Embedded systems

*** What is an Embedded System.

Embedded system:

An embedded system is an electronic/electro-mechanical system designed to perform a specific function and is a combination of both hardware and software.(firmware).

 *** Discuss the history of Embedded s.

In olden days embedded systems are built with old vacuum tubes and transistors and the algorithm was developed in low-level languages.

  The first recognized modern embedded system is the Apollo Guidance Computer  (AGC) developed in 1965 by the MIT Instrumentation Laboratory for the lunar expedition.

Lunar Module featured in total 18 engines. There are 16 reaction control thrusters, a descent engine and an ascent engine.

MIT’s Original design was based on 4K words of fixed memory (ROM) and 256 words of erasable memory (RAM).

After 10K of fixed and 1K of erasable memory at 1963, final configuration is 36K words of fixed memory and 2K words of erasable memory.

The first mass-produced embedded system was the guidance computer for the Minuteman-I.

Apollo project is then newly developed, monolithic integrated circuits to reduce the size & weight.

An early mass-produced embedded system was the Autonetics D-17 guidance computer for the Minuteman missile, released in 1961.

Minuteman-II in 1966, the D-17 was replaced with a new computer, was the first high-volume use of IC’s.

An early µp, Intel 4004  (1971)  was designed  for calculators.

In 1978 National engineering manufacturers association released a “Standard”  for  programmable microcontrollers.

It is a computer-based controllers as single board computers, numerical and event-based controllers.

Embedded system is usually more complex than a traditional solution, most of the complexity is contained within the microcontroller.

Very few additional components are needed and most of the design efforts is in software.

***APPLICATIONS: -  Embedded systems are commonly found in consumer, industrial, automotive , medical, commercial and military, telephone switches, routers, MP 3 players, mobile phones, videogame , digital cameras, GPS receivers, printers, microwave ovens, washing machines & dish washers.

***  Explain General purpose of computer system

 Embedded System:

v It is microcontroller based system.

v It is for specific purpose.

v Power consumption is less.

v Not end user programmable.

v It is build for dedicated purpose.

v Power , memory, cost, real-time, size are the resources of embedded system.

v These are build for fixed run time requirements.

v These are dedicated to a single purpose or a small set of purposes. In

v Embedded systems are found in nearly single purpose or a small set of purposes.

v Embedded systems are found in nearly single piece of modern electronics.

General purpose computer (G.P.C)

v It is microprocessor based system.

v It is for general purpose.

v Power consumption is high.

v End  user  programmable.

v It can be used  for  multipurpose .

v It contains richer in resources, high cost, average speed.

v They are much faster & much better.

v Desktops, notebooks, smart phones & tablets are the example of general-purpose computers.

*** Discuss about the Classification of embedded system

·        Based on generation.

·        Complexity and performance requirements.

·        Based on deterministic behavior.

·        Based on triggering.

Classification Based on Generation.

 First Generation :

        These are built like 8085 & Z80 and 4-bit Microcontrollers.

                          These are simple in hardware circuits with software developed in Assembly code.

Eg: Digital telephone keypads, stepper motor control.

Second Generation:

           These are built with 16-bit µp & 8 (or) 16 bit µc.

                           Instruction set for it is much more complex and powerful.

 Eg: Data Acquisition systems, SCADA Systems.

Third Generation:

             These are built with 32 bit µp & 16-bit µc.

                           Instruction Set of processors became more complex and powerful. In it instruction pipelining also evolved.   

Eg: DSP , Application specific Integrated circuits, Pentium, Motorola 68.

                           Dedicated Embedded real time and general purpose operating systems started in this generation.

4^TH GENERATION:

  Multicore processors are bringing high performance.  In this generation these are designed by high performance real time embedded operating systems for their functioning.

Eg: Smart phone devices, mobile internet devices.

 CLASSIFICATION BASED ON COMPLEXITY AND PERFORMANCE

SMALL SCALE EMBEDDED SYSTEMS:

  These are built as low performance and low cost 8 or 16bit up/uc.

  A small scale embedded system may or may not contain an operating system for its functioning.

Eg: Electronic toy

MEDIUM SCALE EMBEDDED SYSTEMS:

  These are built as medium performance, low cost 16 or 32 bit µp/µc or digital signal processors.

  These contain an embedded operating system for functioning (either general purpose or real time operating system).

  These are slightly complex in hardware and software.

LARGE SCALE EMBEDDED SYSTEMS/COMPLEX SYSTEMS:

  These are built with high performance 32 or 64 bit RISC µp/controller or reconfigurable system on chip or multi core processors and programmable logic devices.

  These are highly complex hardware and software requirements.

Eg: Decoding /encoding of media.

***Explain Embedded system applications?

  The application areas and the products in the embedded domain are countless.

CONSUMER ELECTRONICS: Cameras, camcorders etc

HOUSE HOLD APPLIANCES: Television, DVD Players, washing machine, fridge, microwave oven etc

HOME AUTOMATION AND SECURITY SYSTEMS: Air conditioners, closed circuit television, cameras, fire alarms etc

AUTOMOTIVE INDUSTRY:                                                                 Anti lock breaking system(ABS) engine control, automatic navigation systems etc

TELECOM:  Cellular telephones, telephone switches, handset multimedia applications etc

COMPUTER PERIPHERALS: Printers, Scanners, fax machines

COMPUTER NETWORKING SYSTEMS: Network routers, switches, hubs, firewalls etc

Health Care: Different kinds of scanners, EEG , ECG machines etc

MEASUREMENT AND INSTRUMENTATION: Digital multimeters, digital CROs, logic analyzers, PLC systems etc

BANKING AND RETAIL: Automatic teller machines(ATM) and currency counters, point of sales(POS)

CARD READERS: Barcode, smart card readers, hand held devices etc

  

***EXPLAIN THE PURPOSE OF EMBEDDED SYSTEMS:

  Embedded systems are used in various domains like consumer electronics, home automation, telecommunications, automotive industry, health care, control and instrumentation and banking applications.     

                            

  Embedded system is designed to serve the purpose of any one or combination of different functions. They are

  a   Data collection/ storage/ representation

  b   Data communication

  c   Data (signal) processing

  d   Monitoring

  e   Control

  f   Application specific user interface

DATA COLLECTION/STORAGE/REPRESENTAION:

  Embedded systems designed for the purpose of data collection and performs acquisition of data.

  Data collection is done for storage, analysis, manipulation and transmission.

  Data may be either analog (continuous) or digital(discrete)

  Embedded systems collect analog data and it converts into digital by using ADC

  If the data is digital it doesnot use or interface other circuits.

  The collected data may be stored directly in the system or may be transmitted to other systems or may be process by the system or may be deleted instantly after giving a meaningful representation.

  These actions are purely dependent on the purpose for which embedded system is designed.

Eg: Analog and digital CRO’s without storage memory.

  Some embedded systems store the collected data for processing and analysis.

Eg: Digital camera

DATA COMMUNICATION:

  Embedded data communication systems are ranging from complex satellite communication systems to simple home networking systems.

  The transmission is achieved by a wire line medium or wireless medium.

  In olden days wire-line medium was preferred and now a days wireless communication is preferred in embedded systems.

  Wireless medium offers cheaper connectivity solutions and make the communication link free.

  Data can either be transmitted by analog or by digital. Modern industry prefer the digital communication.

Eg:  Wireless: Bluetooth, wi-fi, GPRS etc

  Wireline: RS-232,USB

DATA (SIGNAL) PROCESSING:

          The data (voice, image, video, electrical signals) collected by Embedded systems may be used for various kinds of data processing.

         Embedded systems with signal processing are speech coding, audio video code c , transmission applications.

Eg: Digital hearing aid improves the hearing capacity of hearing impaired persons.

MONITORING:

         Some Embedded systems designed only for monitoring purpose.

             Almost all embedded products of medical domain are with monitoring functions only.

Eg:- ECG (Electro cardio gram)  machine is used for monitoring the heart beat of a patient.

Eg of embedded systems with monitoring function are digital CRO, digital multimeters.

CONTROL :

        A system with control functionality contains both sensors and actuators.

        Sensors are connected to the input port for capturing the changes for measuring variable.

        The actuators connected to the output port are controlled according to the changes in i/p variable.

Eg: A.C.

        Here i/p variable is sensor to sensing the room temperature variable is also the room temperature.

         The controlling variable is cool air flow by the compressor unit.

         If the controlled variable and i/p variable are not at the same value, then controlling variable tries to equalize them through taking actions on the cool air flow.

APPLICATION SPECIFIC USER INTERFACE:

        These are embedded systems with application specific user interfaces like buttons, switches, keypad, lights, bells, display units.

Eg: Mobile phone

        In mobile phone the user interface is provided through the keypad, graphic LCD module, system speaker vibration alert.

***Explain Quality Attributes of Embedded systems

              Quality attributes are the non functional requirements in any system design.

              The various quality attributes addressed in any embedded system are classified into two namely “Operational Quality Attributes” and “Non operational Quality Attributes”

***Discuss about Operational Quality Attributeses

The operational quality attributes represent the relevant quality attributes related to the embedded system in the Operational mode or Online mode.

The important quality attributes are

1.   Response

2.   Through put

3.   Reliability

4.   Maintainability

5.   Security

6.   Safety

Response:

                  Response is a measure of quickness of the system.

           Most of the embedded systems are fast response and almost Real Time. But it is not necessary that all embedded systems should be Real Time in response.

Eg: In flight control application Real Time response is necessary. For an electronic toy Real time response is not necessary.

Through put:

            Throughput deals with the efficiency of a system.

            In general it can be defined as the rate of production or operation stated at a period of time.

            Through put means how many transactions the reader can perform in a min or in an hour or in a day.

Reliability:

            Reliability is the % of Susceptibility of the system to failures.

            Mean Time Between Failures(MTBF) and Mean Time To Repair(MTTR) are the terms used in defining system reliability.

            MTBF gives the frequency of failure in hrs/weeks/months. MTTR specifies how long the system is allowed to be out of order in a failure.

Maintainability:

            Maintainability is closely related to the system availability.

Maintainability can be classified into two categories

1.   Periodic Maintenance

2.   Corrective maintenance

Eg: Printer

Security:

            Confidentiality, Integrity and Availability are the three major measures of information security.

            Confidentiality deals with the protection of data from unauthorized disclosure.

             Integrity deals with the protection of data from un authorized modification.

             Availability deals with the protection of data from unauthorized users

Eg: PDA (Personal Digital Assistant)

Safety:

            Safety and security are two unique aspects in quality attributes.

            Safety deals with possible damages can happen to the operators, public and the environment due to the breakdown of an embedded system.

            Breakdown of an embedded system may occur due to a hardware or software failure.

***Discuss about Non Operational Quality Attributes

            The operational quality attributes “not” on the basis of operational aspects are known as Non Operational Quality Attributes.

The important Quality attributes

1.   Testability and Debug ability

2.   Evolvability

3.   Portability

4.   Time to prototype and market

5.   Per unit and total cost.

TESTABILITY AND DEBUG ABILITY:

           Testability deals with how easily one can test his/her design.

           For an embedded product, testability is applicable to both the embedded hardware and software.

           Debug ability has two aspects in embedded system as hardware level debugging and software level debugging.

EVOLVABILITY:

            Evolvability is a term that is closely related to Biology.

            For an embedded system, the quality attribute “Evovability” refers the embedded product can be modified to take advantage of new software or hardware technologies.

PORTABILITY:

             Portabililty is a measure of “System Independence”

             An embedded product is said to be portable if the product is capable of functioning in various environments.

             A standard embedded product should always be flexible and portable.

Time –to-prototype and Market :

               The commercial embedded product market is highly competitive.

                There may be multiple players in the embedded industry to develop products of the same category.

                 Product prototyping helps a lot in reducing time-to-market.

                The time to proto type is a critical factor, If the proto type is developed faster.

                To shorten the time to proto type, make use of all possible options like re-usable assets.

Per unit cost and Revenue :

                  Cost is a highly sensitive factor for commercial products.

                  Every embedded product has a product life cycle to starts with the design and development.

                   The different stages of the embedded products life cycle-revenue, unit cost and profit in each stage are represented as product-life cycle graph.

                    The profit increases with increase in sales and a attains a steady value and then falls with a dip in sales.

                    Profit occurs only when the total returns exceed the investment and operating cost.