ahh good idea...should have thought about that...but it was late. Thanks!! Jan-Erik S=F6derholm wrote: Are you sure th= at the line *is* actualy driven low ? You say "changes from an input to an output". Note that if you have done other BCF/BSF operations on the same PORTx/GPIO register (while the pin for the "line" is an input), the bit in the PORTx/GPIO that you *think* is a "low" would now be a "high", and then you're not driven the line low... Try with actualy setting the bit in PORTx/GPIO "low" *right before* changing it to an output. Jan-Erik. alan smith skrev: > Ran across something I thought should work. I have 5 pics, each has a pai= r of pins connected in daisy chain fasion (think I2C like..but its not), wh= ere the master board can send out data to the slave boards, and they get th= e 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 (chang= es 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 h= igh and low, but it never branches on the high condition it simply always b= ranches 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? nev= er!!) 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 pu= p on the signal, that they should behave just fine,and making one of them a= n 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 messi= ng with things...something to check tomorrow I suppose. > = > = > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around = > http://mail.yahoo.com = -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around = http://mail.yahoo.com = -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist