Ran across something I thought should work.  I have 5 pics, each has a pair of pins connected in daisy chain fasion (think I2C like..but its not), where the master board can send out data to the slave boards, and they get the correct data each time (where the four slaves are truly slaves).  However, if I set it up such that everything is an input including the master board, put a 100K pullup on the line, things go kinda wierd.  The idea is, one of the slave boards will have an alarm condition, sending that bit low (changes from an input to an output) and the other 4 boards are still configured as inputs, will sense the bit going low now and react accordingly.
   
  What I see is that while looking in the watch window, I can see the bit high and low, but it never branches on the high condition it simply always branches low (btfss). So the PIC acts like it sees it to be high yet ignores that fact on the conditional check.  I thought bad hardware (a bad pic? never!!) but...it still works fine when getting data from the master board.
  I would think, that if all the devices were set as inputs, with a weak pup on the signal, that they should behave just fine,and making one of them an output to drive the line low (it does drive it low) would not be anything to unusual. 
   
  While writing this at midnight...Im thinking, that maybe the ISR is messing with things...something to check tomorrow I suppose.


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