Multisim and Ultiboard

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Seven Segment display flickering.

I am a beginner in Multisim, I have been asigned to design a 7 Segment display clock from scratch.

I've gotten to the point where I made a 4 bit counter, which worked perfectly fine (tested by the LEDs) until I plugged it into an actual display.

When I do so it starts to flicker random numbers for a fraction of a second (seems to be the same short blink no matter the frequency) while changing the number (I believe it only happens when it switches from 3->4, 5->6, 7->8 and 8->9. It also starts the counter from 1 instead of 0.

I really need help on this subject, I hope someone can figure this out.

Posting some screenshots below to show you how my circuit looks so far.


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From what you are describing, it seems like there are some unwanted states of the counter surprised on the SSD, due to the fact that your Reset logic is asynchronous, the clock as well is combinational, and all this logic can cause such states to appear.

To better analyze the way your circuit works, I recommend using the transient Analysis, for a complete counting cycle, to see where exactly do the states appear and in what conditions.

Another factor is the delays in the D-FF model, they can influence as well.


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