From PICLIST@MITVMA.MIT.EDU Fri Nov 15 06:38:21 2002 Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-7.13) id A6DD19C80080; Fri, 15 Nov 2002 06:38:21 -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 <17.007DB948@cherry.ease.lsoft.com>; Fri, 15 Nov 2002 9:24:15 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8d) with spool id 2912 for PICLIST@MITVMA.MIT.EDU; Fri, 15 Nov 2002 09:24:05 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 0451; Fri, 15 Nov 2002 09:23:20 -0500 Received: from smtp.comcast.net [24.153.64.2] by mitvma.mit.edu (IBM VM SMTP Level 320) via TCP with ESMTP ; Fri, 15 Nov 2002 09:23:19 EST X-Comment: mitvma.mit.edu: Mail was sent by smtp.comcast.net Received: from ScottTouchton (pcp02285524pcs.potshe01.pa.comcast.net [68.83.254.213]) by mtaout06.icomcast.net (iPlanet Messaging Server 5.1 HotFix 1.5 (built Sep 23 2002)) with SMTP id <0H5M00IVNFYTFU@mtaout06.icomcast.net> for PICLIST@MITVMA.MIT.EDU; Fri, 15 Nov 2002 09:23:21 -0500 (EST) MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 X-Mailer: Microsoft Outlook Express 5.50.4807.1700 Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7BIT X-Priority: 3 X-MSMail-priority: Normal References: <004b01c28c23$51b8ba40$6501a8c0@potshe01.pa.comcast.net> <006401c28ca1$b0a4aa40$6501a8c0@potshe01.pa.comcast.net> <009101c28caa$1eec0b30$0300a8c0@main> Message-ID: <007701c28cb1$6e1eaf80$6501a8c0@potshe01.pa.comcast.net> Date: Fri, 15 Nov 2002 09:15:19 -0500 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: Scott Touchton Subject: Re: [PIC]: 16F627 brown out? question To: PICLIST@MITVMA.MIT.EDU X-RCPT-TO: Status: R X-UIDL: 277600668 X-Evolution-Source: pop://mailinglist%40farcite.net@mail.farcite.net/ X-Evolution: 00000770-0000 Thank you Olin. You are 100% right about my lack of info. I probably would have nailed the delete key myself. I really needed help thinking through this and appreciate your response. I have been through this before, but never with the WDT enabled. > > What oscillator mode? What frequency? How do you know it's in > "brownout"? What voltage exactly it it running at? > LP, 32.768Khz, 3.015V The oscillator is alive, though execution has ceased based upon observance of the IO pins. > If brownout detect is disabled, it can't be in "brownout mode", although > the power voltage can be too low for proper operation. Again, what > exactly is the power voltage? I would disagree on this point, but I am confused and it is probably semantics. When I had a brown out problem many years ago, once the condition was reached power supply voltage was not a factor. In exact terms (and this is on the 16C54) when the power supply dipped to 0.705V and then returned to >3V the processor would not execute code though the oscillator was running. Microchip stated the part "was in brown out". We shot the engineer and installed a voltage detector to correct. > > No, you didn't. So this condition only last 1/2 second? What does the > chip do when power comes back? Does the power go all the way to 0 and 5V? > What is the rise time? Here is the normal course of events (which I intend to get rid of, but must live with at the moment). Processor powers up (0 to 3V in under 150uS). Processor reads operating parameters from internal EPROM. Processor takes 150ms scanning an IO port for signal and giving commands to an amplifier. If no signals are found it sends an IO pin high to initiate power shut down. The power supply is terminated, using an RC network to re-apply power 300 ms later. Power supply goes all the way down to 0, and all the way back to 3V. This repeats indefinitely. > > I can't gather that from the information you supplied. Based on Microchips definition to me of "brown out" (oscillator running, no code execution observable). Maybe this definition does not hold true to the interpretation of the list. > The WDT should function normally as long as the power voltage is at the > minimum operating level. The entire chip, including the WDT, may act out > of spec below that. This was exactly what I was wondering.... seems as if the WDT is not functioning although I am at the minimum operating level (3V). -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.