06-05-2011 07:42 PM
I am trying to simulate a ripple countdown.
I use 4 D flip flops and clock each one to the next.
Theoretically, I think this should work.
Please let me know if my d flip flops are wired wrong.
06-05-2011 08:28 PM
Why don't you make it easy for everyone and attach the actual code? Are you able to debug pictures? We certainly can't.
06-05-2011 08:28 PM
It is impossible to tell whether the D Flip Flop will work since you only show the Clear case.
You certainly have much more feedback or "memory" than a hardware flip flop needs. The wires at the right side are tangled enough that it is difficult to even guess at what you are trying to do.
The counter does not look much like a standard counter circuit. Since the D Flip Flop VI uses uninitialized shift registers, what is the purpose of the feedback nodes connected around each flip flop in the counter? Why is the Clock input to the first flip flop always True? A clock signal usually alternates between T and F.
Have you run the VIs? What works or does not work? If you want more help, please post the actual VIs along with an indication of what does not work and how you expect it to work.
Lynn
06-05-2011 08:33 PM
Does this help?
I simplified the D flip flop to not have a reset.
06-05-2011 09:24 PM
The Ripple Countdown VI uses a different D subVI, which you did not post.
The SimpleDFlipFlop produces Q = Q' = True on the first run with both D and Clock false. On successive calls the outputs toggle but remain equal. A flip flop should never have the outputs equal. Labels or descriptions on the wires and shift registers would make it easier to figure out what you are trying to do.
How about a truth table to show what each signal should do?
Lynn
06-05-2011 09:34 PM
I used the D flip flop circuit to create a vi.
06-05-2011 10:03 PM
Here is the Ripple Down Counter that I am trying to implement.
A is Most Significant Bit, D is Least Significant Bit