a comprehensive slide on Embedded System.pptx

An embedded system is a microprocessor-based computer hardware system with software that is designed to perform a dedicated function, either as an independent system or as a part of a large system. At the core is an integrated circuit designed to carry out computation for real-time operations.

1. Introduction to Real-time and Embedded Systems   1

2. What is System? System is an arrangement in which all its unit assemble work together according to a set of rules. System is a way of working, organizing or doing one or many tasks according to a fixed plan. 1

3. System—Time Display System For example, a watch is a time displaying system. Its components follow a set of rules to show time. If one of its parts fails, the watch will stop working. So we can say, in a system, all its subcomponents depend on each other. Watch Parts : hardware, Needles, Battery, Dial, Chassis and Strap. 2

4. System—Time Display System Rules 1.All needles move clockwise only 2.A thin needle rotates every second 3.A long needle rotates every minute 4.A short needle rotates every hour 5.All needles return to the original position after 12 hours 3

5. System—Automatic Clothes Washing System WASHING MACHINE: It is an automatic clothes washing SYSTEM Parts: Status display panel, Switches & Dials, Motor, Power supply & control unit, Inner water level sensor and solenoid valve. 4

6. System—Automatic Clothes Washing System Rules 1.Wash by spinning 2.Rinse 3.Drying 4.Wash over by blinking 5.Each step display the process stage 6.In case interruption, execute only the remaining 5

7. What is Embedded System? Definition 1: Embedded systems (ES) = information processing systems embedded into a larger product such as telecommunication equipment's, transportation services, etc. Definition 2: It is a dedicated computer based system for an application(s) or product. It may be an independent system or a part of large system. Its software usually embeds into a ROM (Read Only Memory) or flash.” 6

8. What is Embedded System? Definition 3: An embedded system is one that has a dedicated purpose software embedded in a computer hardware. Definition 4: It is a dedicated computer based system for an application(s) or product. It may be an independent system or a part of large system. Its software usually embeds into a ROM (Read Only Memory) or flash.” 7

9. What is Embedded System? Definition 5 : It is any device that includes a programmable computer but is not itself intended to be a general purpose computer.” Definition 6 : Embedded Systems are the electronic systems that contain a microprocessor or a microcontroller, but we do not think of them as computers– the computer is hidden or embedded in the system.” – Todd D. Morton 8

10. Components of E mbedded Systems It has Hardware: Processor, Timers, Interrupt controller, I/O Devices, Memories, Ports, etc. It has main Application Software: Which may perform concurrently the series of tasks or multiple tasks. It has Real Time Operating System (RTOS): RTOS defines the way the system work. Which supervise the application software. It sets the rules during the execution of the application program. A small scale embedded system may not need an RTOS. 9

11. Components of E mbedded Systems Most embedded systems do not use keyboards, mice and large computer monitors for their user-interface. Instead, there is a dedicated user-interface consisting of push-buttons, steering wheels, pedals etc. Because of this, the user hardly recognizes that information processing is involved. 10

12. Characteristics of an Embedded System Single-functioned Reactive and Real time Distributed systems Heterogeneous architecture Harsh environment System safety and reliability Control of psychical system Small and low weight Cost sensitivity Power management Connected 11

13. Single-functioned Embedded systems are dedicated towards a certain application. For example, processors running control software in a car or a train will always run that software, and there will be no attempt to run a computer game or spreadsheet program on the same processor. There are mainly two reasons for this: 12

14. Single-functioned Running additional programs would make those systems less dependable or reliable. Running additional programs is only feasible if resources such as memory are unused. No unused resources should be present in an efficient system . 13

15. Real-time Constraints Many embedded systems must meet real-time constraints . Not completing computations within a given time-frame can result in a serious loss of the quality provided by the system (for example, if the audio or video quality is affected) or may cause harm to the user (for example, if cars, trains or planes do not operate in the predicted way). A time-constraint is called hard if not meeting that constraint could result in a catastrophe . All other time constraints are called soft . 14

16. Distributed Systems A common characteristic of an embedded system is one that consists of communicating processes executing on several CPUs or ASICs which are connected by communication links. The reason for this is economy . Economical 48-bit microcontrollers may be cheaper than a 32-bit processors. Even after adding the cost of the communication links, this approach may be preferable. 15

17. Distributed Systems In this approach, multiple processors are usually required to handle multiple time-critical tasks. Devices under control of embedded systems may also be physically distributed. 16

18. Heterogeneous Architectures Embedded systems often are composed of heterogeneous architectures. They may contain different processors in the same system solution. They may also be mixed signal systems. The combination of I/O interfaces, local and remote memories, and sensors and actuators makes embedded system design truly unique. Embedded systems also have tight design constraints, and heterogeneity provides better design flexibility. 17

19. Harsh Environment Many embedded systems do not operate in a controlled environment. Excessive heat is often a problem, especially in applications involving combustion (e.g., many transportation applications). Additional problems can be caused for embedded computing by a need for protection from vibration, shock, lightning, power supply fluctuations, water, corrosion, fire, and general physical abuse. 18

20. Harsh Environment For example, in the Mission Critical example application the computer must function for a guaranteed, but brief, period of time even under non-survivable fire conditions. These constraints present a unique set of challenges to the embedded system designer, including accurately modeling the thermal conditions of these systems. 19

21. System Safety and Reliability As embedded system complexity and computing power continue to grow, they are starting to control more and more of the safety aspects of the overall system. These safety measures may be in the form of software as well as hardware control. Mechanical safety backups are normally activated when the computer system loses control in order to safely shut down system operation. Software safety and reliability is a bigger issue. Software doesn't normally "break" in the sense of hardware. 20

22. System Safety and Reliability However software may be so complex that a set of unexpected circumstances can cause software failures leading to unsafe situations. The main challenge for embedded system designers is to obtain low-cost reliability with minimal redundancy . 21

23. Control of Physical Systems One of the main reasons for embedding a computer is to interact with the environment . This is often done by monitoring and controlling external machinery. Embedded computers transform the analog signals from sensors into digital form for processing. Outputs must be transformed back to analog signal levels. 22

24. Control of Physical Systems When controlling physical equipment, large current loads may need to be switched in order to operate motors and other actuators. To meet these needs, embedded systems may need large computer circuit boards with many non-digital components. Embedded system designers must carefully balance system tradeoffs among analog components, power, mechanical, network, and digital hardware with corresponding software. 23

25. Small and Low Weight Many embedded computers are physically located within some larger system. The form factor for the embedded system may be dictated by aesthetics. For example, the form factor for a missile may have to fit inside the nose of the missile. 24

26. Small and Low Weight One of the challenges for embedded systems designers is to develop non-rectangular geometries for certain solutions. Weight can also be a critical constraint. Embedded automobile control systems, for example, must be light weight for fuel economy. Portable CD players must be light weight for portability purposes . 25

27. Cost sensitivity Cost is an issue in most systems, but the sensitivity to cost changes can vary dramatically in embedded systems. This is mainly due to the effect of computer costs have on profitability and is more a function of the proportion of cost changes compared to the total system cost . 26

28. Power management Embedded systems have strict constraints on power. Given the portability requirements of many embedded systems, the need to conserve power is important to maintain battery life as long as possible. Minimization of heat production is another obvious concern for embedded systems. 27

29. Connected Frequently, embedded systems are connected to the physical environment through sensors collecting information about that environment and actuators controlling that environment. 28

30. Functions of Embedded System Embedded systems provide several functions Monitor the environment ; embedded systems read data from input sensors. Control the environment; embedded systems generate and transmit commands for actuators. Transform the information; embedded systems transform the data collected in some meaningful way, such as data compression / decompression 29

31. Basic Structure of an Embedded System The following illustration shows the basic structure of an embedded system: 30

32. Basic Structure of an Embedded System Sensor – It measures the physical quantity and converts it to an electrical signal which can be read by an observer or by any electronic instrument like an A2D converter A-D Converter – An analog-to-digital converter converts the analog signal sent by the sensor into a digital signal. Processor & ASICs – Processors process the data to measure the output and store it to the memory. D-A Converter – A digital-to-analog converter converts the digital data fed by the processor to analog data. 31

33. Basic Structure of an Embedded System Actuator – An actuator compares the output given by the D-A Converter to the actual (expected) output stored in it and stores the approved output. 32

34. Why Embedded Systems Are Different? Differences between your desktop PC and the typical embedded system. Embedded systems are dedicated to specific tasks, whereas PCs are generic computing platforms. Embedded systems have real-time constraints. If an embedded system is using an operating system at all, it is most likely using a real-time operating system (RTOS), rather than Windows 9X, Windows NT, Windows 2000, Unix, Solaris, or HP- UX. 33

35. Why Embedded Systems Are Different? Embedded systems have far fewer system resources than desktop systems. Embedded systems store all their object code in ROM 34

36. Application Areas The following list comprises key areas in which embedded systems are used: Automotive electronics Aircraft electronics Trains Telecommunication Consumer electronics Robotics 35

37. Automotive electronics Modern cars can be sold only if they contain a significant amount of electronics. These include air bag control systems, engine control systems, anti-braking systems (ABS), air-conditioning, GPS-systems, safety features, and many more. 36

38. Aircraft electronics A significant amount of the total value of airplanes is due to the information processing equipment, including flight control systems, anti-collision systems, pilot information systems, and others. Dependability is of utmost importance. 37

39. Telecommunication Mobile phones have been one of the fastest growing markets in the recent years. For mobile phones, radio frequency (RF) design, digital signal processing and low power design are key aspects. 38

40. Consumer electronics Video and audio equipment is a very important sector of the electronics industry. The information processing integrated into such equipment is steadily growing. New services and better quality are implemented using advanced digital signal processing techniques. Many TV sets, multimedia phones, and game consoles comprise high performance processors and memory systems. They represent special cases of embedded systems. 39

41. Robotics Robotics is also a traditional area in which embedded systems have been used 40

42. Requirements for Embedded Systems Embedded systems are unique in several ways. When designing embedded systems, there are several categories of requirements that should be considered ; Functional Requirements Temporal Requirements (Timeliness) Dependability Requirements 41

43. Functional Requirements Functional requirements describe the type of processing the system will perform. This processing varies, based on the application. Functional requirements include the followings: Data Collection requirements Sensoring requirements Signal conditioning requirements 42

44. Functional Requirements Alarm monitoring requirements Direct Digital Control requirements Actuator control requirements Man-Machine Interaction requirements 43

45. Temporal Requirements Embedded systems have many tasks to perform, each having its own deadline. Temporal requirements define the stringency in which these time-based tasks must complete. Examples include; Minimal latency jitter Minimal Error-detection latency 44

46. Temporal Requirements Temporal requirements can be very tight (for example control-loops ) or less stringent (for example response time in a user interface). 45

47. Dependability Requirements Most embedded systems also have a set of dependability requirements. Examples of dependability requirements include; Reliability Safety Maintainability Availability Security 46

48. Reliability Reliability ; this is a complex concept that should always be considered at the system rather than the individual component level. There are three dimensions to consider when specifying system reliability; 47

49. Reliability Hardware reliability ; probability of a hardware component failing Software reliability ; probability that a software component will produce an incorrect result Operator reliability ; how likely that the operator of a system will make an error. 48

50. Safety Safety ; describe the critical failure modes and what types of certification are required for the system 49

51. Availability Availability ; the probability that the system is available for use at a given time. 50

52. Security Security ; these requirements are often specified as “shall not” requirements that define unacceptable system behavior rather than required system functionality. 51

53. Overview of Real-Time System A real-time system is a system that is required to react to stimuli from the environment (including the passage of physical time) within time intervals dictated by the environment. The Oxford dictionary defines a real-time system as “Any system in which the time at which output is produced is significant”. 52

54. Overview of Real-Time System This is usually because the input corresponds to some movement in the physical world, and the output has to relate to that same movement. The lag from input time to output time must be sufficiently small for acceptable timeliness. 53

55. Overview of Real-Time System Another way of thinking of real-time systems is any information processing activity or system which has to respond to externally generated input stimuli within a finite and specified period. Generally, real-time systems are systems that maintains a continuous timely interaction with its environment 54

56. Real-Time System—Definitions Definition 1 (Real time system) A real time system is a system that must satisfy explicit (bounded) response-time constraints or risk severe consequences, including failure. Definition 2 (Real time system) A real time system is one whose logical correctness is based both the correctness of the outputs and their timeliness. 55

57. Types of Real-Time System There are two types of real-time systems: Reactive and Embedded Reactive real-time system involves a system that has constant interaction with its environment. (e.g. a pilot controlling an aircraft). An embedded real-time system is used to control specialized hardware that is installed within a larger system. (e.g. a microprocessor that controls the fuel-to-air mixture for automobiles). 56

58. Examples of Real-Time System Examples of real-time systems include Software for cruise missile Airline reservation system Industrial Process Control Banking ATM Real-time systems can also be found in many industries; Telecommunication systems Automotive control Air traffic control Satellite systems, etc. 57

59. Real-Time Event Characteristics Real-time events fall into one of the three categories: asynchronous, synchronous, or isochronous. Asynchronous events are entirely unpredictable. For example, the event that a user makes a telephone call. As far as the telephone company is concerned, the action of making a phone call cannot be predicted. 58

60. Real-Time Event Characteristics Synchronous events are predictable and occur with precise regularity if they are to occur. For example, the audio and video in a movie take place in synchronous fashion. Isochronous events occur with regularity within a given window of time. For example, audio bytes in a distributed multimedia application must appear within a window of time when the corresponding video stream arrives. Isochronous is a sub-class of asynchronous. 59

61. Real-Time Vs Time Shared System predictably fast response to urgent events high degree of schedulability stability under transient overload 60

62. Characteristics of Real time system Real-time systems have many special characteristics which are inherent or imposed. The followings are the important characteristics of real time system. Large and Complex Manipulation of real numbers Reliable and safe 61

63. Characteristics of Real time system Concurrent control of separate system components Real-time Facilities Interaction with hardware devices Efficient execution and the execution environment 62

64. Large and Complex Most of the problems associated with developing software are those related to size and complexity. Writing small programs presents no significant problem because they can be designed, coded, maintained and understood by a single person. 63

65. Large and Complex This largeness is related mostly to variety. The variety is that of needs and activities in the real world and their reflection in a program. The real world is continuously changing. It is evolving. So too are, therefore, the needs and activities of society. 64

66. Large and Complex Thus large programs, like all complex systems, must continuously evolve. Software programs tend to exhibit the undesirable property of largeness. This is mainly due to continuous change. Real-time systems undergo constant maintenance and enhancements during their lifetimes. They must therefore be extensible. 65

67. Manipulation of real numbers Many real-time systems involve the control of some engineering activity. 66

68. Reliable and safe The more society relinquishes control of its vital functions to computers, the more it becomes imperative that those computers do not fail. Failure in ATM machine can result in millions of dollars lost irretrievably. A faulty component in electricity generation could fail a life support system in an intensive care unit. 67

69. Concurrent control of separate system components A typical real-time embedded system consists of computers and sensors and actuators. There are usually several co-existing external elements which the computer must interact with simultaneously. The very nature of these external elements is that they exist in parallel. Actions performed by the computer must be carried out in sequence but give the allusion of being simultaneous. In some cases this is not possible. 68

70. Interaction with hardware devices Nature of embedded real-time systems requires them to interact with the external world. Sensors and actuators are used for a wide variety of real-world devices. Many of the operational requirements for real-time systems are device and computer dependent. These devices may generate interrupts in response to certain events and errors. Interrupts usually handled by assembly language (although more and more is now being done in higher level languages). 69

71. Efficient execution and the execution environment Real-time systems are time critical. Therefore, the efficiency of their implementation is more important than in other systems. One of the main benefits of using a higher level language is to allow the programmer to abstract away the details and concentrate on solving the problem. This is not always true in the embedded system world. Some higher level languages have instruction 10 times slower than assembly language. However, higher level languages can be used in real-time systems effectively. 70

72. Real-time Facilities It is very difficult to design and implement systems which will guarantee the appropriate output will be generated at the appropriate times under all possible conditions. Doing this a making use of all computing resources at all times is often impossible. Real-time systems usually constructed using processors with considerable space capacity. This ensures worst case behavior does not produce any unwelcome delays during critical periods of the systems operation. 71

73. Embedded System Processors Processor is the heart of an embedded system. It is the basic unit that takes inputs and produces an output after processing the data. For an embedded system designer, it is necessary to have the knowledge of both microprocessors and microcontrollers . 72

74. Processors in a System A processor has two essential units: Program Flow Control Unit (CU) and Execution Unit (EU) Control Unit (CU): The CU includes a fetch unit for fetching instructions from the memory. Execution Unit (EU): The EU includes the Arithmetic and Logical Unit (ALU) and also the circuits that execute instructions for a program control task such as interrupt, or jump to another set of instructions. 73

75. Types of Processors Processors can be of the following categories: (1). General Purpose Processor (GPP): Microprocessor, Microcontroller, Embedded Processor, Digital Signal Processor, and Media Processor (2). Application Specific System Processor (ASSP) 74

76. Types of Processors (3). Application Specific Instruction Processors (ASIPs) (4). GPP core(s) or ASIP core(s) on either an Application Specific Integrated Circuit (ASIC) or a Very Large Scale Integration (VLSI) circuit 75

77. General-purpose Processor General-purpose processors: Programmable device used in a variety of applications – Also known as “microprocessor” Features: Program memory, General datapath with large register file and general ALU User benefits: Low time-to-market and NRE costs, High flexibility Example: “Pentium” the most well-known, but there are hundreds of others 76

78. Application Specific System Processor(ASSP) ASSP is an application specific dependent system processor used for processing signal of embedded system. Therefore, for different application performing task a unique set of system processors is required. 77

79. Application Specific System Processor(ASSP) ASSP is dedicated to specific tasks and provides a faster solution. An ASSP is used as an additional processing unit for running the application in place of using embedded software. Examples : IIM7100, W3100A 78

80. Application Specific Instruction Processors (ASIPs) ASIP is a component used in system on a chip design. The instruction set architecture of an ASIP is tailored to benefit a specific application. 79

81. Microprocessor A microprocessor is a single VLSI chip having a CPU. In addition, it may also have other units such as coaches, floating point processing arithmetic unit, and pipelining units that help in faster processing of instructions. Earlier generation microprocessors’ fetch-and-execute cycle was guided by a clock frequency of order of ~1 MHz. Processors now operate at a clock frequency of 2GHz. 80

82. Microprocessor The following illustration shows the block diagram of a Microprocessor 81

83. Microcontroller A microcontroller is a single-chip VLSI unit (also called microcomputer ) which, although having limited computational capabilities, possesses enhanced input/output capability and a number of on-chip functional units. 82

84. Microcontroller Microcontrollers are particularly used in embedded systems for real-time control applications with on-chip program memory and devices. 83

85. Microprocessor VS Microcontroller Microprocessors are multitasking in nature. Can perform multiple tasks at a time, whereas microcontrollers are single task oriented. In microprocessors RAM, ROM, I/O Ports, and Timers can be added externally and can vary in numbers, whereas in case of microcontrollers RAM, ROM, I/O Ports, and Timers cannot be added externally. These components are to be embedded together on a chip and are fixed in numbers. 84

86. Microprocessor VS Microcontroller External support of external memory and I/O ports makes a microprocessor-based system heavier and costlier, whereas Microcontrollers are lightweight and cheaper than a microprocessor. In case of microprocessors External devices require more space and their power consumption is higher, whereas External devices require more space and their power consumption is higher. 85