Jan-Erik Soderholm wrote:
>>> Something my professor tried to get through my old, thick skull: You WRITE 
>>> to the LATCH and READ from the PIN.
>>>
>>> You wrote a high to the LATCH on RB5, which was then latched to the RB5 pin.
>>> You next read the PIN, which is still latched high.
>>>
>>> It seems as though you are correct that you have to set that pin low (clear 
>>> it) before making it a switch input if you expect it to be low when you read 
>>> it (switch not pressed).
>>>
>>> Please see section 9, specifically section 9.10.2, Successive Operations on 
>>> an I/O Port, in the PICMicro Mid-Range MCU Family Reference Manual for more 
>>> information.
>> Thanks for the information!
> 
> Which was in part wrong.
> 
> This part :
> 
>  > you have to set that pin low (clear it) before making it
>  > a switch input if you expect it to be low when you read
>  > it (switch not pressed).
> 
> Is nothing but plain wrong.
> 
> A read from an *input* I/O-pin will read whatever
> is on the *pin*, *not* the internal latch.
> 
> Jan-Erik.

Thanks for the clarification.  I knew the latch was disconnected  from
the pin when it was changed to an input, and I assumed he meant that the
pin would stay high unless something pulled it low, which is basically
what that section of the manual says.  I think that's what happened in
my case.  Unless I pull the pin low before I change it to an input the
line stays high - I guess due to the board traces and maybe the switch
acting as a capacitor and storing a charge.

What did you mean by open inputs?  A pin tied to nothing and set as an
input?

Moses
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