>From: "Steph Smith" >Reply-To: "Microcontroller discussion list - Public." >To: >Subject: [PIC] Programming... >Date: Thu, 15 Dec 2005 18:56:21 -0000 > >As far as i'm aware tying unused pins is only really >needed to avoid unwanted states on the pins,PIC's being >basicaly CMOS logic I.C.'s.Unused pins float and can >assume high low or intermediate levels,or if you're really >unlucky,wildly varying ones! Only the pins used during >programing are actually connected,so it shouldn't >make any difference;or have i got it all wrong?%>( >-- Unused input should be tied to known levels, preferraby through a resistor so they can be used later if necessary. In the case of programmable logic, you often have the choice of making a pin an input or output. If you don't want to tie up your unused pins and you can tolerate the slight increase in chip power, the unused pins can be made outputs and driven from code. There are other issues, such as he possible need to refresh the direction (ie TRIS) register and contents periodicly in code. Power consumption, accidental shorts, bus contentions and a bakers-dozen of other issues also need to be considered with unused pins. Rob -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist