Decoder and Encoder - N/a PDF

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The College of Staten Island of the City University of New York

Digital Electronics Laboratory (ENS 221/13406) Spring 2017 Lab #5 Decoder and Encoder 03/28/2017 Name: Mina Habib Partner Name: Instructor: Dr. Sasanthi Peiris

Table of Contents Objectives...... 1 Theory/principle…… 1 Experimental setup and procedure…… 1 Experimental results…… 1-5 Simulation results……. 6 Discussion and conclusion…… 6 References…... N/A

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Objectives Understanding the construction and operational principles of digital decoders and encoders. Demonstrate the operations and applications of Decoders, Encoders.

Theory/principle Decoder is a circuit that converts binary information from n inputs lines to a maximum of 2nd unique output lines. The purpose is to generate the 2nd minterms.it is also used in conjunction with other code converters, such as BCD-to-seven segment decoder. Encoder is a digital circuit that performs the inverse operation of a decoder. An encoder has a number of inputs, only one of which is activated at a given time, and produces an output code, depending on which is activated. That is, the outputs of an encoder generate the binary code corresponding to the input value. A seven –segment indicator is used to display digits 0 to 9. Usually, the decimal digital is available in BCD. A BCD –to-seven-segment decoder accepts a decimal digital in BCD ad generates the corresponding seven-segment code.

Experiment Results Part I, Decoder: We filled up the truth table for a decoder and the 7-segment code. As shown below. Input #Inpu t 0 1 2 3 4 5 6 7 8 9

Output 7-Segment code

BCD code D C 0 0 0 0 0 0 0 0 0 1 0 1 0 1 0 1 1 0 1 0 Not lit=0, lit=1

B 0 0 1 1 0 0 1 1 0 0

A 0 1 0 1 0 1 0 1 0 1

a b c d e 0 0 0 0 0 1 0 0 1 1 0 0 1 0 0 0 0 0 0 1 1 0 0 1 1 0 1 0 0 1 0 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 1 Segment lit=0, segment not lit = 1

Digital Display f 0 1 1 1 0 0 0 1 0 0

g 1 1 0 0 0 0 0 1 0 0

0 1 2 3 4 5 6 7 8 9

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Then we used the 7447 IC is a BCD-to-7-segment decoder. It has 4 inputs for the BCD digit. And outputs a through g. then the outputs are applied to the inputs of the seven-segment display.

As shown in the figure. Then we fixed in the breadboard and worked fine. Part II, Encoder: We filled up the truth table for IC 74147 is a decimal-to-BCD encoder. As shown below.

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then we connected each ouput of the encoder to the decoder inputs then to the 7-segment display. As shown in the figure.

Then we fixed in the breadboard and worked fine. Part III: A combinational circuit has three inputs X,Y,Z and 3 outputs F1,F2,F3. F1=x'y'z'+xz =x'y'z'+xy'z+xyz= S(0,5,7) k-map 1 0

0 1

0 1

0 0

F2=xy'z'+x'y=xy'z'+x'yz'+x'yz= S(2,3,4) k-map 0 1

0 0

1 0

1 0

F3=x'y'z+xy= S(1,6,7) k-map 0 0

1 0

0 1

0 1

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And here is the truth table for the functions. A B C F1 F2 F3 0 0 0 1 0 0 0 0 1 0 0 1 0 1 0 0 1 0 0 1 1 0 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 0 0 0 1 1 1 1 1 0 1 Then we draw the logic diagram. In the figure below.

and then we plugged it in the multisim usingthe mentoned chips 74155, 7404, 7427. In the following pictures below.

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Then we fixed in the breadboard and worked fine.

Simulation results All the three projects were successfully fixed on the C.A.D.E.T. breadboard. They proved to be working fine with no problems. In this lab, the last part was challenging to figure out how the 74155 works and how to fix in the multisim using only 7427 and 7404 chips. It was challenging. For the rest of the projects it was pretty clear and simulation was easy.

Discussion and conclusion From the experiment, we could know more about the encoder and decoder that used in electronic nowadays. the basic rules and laws of both Boolean algebra and Demorgan’s theorem are used to reduce a given expression to a simplified form so that the number of gates are minimized to as far as possible to produce the same output.

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