This document provides an overview of embedded systems with the following key points: 1. Embedded systems are computer systems that are part of larger machines or devices to control or monitor them. They are designed to perform specific tasks, often in real-time. 2. Examples of embedded systems include network printers, mobile phones, satellites, washing machines, and more. 3. Embedded system design involves selecting hardware components like the CPU and memory, designing the hardware and software, testing and debugging, and loading the software onto the system. Real-time operating systems are often used to facilitate software development.

1. A Brief Introduction to
Embedded Systems
K. Raghunathan
Chartered Engineer
FIETE, MIE, MCSI, MISTE, MISTD. MIIMM
Retd. Dy. Controller (R&D) [MoD]

2. Embedded Systems
• Overview of Embedded Systems
• Embedded System Design
• Embedded System Designer
• More Knowledge

3. Overview of Embedded Systems
• What is an Embedded System ?
• Examples of Embedded Systems
• Why an “Embedded” System ?
• Salient Features

4. What is an Embedded System ?
• A computer system, fitted as part of some
Equipment which is not a computer
• The whole system is not called a computer - it is
known by the name of the Equipment
• The embedded computer system controls the
equipment in which it is embedded
• Performs only specific tasks, often in real-time

5. Examples of Embedded Systems
• Network Printer
– Network Interfacing & Routing
• Handheld Barcode Scanner
– Conversion of Image to Number
• Mobile Phone with Internet Connectivity
– Browsing, eMail, FTP, Chat etc

6. Examples of Embedded Systems
• CNC Machines & Robots
– Control the Sequence of Operations
• Satellites
– Remote-sensing, Data-formatting,
Communication, Navigation Control etc
• Televison Set
– Digital on-screen display of menu, channel
number, subtitles etc
• Washing Machines
– Control of Sequence of Operations, Motor
speed & duration control etc

7. Why “embed” a Computer ?
• Computers are more suitable for
– Control
– Data Processing
– Decision Making
– Digital Communication

8. Why “embed” a Computer ?
• Main Equipment is Larger & Costlier;
computer is smaller, cheaper & used for
only some specific purpose
• Using General-purpose computer involves
additional space & wiring. It is better to fit a
small computer inside [or onto] the
equipment itself
• often, main equipment itself may have to
be small & portable

9. Salient Features of Embedded
Systems
• Purpose & Functionality
– Specific Purpose; Limited Functionality
• Size
– Small enough to fit into/onto the main eqpt
• Real-Time
– Response within a specified Time-limit
• I/O Devices
– Very Few; often, only Sensors & Activators
– Conspicuous absence of conventional devices
like keyboard, CRT screen, hard disk etc

10. Embedded Systems
• Overview of Embedded Systems √
• Embedded System Design
• Embedded System Designer
• More Knowledge

11. Embedded System Design
• Selection of CPU & other Hardware
• Design of the Hardware System
• Design & Development of Software
• Testing & Debugging
• Loading the Software into the Embedded
System’s Memory

12. Selection of CPU & other Hardware
• CPU
– Speed
– Instruction Set
– Multitasking Capabilities
– Interrupt- handling Capabilities
– Power Consumption
– Heat Dissipation

13. Memory
• Non-Volatile [ROM/PROM/EPROM]
– Code
– Fixed Data
• Look-Up Tables, Constants, Initial Values of
Variables
• Volatile [RAM]
– Variable Data
– temporary data

14. I/O Devices
• Depends on :
– Main Equipment & its purpose/functions
– Purpose to be served by the embedded
system
• May also need :
– HW & SW Interfaces or Drivers for the i/o
devices

15. Software Development
• Software has to be developed on some
other convenient computer system [Host
System]
• The Code obtained in the Host system
should run in the Embedded System
[Target System]

16. Software Development
• HW configuration of Host & Target will be
different
• Should use Cross Compilers & Cross
Assemblers on the Host, to get Target System’s
Machine Code as the Output
• Often, an RTOS [Real Time Operating System] is
used

17. Software Development
• Usually the SW is developed as a set of
Tasks [functions/procedures] & ISRs
[Interrupt Service Routines]
• Tasks perform some specific actions
– most likely, some of the primary functions of
the Main eqpt
• ISRs interrupt running Tasks based on
certain events [inputs from sensors]
– to take appropriate action for those inputs
– to update data for the tasks

18. Testing & Debugging
• Often not possible to test the program by
actually loading it into the target system &
running it in the Main eqpt
• So, code has to be tested in the Host
system itself
• Need Emulators which can emulate the
embedded system’s CPU

19. Testing & Debugging
• Drivers & Scaffolds to be written
– to simulate actual inputs & behaviour of the
main eqpt
• Test Data
– normally expected range of values
– out-of-range values
– erroneous data

20. Loading SW in the Embedded
System’s Memory
• No operating system in the embedded
system
• Code generated on the Host system
should include start-up [initialising] routines
for the target system
• Use of RTOS ensures automatic addition
of start-up code

21. Loading SW in the Embedded
System’s Memory
• Special programs called Locators enable
developer to specify which blocks of code should
be loaded at what addresses in the embedded
system’s memory
• Output of Locator is in the form of a file stored in
the Host; this file will have a special format [not
the standard executable file you get in desktop
systems]
• Special programs called Loaders
– understand the Locator’s file format
– load the code in embedded systems memory

22. Tools for Embedded Software
Development
• Cross Compilers
• Cross Assemblers
• Locators
• RTOS
• Loaders

23. RTOS
• Easier Development Environment
• Produce Machine Code of Target CPU
• Automatic inclusion of code for Start-up &
system Initialisation & other necessary
functionalities like memory management,
process scheduling etc
• Many RTOSes available
– iRMX86, uC-OS, VxWorks, pSOS, QNX etc
• Many of them written in C/C++
– allow us to develop programs using C/C++

24. RTOS
• Main Features
– Multi-tasking
– Task Scheduling Policies
– Mutual Exclusion using Semaphores
– Message Queues, Mailboxes and/or Pipes for
Inter-Process Communication

25. Hardware Design Considerations
• Physical Size
– Small
• Power Consumption
– Low
• Heat Dissipation
– Very Low
• Cost
– Low cost, without compromising Quality &
Performance

26. Software Design Considerations
• Real Time Response
– No part of the code can take unpredictable
execution time
– ISRs must be kept short
– No Dead-Locks or Circular Waits
• Reliability
– Should run without Human Intervention
– Should NOT Crash
– Robust & Fault Tolerant
– Exception Handling without Malfunction or
unpredictable behaviour

27. Embedded Systems
• Overview of Embedded Systems √
• Embedded System Design √
• Embedded System Designer
• More Knowledge

28. Embedded System Designer
• Specialist
• Knowledge of Theory & Practical
Techniques of both Hardware & Software
• Strong Foundation in
– Digital Logic Ckts, ADCs, DACs, PLCs, FPGAs
– Microcontrollers & Interfacing Techniques
– Assembly Language Programming
– High Level Language Programming [C/C++]
– Writing ISRs
– RTOS

29. Job Oppurtunities
• Employers
– Manufacturers of
• Telecom Products
• Automatons & Industrial Robots
• Automated Production & Diagnostic Eqpt
– Software Development Firms
• Remuneration
– Lucrative

30. Embedded Systems
• Overview of Embedded Systems √
• Embedded System Design √
• Embedded System Designer √
• More Knowledge

31. For More Knowledge
• Books
• Hands-on Training

32. Books on Embedded Systems
• An Embedded System Primer
– David E Simon
• Embedded System Design
– Steve Heath
• The Art of Programming Embedded Systems
– Jack G Ganssle
• Fundamentals of Embedded Software - Where C and
Assembly Meet
– Daniel W Lewis
• Real Time Systems & Programming Languages
– Alan Burns & Andy Wellings
• Real Time Programming
– Moore Grehan

33. Training on Embedded Systems
• TCIL, & their Branches & Franchisees
– Telecom Consultants India Ltd
– formed by DoT
• ECIL, Hyderabad
– Electronic Corporation of India Ltd
• Many institutes boast of embedded system
training
– teach only soldering & assembling, using kits
– do not teach theory or design principles

34. Thank You !
&
Best of Luck !