Fundamentals of Internet of Things (IoT)

Chapter- 2
Internet of Things (IoT)
C. P. Divate

Embedded System Definitions
 An embedded system is a microcontroller or microprocessor based system
which is designed to perform a specific task.
 It is a computer system with a dedicated function within a larger
mechanical or electrical system.
 It is embedded as part of a complete device often including hardware,
software and mechanical parts.
 It is a Microcontroller based, software driven, reliable, real-time control
system.
 A system is a way of working, organizing or doing one or many tasks
according to a fixed plan, program or set of rules.
 A system is also an arrangement in which all its units assemble and work
together according to the plan or program.

Embedded systems Concepts
 An embedded system usually performs a specialized operation.
 It must be of a size to fit on a single chip, must perform fast enough to process data in
real time and consume minimum power to extend battery life.
 Many embedded systems must continually react to changes in the system's
environment and must compute certain results without any delay.
 It must be microprocessor or microcontroller based systems
 Tightly constrained (Tight constraints on embedded systems
a. Ability to fit on a single chip
b. Low power consumption
c. Fast data processing for results.
 Embedded systems control many devices in common use today.
 Ninety-eight percent of all microprocessors are manufactured as components of
embedded systems

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EMBEDDED SYSTEM RULES
Example1: WATCH
It is a time display SYSTEM
Parts: Hardware, Needles, Battery, Dial,
Chassis and Strap
Rules
1.All needles move clockwise only
2.Athin needle rotates every second
3.Along needle rotates every minute
4.Ashort needle rotates every hour
5.All needles return to the original position after 12 hours

5
Example 2: WASHING MACHINE
It is an automatic clothes washing SYSTEM
Parts: Status display panel, Switches & Dials, Motor, Power supply &
control unit, Inner water level sensor and solenoid valve.
Rules
1.Wash by spinning
2.Rinse
3.Drying
4.Wash over by blinking
5.Each step display the process stage
6.In case interruption, execute only the remaining
EMBEDDED SYSTEM RULES

6
EMBEDDED SYSTEM
Definition: An Embedded System is one that has computer hardware with software
embedded in it as one of its important components.
SOFTWARE PROGRAM
#include <16f876a.h>
#use delay (clock=20000000)
#byte PORTB=6
main()
{
set_tris_b(0);
portb=255; //decimal
//hexadecimal
delay_ms(1000);
portb=0x55;
delay_ms(1000);
portb=0b10101010; //binary
delay_ms(500);
}
Its software embeds in
ROM (Read Only Memory). It does
not need secondary memories as in a
computer
HARDWARE

Components of Embedded system
An embedded system is a combination of three major components:
1) Hardware: Hardware is physically used component that is physically connected with an
embedded system. It comprises of microcontroller based integrated circuit, power
supply, LCD display etc.
2) Application software: Application software allows the user to perform varieties of
application to be run on an embedded system by changing the code installed in an
embedded system.
3) Real Time Operating system (RTOS): RTOS supervises the way an embedded system
work. It act as an interface between hardware and application software which
supervises the application software and provide mechanism to let the processor run on
the basis of scheduling for controlling the effect of latencies.

Components of Embedded system
1) Embedded System Hardware
 An embedded system uses a hardware platform
to perform the operation.
 Hardware of the embedded system is assembled
with a microprocessor / microcontroller.
 It has the elements such as input/output
interfaces, memory, user interface and the
display unit.
 Generally, an embedded system comprises of
the following
a) Power Supply
b) Memory
c) Processor
d) Timers
e) Input/Output circuits
f) Serial communication ports
g) SASC (System application specific circuits)

Processor
 A Processor is the heart of the Embedded System.
 An embedded processor is a microprocessor that is used in
 an embedded system.
 For an embedded system designer knowledge of microprocessor
and microcontroller is a must.
Two Essential Units:
1
) Control Unit (CU),
2) Execution Unit (EU)
Operations
Fetch
Execute
7

8
Microprocessor Microcontroller
CPU is stand alone, RAM,ROM, I/O & timer
are separate.
CPU, RAM,ROM, I/O & timer all are on
single chip.
Designer can decide amount of RAM,ROM, &
I/O ports.
Fixed amount of on-chip RAM,ROM, & I/O
ports.
High processing power Low processing power
High power consumption Low power consumption
Typically 32/64 bit 8/16 bit
General purpose Single purpose(control oriented)
Less reliable Highly reliable
Eg.- 8086,8085 8051
Processor
Difference between Microprocessor and Microcontroller

Processor
Difference between Microprocessor and Microcontroller

8
Processor
• The different kinds of processors used in an embedded system include
Digital Signal Processor (DSP), RISC(Reduced Instruction Set Computer)
processor, microcontroller, ASSP(application-specific standard product)
processor, ASIP(Application-specific instruction set processor) processor,
and ARM(Advanced RISC Machines and originally Acorn RISC Machine)
processor.

8
2) Embedded System Software
 The software of an embedded system is written to execute a particular
function.
 It is normally written in a high-level setup and then compiled down to
offer code that can be stuck within a non-volatile memory in the
hardware.
 An embedded system software is intended to keep in view of the following
three limits
1) Convenience of system memory
2) Convenience of processor’s speed
3) When the embedded system runs constantly, there is a necessity to
limit power dissipation for actions like run, stop and wake up.

 A system which is essential to finish its task and send its service on
time, then only it said to be a real time operating system.
 RTOS controls the application software and affords a device to allow the
processor run.
 It is responsible for managing the different hardware resources of a
personal computer and also host applications which run on the PC.
 This operating system is specially designed to run various applications
with an exact timing and a huge amount of consistency.
 Particularly, this can be significant in measurement & industrial
automation systems where a delay of a program could cause a safety
hazard.
3) RTOS (Real Time Operating System)

characteristics of embedded systems

Features of an embedded system
Single-functioned
▶ Executes a single program, repeatedly
Tightly-constrained
▶ Low cost, low power, small, fast, etc.
▶ Life threatening
▶ 24 x 7 x 365 Hrs. Reliable.
Reactive and real-time
▶ Continually reacts to changes in the system’s environment
▶ Must compute certain results in real-time without delay

Examples of Embedded system
 Embedded systems range from portable devices such as digital watches
and MP3 players, to large stationary installations like traffic lights,
factory controllers, and largely complex systems like hybrid vehicles,
MRI, and avionics.
 Embedded systems are commonly found in consumer, cooking,
industrial, automotive, medical applications. Some example of
embedded systems are MP3 players, mobile phones, videogame
consoles, digital cameras, DVD players, and GPS.
 Household appliances, such as microwave ovens, washing machines
and dishwashers, include embedded systems to provide flexibility and
efficiency.
 Its complexity varies from low, with a single microcontroller chip, to
very high with multiple units, peripherals and networks mounted
inside a large enclosure.

SENSORS
CONTROL
UNIT ACTUATOR
BLOCK DESCRIPTION OF THE EMBEDDED SYSTEM

Basic structure of an Embedded system
Embedded system comprises of the following parts:
1) Sensor
2) A-D Converter
3) Processors & ASIC(Application Specific Integrated Circuits)
4) D-A Convertor
5) Actuator
6) Memory

Parts of Embedded system
1) Sensor − It measures the physical quantity and converts it to an electrical signal
which can be read by an observer or by any electronic instrument like an A2D
converter. A sensor stores the measured quantity to the memory.
2) A-D Converter − An analog-to-digital converter converts the analog signal sent by the
sensor into a digital signal.
3) Processor & ASICs − Processors process the data to measure the output and store it to
the memory.
4) D-A Converter − A digital-to-analog converter converts the digital data fed by the
processor to analog data.
5) Actuator − An actuator compares the output given by the D-A Converter to the actual
(expected) output stored in it and stores the approved output.

Embedded processors
Embedded processors can be broken into two broad categories.
Ordinary microprocessors (μP) use separate integrated circuits for memory
and peripherals.
Microcontrollers (μC) have on-chip peripherals, thus reducing power consumption,
size and cost.
Word lengths vary from 4-bit to 64-bits and beyond, although the most typical
remain 8/16-bit
Numerous microcontrollers have been developed for embedded systems use.
General-purpose microprocessors are also used in embedded systems, but generally
require more support circuitry than microcontrollers.

Peripherals interfaces
 Serial Communication Interfaces (SCI):
 Synchronous Serial Communication Interface:
I2C, SPI, SSC and ESSI (Enhanced
Synchronous Serial Interface)
 Universal Serial Bus (USB)
 Multi Media Cards (SD cards, Compact Flash,
etc.)
 Networks: Ethernet, LonWorks, etc.
 Fieldbuses: CAN-Bus, LIN-Bus, PROFIBUS, etc.
 Timers: PLL(s), Capture/Compare and Time
Processing Units
 Discrete IO: aka General Purpose Input/output
(GPIO)
 Analog to Digital/Digital to Analog (ADC/DAC)
 Debugging: JTAG, ISP, ICSP, BDM Port, BITP,
and DB9 ports.

Applications of Embedded systems
 Embedded systems are commonly found in consumer, industrial, telecommunication, automotive,
medical, commercial and military applications.
 Telecommunications systems employ numerous embedded systems from telephone switches for
the network to cell phones at the end user. Computer networking uses dedicated routers and
network bridges to route data.
 Embedded Wi-Fi modules provide a simple means of wirelessly enabling any device which
communicates via a serial port.
 A new class of miniature wireless devices called motes are networked wireless sensors. These
motes are completely self-contained, and will typically run off a battery source for years before the
batteries need to be changed or charged.
 Various electric motors — brushless DC motors, induction motors and DC motors — use
electric/electronic motor controllers.
 Embedded systems are used in transportation, fire safety, safety and security, medical
applications and life critical systems, as these systems can be isolated from hacking and thus, be
more reliable.
 For fire safety, the systems can be designed to have greater ability to handle higher temperatures
and continue to operate.
 In dealing with security, the embedded systems can be self-sufficient and be able to deal with cut
electrical and communication systems

Consumer Applications of Embedded systems
Consumer electronics include personal digital assistants (PDAs), MP3 players, mobile
phones, videogame consoles, digital cameras, DVD players, GPS receivers, and
printers.
Household appliances, such as microwave ovens, washing machines and
dishwashers, include embedded systems to provide flexibility, efficiency and features.
Advanced HVAC(Heating Ventilation & Air Conditioning) systems use networked
thermostats to more accurately and efficiently control temperature that can
change by time of day and season.
Home automation uses wired- and wireless-networking that can be used to control
lights, climate, security, audio/visual, surveillance, etc., all of which use embedded
devices for sensing and controlling.

Advantages & Disadvantages
Advantages:
1. Easily Customizable
2. Low power consumption
3. Low cost
4. Enhanced performance
5. It has Better steady
6. Higher Speed
7. Reliable
8. Compatible to other devices
Disadvantages:
1. High development effort
2. Larger time to market

Languages for Programming Embedded Systems
 Assembly language was the pioneer for programming
embedded systems till recently.
 Nowadays there are many more languages to program these
systems.
 Some of the languages are C, C++, Ada, Forth, and Java
together with its new enhancement J2ME.
 The majority of software for embedded systems is still done in C
language.
 C++ is also increasing its presence in embedded systems. As C++
is based on C language, thus providing programmer the object
oriented methodologies to reap the benefits of such an approach.

Classifications of Embedded System

Real-time Systems
 Embedded systems in which some specific work has to be done in a specific time period
are called real-time systems.
 Real time embedded systems are classified into two types such as soft and hard real
time systems.

Stand Alone Embedded Systems
 Stand alone embedded systems do not require a host system like a computer, it works by
itself.
 It takes the input from the input ports either analog or digital and processes, calculates and
converts the data and gives the resulting data through the connected device-Which either
controls, drives and displays the connected devices.
 Examples:- mp3 players, digital cameras, video game consoles, microwave ovens and
temperature measurement systems.

Networked Embedded Systems
 These types of embedded systems are related to a network to
access the resources.
 The connected network can be LAN, WAN or the internet.
 Example:- home security system wherein all sensors are connected and run
on the protocol TCP/IP, ATM

Mobile Embedded Systems
 Mobile embedded systems are used in portable embedded devices like cell
phones, mobiles, digital cameras, mp3 players and personal digital assistants,
etc.
 The basic limitation of these devices is the other resources and limitation of
memory.

Small Scale Embedded System
 Single 8 bit or 16bit Microcontroller.
 Little hardware and software complexity.
 They may even be battery operated.
 Usually “C” is used for developing these system.
 The need to limit power dissipation when system is running
 continuously.
 Examples:- digital watches Programming tools:
 Editor, Assembler and Cross Assembler

 Single or few 16 or 32 bit microcontrollers or Digital Signal Processors
(DSP) or Reduced Instructions Set Computers (RISC).
 Both hardware and software complexity.
 Examples:- Ipod’s Programming tools:
 C, C++, java, RTOS, Source code Engineering Tool, Simulator,
Debugger and Integrated Development Environment (IDE).
Medium Scale Embedded System

Sophisticated Embedded System
 It uses more than 32 bit microcontroller.
 Enormous hardware and software complexity
 Which may need scalable processor or configurable processor and programming logic
arrays.
 Constrained by the processing speed available in their hardware units.
 Examples:-washing machine
 Programming Tools:
 For these systems may not be readily available at a reasonable cost or may not be
available at all. A compiler or retargetable compiler might have to br developed for
this.

Embedded System Constraints
 An embedded system is software designed to keep in view three
constraints:
 Available system memory
 Available processor speed
 The need to limit the power dissipation
 When running the system continuously in cycles of wait for events, run,
stop and wakeup.

 Household appliances:
 Microwave ovens, Television, DVD Players &
Recorders
 Audio players
 Integrated systems in aircrafts and missiles
 Cellular telephones
 Electric and Electronic Motor
 controllers
 Engine controllers in automobiles
 Calculators
 Medical equipments
 Videogames
 Digital musical instruments, etc.
Applications if Embedded Systems

 AVR was developed in the year 1996 by Atmel Corporation.
 The architecture of AVR was developed by Alf-Egil Bogen and Vegard Wollan.
 AVR derives its name from its developers and stands for Alf-Egil Bogen Vegard Wollan
RISC microcontroller, also known as Advanced Virtual RISC.
 The AT90S8515 was the first microcontroller which was based on AVR architecture
however the first microcontroller to hit the commercial market was AT90S1200 in the
year 1997.
 AVR microcontrollers are available in three categories:
1. TinyAVR – Less memory, small size, suitable only for simpler applications
2. MegaAVR – These are the most popular ones having good amount of memory
(upto 256 KB), higher number of inbuilt peripherals and suitable for moderate to
complex applications.
3. XmegaAVR – Used commercially for complex applications, which require large
program memory and high speed.
AVR(Alf-Egil Bogen Vegard Wollan RISC microcontroller or
Advanced Virtual RISC processor) Embedded Systems

 The following table compares the above mentioned AVR series of microcontrollers:
Series Name Pins Flash Memory Special Feature
TinyAVR 6-32 0.5-8 KB Small in size
MegaAVR 28-100 4-256KB Extended peripherals
XmegaAVR 44-100 16-384KB DMA , Event System included

 They are fast: AVR microcontroller executes most of the instructions in single execution
cycle.
 AVRs are about 4 times faster than PICs, they consume less power and can be operated
in different power saving modes.
 Let’s do the comparison between the three most commonly used families of
microcontrollers.
Property 8051 PIC AVR
SPEED Slow Moderate Fast
MEMORY Small Large Large
ARCHITECTURE CISC RISC RISC
ADC Not Present Inbuilt Inbuilt
Timers Inbuilt Inbuilt Inbuilt
PWM Channels Not Present Inbuilt Inbuilt

 AVR is an 8-bit microcontroller belonging to the family of Reduced Instruction Set
Computer (RISC).
 In RISC architecture the instruction set of the computer are not only fewer in number but
also simpler and faster in operation.
 The other type of categorization is CISC (Complex Instruction Set Computers).

 Atmega8 Microcontroller Applications:
1) AVR Microcontroller based LED Matrix Interfacing
2) UART communication between Arduino Uno and ATmega8
3) Interfacing of Optocoupler with ATmega8 Microcontroller
4) AVR Microcontroller based Fire Alarm System
5) Measurement of Light Intensity using AVR Microcontroller and LDR
6) AVR Microcontroller based 100mA Ammeter
7) ATmega8 Microcontroller based Anti-Theft Alarm System
8) AVR Microcontroller based Interfacing of Joystick
9) AVR Microcontroller based Interfacing of Flex Sensor
10)Stepper Motor Control using AVR Microcontroller

 The ARM processors have a less number of transistors because they have a reduced
instruction set, which allows a smaller size for the IC.
 Thereby being space efficient also.
 Most of the electronic devices such as tablets, mobiles, smart phones and other
mobile devices consist of these processors.
 By combining the ARM microprocessor with RAM, ROM and other peripherals in one
single chip, we get an ARM microcontroller, for example, LPC2148.
ARM microcontroller Embedded Systems

VERSIONS AND FEATURES OF ARM MICROCONTROLLER
 One of the most advanced form of these microcontrollers is the cortex microcontroller,
developed by ARMv7. The cortex family is further divided as:
1) Cortex Ax series
2) Cortex Rx series
3) Cortex Mx series

CORETEX M3 MICROCONTROLLER architecture

CORETEX M3 MICROCONTROLLER FEATURES
 One of the most advanced form of It is a 32 bit processor offering many advantages over
other microcontrollers.
 It is a ‘harward architecture’. For communication with Ram and Rom, this architecture
provides separate instruction buses and data buses.
 It consists of a 3 stage pipeline which fetches the instructions, then decodes it and then
finally executes the instruction.
 The memory required for the program has been reduced and also it provides high code
density because of the usage of THUMB-2 technology in coretex-M3.
 For the good interrupt performance, the core m3 is closely integrated to NVIC (Nested
Vector Interrupt Controller).
 It is a Reduced Instruction Set Computing (RISC) controller. It has a high performance
CPU of 32 bits and the pipelining is done through 3 stages.

CORETEX M3 MICROCONTROLLER FEATURES
 The Thumb-2 technology has been integrated in these controllers, which means they can
handle 16 bit as well as 32 bit instructions.
 This technology also provides high performance in operations and executions.
 It has low power modes. Sleep modes are also supported by it.
 It controls the software efficiently and it consists of multiple domains of power.
 The NVIC, Nested Vectored interrupt controller provides low latency as well as low jitter
interrupts response.
 Another advantage is that there is no need of assembly programming in it.

APPLICATIONS of ARM microcontrollers
 Advanced Electronic Voting Machine (EVM) using ARM
 ARM-based Ear Recognition Embedded System
 ARM and RFID Based Security System (Home, Office, Industrial)
 Voice-Based GPS Navigation System Using ARM
 Temperature and Humidity Control System Using ARM and Graphical LCD
 Postpaid and Prepaid Energy Meter Using ARM
 Secured Communication between Two Army Stations using ARM7
 Automatic Touch Screen Based Vehicle Driving System using ARM
 ARM-Based Home/ Industrial Automation Using GSM
 ARM-Based Digital Notice Board using GSM
 ARM-Based Hospital Enquiry System

APPLICATION SPECIFIC INTEGRATED CIRCUIT microcontrollers
ASIC microcontroller Embedded Systems
 An application-specific integrated circuit (ASIC) is an integrated circuit (IC) chip
customized for a particular use, rather than intended for general-purpose use.
 For example, a chip designed to run in a digital voice recorder or a high-
efficiency bitcoin miner is an ASIC.
 Application-specific standard product (ASSP) chips are intermediate between
ASICs and industry standard integrated circuits like the 7400 series or the 4000
series.
 Modern ASICs often include entire microprocessors, memory blocks including
ROM, RAM, EEPROM, flash memory and other large building blocks. Such an
ASIC is often termed a SoC (system-on-chip).
 Designers of digital ASICs often use a hardware description language (HDL)

Types of ASIC

Full Custom ASIC microcontrollers
 In this type of design all the logic cells are tailored made for specific application
.i.e. designer has to specially make the logic cells for the circuits.
 All the mask layers for interconnection are customized. So programmer can’t
change interconnections of the chip and while programming he has to be aware of
the circuit layout.
 One of the best examples of Full custom ASIC is a microprocessor.
 This type of customization allows designers to built various analog circuits,
optimized memory cells, or mechanical structures on a single IC.
 This ASIC is costly and very time consuming to manufacture and design. The time
is taken to design these ICs is around eight weeks.
 These are usually intended for high-level applications. Maximum performance,
minimized area and highest degree of flexibility are major features of Full custom
design.
 Eventually, the risk is high in design as the logic cells, resistor etc… circuit
elements used are not pretested.

Semi-Custom ASIC microcontrollers
 In this type of design logic cells are taken from standard libraries .i.e. they are not
handcrafted as in Full custom design.
 Some masks are customized while some are taken from the predesigned library.
 Based on the type of logic cells taken from the library and amount of
customization allowed for interconnects these ASICs are divided into two types-
Standard cell-based ASIC and Gate Array-based ASIC.

Semi-Custom ASIC microcontrollers
1). Standard cell-based ASIC
 To know these IC first let us understand what a standard
cell library stands for.
 Some of the logic cells such as AND gates, OR gates,
multiplexers, flip-flops are predesigned by designers using
different configurations, standardized and stored in the form
of a library.
 This collection is known as standard cell library.
 In standard cell-based, ASIC logic cells from these standard libraries are used.
 On the ASIC chip standard cell area or flexible block are made up of standard cells arranged in
the form of rows.
 Along with these flexible blocks mega cells like microcontrollers or even microprocessors are used
on-chip.
 These mega cells are also known as Mega functions, system level macros, fixed blocks,
Functional standard blocks

2). Gate Array Based ASIC microcontrollers
This type of semi-custom ASIC have predefined transistors on the silicon wafer .i.e. the
designer cannot change the placement of the transistors present on the die.
Base array is the predefined pattern of the gate array and the base cell is the smallest
repetitive cell of the base array.
The designer only has liability to change interconnection between transistors using the first
few metal layers of the die.
The designer chooses from the gate array library. These are often called as Masked Gate
Array.
Gate Array Based ASIC are of three types.
They are Channeled Gate Array, Channel less gate array and a structured gate array.

a).Channeled Gate Array
 In this type of gate array, wiring space is left between rows of transistors.
 These are similar to CBIC as space is left for interconnection between blocks but in
channeled gate array cell rows are fixed in height whereas in CBIC this space can be
adjusted.
 Some of the main features of this gate array are- this gate array uses predefined spaces
between rows for interconnection.
 Manufacturing time is two days to two weeks.

b) Channel Less Gate Array
 There is no free space left for routing between rows of cells as seen in the channeled
gate array.
 Here routing is done from above the gate array cells as we can customize the
connection between the metal 1 and transistors.
 For routing, we leave the transistors lying in the path of routing unused.
 The manufacturing lead time is about two weeks.

c). Structured Gate Array
 This type of gate array has an embedded block along with gate array rows as seen above.
 Structured gate array has a higher area efficiency of CBIC.
 Like Masked gate array these have lower cost and faster turnaround.
 Here the fixed size of the embedded function poses a limitation on the structured gate
array.
 For example, is this gate array contains an area
reserved for 32k bit controller but if in an application
we only require an area for 16k bit controller the
remaining area gets wasted.
 All the gate array have a turnaround time of two days
to two weeks and all have customized interconnect.

Programmable ASIC microcontrollers
There are two types of programmable ASICs. They are PLD and FPGA,
1) PLDs (Programmable Logic Devices)
2) FPGAs (Field Programmable Gate Array)
PLDs (Programmable Logic Devices)
 These are the standard cells readily available.
 We can program a PLD to customized a part of the application, so they are considered as
ASIC.
 We can use different methods and software to program a PLD.
 These contain a regular matrix of logic cells usually
programmable array logic along with flip-flops or latches.
 Here interconnects are present as a single large block.
 PROM is a common example of this IC. EPROM uses MOS
transistors as interconnect so by applying high voltage we can
program it.
 PLDs have no customized logic cells or interconnect. These have
a fast design turnaround.

Fundamentals of Internet of Things (IoT)

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