Embedded System Introduction and Basics

Module - 1
Introduction to Embedded Systems
Presentation
By
Dr. Kesavan Gopal
Course Embedded System
Dr. Kesavan Gopal

Outline
• What an embedded system is?
• Difference b/w General Purpose and Embedded
System
• Classification
• Purpose
Dr. Kesavan Gopal

What an embedded system is?
* An embedded system is an electronic / electro
mechanical system designed to perform a specific function
and is a combination of both Hardware and software
(Firmware).
Dr. Kesavan Gopal

Difference - Embedded & General
Computing Systems
Parameters/
Metric
General
Purpose
System
Embedded
System
Hardware
& Software
Generic HW &
General
Purpose OS
Variety of
Applications
Specific HW &
Embedded OS
Specific Set of
Applications
Operating
System (OS)
General Purpose
Operating System
(GPOS)
May or May not
have an OS for
functioning
Dr. Kesavan Gopal

Programmable Applications are
alterable by user
Not alterable by
End User –
Pre -Programmed
Key Factor Performance is Key
Factor (KF).
Faster is always
better
Application Specific
Requirements,
Power,
Performance
and
Memory are key
factors
Power
Consumption
More Less
Response
Time
Not- Critical Critical for some
applications
Dr. Kesavan Gopal

History of Embedded Systems
Will be taken up later.
Dr. Kesavan Gopal

Classification of Embedded Systems
• Based on Generation
• Complexity and Performance Requirements
• Based on Deterministic Behaviour
• Based on Triggering.
Dr. Kesavan Gopal

Based on Generation
• First Generation
– Build around 8-bit microprocessors
– Like 8085, Zilog Z80
– Simple Hardware
– Firmware developed in Assembly Code
– Digital Telephone Keypads, Stepper Motor Control
• Second Generation
– Build based on 16-bit MPU or MCU
– Complex & Powerful instruction sets than 1G
Systems.
– Embedded OS for operations
– Examples, Data Acquisition Systems, SCADA
Systems Dr. Kesavan Gopal

Cont…
• Third Generation
– 32-bit MPU & 16-bit MCU
– DSPs & ASICs
– Complex & Powerful Instruction set + Pipelining
– Examples, Robotics, Media, Industrial Process Control,
Networking
• Fourth Generation
– SoC, Reconfigurable Processors, Multi core Processors
– Miniaturization
– Total system on a Chip
– High Performance Real-time Embedded OS
– Examples, Smart Phones
– Mobile Internet Devices (MIDs)
Dr. Kesavan Gopal

Based on Complexity and Performances
• Small-Scale Embedded Systems:
– Simple in application needs
– Non-time Critical
– Low performance, Low Cost
– Built around 8 or 16 – bit MCU/MPU
– May
• Medium Scale Embedded Systems:
– Slightly Complex in Hardware and Software
(Firmware)
– Medium Performance Requirements
– Low cost 16/32 – MCU/MPU or DSPs
– Contains an Embedded OS or may not have OS
Dr. Kesavan Gopal

Cont…
• Large Scale Embedded systems:
– High complex Hardware and Software (Firmware)
– Mission critical Applications, High Performance
Requirements
– 32 / 64 – RISC Processors / Reconfigurable SoCs /
Multi-core / PLDs
– Multiprocessors, Controllers / Co-units / Hardware
Accelerators offloading and processing
– Decoding and encoding of Media, Cryptographic
functions
– Consists of Real Time Operating System (RTOS)
for task Scheduling, Prioritization and Management
Dr. Kesavan Gopal

Based on Deterministic Behavior
• Applicable for Real-Time Systems
• Behavior of system Deterministic or non
deterministic
• Classified based on Hard or Soft
Dr. Kesavan Gopal

Hard Real Time system
• System should adhere to the timing constraints
of the system.
• System should meet the timing deadlines
without any delay
•Missing deadline causes serious failure to the
system or user
•EX: Airbag Control System, Antilock Braking
System
• hard real-time system, “A late answer is
always a wrong answer”.
Dr. Kesavan Gopal

Soft Real Time system
• Deadline is NOT strictly followed.
• Missing Dead lines for tasks are acceptable for soft-
real time systems.
• Frequency of deadlines missing should be within
the compliance limit.
• EX: ATM – delay in delivering the cash few seconds
is still acceptable.
• May cause serious problem.
• In this case, “a late answer is an acceptable
answer”, but it could have been done a bit faster
Dr. Kesavan Gopal

Based on Triggering
• Embedded Systems are reactive in nature
–Process Control systems
– Based on trigger
• trigger
– Event triggered
–Time triggered
Dr. Kesavan Gopal

Major Purpose of Embedded System:
1. Data collection/Storage/Representation (Ex.
Camera)
2. Data communications (Wireless router)
3. Data (signal) Processing (Hearing Aid)
4. Monitoring (Patient Monitoring)
5. Control (AC)
6. Application specific User Interfaces (Smart Shoes,
Smart Phones)
Dr. Kesavan Gopal

Application Areas of Embedded System
1. Consumer electronics: Camcorders, Cameras etc
2. Household appliances: Television, DVD players,
Washing machines, fridge, microwave over etc
3. Home automation and security systems: Air
conditioners, sprinklers, intruder detection alarms,
closed circuit television cameras, fire alarms etc
4. Automotive industry: Anti-lock breaking systems
(ABS), engine control, ignition systems, automatic
navigation systems, etc
5. Telcom: Cellular telephones, telephone switches,
handheld multimedia applications, etc
Dr. Kesavan Gopal

Cont…
6. Computer peripherals: Printers, Scanners, fax
machines, etc
7. Computer Networking System: Network routers,
switches, hubs, firewalls, etc.
8. Healthcare: Different kinds of scanners, EEG, ECG
machines etc
9. Measurement & Instrumentation: Digital
mustimeters, Digital CROs, Logic Analysers, PLC systems,
etc.,
10. Banking & Retail: Automatic teller machines (ATM)
and currency counters, point of sales (POS)
11. Card Readers: Barcode, smart card readers, hand
held devices, etc.
Dr. Kesavan Gopal

Keywords:
1. Embedded system
2. Microprocessor
3. Microcontroller
4. DSP
5. ASIC
6. Sensor
7. Actuator
8. LED
9. Operating System
10. SCADA – Supervisory Control and Data Acquistion
11.ADC
Dr. Kesavan Gopal

Upcoming
Embedded System Design Challenges
Attributes of Embedded System
o Operational
o Non Operational
Dr. Kesavan Gopal

Embedded System - Design Challenges
• Unit Cost: The monetary cost of manufacturing
each copy of the system excluding NRE Cost.
• NRE Cost: (Non- Recurring Engineering Cost): The
one-time Monetary cost of designing the system
• Size: the physical space required by the System
• Performance: The execution time and 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.
Dr. Kesavan Gopal

Cont…
• 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, Testability, Manufacturability:
And much more.
Dr. Kesavan Gopal

ToM – Time to Market
• Time required to develop a product to the point it
can be sold to customers.
• Markov Window: The period during which the
Product would have highest sales.
• Average ToM is around 8 months
• Delays can be costly.
Dr. Kesavan Gopal

Losses Due to Delayed Market Entry
Area = 1/2 * base * height
On-time = 1/2 * 2W * W
Delayed = 1/2 * (W-D+W)*(W-D)
Percentage revenue loss =
(D(3W-D)/2W2)*100%
–Lifetime 2W=52 wks, delay D=4 wks
–(4*(3*26 –4)/2*26^2) = 22%
–Lifetime 2W=52 wks, delay D=10 wks
–(10*(3*26 –10)/2*26^2) = 50%
–Delays are costly!
Try some examples:
Dr. Kesavan Gopal

NRE and Unit Cost Metrics
• Costs:
– Unit cost: the monetary cost of manufacturing each copy of
the system, excluding NRE cost
– NRE cost (Non-Recurring Engineering cost): The one-time
monetary cost of designing the system
– total cost = NRE cost + unit cost * # of units
– per-product cost = total cost / # of units
= (NRE cost / # of units) + unit cost
Dr. Kesavan Gopal

The Performance Design Metric
• Widely-used measure of system, widely-abused
– Clock frequency, instructions per second – not good measures
– Digital camera example – a user cares about how fast it processes
images, not clock speed or instructions per second
• Latency (response time)
– Time between task start and end
– e.g., Camera’s A and B process images in 0.25 seconds
• Throughput
– Tasks per second, e.g. Camera A processes 4 images per second
– Throughput can be more than latency seems to imply due to
concurrency, e.g. Camera B may process 8 images per second (by
capturing a new image while previous image is being stored).
• Speedup of B over S = B’s performance / A’s
performance
– Throughput speedup = 8/4 = 2
Dr. Kesavan Gopal

Key Technologies for Embedded System
– Processor technology
• General Purpose
• ASIC
• Single Purpose
– IC technology
• Full-Custom/VLSI
• Semicustom ASIC
• PLDs
– Design technology
• Unified Hardware and Software Co-Design
• General Vs custom Design
Dr. Kesavan Gopal

Queries ?
• Please direct your queries through e-mail
gkesavan1@gmail.com.
Dr. Kesavan Gopal

Embedded System Introduction and Basics

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