Embedded C program

1. Course Title Embedded Systems
Course Code 22ECU14
Class II BSc - Electronics and Communication Systems
Facilitator
Dr.S.Devendiran
Assistant Professor
Department of Electronics and Communication Systems
Department of Electronics and Communication Systems
SRI KRISHNA ARTS & SCIENCE COLLEGE
Coimbatore - 641 008
1
Unit I - Lecture 1
Introduction to Embedded Systems

2. Course Learning outcomes
At the end of this course, students will be able to:
 Recognize the major components that constitute an embedded system
 Become familiar with programming environment used to develop embedded systems
and also recognize the key concepts of embedded systems like IO, timers, interrupts,
interaction with peripheral devices
 Apply small programs to solve well-defined problems on an embedded platform
 Practice to do hardware/software co-design for embedded systems
 Implement the embedded system with PIC 16F877A Microcontroller and hardware
components
 Work with both collaboratively and individually on embedded system projects
Embedded Systems with PIC
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3. Learning Objectives
 Learn what is an Embedded System.
 Learn the difference between Embedded Systems and General Computing Systems
 Know the history of Embedded Systems
 Learn the classification of Embedded Systems based on performance, complexity and
the era in which they evolved
 Know the domains and areas of applications of Embedded Systems
 Understand the different purposes of Embedded Systems
 Analyze a real life example on the bonding of embedded technology with human life
Introduction to Embedded Systems
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4. 1. Introductory Lecture Video on Embedded Systems
Reference:
NPTEL Lecture series on Embedded Systems
Dr.Santanu Chaudhury, Dept. of Electrical Engineering, IIT Delhi
2. Lecture 1: Introduction to Embedded Systems
Reference:
Prof. Sachin S Patil, ECE, HSIT, Nidasoshi
3. Lecture 1: Animation Video
Video Materials
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5.  Embedded systems are combination of hardware
and software systems designed to perform a
specific function.
 Every embedded system is unique and the
hardware as well as the software is highly
specialized to the application domain.
 Embedded systems are becoming an
inevitable part of any product or equipment in
all fields including household
telecommunications, medical
appliances,
equipment,
industrial control, consumer products, etc.
What is an Embedded System?
Design to serve the purpose of any
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one or a
collection/
combination of data
storage /
representation, data communication,
data (signal) processing, monitoring,
control or application specific user
interface

6. Major components of Embedded Systems
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Usually, an embedded system consists of:
 Power Supply
 CPU
 Memory
 Timers
 Input / Output ports
 Communication ports
 Sensors and Actuators
 System application specific circuits

7. Embedded Systems vs General Computing Systems
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8.  The first recognized embedded system is the Apollo Guidance Computer (AGC) developed
by MIT lab. AGC was designed on 4K words of ROM & 256 words of RAM.
 The clock frequency of first microchip used in AGC was 1.024 MHz.
 The computing unit of AGC consists of 11 instructions and 16 bit word logic. It used 5000
ICs.
 The User Interface of AGC is known DSKY(display/keyboard) which resembles a
calculator type keypad with array of numerals.
 The first mass-produced embedded system was guidance computer for the
Minuteman-I missile in 1961.
History Of Embedded System
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9.  In the year 1971 Intel introduced the world's first microprocessor 4004, which used in
calculators and small systems.
 1970’s 8 bit microprocessor was normal but in general still required external memory
chips, and decoding logic, as well as any interfaces to the external world.
 In mid 1980’s higher level of integration meant that most of the previously external
systems components moved onto the same chip as the processor.
 Such integrated systems were called microcontrollers.
 By the end of 1980’s embedded system were the normal for almost all electronic
circuits, this trend has continued.
History Of Embedded System
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10. The classification of embedded system
is based on following criteria's:
 On generation
 On complexity & performance
 On deterministic behavior – RTS
 On triggering
Classification of Embedded Systems
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11. Classification based on Generation
1. First generation(1G)
 Built around 8-bit microprocessor & 4 bit microcontroller. (8085 & Z80)
 Simple in hardware circuit & firmware developed.
 Examples: Digital telephone keypads, stepper motor control units.
2. Second generation(2G)
 Built around 16-bit μp & 8/16-bit μc.
 They are more complex & powerful than 1G μp & μc.
 OS for their operation
 Examples: SCADA systems, Data acquisition systems.
Classification of Embedded Systems
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12. 3. Third generation(3G)
 Built around 32-bit μp & 16-bit μc.
 Concepts of application & domain specific processors/controllers like Digital Signal
Processors(DSPs), Application Specific Integrated Circuits(ASICs) evolved.
 Instruction set complex & powerful, instruction pipelining came into picture.
 Examples: Robotics, Media, industrial process control, networking, etc
4. Fourth generation
 Built around 64-bit μp & 32-bit μc.
 The concept of System on Chips (SoC), Multicore Processors evolved.
 High performance real time OS for their functioning.
 Highly complex & very powerful.
 Examples: Smart Phones, Mobile internet devices.
Classification of Embedded Systems
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13. Classification based on complexity and Performance
1. Small-scale
 Simple in application need - Performance not time-critical - Built around low
performance & low cost 8 or 16 bit μp/μc. - May or may not contain an OS
 Example: an electronic toy
2. Medium-scale
 Slightly complex in hardware & firmware requirement - Built around medium
performance & low cost 16 or 32 bit μp/μc or DSP - Usually contain embedded
operating system (GP/RTOS)
 Examples: Industrial machines.
Classification of Embedded Systems
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14. 3. Large-scale
 Highly complex hardware & firmware
 Built around high performance 32 or 64 bit RISC μp/μc or PLDs or Multicore
Processors.
 Response time is critical.
 RTOS for task scheduling, prioritization & management
 Examples: Mission critical applications
Classification of Embedded Systems
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15. Classification based On deterministic behavior
 This classification is applicable for “Real Time” systems.
 The task execution behaviour for an embedded system may be deterministic or non-
deterministic.
 Based on execution behaviour Real Time embedded systems are divided into Hard
and Soft.
Classification based On triggering
Embedded systems which are “Reactive” in nature can be based on triggering.
Reactive systems can be:
 Event triggered
 Time triggered
Classification of Embedded Systems
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16. Major Application Areas
The application areas and the products in
the embedded domain are countless. Few of
the important domains and products are
listed below:
Consumer electronics
Camcorders, cameras, etc.
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Household appliances
Television, DVD players,
fridge, microwave oven, etc.
washing machine,
Home automation and security systems
Air conditioners, sprinklers, intruder detection
alarms, closed circuit television cameras, fire
alarms, etc.
Embedded system Applications:
from simple electronic toys to
complex flight and missile control
systems

17. Automotive industry: Anti-lock breaking systems (ABS), engine control, ignition
systems, automatic navigation systems, etc.
Telecom: Cellular telephones, telephone switches, handset multimedia
applications, etc.,
Computer peripherals: Printers, scanners, fax machines, etc.
Computer Networking systems: Network routers, switches, hubs, firewalls, etc.
Healthcare: Different kinds of scanners, EEG, ECG machines etc.
Measurement & Instrumentation: Digital multi meters, digital CROs, logic
analyzers PLC systems, etc.
Banking & Retail: Automatic teller machines (ATM) and currency counters, point
of sales (POS).
Card Readers: Barcode, smart card readers, hand held devices, etc.
Major Application Areas
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18. Embedded systems are used in various domains like consumer electronics, home automation,
telecommunications, automotive industry, healthcare, control & instrumentation, retail and
banking applications, etc. Within the domain itself, according to the application usage context,
they may have different functionalities.
Each embedded system is designed to serve the purpose of any one or a combination of the
following tasks:
 Data collection/Storage/Representation
 Data Communication
 Data (signal) processing
 Monitoring
 Control
 Application specific user interface
Purpose of Embedded Systems
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19. (I) Data Collection/Storage/Representation
 Embedded systems designed for the purpose of data collection performs acquisition of data
from the external world.
 Data collection is usually done for storage, analysis, manipulation and transmission.
 The term “data” refers all kinds of information, such as text, voice, image, video, electrical
signals and any other measurable quantities.
 Data can be either analog (continuous) or digital (discrete).
 Embedded systems with analog data capturing techniques collect data directly in the form of
analog signal whereas embedded systems with digital data collection mechanism converts
the analog signal to the digital signal using analog to digital (A/D) converters and then collects
the binary equivalent of the analog data.
 If the data is digital, it can be directly captured without any additional interface by digital
embedded systems.
 The collected data may be stored directly in the system or may be transmitted to some other
systems or it may be processed by the system or it may be deleted instantly after giving a
meaningful representation.
 These actions are purely dependent on the purpose for which the embedded system is
designed.
Purpose of Embedded Systems
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20. (i) Data Collection/Storage/Representation (Cont’d)
 Embedded system designed for pure measurement applications without storage, used in
control and instrumentation domain, collects data and gives a meaningful representation of
the collected data by means of graphical representation or quantity value and deletes the
collected data when new arrives at the data collection terminal.
 Analog and digital CROs without storage memory are typical examples of this. Any
measuring equipment used in the medical domain for monitoring without storage
functionality also comes under this category.
 A digital camera is a typical example of an embedded system with data
collection/storage/representation of data. Images are captured and the captured images
stored within the memory of the camera. The captured image can also be presented to the
user through a graphic LCD unit.
Purpose of Embedded Systems
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21. (ii) Data Communication
 Embedded data communication systems are deployed in applications from
complex satellite communication systems to simple home networking systems.
 The data collected by an embedded terminal may require transferring of the
same to some other system located remotely.
 The transmission is achieved either by a wired medium or by a wire-less
medium.
 Wire-line medium was the most common choice in all olden days embedded
systems.
 As technology is changing, wireless medium is becoming the standard for data
communication in embedded systems. It offers cheaper connectivity solutions
and make the communication link free from the hassle of wire bundles.
Purpose of Embedded Systems
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22. (ii) Data Communication (Cont’d)
 The data collecting embedded terminal itself can incorporate data
communication units like Wireless modules (Bluetooth, ZigBee, Wi-Fi, EDGE,
GPRS, etc.) or wire-line modules (RS-232C, USB, TCP/IP, PS2,etc).
 Certain embedded systems act as a dedicated transmission unit between the
sending and receiving terminals, offering sophisticated functionalities like data
packetizing, encrypting and decrypting.
 Network hubs, routers, switches, etc. are typical examples of dedicated data
transmission embedded systems.
 They act as mediators in data communication and provide various features like
data security, monitoring, etc.,.
Purpose of Embedded Systems
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23. (iii) Data (Signal) Processing
 The data (voice, image, video, electrical signals and other measurable quantities)
collected by embedded systems may be used for various kinds of data processing.
 Embedded systems with signal processing functionalities are employed in
applications demanding signal processing like speech coding, speech
processing, video processing, audio/video coding, transmission applications,
etc.
 A digital hearing aid is a typical example of an embedded system employing
signal processing. Digital hearing aid improves the hearing capacity of hearing
impaired persons.
Purpose of Embedded Systems
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24. (iv) Monitoring
 Almost all embedded products coming under the medical domain are with
monitoring functions only.
 They are used for determining the state of some variables using input sensors.
They cannot impose control over variables.
 A very good example is the electro cardiogram (ECG) machine for monitoring the
heartbeat of a patient.
 The machine is intended to do the monitoring of the heartbeat of a patient but it
cannot impose control over the heartbeat. The sensors used in ECG are the
different electrodes connected to the patient’s body.
 Other examples with monitoring function are measuring instruments like digital
CRO, digital multimeters, logic analyzers., etc. used in control & instrumentation
applications. They are used for knowing (monitoring) the status of some
variables like current, voltage, etc. They cannot control the variables in turn.
Purpose of Embedded Systems
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25. (V) Control
 Embedded systems with control functionalities impose control over some
variables according to the changes in input variables.
 A system with control functionality contains both sensors and actuators.
 Sensors are connected to the input port for capturing the changes in
environmental variable or measuring variable.
 The actuators connected to the output port are controlled according to the
changes in the input variable to put an impact on the controlling variable to bring
the controlled variable to the specified range.
 Air conditioner system used in our home to control the room temperature to a
specified limit is a typical example for embedded system for control purpose. An
air conditioner contains a room temperature sensing element (sensor) which may
be thermistor and a handheld unit for setting up (feeding) the desired
temperature.
Purpose of Embedded Systems
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26. (v) Control (Cont’d)
 The handheld unit may be connected to the central embedded unit residing
inside the air conditioner through a wireless link or through a wired link.
 The air compressor unit acts as the actuator. The compressor is controlled
according to the current room temperature and the desired temperature set by
the end user.
 The input variable is the current room temperature and the controlled variable is
also the room temperature.
 The controlling variable is cool air flow by the compressor unit.
 If the controlled variable and input variable are not at the same value, the
controlling variable tries to equalize them through taking actions on the cool air
flow.
Purpose of Embedded Systems
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27. (VI) Applications specific user interface
 Buttons, switches, keypad, lights, speakers, display units, etc. are application-
specific user interfaces.
 Mobile phone is an example of application specific user interface. In mobile
phone, the user interface is provided through the keypad, graphic LCD module,
system speaker, vibration alert, etc.
Purpose of Embedded Systems
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