S.K.CHAUDHARY EDUCATIONAL TRUST’SSHANKARA INSTITUTE OF TECHNOLOGY

KUKAS, JAIPUR

PRESENTED BY:SHRUTI NARAYANB.TECH. 4TH YEAR

12ESIEC051

SESSION (2015-2016) ARMBEDDED ELECTROICS PVT.LTD.

A SUMMER TRAINING PRESENTATION ON 7-SEGMENT DISPLAY

PRESENTED TO:MR. RAJESH KANWADIA (ASSISTANT PROF.)MS. SHWETA AGARWAL (ASSISTANT PROF.)E.C.E. DEPARTMENT

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ARMbedded Electronics Pvt.Ltd. is an Embedded design house. It is registered under company act. 1956 and ISO 9001:2008 Certified Company. The Company undertake various projects related to industrial automation, domestic applications and higher end biomedical applications designed on Embedded System Design, Embedded Wireless,VLSI, MATLAB.

It provides an environment which equips an engineer/student to use the practical knowledge gained during the training period, fully in the technical field. It also undertake training for corporate in all the respective domains.

About ARMbedded Electronics

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seven segment display

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INTRODUCTION

INTRODUCTION TO LEDs

LED WORKING

TYPES OF SSD

DRIVING A 7-SEGMENT DISPLAY USING A SWITCH

DRIVING A 7-SEGMENT DISPLAY USING 4511 IC

CONTENTS

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INTRODUCTION

A seven-segment display (SSD), or seven-segment indicator, is a form of electronic display device for displaying decimal numerals.

The Seven segment display consists of seven LEDs arranged in a rectangular fashion.

Each of the seven LEDs is called a segment. Each segment is labelled from “a” to “g” and decimal

point by “dp”.

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By forward biasing, the LED glow and desired character pattern or number is displayed.

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SSD possibilities

Decimal Digits 0-9

Select Alpha Characters

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The main element needed to manufacture a seven segment display are LEDs, so we must have review of LEDs.

A light emitting diode (LED) is essentially a PN junction opto-semiconductor device that emits a light by electroluminescence, in the UV, visible or infrared regions of the electromagnetic spectrum when operated in a forward biased direction.

LEDs convert electrical energy into light energy .

Introduction to LEDs

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Structure of LED

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LED works on the principle of electroluminescence. Electroluminescence (EL) is an optical

phenomenon and electrical phenomenon in which a material emits light in response to the passage of an electric current through it or to a strong electric field.

Electroluminescence is the result of radiative recombination.

LED Operation principle

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Excitation

Electron excited by the forward biased voltage

Hole is in valance band

Normally the recombination takes place between transition of electrons between the bottom of the conduction band and the top of the valance band (band exterma). The emission of light is therefore;hc/ = Ec-Ev = Eg(only direct band gap allows radiative transition)

E

k

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Under forward bias – majority carriers from both sides of the junction can cross the depletion region and entering the material at the other side.

These diffused carriers recombine with the majority carriers at other side.

The recombination causes light to be emitted

Such process is termed radiative recombination.

Working of LED

P-n junction

Electrical Contacts

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For LED which emit visible light, the band gap of the materials that we use must be in the region of visible wavelength = 390- 770nm. This coincides with the energy value of 3.18eV- 1.61eV which corresponds to colours as stated below:

Visible LED

Violet ~ 3.17eVBlue ~ 2.73eVGreen ~ 2.52eV Yellow ~ 2.15eVOrange ~ 2.08eVRed ~ 1.62eV

The band gap, Eg that the

semiconductor must posses to emit each light

Colour of an LED should emits

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Arrangement of LEDs in SSD

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The SSD common pin is generally used to identify which type of 7-segment display it is. As each LED has two connecting pins, one called the “Anode” and the other called the “Cathode”, there are therefore two types of LED 7-segment display called: Common Cathode (CC) and Common Anode(CA).

The difference between the two displays, as their name suggests, is that the common cathode has all the cathodes of the 7-segments connected directly together and the common anode has all the anodes of the 7-segments connected together and is illuminated as follows.

Types of SSD

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Common Cathode 7-segment Display

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Common anode 7-segment display

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Pin configuration of SSD

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Driving a 7-segment Display using switches

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The segments of a common anode display can be illuminated using the switches.

In this a LOW condition is required to activate the LED segments on this common anode display.

eg: illuminate the decimal number “4” on the display, the switches b, c, f and g would be closed to light the corresponding LED segments.

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Driving a 7-segment Display using 4511 IC

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7-segment Displays are usually driven by a special type of integrated circuit (IC) like CMOS 4511. This 7-segment display driver is able to illuminate both common anode or common cathode displays.

This BCD-to-7 segment driver takes a four-bit BCD input and has outputs that will pass current through the segments to display the decimal digit.

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ConclusionAs Seven segment display provides a

convenient way to display decimal numbers in digital form, it is helpful in general purpose devices and reduces the complexity of data delivered.

It is used in many devices of our day to day life, like in traffic signals, watches, cd/dvd players etc.

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https://en.m.wikipedia.org/wiki/Seven_segment_display

https://www.electronics-tutorials.ws/blog/7-segment-display-tutorial.html

https://en.m.wikipedia.org/wiki/Light_emitting_diode

https://www.electronicsblog.org/seven-segment-display-everything-you-need-to-know-about/

https://www.instructables.com/id/Seven-Segment-Display-Tutorial/

References

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Thanks