---- START NEW MESSAGE --- Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-8.05) id A6D7448023E; Thu, 29 Jan 2004 13:10:47 -0800 Received: from PEAR.EASE.LSOFT.COM (209.119.0.19) by cherry.ease.lsoft.com (LSMTP for Digital Unix v1.1b) with SMTP id <12.00CC32AA@cherry.ease.lsoft.com>; Thu, 29 Jan 2004 15:36:04 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8e) with spool id 0992 for PICLIST@MITVMA.MIT.EDU; Thu, 29 Jan 2004 15:35:57 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 1937; Thu, 29 Jan 2004 15:35:46 -0500 Received: from svs19.virtualis.com [64.55.166.80] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with ESMTP ; Thu, 29 Jan 2004 15:35:41 EST X-Comment: mitvma.mit.edu: Mail was sent by svs19.virtualis.com Received: from home (69-144-22-151.client.bresnan.net [69.144.22.151]) by svs19.virtualis.com (8.12.9/8.12.9) with SMTP id i0TKZYtB019253 for ; Thu, 29 Jan 2004 12:35:37 -0800 (PST) References: <45.41826b6.2d4a9ace@aol.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Message-ID: <01b201c3e6a7$72fe4820$0302a8c0@Home> Date: Thu, 29 Jan 2004 13:35:32 -0700 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: Tech Subject: Re: 12F675 To: PICLIST@MITVMA.MIT.EDU Precedence: list X-RCPT-TO: Status: U X-UIDL: 371856330 > Second posting - don't think the first one made it. > > We are looking at the 12F675 and after reading the data sheet understand most > of it. I have one question - pin 4 is indicated as an I/O and MCLR. My > understanding is the MCLR must always be pulled high for normal operation. > > How can this be accomplished and the pin still be used as an I/O. Can > someone enlighten me, please. > > > Sid Weaver You decide at burn-time or include config parameters in your code to configure this pin to function as /MCLR (reset) or as an "input only" pin by setting or clearing bit 5 in config word. Most device programmers will have a menu for setting config options before you burn the target, and/or you can assemble or compile config settings in your code as well. Asm: __CONFIG _INTRC_OSC_NOCLKOUT & _MCLRE_OFF Same deal here; PBP: @ DEVICE INTRC_OSC_NOCLKOUT, MCLR_OFF With /MCLR turned OFF the pin is configured for digital I/O, and you don't need the external pull-up to Vcc since it no longer functions as the reset pin. With the /MCLR option turned ON you do. Like most PICs' you have more than 1 option or feature on I/O-pins, and the datasheet becomes a necessity if you want to take advantage of & learn how to configure them...;o] Regards, -Bruce tech@rentron.com http://www.rentron.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. .