Flip-Flop Orcad Pspice Simulation

[paragon]

pspice flipflop

Hello All,

I am new to this forum as well as Orcad.

I having some problems simulating a Flip-Flop ( 74LS74 from the psice lib)

When running the simulation I can see the alternating digital output from dstm into the clk of the flip-flop but when monitoring the D Q and QBar of the flip-flop all I see is three red flat lines ie no digital output.

If anyone could help explain how to implement this or even point me to a good tutorial / guide that would be great as I have googled this to death ;-)
I have purchased some books for Orcad from Amazon but am awaiting delivery.

I have uploaded two images, one of the capture and the other of the ocilloscope (pspice simulation)

TIA
SRG

 

[sudheerkm]

Give power supply and ground

u give D to VDD and see the output first

u see output file it will have the clear error message

 

[southindia]

Hi,
I am also facing the same problem by getting straight lines.
I think u must have finished analysing the outputs,
Could any one can help me..


Thanks in advance

 

[FvM]

The FF state is unknown, because no initial condition or reset signal is applied.

 

[ernischic]

you have to define the initial status for the flipflops

In Analysis --> Setup --> Digital Setup you may see FlipFlop Initialization marked as All X. Change the value to All 0 or All 1 and see if you can now simulate it.

 

[keith1200rs]

Clear and preset should be high if you want to clock it.

Keith