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Copyright © 2012 Embedded Systems Committee Introduction To ES Mohamed Abd Elhay
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Copyright © 2012 Embedded Systems

Committee

Introduction To ES

Mohamed Abd Elhay

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Copyright © 2012 Embedded Systems

Committee

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Committee

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Committee

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Copyright © 2012 Embedded Systems

Committee

Embedded Systems

Embedded Systems Applications

Embedded Systems Types

Memories

Embedded system developing

Embedded Systems Market in Egypt

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Copyright © 2012 Embedded Systems

Committee

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Copyright © 2012 Embedded Systems

Committee

•Embedded system is a special purpose system designed to

perform one or a few dedicated

functions.

• Embedded systems are computing systems with tightly

coupled hardware and software integration.

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Copyright © 2012 Embedded Systems

Committee

The Word “Embedded” reflects the fact that these systems are

usually an integral part of

a larger system, known as the embedding system.

“A computer built into a system and not seen by the user as

being a computer”

It is usually Embedded as a part of a complete device

including hardware and mechanical parts.

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Copyright © 2012 Embedded Systems

Committee

Can Personal Computer be considered as an Embedded

System as it integrates hardware and software to

perform functions? Why?

NO

PC cannot be considered as an embedded system

because

1. It uses a General-Purpose Processor

2. The system is built independently from the software

runs on it.

Else ATM machine

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Committee

Communication:

Mobile Handsets

Switches and Routers

Image processing and Consumers:

Cameras

Mp3 and Mp4 players

PlayStation

Automotive:

Engine Management System

Claimant Control System

Appliances:

Microwave

Washing Machines

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Committee

1) Microprocessors.

2) Microcontrollers.

3) DSPs.

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Committee

1-Microprocessor:

• CPU = ALU + Registers + Control unit

• Microprocessor function is to fetch the instructions

from the memory then decode and execute them.

• Microprocessor alone is useless

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Committee

1-Microprocessor: a-General Purpose Processors

32 or 64-bit data path

Central processing engine of a mainframe, workstation, PC, PDA

X86, PowerPC, SPARC, Pentium

Complex in design because these processors provide a full scale of features and a wide spectrum of functionalities

Modern processors have:

a built-in memory management unit (MMU) to provide memory protection and virtual memory for multitasking-capable.

General-purpose operating systems.

Have advanced cache logic.

Built-in math co-processor capable of performing fast floating-point operations.

Interfaces to support a variety of external peripheral devices.

These processors result in large power consumption, heat production, and size

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Committee

1-Microprocessor:

b-Embedded general purpose Processors

Designed for a wide range of application (consumer and communication)

8/16 or 32-bit data path

Limited functionality depends on the application

Scaled-down versions of existing computational micros

Reaches around 200 MHz

Usually integrated into larger dedicated systems in a SoC (System on Chip), also called core-based ASIC

Examples: ARM, PowerPC, MIPS, 68K, x86

ARM has seized the lion’s share of the market

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Committee

2-Microcontroller:

• Microcontrollers are often referred to as single chip devices or single

chip computers in a small size that its resources are far more limited than

those of a desktop personal computer.

• Microcontroller = CPU + Memory + Peripherals

•The workhorse of industrial electronics.

•Designed for standalone operation.

•Include processing unit 8-bit, 16-bit, 32-bit.

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Committee

2-Microcontroller:

Microcontroller Main Components

Microcontroller has eight main components:

1. Central processing unit (CPU)

2. ROM

3. RAM

4. Input and Output (GPIO or DIO)

5. Timer

6. Interrupt circuitry

7. Buses

8. Watchdog

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Committee

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Committee

Processor Control Unit Architecture:

» Harvard Architecture:

includes two memory units :

► An instruction memory holds the program

► A separate data memory is used for computations

► The advantage is that we can read an instruction and load or

store data in the same clock cycle

» Von Neumann Architecture:

includes one memory unit :

► a single main memory that holds both program instructions

and data

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Committee

Instruction Set Architecture:

RISC is short for “Reduced Instruction Set Computer”

RISC is a set of building concepts, that can be followed to

optimize and simplify computer system design

CISC is short for “Complex Instruction Set Computer”

CISC is an old concepts that dates back when memory access

was slow

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Instruction Set Architecture:

CISC aimed to integrate several functionalities in one instruction, in order to

limit the program size, and thus limit memory access in order to gain some

speed

RISC on the other hand, aims to optimize execution of instructions by

limiting the capabilities of a single instruction, thus gaining speed from

execution point of view

As memory technology developed more and more, memory access became

faster, and the limitation of memory access diminished

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3-Digital Signal Processors:

• Like microcontrollers BUT Focus on very efficient execution of

arithmetic operations.

• DSP has :

– specialized arithmetic units,

– optimized design in the memory,

– Addressing and bus architectures with multiprocessing capability that

allow the DSP to perform complex calculations extremely fast in real

time.

• Used widely in digital signal processing in communications systems

such as Cell phones and Image and video processing.

• TI (Texas Instruments) has been the dominant player in the DSP market

for several years.

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Advanced Embedded System

• Multi-core system on chip

Like mobile handset which has one chip contains:

1. DSP processor

2. Embedded processors like ARM

3. Custom hardware for GSM

4. Custom peripherals for board interface (keyboard, touch screen, memory card interface)

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RAM

ROM

EEPROM/FLASH

Memory Mapping

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Random Access Memory (RAM)

Also called Read/Write Memory, The term random access refers to the ability to access any memory cell directly. RAM is much faster than ROM

Volatile memory, requires external power to maintain memory content.

Used to store data as long as Microcontroller is powered and the program is running

Modifiable through program instructions

Addressable in instruction sets through different addressing Mode

1-RAM:

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RAM Types:

1. Dynamic RAM (DRAM): DRAM is a RAM device that requires periodic refreshing to retain its content.

2. Static RAM (SRAM): SRAM is a RAM device that retains its content as long as power is supplied by an external power source. SRAM does not require periodic refreshing and it is faster than DRAM.

3. Non-Volatile RAM (NVRAM) • NVRAM is a special type of SRAM that has backup battery power so it can

retain its content after the main system power is shut off.

• Another variation of NVARM combines SRAM and EEPROM so that its content is written into the EEPROM when power is shut off and is read back from the EEPROM when power is restored.

1-RAM:

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RAM contents

Divided virtually to:

1. General purpose registers for CPU acts as

accumulators

2. Peripherals control special registers

3. Data RAM: all static variables in the program i.e.

each variable has a static address and its last value

lasts until microcontroller power off.

4. Stack

1-RAM:

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Permanent memory (Non-Volatile)

Written upon programming the microcontroller

Can’t be written/modified at run time

2-ROM

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ROM types

• OTP:

– one time programming ROM

– used in products

• Mask ROM:

– Programmed upon microcontroller production

• Flash ROM:

– Program electrically many times

– Used during development time

– Currently used in products to be updatable

2-ROM

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Committee

ROM contents:

I. Program code

II. Constant data

– Handled through const keyword in C.

2-ROM

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Electrically erasable programmable Read only Memory

Acts as peripheral of microcontroller

Accessed through special registers

Could write/modify Data during Run time

Take more time in read/write access than RAM

keep data even the microcontroller is powered off

the FLASH memory is a variation of EEPROM, which

allows for block-level (e.g., 512-byte) programmability

that is much faster than EEPROM.

EEPROM/FLASH

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Memory Mapping

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Trade off between HW and SW

For a certain application

Which functional blocks should be performed in Hardware??

Which functional blocks should be performed in software??

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Software characteristics

Highly configurable

Shorter development cycle

Easier in versions updates

Cheaper

Constrained with processor speed which may satisfy real

time application and may not

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Committee

Hardware characteristics

Longer development cycle

Customized for specific application

Better performance in high speed real time application

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Board

SYSTEM ON BOARD

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SYSTEM ON CHIP

Keyboard

controller USB interface

Memories CPU

Customized

hardware

LCD

controller

ASIC Chip

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• In complicated systems functional blocks could be:

Level 1: External discrete hardware component on board.

Level 2: Hardware integrated with CPU on chip (SoC).

Level 3: Done by software running on CPU.

HW / SW Partitioning

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“Those systems in which the correctness of the system

depends not only on the logical result of the computation, but

also on the time at which the results are produced”

Real Time Systems are a very fast systems?

Real-time means completing tasks within specified deadlines,

it is not defined or limited by a specific execution speed.

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System Development Cycle

1. System Specification Analysis

2. System Design

3. Development

Hardware Development

Software Development

4. System Integration

5. System Validation

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Committee

Software Development Cycle

1-Software Specification

2-Software Design

3-Coding / Testing

4-Software Integration

5-Software Validation

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1- Assembly

a-Lowest level human readable

b-Platform specific.

c-Assembly has one-to-one corresponding machine language

d-Using compiler to convert High Level language to Assembly

2-C Language

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Committee

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References

• ESC Training Team

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Committee

[email protected]