D flip flop from T flip flops

WBahn

Joined Mar 31, 2012
29,932
Any circuit that you can make with any of the basic edge-triggered FF types (JK, D, T) you can make with either of the other two. This includes implementing the other two FF types.
 

WBahn

Joined Mar 31, 2012
29,932
I guess I'll be interested in the result.
Think about it for a moment and it will probably come to you with a head slap.

With a DFF if you tell me what the value of D is (during the critical setup/hold window) I can tell you what the value of Q will be after the next active clock edge.

If I give you a TFF and you know what its current Q output is and I tell you what I want the next Q output to be, can you tell me if you want it to toggle or not?
 

Papabravo

Joined Feb 24, 2006
21,094
I suppose, if gating the clock is fair game. I didn't make that assumption initially, since I would seldom if ever do that in practice.
 

Papabravo

Joined Feb 24, 2006
21,094
Ah..you're right. In my text (ca. 1960), the toggle flip-flop had only a single input, the clock input. That explains why I was having a hard time visualizing how to do it. That and nobody ever made an integrated circuit that implemented one, could explain a my confusion. Old dogs should really try to learn new tricks.
 

MrChips

Joined Oct 2, 2009
30,621
(Edit: I started typing a response 5 hours ago but got distracted.)

Yes, it is possible.
A T-flip flop has a T input.

Draw a truth table of all possible states of the present Q and the given D input. Show the desired T input required to implement the D-type flip-flop result.
You should be able to arrive at a logic function to give the solution.
 

Papabravo

Joined Feb 24, 2006
21,094
As I explained I was laboring under an antiquated definition from a very old text. With the proper definition of the device it is straightforward.
 
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