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Chapter 3 Device and Serial and Parallel communication Buses for Devices Network - I By Suhas B Shirol

Chapter3.Device and Serial and Parallel Comm for Device Nw

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Chapter 3

Device and Serial and Parallel communication Buses for Devices

Network -IBy Suhas B Shirol

Formalization of System Design using Top – Down approach

• Requirements and Specifications ofhardware and software

• Define architectures of hardware andsoftware

• Coding and implementation as perarchitecture

• Testing, validation and verification ofsystem

Diagrammatic model - UML (Universal Modeling Language)

• Conceptual design modeling• Classes and Objects to describe identity, attributes, components and behaviour– Inheritances in classes and objects– Interfaces with the objects and their

implementation in the objects,• Structural description of the design

components

Behavioral description in terms ofstates, state machine and signals

Events description

Case Study:AUTOMATIC CHOCOLATE VENDING MACHINE

(AVCM)

ACVM Specifications

• Alphanumeric keypad on the top ofthe machine.

• A child interaction with it whenbuying a chocolate.

• Owner commands and interactionwith the machine.

Cont……….

• Three line LCD display unit on thetop of the machine.

• Displays menus, entered text,pictograms, and welcome, thank andother messages, and time and date.

• Child as well as the ACVM owner GUIs with the machine using keypad

and display.

Coin insertion and delivery slots, andInternet port

• Coin insertion slot so that the childcan insert the coins to buy a chocolate

• Delivery slot to collect the chocolate,and coins if refunded

• Internet connection port so that owner can interact with ACVM from remote

Basic system in ACVM

Reprogram of the codes and relocation

of the codes• The system ROM or flash or EPROM whenever

the following happens: (i) the price of chocolate increases,

(ii) the message lines or menus or advertisement graphics needs to be changed or (iii) machine features change.

Block diagram of ACVM hardwareincluding Microcontroller

Software architecture (ISRs and Tasks) for ACVM

Case Study: Digital Camera

Specifications

• Camera records the pictures using a charge coupled devices (CCD) array.

• The array consisting of large number of horizontal rows and vertical columns ofCCD cells for the picture

• In each row of cells, a number of CCD cellunexposed to the picture but used for off-setcorrections in the each-row output from thepicture cells.

Camera Picture resolution

• 2592 × 1944 pixels, there are 2592 ×1944 = 5038848 set of cells.

• Each set of pixel has three cells, for thered, green and blue components in a pixel.

• Each cell gets exposed to a picturewhen shutter of camera opens on a usercommand.

Controllers, LCD display, Switches andbuttons

• A set of controllers─ to control shutter, flash, auto focus and eye-ball image control.

• LCD display for graphics and GUI• Switches and buttons for inputs at camera.• User gives commands for switching on the

camera, flash, shutter, adjust brightness,contrast, color, save and transfer.

• When a button for opening the shutter ispressed, a flash lamp glows and a self-timercircuit switches off the lamp automatically

Picture transfer Ports

• JPEG file for a picture can be copied ortransferred to a memory stick using acontroller

• Sony memory stick Micro (M2) size15×12.5×1.2 mm, flash memory of 2 GBand 160 Mbps data transfer rate.

• A picture jpg can be copied to a computerconnected through USB port controller.

Digital camera hardware architecture

Software architecture upper layers

Software architecture lower layers

Classification and DevelopmentSkills Requirements for the

Embedded Systems

Classification of ES

• Small Scale Embedded Systems

• Medium Scale Embedded Systems

• Sophisticated Embedded Systems

Skills for ES

• Skills for Small Scale SystemFull understanding of a microcontroller with a basic knowledge of computer architecture, digital electronic design, software engineering, data communication, control engineering, motors and actuators, sensors and measurements, analog electronic design and IC design and manufacture

Cont………..• Median Scale Embedded Systems

'C'/C++/Java programming and RTOS programming and program modeling skills

Programming the Tasks or threads and their scheduling by RTOS.

Programming priorities and Cooperative and preemptive scheduling.

Use of Inter processor communication functions.

Use of shared data, and programming the critical sections and re-entrant functions.

Use of semaphores, mailboxes, queues, sockets and pipes.

Handling of interrupt-latencies and meeting task deadlines.

Use of various RTOS functions.

Use of physical and virtual device drivers.

Cont……………• Sophisticated Scale Embedded Systems

Team is needed to co-design and solve the high level complexities of the hardware and software design.

An embedded system hardware engineer should have full skills in hardware units and basic knowledge of 'C'/C++ and Java, RTOS and other programming tools.

Software engineer should have basicknowledge in hardware and a through knowledge of 'C', RTOSand other programming tools. A final optimum design solution is then obtained by system integration.

IO port types- Serial andparallel IO ports

Port

• A port is a device: To receive the bytes from external

peripheral(s) [or device(s) or processor(s) orcontrollers] for reading them later usinginstructions executed on the processor or

To send the bytes to external peripheral ordevice or processor using instructionsexecuted on processor

I/O Example

• SI serial interface in 8051• SPI serial peripheral interface in 68HC11• PPI parallel peripheral interface 8255• Ports P0, P1, P2 and P3 in 8051 or PA, PB,• PC and PD in 68HC11• COM1 and COM2 ports in an IBM PC

IO Port Types

Types of Serial ports:• Synchronous Serial Input• Synchronous Serial Output• Asynchronous Serial UART input• Asynchronous Serial UART output• Both as input and as output, for example,

modem.

Cont…………

Types of parallel ports:• Parallel port one bit Input• Parallel one bit output• Parallel Port multi-bit Input• Parallel Port multi-bit Output

Synchronous Serial Input Example

Synchronous Serial Output Example

Synchronous Serial Input/output

Asynchronous Serial input RxD at UART

COM Port

Format of bits at UART protocol

Asynchronous Serial Output

• Asynchronous output serial port line TxD(transmit data).

• Each bit in each byte transmit at fixedintervals but each output byte is not insynchronization (separates by a variableinterval or phase difference). Minimumseparation is 1 stop bit interval

Parallel Port single bit input

• Completion of a revolution of a wheel• Achieving preset pressure in a boiler• Exceeding the upper limit of permitted weight

over the pan of an electronic balance,• Presence of a magnetic piece in the vicinity of

or within reach of a robot arm to its end point and Filling of a liquid up to a fixed level.

Parallel Port Output- single bit• PWM output for a DAC, which controls

liquid level, or temperature, or pressure, orspeed or angular position of a rotating shaftor a linear displacement of an object or ad.c. motor control

• Pulses to an external circuit

• Control signal to an external circuit

Parallel Port Input- multi-bit

• ADC input from liquid level measuringsensor or temperature sensor or pressuresensor or speed sensor or d.c. motor rpmsensor

• Encoder inputs for bits for angular positionof a rotating shaft or a linear displacementof an object

Parallel Port Output- multi-bit• LCD controller for Multilane LCD display

matrix unit in a cellular phone to display onthe screen the phone number, time,messages, character outputs or pictogrambit-images for display screen or e-mail orweb page

• Print controller output

• Stepper-motor coil driving bits

Thank U