piclist 2001\01\04\150523a >
Thread: strange output port.
face picon face BY : Olin Lathrop email (remove spam text)

> >I tryed  to use  PIC16C621A, RA4 as output, open drain. I put a 10K
> >to Vcc and the base of a npn transistor in RA4 to drive a relay (relay
> >conected on colector with diode self induction protection, and emitter to
> >zero).
> Do you have a resistor between RA4 and the base? If not,
> put one in.

And why should that help?  If it is open drain, then he should be able to
connect the base of the NPN directly to the pin because the current into the
base can only come from the pullup resistor.  Adding an additional series
resistor has no advantage and will slow down the response.

Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, TakeThisOuTolinRemoveMEspamembedinc.com, http://www.embedinc.com

http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

<001d01c07685$cd0552e0$260bf6cd@pc> 7bit

See also: www.piclist.com/techref/microchip/ios.htm?key=output
Reply You must be a member of the piclist mailing list (not only a www.piclist.com member) to post to the piclist. This form requires JavaScript and a browser/email client that can handle form mailto: posts.
Subject (change) strange output port.

month overview.

new search...