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Unused port pins on 20 pin package vs 28 pin.

Question asked by Graham Pratt on Jun 11, 2013
Latest reply on Jun 25, 2013 by Monica Arvizu

MCUs in question are '908JK3 vs '908JL3. The JK3 does not have PTA0-5 and PTD0-1 available whereas the JL3 does. If I were using the JL3 I would either configure unused port pins as output and let them float, or preferably, as input as tie them to ground. What though of the port lines PTA0-5 and PTD0-1 that are not available on the 20 pin package? Is it bad to have them as inputs and let them float? I think maybe it is. I have done this in the past and generally not had any obvious trouble, but now I am thinking it would be better to just make them outputs seeing I cannot physically tie them to anything. Or for that matter, are the io ports implemented on the die used in the 20 pin package?

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