ES-Basics.pdf

EMBEDDED SYSTEMS
&
EMBEDDED PROCESSORS
BASICS
By
Prof.K.Babulu, JNTU-GV
Vizianagaram.

ES-INTRODUCTION
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An Embedded System is deﬁned as a Computing
Device that does a Speciﬁc focused job.
They are Self-Contained Programs that are
Embedded within a piece of Hardware.
Embedded Software is also known as ‘FIRMWARE’.

ES-CHARACTERISTICS
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Reliability
Performance
Power Consumption
Cost
Size
Limited User Interface
Software Up Gradation Capability

ES-CATEGORIES
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Stand-Alone Embedded Systems
Real-Time Systems
Networked Information Appliances
Mobile Devices

Digital Camera
Desktop
Computer Internet
Weather
Monitorin
g
System
NETWORKED INFORMATION APPLIANCES
HARD REAL-TIME EMBEDDED SYSTEM STAND-ALONE EMBEDDED SYSTEM
Missile Embedded with
a Tracking System
Aircraft

EMBEDDED SYSTEM ARCHITECTURE
• .
Hardware
OS
Application
Software

ES-HARDWARE ARCHITECTURE
.
Output
Device
Communication
Interfaces
Application-Speciﬁc
Circuitry
RAM ROM
CPU
Input
Device

ES-SOFTWARE ARCHITECTURE
• .
1.Operating System
a) Communication Software
b) File System
c) Kernel
d) Libraries
e) Device Manager
2.Application
Programming Interface
(API)
3.Application Software
OS
API
AS
a b
c
d
e

ES-Application Software Function Calls
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To Create, Suspend and Delete Tasks.
To do Task Scheduling for Meeting Real-Time
Requirements.
To Facilitate Inter-Task Communication and
Synchronization between Tasks.
To Allocate and Free Memory.
To Access the I/O Devices.
To Access the Communication Protocol Stack.

ES-APPLICATIONS:
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Consumer Appliances
Oﬃce Automation
Industrial Automation
Medical Electronics
Computer Networking
Tele Communications
Wireless Technologies
Instrumentation
Security
Finance

Considerations in Embedded Systems Design
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An Embedded System receives input from its
environment through Sensors, processes this input and
acts upon its environment through Actuators.
Besides the usual Software and Hardware Design issues,
the Embedded System Designer must consider the
properties of the Sensors and Actuators and the
Environment.
The ultimate Test of an Embedded Systems are the
Laws of Physics.

Embedded Systems Design Approach
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Design Algorithms (control, signal processing) that
will be implemented on Embedded Microprocessors
Design Microprocessors to be used in Embedded
Applications
Design Software (e.g.RTOS) for the Embedded Market
Work in Application ﬁelds that involve an Embedded
Microprocessor
Develop Sensors/Actuators (e.g.MEMS devices) that
may be used in Embedded Systems

Skills Needed for Embedded Applications
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An embedded System Application involves a Diverse Set
of Skills that extend across Traditional Disciplinary
Boundaries, including
Computer Hardware
Software
Algorithms
Interface Electronics
Application Domain

Design Challenge-Optimizing Design Metrics
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Common Metrics:
Unit Cost: The Monetary Cost of manufacturing each copy of the
System, excluding NRE (Non-Recurring Engineering Cost) Cost.
NRE Cost: The one-time Monetary Cost of Designing the System.
Size: The Physical Space required by the System.
Performance: The Execution Time or Throughput of the System
Power: The Amount of Power consumed by the System.
Flexibility: The Ability to change the Functionality of the System
without incurring Heavy NRE cost.

Design Challenge-Optimizing Design Metrics
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Common Metrics:
Time-to-Prototype: The time needed to build a
working version of the System.
Time-to-Market: The time required to develop a
System to the point that it can be released and sold to
customers.
Maintainability: The ability to modify the System after
its initial release.
Correctness, safety, many more.

Real-Time System
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A Real-Time System is a Computer System where the
Correctness of the System behavior depends not only on
the Logical Results of the Computations, but also on the
Physical Time when these Results are Produced.
System Behavior means the Sequence of Outputs in-
time of a System.
A Real-Time Computer System must react to Stimuli
from its Environment.

Real-Time System
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The Instant when a Result must be produced is called
‘Deadline’.
If a Result has passed even after the Deadline, the
Deadline is classified as Soft, otherwise it is Firm.
Severe Consequences could result if a Firm Deadline is
missed, the Deadline is called Hard.
Example: Consider a traffic signal at a road before a
railway crossing. If the traffic signal does not change to
red before the train arrives, an accident could result.

Classiﬁcation of Embedded Systems
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Real-time versus Non Real-Time ES.
Hard Deadline
Failsafe
Fail-operational
Soft Deadline
Firm Deadline
Centralized versus Distributed ES.

Embedded System Requirements
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Essentially turning a Concept into a Product.
Asking Customers, understanding their Needs.
Determining the Best Feature and Price Point.
Sales and Marketing usually Responsible.
R&D Engineers Contribution must be Required.

Embedded System Requirements
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Functional: Describe each Function of the System.
Input
Output
Processing
Non-functional: System Properties not related to its
Function.
Power Consumption
Cost
Time-to-Market
Reliability
Portability
Maintainability
Security

Embedded System Implementation Platform
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The Hardware on which the Embedded Computing System will execute the
Software.
Could be a Combination of Platforms.
Hardware platforms:
General Purpose Processors
RISC Processors
CISC Processors
Application-Speciﬁc Processors
Microcontrollers
Digital Signal Processors
ASIPs
Hardware Accelerators
GPUs
FPGAs
Custom ICs

General Purpose Processors
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High Flexibility
General Instruction Set
Good for all Applications
Low Development Time
Programming in High-Level Language
Low/Medium Processing Power
Medium Cost
High Power Consumption

Application-Speciﬁc Processors:
Microcontrollers
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Medium Flexibility
ISA optimized for Control Applications
Low Processing Power
Not suitable for Data Intensive Applications
Low Power Consumption
Low Cost

Application-Speciﬁc Processors:
DSPs
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Medium Flexibility
ISA optimized for Fast Execution of Numerical
Algorithms necessary for Analyzing Signals
Medium/High Processing Power
Low/Medium Power Consumption
Medium Cost

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