[TriEmbed] CD4027 Flip Flop & My Traffic Light Project

Pete Soper pete at soper.us
Thu Apr 17 16:36:06 CDT 2014


I was too lazy to read some more and remind myself about 
"metastability." (I took an EE switching theory course three eons ago 
and have forgotten most of it). The real answer is that the results of 
both the RPI asserting reset and the person asserting the set input to 
the flip flop at the same time is indeterminate. I want to believe at 
the point either input changes back to a low then "the right thing" will 
happen.

But this raises an important point. At power up it's absolute random 
chance whether the latch will be set one way or the other. So the first 
thing the RPI must do is reset the latch as part of it's preparation of 
the system.

-Pete




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