ECET 105 Week 7 Lab Project Detailed Directions

7/23/2019 ECET 105 Week 7 Lab Project Detailed Directions

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ECET105—Digital Fundamentals

Lab #7 Detailed Directions

I. O!ECTI"E

1. To test the operation of a 74LS74 D flip-flop and compare the operation with the predicted behavior

2. To test the operation of a 74LS112 J-K flip-flop and compare the operation with the predicted behavior

. To meas!re propa"ation dela#s of a 74LS112 J-K flip-flop

4. To b!ild and test an enhanced adder-s!btractor

II. $%&T LIT

$%!ipment& '() *+ or +ompatible with ,indows 2 or i"her

/!art!s '' Desi"n Software0ersion .1

3re%!enc# enerator 5scilloscope

*arts&

2 6 resistors8 9 , 2 6 :ed L$Ds

1 6 74LS74 d!al D flip-flop 1 6 reen L$D 1 6 74LS112 d!al J-K flip-flop 1 6 S*DT Switch8 D'* confi"!ration

1 6 eS5+ ''' 3*; (oard

III. $&OCED'&E

%. Test t(e 7)L7) D Fli*+Flo*

1. (!ild the D flip-flop circ!it shown in Figure 7.1. The L$Ds are wired as active-L5,since the flip-flop can s!ppl# more c!rrent in a low state than in a hi"h state. This means

that the "reen L$D is on when / is ' and the red L$D indicates / is '.

:emember to attach ++ to pin 14 and "ro!nd to pin 7.

Course Number: ECET105 Laboratory Number: 7 Page 1 of 14



Figure 7.1—7)L7) D Fli*+Flo* Test Circuit

The pin o!t of 7474 is shown below&

2. <sin" the circ!it8 verif# that the operation follows the tr!th table for this device.




Theoretical Tr!th Table&

The circ!it constr!ction is shown below =if #o! are not able to find a similar S*DT switch in

#o!r parts and tools bo> as shown in the circ!it dia"ram8 tr# to !se a ?!mper wire to switch

between cc and the ro!nd@

The circ!it operation sho!ld reflect the theoretical tr!th table. Ao! need to show some photos here to demonstrate the circ!it operations.




Im*ortant as*ects to *a, attention-

The clocB inp!t si"nal from the f!nction "enerator sho!ld be obtained from the *!lse

enerator of #o!r trainer bo> as shown below.

Ao! can !se the scope to meas!re clocB si"nal "enerated. ;d?!st the si"nal as necessar#.




<se D)) to meas!re volta"e points when checBin" the circ!it and performin"

tro!bleshootin".

:emember to connect all "ro!nd points to"ether.

. ,hat happens when both *:$ and +L: are set lowC

ro!nd pins 1 and 4 and 5bserve the o!tp!t L$Ds stat!s.

. Test t(e 7)L11 !+/ Fli*+Flo*

1. (!ild the J-K flip-flop circ!it shown in Figure 7.. :emember to attach ++ to pin 1E

and "ro!nd to pin F.




Figure 7.—7)L11 !+/ Fli*+Flo* Test Circuit

74112 pin o!t is shown below.

2. <sin" the circ!it8 verif# that the operation follows the tr!th table for this device.

Theoretical Tr!th Table&

3ind o!t the theoretical tr!th table and maBe s!re #o! !nderstand the concept and operationof GT =ne"ative "oin" transition@ and *T.




The circ!it constr!ction is shown below&

The circ!it operation sho!ld reflect the theoretical tr!th table.

+hecB / and Q́ for inp!ts JH8 KH1I JH18 KHI and

+hecB / and Q́ for both JHKH1. 3or clocB inp!t8 t!rn fre%!enc# down8 #o! sho!ld

observe the to""lin" on L$Ds.

'mportant aspects to pa# attention&

• The clocB inp!t from the f!nction "enerator =refer to the previo!s disc!ssion and

photo@

• <se D)) to meas!re volta"e points when checB the circ!it the doin"

tro!bleshootin"

• :emember to connect all "ro!nd points to"ether

. 'ncrease the p!lse "enerator o!tp!t to 1. ). Set the switches so that all of the flip-

flop inp!ts are hi"h and remove the L$Ds and resistors. <sin" the oscilloscope8 meas!re

the propa"ation times for the / o!tp!t from the active clocB ed"e. :ecord the val!e below.




'f #o! are not able to "et 1 ) from #o!r p!lse "enerator8 #o! ma# tr# to "et a lower

fre%!enc# =lets sa# 4 K@ as shown below.

See screen prints from the scope as follows.

5n this screenshot8 +hannel 1 is the inp!t clocB si"nal =!pper si"nal@. +hannel 2 is theo!tp!t si"nal at / =lower si"nal@.




The si"nal below shows the dela# time between inp!t si"nal and o!tp!t si"nal. Ao! can r!n

the stop mode on the scope8 decease the time scale to have better view of the si"nals. :eview

the concepts of and how to meas!re t pLH and t pHL =if the# are not clear in the lect!re or

in the te>tbooB8 there are "ood websites e>plainin" them@. +hecB datasheet for the

theoretical ran"e and #o!r meas!rements sho!ld be within it.

t*L H t*L H




C. En(anced %dder+ubtractor

1. The adder-s!btractor circ!it b!ilt in Lab has a f!ndamental weaBness. ,henever an# of

the inp!ts is chan"ed8 the o!tp!t chan"es. This wo!ld present a si"nificant problem in

b!ildin" a calc!lator since the !ser onl# wants the selected operation to occ!r when the

e%!al b!tton is pressed. ,e can modif# the circ!it from Lab to operate in this wa# b#addin" in flip-flops to store the o!tp!ts onl# on the activation of a clocB si"nal.

2. <sin" /!art!s ''8 modif# the circ!it from Lab as shown in Figure 7. b# addin" three

7474 D-flip-flip chips. Gote that a clear f!nction has been added and that the flip-flop

presets are inactive since the# are tied to M =labeled ++@.

)aBe s!re #o!r circ!it is wired correctl#. 't is eas# to maBe a simple mistaBe and #o! need to

do!ble checB. 5ne wirin" error is "oin" to cost #o! a lot of tro!bleshootin" effort.

Figure 7.—En(anced %dder+ubtractor

. *erform a sim!lation to verif# the correct operation of the circ!it. Gote that in this case

=for the act!al eSoc board@8 the +L5+K si"nal is not a periodic si"nalI the +L5+K si"nalis a discrete si"nal occ!rrin" on a switch clos!re.




This pict!re shows the waveforms of s!ccessf!ll# e>ec!ted sim!lation res!lts.

3or the above waveforms -

+ase 1& from time d!ration -1 ns&

;H11I (H1I ;DDS<( H 1 =meanin" performin" s!btraction@I the S<) o!tp!tS4SS2S1H1I and +arr# +5<TH1 =meanin" positive res!lt@. Ao! dont need to perform

2s complement for positive res!lt.

The waveform verifies that in (ase-18 its& -1HM2

+ase 2& from time d!ration 1-2 ns&

;H1I (H11I ;DDS<( H 1 =meanin" performin" s!btraction@I the S<) o!tp!t

S4SS2S1H111I and +arr# +5<TH =meanin" ne"ative res!lt@.

2s complement for S<) H 11

The waveform verifies that in (ase-18 its& 2-H -




+ase & from time d!ration 2- ns&

;H1I (H11I ;DDS<( H =meanin" performin" addition@I the S<) o!tp!t

S4SS2S1H111I and +arr# +5<TH =meanin" no carr# o!t for this addition operation@.

The waveform verifies that in (ase-18 its& 2MH 7

). ;ssi"n pins to the inp!ts and o!tp!ts. <se the D'* switches for #o!r inp!ts =- for ;8 F-

11 for (8 7 for +L$;:8 1 for ;DDS<(@8 one of the debo!nced p!shb!ttons for

+L5+K and the red L$Ds for o!tp!ts =:D-4@.

The pin planner map is shown below.

5. Download #o!r pro"ram to the eS5+ ''' board and test the operation of the circ!it.

E. *hoto"raph #o!r final circ!it for s!bmission =online@ or demonstrate #o!r circ!it to #o!r

professor =onsite or blended@.

*hotos below show the circ!it after the pro"ram is s!ccessf!ll# downloaded and e>ec!ted.

(elow demonstrate +ase 1& ;H11I (H1I ;DDS<( H 1 =meanin" performin"s!btraction@I the S<) o!tp!t S4SS2S1H1I and +arr# +5<TH1 =meanin" positive

res!lt@.




The waveform verifies that in (ase-18 its& -1HM2

(elow shows +ase 2& ;H1I (H11I ;DDS<( H 1 =meanin" performin" s!btraction@I

the S<) o!tp!t S4SS2S1H111I and +arr# +5<TH =meanin" ne"ative res!lt@.

2s complement for S<) H 11

The waveform verifies that in (ase-18 its& 2-H -




+ase is shown in the followin" photo& ;H1I (H11I ;DDS<( H =meanin"

performin" addition@I the S<) o!tp!t S4SS2S1H111I and +arr# +5<TH =meanin" no

carr# o!t for this addition operation@.

The waveform verifies that in (ase-18 its& 2MH 7

ote to students- Direct co*, and *aste o2 an, *(oto in

t(is document to ,our *ro3ect re*ort is *ro(ibited and 4illbe considered as *lagiarism. our *ro3ect re*ort must

s(o4 *(otos o2 addition and subtraction o*erations using

6alues di22erent 2rom t(e eam*les s(o4n in t(is

document to 6eri2, ,our o4n 4or8.

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ECET 105 Week 7 Lab Project Detailed Directions