Introduction to Embeded System chapter one and 2.pptx

Chapter 1: Introduction to Embedded
Systems
Embedded Systems
19.01.2025 Embedded System by Gadisa A. 1

Chapter One
INTRODUCTION TO EMBEDDED SYSTEMS
By Gadisa A.[MSc.]

What is Embedded System?
Embedded System:-
 An embedded system is a system that has
software embedded into computer
hardware, which makes a system dedicated
to an application(s) or specific part of an
application or product or part of a larger
system.
 An embedded system has a dedicated
purpose software embedded in computer
hardware

What is an Embedded System?
Embedded System:-
 It is a dedicated computer-based
system for an application(s) or
product. It may be an independent
system or a part of a large system. Its
software usually embeds into a ROM
(Read Only Memory) or flash.

Microcontroller as heart of the embedded system
 Microcontroller is an IC chip that takes input
process data according to the program written in its
memory and gives output as a control signal for
controlling other machines and devices.
 A microcontroller (sometimes abbreviated µC, uC
or MCU) is a small computer on a single integrated
circuit containing a processor core, memory, and
programmable input/output peripherals.

embedded system examples with real life application
• In today's world of technology, we found Microcontrollers in
almost every electronic device we uses. Almost all general-
purpose devices such as Digital Watches, Washing Machines,
CD/DVD Players, Mobile Phones and Microwave Ovens works
on the bases of Microcontroller.
uC
Mobile
Phones
Came
ras
Microwa
ve Oven.
Securit
y
Alarms
CD/
DVD
Playe
rs
Electronic
Measurem
ent
Instrument
s.

Differentiate Microcontroller and microprocessor
Microprocessor :
 The microprocessor is the heart of any processing device. It’s a basic building block of
modern processors and controllers.
 It’s a register-based multi-purpose electronics device that takes input from us,
processes that input data according to the program written in external memory, and
gives us useful results.
 This device only consists of a processing unit, that is Memory and I/O devices need to
be connected externally.
 As it requires external memory and I/O devices it requires large space and is larger in
size. It is of no use without interfacing with external memory and I/O ports.
 Example: Personal Computer/Laptop
 No Predefined Rules

Differentiate Microcontroller and Microprocessor
Microcontroller :
 Microcontroller is also like a Microprocessor except that a Microcontroller
is made by Integrating Memory and I/O ports on a single chip.
 It doesn’t require external ROM, or I/O ports for its operation. As memory
such as ROM/RAM is integrated into a single IC chip, thus it is small in
size.
 It is used for controlling various machines.
 The programming of both microcontrollers and microprocessors is almost
similar.
 They are used for Specific tasks
 Example: Camera, washing machine, microwave oven

Differentiate Microcontroller and Microprocessor

Microcontrollers

Advantages of Microcontroller Application
Some of the benefits of microcontroller are:
 High reliability and high degree of integration;
 Reduction in size;
 Reduced component count and manufacturing cost owner;
 Shorter development time;
 Shorter time to market;
 Lower power consumption.

Developing Embedded System

Hardware Development

19.01.2025 Embedded System by Gadisa A.
CHAPTER TWO
EMBEDDED SYSTEM ARCHITECTURES
15
By Gadisa A.[MSc.]

INTRODUCTION TO EMBEDDED SYSTEMS
• Introduction to Embedded Systems
• The Build process for embedded systems
• Structural units in Embedded processor
• Selection of processor
• Selection of Memory devices

Examples Embedded System

Components in Embedded System
•

System
A system is a way of working, organizing or
doing one or many tasks, which are performed in
a system according to a fixed plan, program or
set or rules

General Computing System Components
• Microprocessor
• Large memory
• Input Units
• Out put Units
• Networking Units
• An Operating System

Embedded System
An embedded system is a system that has
embedded software in computer hardware. The
system is dedicated to either an application(s) or
a specific part of an application or product or a
component of a large system
Example.
Washing machine
Cooking machine
Automative chocolate vending machines
Multitasking toys

Classification of Embedded System
i. Small Scale Embedded Systems
ii. Medium Scale Embedded Systems
iii. Sophisticated Embedded Systems

Embedded System Components
• It embeds Hardware similar to a computer
• Software usually embeds in the ROM, flash
memory or media card
• It embeds a Real Time Operation System
(RTOS)

Components of Embedded System Hardware

Building Blocks of Embedded System Hardware
• The Hardware consists of the following building blocks and
devices:
• Power source
• Clock Oscillator and Clocking Units
• System Timer
• Real Time Cock
• Reset Circuit
• Power Up Reset
• Memory
• I/O ports
• I/O buses
• I/O Interfaces

The Build Process
• The first step is selecting a processor
• The processor is selected from the following
considerations
 Instruction Set
 Maximum bits in an operand in an operation
 Clock frequency in MHz or GHz and the
processing speed in Million Instructions per
second.
 Processor ability to solve the complex algorithms
used in meeting the deadlines for their processing

The Build Process
• The build process for embedding software
consists of the following steps
 Project file consisting of source file and library
files
 Compilation of the project files
 Linking all object files and locating them onto a
single re-locatable object file
 Converting the object file in a form called hex-file
to a binary image

The Build Process

Abstraction of Steps in the Design Process

Structural Units in Embedded Processor
• Internal Buses:
 It internally connects all the structural units inside the processor.
 Its width can be 8,16,32 or 64 bits
• Address Bus
 It is the external bus that carries the address from the MAR to the memory as well as
the IO devices and the other units of the system
• Data Bus
 It is an external bus that carries the data from or to the address
• Control Bus
 It is an external bus to carry the control signal between the processor and memory
devices
• Bus Interface Unit
 It is the interface unit between the processor’s internal units with the external buses
• MAR:
 Memory Address Register
 It holds the address of the byte or word to be fetched from external memories
• MDR:
 It holds the byte or word fetched from/to external memory or I/O address

• Program Counter
 PC holds the memory address of the next instruction that would be
executed.
• Stack Pointer
 It is a pointer for an address that corresponds to stack top in the
memory
• Instruction Register
 It takes sequentially the instruction codes to the execution unit of
the processor
• Instruction Decoder
 It decodes the instruction opcode received at the IR passes it to the
processor CU
• Instruction Queue
 It is the queue of instruction so that the IR does not have to wait for
the next instruction after one has been carried out

• Arithmetic and Logical Units
 It is a unit to execute arithmetic and logical
instruction according to the current instruction
present in the IR
• Floating Point Processing Unit (FPPU)
 A unit separate from ALU for floating point processing
which is essential in processing mathematical
functions fast in a microprocessor or DSP
• Floating Point Register Set(FPRS):
 A register set dedicated to storing floating point
numbers in a standard format and used by FPPU for
its data and stack

• Control Unit
 It controls all the bus activities and unit functions
needed for processing
• Memory Management Unit (MMU)
 It manages the memory such that instruction and
data are readily available for processing
• Application Register Set
 It is a set of on-chip registers used during
processing the instruction of the application
program of the user

• Instruction Cache
 It sequentially stores, like an Instruction queue,
the instructions in FIFO.
• Data Cache
 It stores the pre-fetched data from the external
memory
 The data cache generally holds both the key and
the value together at the location

Embedded System Characteristics
 System functions in real time
 Program is preloaded in the ROM(s) or flash
memory
 Dedicated set of functions
 Complex dedicated purpose preprogrammed
algorithms
Hardware
Graphics and Other user interfaces
 Multirate operations with different
predetermined time constraints to finish the
different operations

Constraints of Embedded Systems
 Available System Memory
 Available Processor Speed
 Meeting Deadlines
 Performance
 Power
 Size
 Design and Manufacturing Cost

Selection of Processor
 Different systems require different processor
features
 The processor is selected from the following
considerations
 Instruction Set
 Maximum bits in an operand in an operation
 Processing Speed
 Ability to solve complex algorithms
 A processor gives high computing performance when it
has
Pipeline and Superscalar architecture
Pre-fetch cache unit, caches, register files
RISC core architecture

Selection of Processor
 A processor with register windows provides fast
context switching in a multitasking system
 Processor has auto shut-down features for its
units
 A processor with burst mode accesses external
memories fast

Selection of Memory Devices
 Software designer coding is over and the ROM
image file is ready, a hardware designer of a
system is faced with the questions, of
 what type of memory?
 what to use?
 how much size of each, should be to used???

• Some of the Memory selection processes are,
 Internal ROM
 Internal EPROM
 Internal EEPROM
 Internal RAM
 ROM Device
 EPROM Device
 EEPROM Device
 Flash Device
 RAM device

• Masked ROM or EPROM stores the embedded
software
• EEPROM is used for testing and design stages and
also is used to store the results during the system
program run time
• Flash stores the results byte by byte during a system
run after a full sector erase
• RAM is mostly used in SRAM form in a system
• Sophisticated system use RAM in the form of
DRAM and SDRAM.

DMA
 I/O devices need to transfer the data of other
systems to the memory addresses in the
system
 A system may also need to transfer data to the
IO devices
 A Direct Memory Access is required when a
block of data is to be transferred between two
systems without the CPU intervening, except
at the start and at the end

DMA

DMA
• DMA supports 3 modes of operations
 Single transfer at a time and then release of the
hold on the system bus
 Burst transfer at a time and then release of the
hold on the system bus. A burst may be a few Kilo
Bytes
 Bulk transfer and then release of the hold on the
system bus after the transfer is completed

DMAC
 DMA transfer is facilitated by the DMAC (DMA
Controller)
 Data transfer occurs efficiently between I/O
devices and system memory with the least
processor intervention using DMAC
 The system address and data buses become
unavailable to the processor and available to the
IO device that connects DMAC

Memory Management Methods
How MMU works
 Keep track of what part of memory are in use
 Allocate memory to processes when needed
 De-allocate when processes are done
 Swapping or Paging between main memory and
disk

Memory Management Methods
In general, memory management responsibilities
include:
 Managing the mapping between logical memory
and task memory references
 Determining which processes to load into the
available memory space
 Allocating and de-allocating memory for processes
that make up the system
 Tracking the memory usage of system components
 Ensuring process memory protection

User Memory Space
 Because multiple processes are sharing the same
physical memory when being loaded into RAM for
processing, there also must be some protection
mechanism so processes cannot unintentionally
affect each other when being swapped in and out of a
single physical memory space
 The OS typically resolves these issues through
“memory swapping” where partitions are swapped at
run time.

Segmentation
 A process encapsulates all the information that is
involved in executing a program, including source
code, stack and data.
 All of the different types of information within a
process are divided into logical memory units of
variable sizes called SEGMENTS
 Most OS typically allow processes to have all or some
combination of five types of information within
segments such as
 Code Segment
 Data Segment
 Block started by Symbol
 Stack Segment
 Heap Segment

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