Question

D-flip flop with set and CLR wave forms

Answer 1

@ganeshie8

Answer 2

From what I heard, the only difference is that if set or clear is ever low...it doesn't matter what CK or D will be...Q will be high..?

Answer 3

Note: that is my friend's work

Answer 4

what are the labels on waveforms ?

Answer 5

because if what he said was true...

why is q here low?

Answer 6

CK
D
?
?
Q

Answer 7

First help me understand the waveforms
I can't understand them w/o knowing the labels correctly... the labels in the attached picture are not readable

Answer 8

^CK
D
NOT SET
NOT CLR
Q

Answer 9

OK here SET and CLR are active LOW signals

that means they are active when 0

Answer 10

when SET is 0, the Q goes 1
when CLR is 0, the Q goes 0


when both SET and CLR are 1, the flipflop functions normally

Answer 11

in the picture isn't it that set is 1 and the clr is 0

Answer 12

Yes. CLR = 0 so the Q has to become 0

Answer 13

so in other words

when set is low, q will be high
when clear is low, q will be low

Answer 14

Exactly!

Answer 15

becaust set and clear are ACTIVE-LOW signals here

Answer 16

let's say the there were no "nots" on the set and clear, it would just be the opposite right?

if set is high, q will be high
if clear is high, q will be low

Answer 17

You got it!

Answer 18

and if there are both 1 (in this case), the flip flips run normally. what about if it's both 0? or is that "illegal"

Answer 19

if both are 0, you can give priority to any one of them by design
usually we give priority to CLR

Answer 20

so a double zero on a regular set or clear without nots, will allow the flop to run normally? and a 1, 1 will be based on choice?

Answer 21

Yep!

Answer 22

oh man....got a test tomorrow...this really cleared things up. thank you so much.

Answer 23

np :) good luck wid the test!