested under average (ideal) conditions Slide credit – T Givargis

55. 55 Soft Real-time System designed to meet as many deadlines as possible System designed to meet as many deadlines as possible –Best effort to complete within specified time, but may be late For examples: network switch or router For examples: network switch or router System hardware designed for average case performance System hardware designed for average case performance System software tested under averaged (ideal) conditions System software tested under averaged (ideal) conditions Slide credit – T Givargis

56. 56 Levels of System Design requirements specification architecture component design system integration

57. 57 Traditional Embedded System Design Approach Decide on the hardware Decide on the hardware Give the chip to the software people. Give the chip to the software people. Software programmer must make software ‘fit’ on the chip and only use that hardware’s capabilities. Software programmer must make software ‘fit’ on the chip and only use that hardware’s capabilities.

58. 58 Problems with Increased Complexity Systems are becoming more and more complex. Systems are becoming more and more complex. Harder to think about total design. Harder to think about total design. Harder to fix ‘bugs.’ Harder to fix ‘bugs.’ Harder to maintain systems over time. Harder to maintain systems over time. Therefore, the traditional development process has to change, Therefore, the traditional development process has to change,

59. 59 Design with Time Constraint In embedded electronics, the total design cycle must decrease. In embedded electronics, the total design cycle must decrease. Historically, design for automotive electronic systems takes 3-5 years to develop. Historically, design for automotive electronic systems takes 3-5 years to develop. Must be reduced to a 1-3 year development cycle. Must be reduced to a 1-3 year development cycle. Must still be reliable and safe. Must still be reliable and safe. B. Wilkie, R. Frank and J. Suchyta - Motorola Semiconductor Products Sectors, ‘Silicon or Software: The Foundation of Automotive Electronics’, IEEE Vehicular Tech., August 95.

60. 60 Possible Ways to Do Decomposable hierarchy (object-oriented). Decomposable hierarchy (object-oriented). Reuse previous designs: Reuse previous designs: –When a design changes, reuse similar sections. –Don’t throw away last year’s design and start from scratch! Automated verification systems. Automated verification systems.

61. 61 Levels of Embedded System Design

62. 62 Design Abstraction

63. 63 Abstraction Levels

64. 64 Abstraction Levels

65. 65 Abstraction Levels

66. 66 Abstraction Level

67. 67 Hardware vs Software Many functions can be done by software on a general purpose microprocessor OR by hardware on an application specific ICs (ASICs) Many functions can be done by software on a general purpose microprocessor OR by hardware on an application specific ICs (ASICs) For examples: game console graphic, PWM, PID control For examples: game console graphic, PWM, PID control Leads to Hardware/Software Co-design concept Leads to Hardware/Software Co-design concept

68. 68 Hardware or Software? Where to place functionality? Where to place functionality? –ex: A Sort algorithm »Faster in hardware, but more expensive. »More flexible in software but slower. »Other examples? Must be able to explore these various trade-offs: Must be able to explore these various trade-offs: –Cost. –Speed. –Reliability. –Form (size, weight, and power constraints.) Slide credit - W. McUmber, MSU

69. 69 Hardware vs Software Slide credit - Mike Schulte Embedded Application-Specific Processors Embedded Domain-Specific Processors General-Purpose Processors FFT Processors MPEG Processors FIR Processors Graphics Processors DSP Processors Network Processors Workstations Personal Computers Power/Performance Programmability and Flexibility

70. 70 Hardware vs Software Slide credit – Ingo Sander

71. Processors 71

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74. 74 Microcessor technology Slide credit Vahid/Givargis, Embedded Systems Design: A Unified Hardware/Software Introduction, 2000 Processors vary in their customization for the problem at hand 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

75. 75 General-purpose processors Programmable device used in a variety of applications Programmable device used in a variety of applications Features Features –Program memory –General datapath with large register file and general ALU Drawbacks Drawbacks - Low performance - Size and power increase User benefits User benefits –Low time-to-market and NRE costs –High flexibility IRPC Register file General ALU DatapathController Program memory Assembly code for: total = 0 for i =1 to … Control logic and State register Data memory

76. 76 Single-purpose processors Digital circuit designed to execute exactly one program Digital circuit designed to execute exactly one program –a.k.a. coprocessor, accelerator or peripheral Features Features –Contains only the components needed to execute a single program –No program memory Drawbacks Drawbacks - Design time higher, low flexibility, higher NRE cost, Benefits Benefits –Fast –Low power –Small size Datapath Controller Control logic State register Data memory index total +

77. 77 Application-specific processors Examples. DSP Examples. DSP Programmable processor optimized for a particular class of applications having common characteristics Programmable processor optimized for a particular class of applications having common characteristics –Compromise between general-purpose and single-purpose processors Features Features –Program memory –Optimized datapath –Special functional units Benefits Benefits –Some flexibility, good performance, size and power IRPC Registers Custom ALU DatapathController Program memory Assembly code for: total = 0 for i =1 to … Control logic and State register Data memory

78. How many processors needed? 78

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80. Case Study How many processors needed inside a car? How many processors needed inside a car? 80

81. 81 Software Costs

82. 82 Disciplines Used in Embedded System Design

83. 83 Trends in Embedded Systems

84. 84 Future Embedded Systems

85. 85 Future Embedded Systems

86. 86 Future Embedded Systems

87. 87 Observations on Future Embedded Systems More complexity (people expect more functions and higher performance from their electronic products) More complexity (people expect more functions and higher performance from their electronic products) This leads to more complex software This leads to more complex software Which requires better design process Which requires better design process More importantly, thorough testing for safety critical systems (diagnostics codes of engine ECUs is half of its total software codes) More importantly, thorough testing for safety critical systems (diagnostics codes of engine ECUs is half of its total software codes)

88. 88 Research in Embedded Systems Hardware – to improve performance (sensors and actuators), verification, etc.Hardware – to improve performance (sensors and actuators), verification, etc. Software – reusability, testing, verification, OS, etc.Software – reusability, testing, verification, OS, etc. Network – higher connectivity between systems (e.g. smart homes link many systems together, standardised protocols, etc.Network – higher connectivity between systems (e.g. smart homes link many systems together, standardised protocols, etc. Security – protection against attacksSecurity – protection against attacks Design – improved methodology, more automation, formal verificationDesign – improved methodology, more automation, formal verification