Simple feedback circuit

Apr 30, 2009 at 10:16 AM
Hello,
the program isn´t possible to calculate a simple feedback circuit. So, if you take two D-Flip Flops and connect the output of the last one to the input of the first on, an error message occurs (description: "oscillation"). I´ve tested the functionality of the DFF´s. The DFF´s works fine in a sequential scenario.
Can anyone tell me whats wrong? Or is simply the program not able to do this?

Thanks in advance...
Coordinator
May 3, 2009 at 4:19 AM
Thank you for your feed back. Can you please send me your circuit to ease of repro?
May 4, 2009 at 9:20 AM
Hello,
the test circuit is attached to this mail. This circuit only demonstrate the oscillation error.
I found this error during built my crc32 circuit.

Best regards


p.s.: thanks for your great program, i think its a good choice for learning digital basics!





eugenelepekhin schrieb:

From: eugenelepekhin

Thank you for your feed back. Can you please send me your circuit to ease of repro?

Coordinator
May 6, 2009 at 4:56 AM
I’ve added new wiki page that should help you.
http://logiccircuit.codeplex.com/Wiki/View.aspx?title=Oscillation
Please let me know if you have any other questions.
May 6, 2009 at 2:39 PM
>So, if you take two D-Flip Flops and connect the output of the last one to the input of the first on,
so in real life you would need a preset and clear value on the d flip flop. (so on startup it will be 0 or a 1 on the D input)
else you won't be able to control the values rotating across the flip flops.

or you can setup a mux for the first input of the d flip flop where the control line controls weather it's getting values from external source (initialization) or from the rotating values.

sounds like your in the section of designing a shift register in your class .. : ]

if you are needing this i would probably download altera quartus to simulate your digital logic.
May 7, 2009 at 9:37 AM
It would be very nice, if you have the opurtunity to change between rising and falling flank!

May 7, 2009 at 9:43 AM
I mean recognize...

It would be very good for Master Slave FF's.....