03-15-2018 07:06 AM
If I define the RESET pin in my design, but I did not assign a pin number (UCF file),
How is it implemented in the design?
I can see that a pin number is assigned by the compiler, but how is the "internal" global reset interact with my design?
do I now have to reset pins?
any app notes?
03-15-2018 08:05 AM - edited 03-15-2018 08:07 AM
I don't work with ISE (Spartan3), but if there is reset port on your top level design and its pin assignment in UCF is missing, then doesn't ISE complain in the Impl stage?
Assign the reset to a standard available inout pin.
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03-15-2018 11:40 AM
If I remember ISE correctly, there is a bitgen switch you can set that will allow bit file generation with the tool defined pinout. If this is true, there is a reset pin in the design on what is probably an undriven pin. This should lead to some mighty erratic behavior. I would suggest defining a reset pin in the UCF or just removing the reset pin and relying on the power-up initialization.