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Characteristics & Quality Attributes of Embedded Systems rss 43, , , , [aa mrRoDuerION, , , , Embedded systems are designed to do some specific task, rather than be a, general-purpose computer for multiple tasks. Some also have real-time, performance constraints that must be met, for reasons such as safety and, usability; others may have low or no performance requirements, allowing the, system hardware to be simplified to reduce costs. Embedded systems are not, always standalone devices. Many embedded systems consist of small,, computerized parts within a larger device that serves a more general purpose. For, example, the Gibson Robot Guitar features an embedded system for tuning the, strings, but the overall purpose of the Robot Guitar is, of course, to play music., Similarly, an embedded system in an automobile provides a specific function as a, subsystem of the car itself,, , , , , , The program instructions written for embedded systems are referred to as, , firmware, and are stored in read-only memory or Flash memory chips. They run, , jth limited computer hardware resources: little memory, small or non-existent, keyboard or screen., , (4.2 OBJECTIVES, , 1. Todiscuss the characteristics of Embedded system, 2. To discuss the attributes related to quality of embedded system., , 4.3 CHARACTERISTICS OF EMBEDDED SYSTEM, , Most embedded systems are designed to perform an continued action at a, low cost. Most of these systems also have constraints on the performance in, terms of hardware and software, such as require operating in real time when a, system needs high sped while executing some functions, but may tolerate lower, speed for other activities. | 4, , It is difficult to characterize the speed or the cost of an generic embedded ,, system, especially for systems that have to process a large quantity of data. F “4, Fortunately most of the embedded systems have the essential characteristics that ;, can be designed with a combination of hardware and high-performance software., To get an idea, justthink of a decoder for a satellite television. Although a system, should process tens of megabits of data per second, most of work performed by, dedicated hardware, separates rule and decoding of the data flow in mulltichannels digital video output. :, , Embedded CPU calculated the locations of the data in the system, manages, interrupts and clock systems Usually, the hardware of an embedded system, must comply with the performance requirements much less stringent in, according to the hardware of the primary system itself. This allows that the \, architecture of an embedded system, for example, must be intentionally a, simplified and compared to that of a general-purpose computer withthe same |, tasks, using a CPU more economic that basically behaves well for these ;, secondary functions. |, , In the case of portable systems, costs reduction becomes a priority. This kind, of system, in fact, often are made by a highly integrated CPU, a chip dedicated to f, all other functions and a single board of memory. In this case each component is, Selected and designed to reduce as much as possible the costs. The useful, software to manage many embedded systems is called firmware. The. firmware is, a type of software that, for example, can be found in ROM or Flash memory, chips. The software and firmware are designed and tested with much more, attention than traditional software for personal computers.

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.Sc.LT.) (Sem _y, m (S.¥. B.Sc. Mj, 44 pmbedded Syste! 4, , rer 4 components with moving pan,, , Many embedded systems avoid incorporating siid-state components such,, Such as hard disk) that are less reliable than 5° not be physically accessip,, flash memory. Moreover, embedded systems May of a self-reset in Cage, , apable ( sare, (€.8. space systems): therefore, the system must be “ptained with the addition ,, va e, , of data loss or corruption. This feature is very 0! outer in regular time intervay,, & component called Watchdog that resets the com reliable embedded system j,, by an internal timer, In the design of a modern an rogram ability and the, Possible to note two fundamental characteristics: TP, dimension,, , , , , , icated system can be readapted it, dded systems are a Classica, dvanced optimization becaug,, ly, making the control System, a IC) is an integrateg, , In fact, it would be helpful to think of a ded, for example, system upgrade is required. Embe', discrete elements of ASIC design that allow the a, the hardware eccupies the necessary space strictl. :, , hy fisteioy s caapaN CRS SERIE ted circuit (AS, asily integrated. An application-specitic integra se. Today the control o, creuit (IC) that has been customized for purpose UW e ms. In a single high., vehicles is one of the main applications of embedded systems. ECU (Electronj, end car you can find hundreds of embedded systems called the different, Control Unit), physically distributed in the vehicle and connected to the eng, internal networks (networks intra-vehicle) specially designed, in most cases with, stringent requirements of ‘quality of service’., , A computer is the first and foremost versatile: it can be progr: ammed to Suit, vanous areas of application. Conversely, the embedded ‘system is a device, Gedicated to the performance of a single task, or a very narrow class of tasks. of, cest and performance. The general purpose of the computers is designed with, Standards and reference architectures; and vice versa is difficult to define, Standards for embedded systems because each specific: application leads to, different design choices. Typical functions of embedded systems can be the, following : taidition to the paré, , @ Processing : ability to process the analog/digital signals. tess and embedded ¢, , ©@ Communication : ability to transfer signals (“Information”) from/to the tea phase is necessary, outside world., , , , , , , , , , , , , , @ Storage : the ability to preserve the. temporary information within the "Relability * realis, embedded system, Whintainability :, , @ Each specific application made by an embedded system has different ‘ine interval,, requirements for processing, power supply, Storage and communication., @ A same functionality (e.g., the ability to ac, sensor) can be optimized radically in different w;, , example, a digital camera or a cell Phone or a digital camcorder, , systems can be described in, , @ Final Cost : The cost of the final product is ave, the design choices., @ Time to market : in the design of an embedded ayste, i m1 S rs De), in mind the timing you want the product listed on the ene keep, long to design a device means that it’s difficut arket; taking too, changes in the market. me the fast, ®@ Life time ; Another important factor is the expected 1;, product; which can varied from a few days to several pee life, @ Volume : the quantity of stock planned for the aysten, factor in the design phase. Ste, , 'y important Parameter for, , to overcor, , time for the, ars or decades., , ™ is one important

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and e aid, systems can be described in the following ll characteristics of embedded, , ommunica ‘, , ° Seater is oe ieee * typically the sale price of an embedded, , “ a ’ . communication inte j sei ‘, , greatly affects the final price of the eae interfaces is critical because it, , e User Interface, , a few buttons, system,, , a . many embedded systems the user interface consists of, and/or LEDs; in others, it uses the user interface of a host, , e@ Power management : is a crucial factor to be considered for all, embedded systems are powered by batteries., , e Dimensions and weight : in many cases, the physical characteristics are, another critical factor; usually the embedded system must be small, very, light or with a particular form (for example, very thin)., , e Quality of service : many applications of embedded systems have, stringent requirements in terms of QoS (Quality of Service); as a, particular case, many applications require the provision of services in real, time with stringent timing constraints., , Code size : the storage capacity of embedded systems is limited, so the size of, theinternal program (e.g. firmware) is a important factor., , e@ Numeracy/Communication skills/Storage : commensurate to the, specific application performed by the embedded'system., , @ Updating the program : it is useful to include the ability to update the, programs in embedded systems so as to correct errors discovered after, the production and introduce new features., , In addition to the parameters involved in the market, the hardware, software, features and embedded systems are used to be dependable. Actually, in the, design phase is necessary to consider the following aspects :, , © Reliability : realistic assessment of the probability that the system fails., , @ Maintainability : the system can be repaired or replaced within a certain, time interval., , © Availability : probability that the system is working; essentially depends, on the reliability and maintainability., , @ Safety : properties related to the possibility that in the event of system, failure are caused damages to people or things., , ® Security : resilience of the system against unauthorized use., , To design the embedded systems, it should take into account aspects such, , as the speed of development, the economy of scale, maintainability and so on,, Consequently it is not possible to develop the hardware also without consider, e ' f, , : acl 6 a a safety-critical, the choice of the, the software design. If the embedded system is satet) a, software cman plays a crucial role in the ability to certify the system for, the use to which itis intended. a, , The real-time system is a system designed to operate within the cere, time Parameters Practically, a real-time system operates correc a dice, input configuration is produced by the right output respecting well st ned time, , Constraints.

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2g, TTRIBUTES OF EMBEDDED S8¥', , 7 leci, tributes that together form the d, system., , There are two types of quality attributes are:, , ‘STEM, , (4.4 QUAL, ITY a’ ding factor about the ual, , Following at, of an embedded, , 1. Operational Quality Attributes. functioning of an embecg, ; : i u: 1 ;, ater eet attributes related to operation or ia overall quality. 5, , © way an embedded system operates alle, 2. Non-Operational Quality Attributes. soning of an emb., , These are attributes not related to operation or Se ell quality, ni, System. The way an embedded system operates affects its ove! before it me, are the attributes that are associated with the embedded system “nly, put in operation,, , Quality Attributes of ES., , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Fig. 4.4 (a) : Overview of Quality Attributes of Embedded System, 4.4.1 Operational Attributes, , The operational quality attributes represent the rel, related to the embedded system when it is in the ope:, mode.Operational Q.A are :, , Response -It is the measure of quickness of the, system is tracking the changes in inputvariables.M, response which should be almostreal time., , Ex ~ Flight control application,, , Throughput, @ It deals with the efficiency of a system. Jt can b, production or operation of a defined process, , evant quality attribute:, rational mode or onilint, , over a stated period od, , Ex — In case of card reader throughput means, , Tin a day, , Throughput is generally measured in terms of, , is a reference point by which something can i ", ‘ured,, , system.It tells how fast th’), ost of the E.S demand fas!), , e defined as the rate, , ; : how : f, reader can perform in a minute or in an hour 06 many transactions tht!, , “Benchmark”.A Benchmat), , I, , , , , ¢ Confident, unauthor, applicatic, © Availabili, unautho}, , Safety, , Safe, , Pubig - deals, embedded € e, Safety