From PICLIST@MITVMA.MIT.EDU Fri Nov 15 07:56:29 2002 Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-7.13) id A92D15A70084; Fri, 15 Nov 2002 07:56:29 -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 <11.007DCB51@cherry.ease.lsoft.com>; Fri, 15 Nov 2002 10:42:23 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8d) with spool id 4067 for PICLIST@MITVMA.MIT.EDU; Fri, 15 Nov 2002 10:42:16 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 2230; Fri, 15 Nov 2002 10:40:35 -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 10:40:34 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 mtaout01.icomcast.net (iPlanet Messaging Server 5.1 HotFix 1.5 (built Sep 23 2002)) with SMTP id <0H5M00IK6JJKI7@mtaout01.icomcast.net> for PICLIST@MITVMA.MIT.EDU; Fri, 15 Nov 2002 10:40:35 -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> <007701c28cb1$6e1eaf80$6501a8c0@potshe01.pa.comcast.net> <001f01c28cb7$5f128bf0$0300a8c0@main> Message-ID: <00d201c28cbc$38655320$6501a8c0@potshe01.pa.comcast.net> Date: Fri, 15 Nov 2002 10:32:34 -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: 277600686 X-Evolution-Source: pop://mailinglist%40farcite.net@mail.farcite.net/ X-Evolution: 00000780-0000 > As an experiment, try making the 300mS time much larger so that the > processor is held at 0V power longer There be the other aspect of the problem. I have had about 50 of these fail in the field. I have not been able to duplicate the problem in my lab. The customer removes the battery, thus clearing the problem. This probably means you are right... receiver was at 0V much longer than 300mS. I could change the timing and put a bunch in the field to see what happens. I have one on my bench that got returned with the battery in it. Managed to remove it from its case without disturbing power so I can make observations and try some things. I like your suggestion, just can't duplicate the problem to test. I know if I power down the on my bench it will power back up just fine (at least with my luck it will). I have tried temperature and battery voltage variation to duplicate the issue with no luck. > crystal oscillator takes a while (1000 cycles if I remember right) before > the chip is allowed to run. This is independent of the powerup timer, and > would be over 30mS in your case. So that means the oscillator should be stabilized before the program is released, right? > The 16F627 should draw under 10uA with a 32KHz crystal. Is it really > worth it to shut down the processor completely for such short periods of > time? Nope... total waste to power it down. This is all going away in my redesign. I don't know why the engineer before me did it this way. > ***************************************************************** > Embed Inc, embedded system specialists in Littleton Massachusetts > (978) 742-9014, http://www.embedinc.com > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.