FREQUENCY COUNTER/METER SCHOOL OF ELECTRICAL AND ELECTRONIC ENGINEERING DEPARTMENT OF SIGNAL AND INFORMATION PROCESSING EMBEDDED SYSTEM DESIGN PROJECT Eng DENNIS MWIGHUSA ( 唐 （） 1
The object of this project is to determine and display the frequency of the input power. This is done by using 8051 microcontroller. The circuit of our designed frequency meter includes 8051 microcontroller, Liquid Crystal Display(LCD),Cathode Ray Oscilloscope(CRO) and variable power supply unit.
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FREQUENCY COUNTER/METERSCHOOL OF ELECTRICAL AND ELECTRONIC
ENGINEERINGDEPARTMENT OF SIGNAL AND INFORMATION PROCESSINGEMBEDDED
SYSTEM DESIGN PROJECTEng DENNIS MWIGHUSA ( ABSTRACTThe object of
this project is to determine and display the frequency of the input
power.Thisisdonebyusing8051microcontroller.Thecircuit
ofourdesignedfrequencymeter includes 8051 microcontroller, Liquid
rystal !isplay"L!#,athode $ay%scilloscope"$%# and &ariable
power supply unit. The $% is used to display the frequency
wa&eform of the gi&en input power. 'asedon the source code
gi&en to the 8051 microcontroller it detects the frequency
&alue anddisplays that &aluewiththehelpoftheL!employed.
!ependingonthepowersupply the &alue of the frequency on the L!
changes. 1(ost frequency counters wor) by using a *counter+ which
accumulates the number ofe&ents occurring within a specific
period of time. ,fter a preset period "1 second, fore-ample#, the
&alue in the counter is transferred to a display and the
counter is reset to.ero. /f the e&ent being measured repeats
itself with sufficient stability and thefrequencyis
considerablylower thanthat of the cloc)oscillator beingused,
theresolution of the measurement can be greatly impro&ed by
measuring the time requiredfor anentirenumber of cycles, rather
thancountingthenumber of entirecyclesobser&ed for a pre0set
duration. 1requency counters are commonly used in
laboratories,factories, and field en&ironments to pro&ide
direct frequency measurements of &ariousde&ices. The most
common applications for frequency counters are measurement
andcharacteri.ation of oscillator and transmitter frequencies.
CONTENTS1. /ntroduction222222222222222222222222222..31.1 Types of
frequency meter22222222222222222222.....3 1.4 'loc)
!iagram22222222222222222222222...2 54. The 'asic Theory of
1requency ounter2222222222222222....5 4.1 'asic ounter
ircuits22222222222222222222....263.
7ardware222222222222222222222222222228 3.1
(icrocontroller2222222222222222222222..2.283.1.1
1eatures2222222222222222222222222..83.1.4 9in
diagram22222222222222222222222283.4
ounters222222222222222222222222222....83.3 /:01
9rescaler2222222222222222222222222...;3.5 /:04
9re0amplifier22222222222222222222222....;3.5 'y passing
/:04,mplifier22222222222222222222....;3.6 /:04 9olarity >char nB
while"1# f T(%!R0-15B intrR1B TL0R0-00B T70R0-00B T$0R1B
%or/i001i2281i334f TL1R0-00B 20T71R0-00B T$1R1B while"T11RR0#B
T$1R0B T11R0B g 90RTL0B lRTL0B 7RT70B )RlH7B >>7R7e0-f0B
lcdcmd"0-0G#B delay"450#B lcdcmd"0-01#B delay"450#B
>>lcdcmd"0-06#B >>delay"450#B >>lcdcmd"0-86#B
>>delay"450#B lcddata1"E1requecyRE#B delay"100#B
lcata/k41>>lcddata"7#B delay"450#B g g &oid lcdcmd"char
&alue# f ldata R &alueB rsR0B 21rwR0B enR1B delay"4#B enR0B
g >e&oid lcddata"int &alue# f ldataR&alueB rsR1B
rwR0B enR1B delay"4#B enR0B ge> &oid delay"int time# f int
i,jB for"iR0BiNtimeBiHH# for"jR0BjN145BjHH#B g &oid lcddata"int
&alue# f int a*5+,i,sendR0,nR0B for"iR0B&aluehR0BiHH# f
sendR&aluei10B &alueR&alueB a*i+RsendB nHHB g
22for"iRn01BiOR0Bi00# f ldataRa*i+H0-30B rsR1B enR1B delay"1#B
enR0B g returnB g &oid lcddata1"char ename# f int iB
for"iR0Bname*i+hRIj0IBiHH# f 91Rname*i+B rsR1B rwR0B enR1B
delay"1#B enR0B g returnB 7.23
