rotary dialer presentation

7/25/2019 Rotary Dialer Presentation

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MICRO COMPUTER HARDWARE AND

SOFTWARE

ROTARY DIALER PIC INTERFACE USING PIC 16F877

PRESENTION BY: AHMED BABANGIDA USMAN

AISHA IYA ABBAS

FATIMA SULE ALHASSAN

MAIMUNA KIGBU

13THJAN. 21!


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INTRODUCTION

PIC 16F877 is one of the most advancedmicrocontroller from microchip. This controller iswidely used for experimental and modern applicationsecause of its low price! wide ran"e of applications!hi"h #uality! and ease of availaility. It is ideal forapplications such as machine control applications!measurement devices! study purpose! and so on. The$"ure of the PIC 16F877 is shown elow.


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FEATURES OF PIC 16F877

The PIC 16F877 features the followin"%

8 &ytes of F'()* pro"ram memory

+68 ytes of ,ata -emory

++ input or output pins

*i"h performance I)C CP/

0nly + simple word instructions

23-*4 operatin" speed 5233 ns instruction cycle


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ROTARY DIALER

( rotary dial is a component of a telephone or atelephone switchoard that implements a si"nalin"technolo"y in telecommunications nown as pulse

dialin".

0n the rotary dial! the di"its are arran"ed in acircular layout so that a $n"er wheel may erotated with one $n"er from the position of eachdi"it to a $xed stop position! implemented y the$n"er stop! which is a mechanical arrier to

prevent further rotation.


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STEP 1: WHAT YOU WILL NEED

1 otary phone! + 223 0hm resistors

2 3.1uF capacitors ! 2 23& resistor 5cansustitute anythin" etween 13& and 97&

2 : ';,s! 1 PIC development oard

1 23 -*< resonator or crystal! 1 =readoard

1 > power source! 1 ( foot or so of hooup wire

1 : )crewdriver! 1 ?ire stripper


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STEP 2: DISSECT THE PHONE

0pen up your rotary phone. 0n the inside you will noticethe few asic parts@ the rotary dial! the rin"er! two Aacs!the hoo switch and the asic circuitry which is usuallyencased in a metal Aunctionoxlie thin".

There will e four wires runnin" from the rotary dialer tothis Aunctionoxlie thin". The wires should e held inplace y little more than ti"htened screws. 'oosen thescrews and disconnect the wires.

(fter that! disconnect the rotary dialer from the phoneitself.


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DISSECTING THE PHONE


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STEP 3: DETERMINE WHAT THE

WIRES DO

?ire up two ';,s as shown in the dia"ram elow.

The two white wires should e the pair that closes theswitch that lets you now when the dial is turned. The lueand "reen wire should e the pair that lets you now whatnumer was dialed.

(s such! when you turn the dial! the ';, connected to thewhite wires should turn on! and when you let "o of the dial!the ';, connected to the lue and "reen wires should linon and oB as many times as the numer you dialed


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STEP ": CONNECT THE DIALER TO

THE PIC CHIP

Connect the rotary dialer to the PIC chip as seen inthe dia"ram. otice that I am readin" in the stateof the rotary dialer y usin" Ctimin". In otherwords! the PIC chip is countin" the numer oftimes it taes for a capacitor to dischar"e 5whichchan"es when resistance is added.

That is where the 23& resistor comes in. (ddin"this to the input allows for a clear diBerentiationetween the si"nal from a closed and open rotaryswitch connection.


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THE PIC CHIP


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STEP !: ASSEMBLE THE CODE

The code is essentially determinin" when someonehas turned the dial and then does ed"edetectionon the si"nal 5determinin" lowhi"h transitionsuntil the dial recoils to its initial state. (ftertallyin" the numer of times it measures a si"nal

transition! it then lins the ';, accordin"ly.

For instance! if you dial +! the PIC will count threelowhi"h transitions and then lin an ';, + times.


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STEP 6: TESTING AND

CONCLUSION

If you read and follow every step correctly! itshould worD

If it doesnEt wor! mae sure that you wiredeverythin" correctly and that the code is copiedcorrectly. (lso! e certain that your resonator 5orcrystal is 23 -*

rotary dialer presentation

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