At 10:57 PM 5/6/03 -0500, Picdude wrote: >But this seems like a workable option to me... > > Rp > .--'\/\/\,---> V+ > | > | | / load >PIC O/P >---'---------------------|< NPN > RA4 | \ gnd Except for R-M-W issues. If you manipulate port RA bits directly, pin RA4 is always going to read logic 0 since the E-B forward voltage drop is only about 0.6 .. 0.7V. So: you set pin RA4 high. Now you set pin RA3 high. Pin RA4 magically goes LO by itself. This may be a desirable feature in this project but you need to be aware of it. One final thought: I've never liked driving transistors directly from PIC pins because of the carnage that can happen if the transistor fails (I'm thinking about C-B shorts or E-B-C shorts with the emitter lead blown open). I'm also often concerned about voltage drop between the transistor E and the PIC ground. In other words, I usually have a simple voltage divider consisting of the series base resistor and a shunt resistor between E-B. Just something to consider. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- 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