Embedded systems unit 5

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Unit 5
Embedded system development
Embedded for Mechatronics
Dr.Mahalingam College of Engg & Tech
2020
Embedded for Mechatronics Unit 5

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ESD is about implementation of a set of functionalities sat-
isfying number of constraints like performance, cost, power
consumption, size and weight etc.
Modern embedded systems are assemblage of multiple
functional units or subsystems that carry out computation
These functional systems are nothing but ﬂexible architec-
tures, implemented using composition of variety of compo-
nents both hardware and software.
As hardware- based implementation is time consuming and
expensive, the interest in software-based implementation
has risen to previously unseen levels.

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UML
Uniﬁed Modeling Language (UML)
UML is an object-oriented modeling language standardized
by Object Management Group (OMG) mainly for software
systems development
UML is used to specify, visualize, construct and document
the artifacts of a software system. It captures decisions and
understanding about systems to be constructed
It is used to understand, design, browse, conﬁgure, main-
tain and control information about such systems. UML cap-
tures static as well as dynamic behavior of a system.
UML consists of a set of basic building blocks, rules that
dictate the use and composition of these building blocks,
and common mechanisms that enhances the quality of UML
models

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UML Notation
The UML notation is useful in capturing the requirements,
documenting the structure,decomposing into objects and
deﬁning relationships between objects
It is a notational language that is very useful in modelling
the real-time embedded systems.

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UML MODELLING OF THE SYSTEM
Requirements Modelling
The ﬁrst phase in development of an embedded system ei-
ther hardware or software is functional requirementss cap-
turing
This basically deﬁnes what the system is supposed to do.
In case of UML, the requirements are captured using use-
case diagrams from external actors’ point of view
A use-case tells what the system does for each actor
In the present system (Stabilization System), the actor can
be a human user as well as the external I/O devices

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Use case diagram

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Use case description

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Design Examples of Embedded system
Automatic Chocolate Vending Machine
The design steps mainly include the following.
1.Requirements
2.Speciﬁcations
3.Hardware and software functioning
Requirements
When a child inserts a coin into the machine and selects the
particular chocolate that he wants to purchase.
Inputs
1.Coins, user selection.
2.An interrupt is generated at each port whenever a coin is
inserted.
3.A separate notiﬁcation is sent to each port

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Design Examples of Embedded system
Outputs
1.Chocolate
2.Refund
3.A message is displayed on LCD like date, time, welcome
message.
System Function
Using a graphical user interface, the child commands to the
system which chocolate the child wants to purchase.
Where the graphical user interface has an LCD, keypad,
touch screen.
The machine delivers the chocolate when the child inserts
the coin if the coins inserted are excess than the actual
cost of selected chocolate. The ACVM machine refunds
the money back.

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Hardware
Microcontroller 8051
64 KB RAM and 8MB ROM
Keypad
Mechanical coin sorter
Chocolate channel
Coin channel
USB wireless modem
Power supply

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Block diagram

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Softwares

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Design Examples
Automated teller machine (ATM)
It is a computerized device used in banking.
A customer can access and perform his transactions
without going to the bank and meeting some assistant.
This machine consists of a card reader for detecting card
and accessing information of the person.
Also it has a keypad so the user can enter his commands
and password.
A screen displays information. A printer prints the receipts
and cash is received from cash dispenser.
A network is present between the bank computer and ATM
machine through a host computer.
All the data is veriﬁed with the bank computer and all
transactions are stored in it.
All these operations are carried with microcontroller .

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ATM

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Design Examples-Elevator control

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Design Examples-Ink-jet Printer
Ink-jet printer
An inkjet printer is any printer that places extremely small
droplets of ink onto paper to create an image

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Design Examples-Ink-jet Printer
Ink jet printer
1.The dots are extremely small usually between 50 and 60
microns in diameter, so small that they are tinier than the
diameter of a human hair 70 microns
2.The dots are positioned very precisely, with resolutions of up
to 1440x720 dots per inch
3.The dots can have different colors combined together to
create photo-quality images.

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Ink jet printer

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Print head
1.Print head - The core of an inkjet printer, the print head con-
tains a series of nozzles that are used to spray drops of ink.
2.Ink cartridges - Depending on the manufacturer and model of
the printer, ink cartridges come in various combinations, such as
separate black and color cartridges, color and black in a single
cartridge or even a cartridge for each ink color. The cartridges
of some inkjet printers include the print head itself.
3.Print head stepper motor - A stepper motor moves the print
head assembly (print head and ink cartridges) back and forth
across the paper. Some printers have another stepper motor
to park the print head assembly when the printer is not in use.
Parking means that the print head assembly is restricted from
accidentally moving, like a parking brake on a car.
4.Belt - A belt is used to attach the print head assembly to the
stepper motor.

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Paper feed assembly
1.Paper tray/feeder - Most inkjet printers have a tray that you
load the paper into. Some printers dispense with the standard
tray for a feeder instead. The feeder typically snaps open at an
angle on the back of the printer, allowing you to place paper in
it.
2.Rollers - A set of rollers pull the paper in from the tray or feeder
and advance the paper when the print head assembly is ready
for another pass.
3.Paper feed stepper motor - This stepper motor powers the
rollers to move the paper in the exact increment needed to en-
sure a continuous image is printed.
4.Power supply - While earlier printers often had an external
transformer, most printers sold today use a standard power sup-
ply that is incorporated into the printer itself.
5.Control circuitry - A small but sophisticated amount of circuitry
is built into the printer to control all the mechanical aspects of
operation, as well as decode the information sent to the printer
from the computer.Embedded for Mechatronics Unit 5

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Inkjet technologies
1.Thermal bubble - Used by manufacturers such as Canon and
Hewlett Packard, this method is commonly referred to as bubble
jet. In a thermal inkjet printer, tiny resistors create heat, and this
heat vaporizes ink to create a bubble. As the bubble expands,
some of the ink is pushed out of a nozzle onto the paper. When
the bubble ”pops” (collapses), a vacuum is created. This pulls
more ink into the print head from the cartridge. A typical bubble
jet print head has 300 or 600 tiny nozzles, and all of them can ﬁre
a droplet simultaneously. Click the button to see how a thermal
bubble inkjet printer works.
2.Piezoelectric - Patented by Epson, this technology uses piezo
crystals. A crystal is located at the back of the ink reservoir
of each nozzle. The crystal receives a tiny electric charge that
causes it to vibrate. When the crystal vibrates inward, it forces a
tiny amount of ink out of the nozzle. When it vibrates out, it pulls
some more ink into the reservoir to replace the ink sprayed out.

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Sequence of events
Sequence of events
The software application you are using sends the data to be
printed to the printer driver.
The driver translates the data into a format that the printer
can understand and checks to see that the printer is online
and available to print.
The printer receives the data from the computer. It stores a
certain amount of data in a buffer. The buffer can range from
512 KB random access memory (RAM) to 16 MB RAM, de-
pending on the model. Buffers are useful because they al-
low the computer to ﬁnish with the printing process quickly,
instead of having to wait for the actual page to print
If the printer has been idle for a period of time, it will nor-
mally go through a short clean cycle to make sure that the
print head(s) are clean. Once the clean cycle is complete,
the printer is ready to begin printing.

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Sequence of events
Sequence of events
The control circuitry activates the paper feed stepper motor.
This engages the rollers, which feed a sheet of paper from
the paper tray/feeder into the printer. A small trigger mech-
anism in the tray/feeder is depressed when there is paper
in the tray or feeder.
Once the paper is fed into the printer and positioned at the
start of the page, the print head stepper motor uses the
belt to move the print head assembly across the page. The
motor pauses for the merest fraction of a second each time
that the print head sprays dots of ink on the page and then
moves a tiny bit before stopping again
Multiple dots are made at each stop. It sprays the CMYK
colors in precise amounts to make any other color imagin-
able.

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Sequence of events
Sequence of events
At the end of each complete pass, the paper feed stepper
motor advances the paper a fraction of an inch. Depending
on the inkjet model, the print head is reset to the beginning
side of the page, or, in most cases, simply reverses direction
and begins to move back across the page as it prints.
his process continues until the page is printed. The time it
takes to print a page can vary widely from printer to printer.
It will also vary based on the complexity of the page and
size of any images on the page. For example, a printer may
be able to print 16 pages per minute (PPM) of black text but
take a couple of minutes to print one, full-color, page-sized
image.
Once the printing is complete, the print head is parked. The
paper feed stepper motor spins the rollers to ﬁnish pushing
the completed page into the output tray.

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Fault tolerance
Fault tolerance
Fault tolerant systems are the systems that ensure contin-
ued execution of the intended function even if there is a sin-
gle or multiple faults (based on design) in the system.
Applications like aircraft controls and nuclear-plant controls
that are critical and failure can be life-threatening. For these
systems, fault-tolerance will be implemented based on the
criticality of the situation

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Reliability Evaluation
Reliability Evaluation
Failures in air trafﬁc control systems, nuclear reactors, or
hospital patient monitoring systems can bring catastrophic
consequences
In order to enhance the dependability of computing sys-
tems, an effective evaluation of their reliability is desired.
Any kind of technique, which ensures the device will operate
safely under given conditions and upto desired time is called
reliability evaluation technique.

Embedded systems unit 5

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Embedded systems unit 5