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Subject:Embedded Computing Systems

Subject Code:06CS74

Subject In-Charge: Ashok Babu A

PART A

UNIT - IIINTRODUCTION TO EMBEDDED SYSTEMS 2, DEVICES - 1: Formalization of system design; Design process and design

examples; Classification of embedded systems; Skills required for an embedded system designer. I/O types and

examples; Serial communication devices; Parallel device ports; Sophisticated interfacing features in device ports.

6 HoursText Book: Chapter 1(1.9 - 1.12) and Chapter 3(3.1 - 3.4)

Formalization of system design:

Formalization of system design is done using a top-down approach by abstraction and by

Detailing requirements and specifications of Hardware and software. Defining architectures of hardware and software. Coding and implementation as per architecture. Testing, Validation and verification of system.

Since a diagrammatic model clears the design concepts better than abstraction, a modeling Language, for

formalization can be used. The Universal Modeling Language ( UML ) is used. In UML, a designer describes

the following.

1. User Diagram, Object Diagram, Class Diagram and Activity Diagram.2. Classes and Objects3. Inheritances of Classes and Objects4. Interface of objects5. Structural Description of the design components6. Behavioral description in terms of states, state machine and signals7. Event Description

Design process and design examples System Design Process Examples1. ACVM2. Digital Camera3. TCP/IP Network4. Orchestra Robots5. Automobiles6. Smart Card7. Mobile Phone

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Automatic Chocolate Vending Machine ( ACVM )Diagrammatic Representation of ACVM.

ACVM Functions

1. The ACVM displays the GUIs and if the user wishes to enter contact information , it displays theappropriate menu.

2. It displays a welcome message when in idle state. It continuously displays time and date at the rightbottom corner of display screen.

3. When first coin is inserted, a timer also starts. The user is expected to insert all required coins in twominutes.

4. After 2 minutes the ACVM will display a query to the child if the child does not insert sufficient coins. Ifthe query is not answered the coins are refunded.

5. Within 2 minutes of sufficient coins are collected. It displays the message. Thanks , wait for a fewmoments please! delivers the chocolate through the delivery slot and displays the message, Collect

the chocolate and visit again, please!.

Hardware Units:

1. Microcontroller or ASIP.2. RAM3. ROM4. Flash Memory5. Timer and Interrupt Controller6. A TCP/IP Port7. ACVM Specific Hardware to sort coins of different denominations8. Power supply

Software components:

1.

Keypad input read task.2. Display Task3. Read Coins task for finding coins sorted.4. Deliver chocolate task5. TCP/IP stack processing task6. TCP/IP stack communications task

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Smart CardDiagrammatic Representation

Embedded Hardware:

Microcontroller or ASIP RAM One time programmable RAM Flash Timer and Interrupt Controller A carrier frequency Interfacing circuit for the IOs Charge pump for delivering power to the antenna.

Embedded software:

1. Boot-up, initialization and OS programs2. Smart-card secure file system3. Connection establishment and termination4. Communication with host5. Cryptography algorithm6. Host authentication7. Card authentication8. Saving addition parameters or recent new data sent by the host.

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Digital Camera

Camera Functions:

1. It displays the frame view on the LCD screen2. It displays the saved images on the LCD using navigation keys3. The frame light falls on the CCD array, which transmits the bits for each pixel in each row in the frame

through an ADC.

4. The CCD bits of each pixel in each row and column are offset corrected5. The processed signals are compressed using a JPEG CODEC

Digital Hardware Units:

1. Microcontroller or ASIP2. Multiple processors3. RAM4. ROM5. Timer , flash memory6. USB Controller7. DMA8. LCD Controller9. Battery

Software components:

1. CCD Signal processing for off-set correction2. JPEG coding3. JPEG decoding4. Pixel processing before display5. Memory and file systems6. Light, flash and display device drivers7. COM,USB port and Bluetooth device Drivers

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Classification of embedded systems

Small Scale Embedded Systems.

Designed with a single 8- or 16-bit microcontroller Little hardware and software complexities and involve board-level design. Tools for development of embedded software Editor, assembler and cross assembler. Integrated development environment (IDE). Specific to the microcontroller or processor used. C or Java used for developing C program compilation is done into the assembly, and executable codes are then

Appropriately located in the system memory.

Software fits within the memory available and keep in view the need to limit powerDissipation when system is running continuously.

Medium Scale Embedded Systems. Designed with a single or few 16- or 32- bit microcontrollers or DSPs or Reduced

Instruction Set Computers (RISCs).

Employs the readily available single purpose processors. Employ the readily available IPs for the various functionsfor example, for the bus interfacing, Both hardware and software complexities Programming tools: C/C++/Visual C++/Java, RTOS, and Source code engineering tool, Simulator, Debugger and Integrated Development Environment (IDE).Sophisticated Embedded Systems. Enormous hardware and software complexities and may need scalable processors or configurable

processors and programmable logic arrays.

Used for cutting edge applications that need hardware and software co-design and componentsintegration in the final system

Constrained by the processing speeds available in their hardware units. Certain software functions such as encryption and deciphering algorithms, discrete cosine

transformation and inverse transformation algorithms, TCP/IP protocol stacking and network driver

functions implemented in the hardware to obtain additional speeds by saving time.

Development tools for these systems may not be readily available at a reasonable cost or may not beavailable at all.

In some cases, a compiler or retargetable compiler might have to be developed for these. [Aretargetable compiler is one that configures according to the given target]

Skills required for an embedded system designer Full understanding of a microcontroller with a basic knowledge of computer architecture, digita

electronic design, software engineering, data communication, control engineering, motors and

actuators, sensors and measurements, analog electronic design and IC design and manufacture Tim

Wilmshurst

Specific skills will be needed in specific situations. For example, control engineering knowledge will beneeded for design of control systems and analog electronic design knowledge will be needed when

designing the system interfaces.

Computer architecture and organization. Interfacing the memories.

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Burning the executable machine codes in PROM or ROM. Use of decoders and demultiplexers. Use of Direct memory accesses. Device drivers in assembly. Simple and sophisticated buses. Timers. Interrupt servicing mechanism. C programming elements. Memory optimization. Selection of hardware and microcontroller. orts and device- Use of ICE (In-Circuit-Emulators), crossassemblers and testing equipment. Debugging the software and hardware bugs by using test vectors. Basic knowledge in the other areas software engineering, data communication, control engineering, motors and actuators, sensors and

measurements, analog electronic design and IC design and manufacture.

I/O types and examples

A serial port is a port for serial communication. Serial communication means that over a given line or channel

one bit can communicate and the bits transmit at periodic intervals generated by a clock.

A serial port communication is over short or long distances.

A parallel port is a port for parallel communication. Parallel communication means that multiple bits can

communicate over a set of parallel lines at any given instance. A parallel port communicates within the same

board , between ICs or wires over very short distances of at most less than a meter.

Fig 3.1( a) : Input Serial Port, Output Serial Port

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Fig 3.1( b) : Hand Shaking Signals at COM port and UART serial port bits

Examples of various types of IO Devices. (Tables )