internal workings of CNT/DLY with Edge Detect

How exactly does a CNT/DLY macrocell work in "Delay" mode with "Both" edges selected?

For instance; if the input is low and goes high, does the signal have to stay high for the entire DLY time for the rising edge to be detected?

Is there a simplified schematic somewhere of what is actually happening inside the macrocell?

Is this documented somewhere in a way that is understandable?

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  • Hi, 

    If you use the CNT/DLY macrocell  in "Delay" mode with "Both" edges selected,  you will be delaying the appearance of input change for both positive edges and negative edges based on the time determined by the count value.  In the example shown below, a positive edge on the input will start the macrocell counting, and 200 uS later there will be a positive edge on the output for the macrocell.  Similarly, a negative edge on the input will start the macrocell counting, and 200 uS later there will be a negative edge on the output for the microcell.  If the positive and negative edges on the input come faster than 200uS, there will be no change on the output, as the counting will never reach the value in the counter data. 

    I hope this helps, let us know if you still have any questions?

     

     Thanks 

    AB

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