Rick wrote > Writing a 1 to RA4 in software sets it to "high > impedance". Writing a 1 to RA4 in software does put it to high impedance, but with a pullup resitor the pin gets set to a high logic level. The problem I outlined was that when you want to read that pin's value back into the PIC, if you don't have a pullup resitor, the value gets read as a 0, whatever you have set it to. In my case sometimes it was sometimes read as a 0 and sometimes as a 1, because of the combination of the resistors making the level on the pin be about 3V when it was supposed to be about 5V. All the best...Mike. ----- Original Message ----- From: "Rick Regan" To: Sent: Tuesday, April 08, 2003 7:50 PM Subject: Re: [PIC]:PORTA 4 of 16F84 changing its state - erratic behavior > > RA4 would only assert for a few 10's of > > micro seconds, then return to zero. > > I'm not sure what you mean by this. Since RA4 > is "open drain", it can only drive a 0, not a 1. > Writing a 1 to RA4 in software sets it to "high > impedance". > > In any case, you said this worked on your breadboard, > so I suppose it's not related to your problem? > > > __________________________________________________ > Do you Yahoo!? > Yahoo! Tax Center - File online, calculators, forms, and more > http://tax.yahoo.com > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.