---- START NEW MESSAGE --- Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-8.05) id A1A447E01A0; Fri, 30 Jan 2004 09:17:24 -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 <10.00CC50FA@cherry.ease.lsoft.com>; Fri, 30 Jan 2004 12:17:13 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8e) with spool id 1764 for PICLIST@MITVMA.MIT.EDU; Fri, 30 Jan 2004 12:17:07 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 3944; Fri, 30 Jan 2004 12:15:56 -0500 Received: from smtp1.globo.com [200.208.9.168] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with ESMTP ; Fri, 30 Jan 2004 12:15:55 EST X-Warning: mitvma.mit.edu: Host smtp1.globo.com claimed to be mail.globo.com Received: from user88l53zxzyb (200.158.165.90) by mail.globo.com (6.0.053) id 3FD4F1170036CD35 for PICLIST@MITVMA.MIT.EDU; Fri, 30 Jan 2004 15:15:54 -0200 References: <401A9A93.20071.28A7C0C@localhost> 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 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Message-ID: <006201c3e75d$14b7f200$0301a8c0@user88l53zxzyb> Date: Fri, 30 Jan 2004 15:12:35 -0300 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: Pedro Drummond Subject: Re: [EE]: Challenge for keen minds To: PICLIST@MITVMA.MIT.EDU Precedence: list X-RCPT-TO: Status: U X-UIDL: 371856531 Thank you all for the help and interest. Ok, time for more data: The space being protected is a metallic box, the size of an elevator, that will be towed by small trucks. Its metallic "door" (actually a double door) is the gate I mentioned. During long trips, these boxes are commonly moved from truck to truck, with long periods waiting for the next one, with no guards nearby. Although there is a very strong lock, theft was detected at final destination in locked boxes (i.e., someone opened it, took some goods, and somehow relocked it). A redesign of the metal box is being made, but it will be a long time until all of them are replaced. It is enough for now to help the insurance company in detecting WHEN and for HOW LONG it was opened, so the responsible will be known. I do not mind reading its information only when the gate is open, and I cannot modify the gate, only add some small device close to the door. To comment some of the group ideas: Using a contact method for data transfer - I am afraid of dust, grease, etc. But maybe. RFID - cheap tag, but expensive sensor (I guess). Gyro/acceleration sensors - can't do, since it will be towed by a truck. Hinge sensored - can't alter the hinge. BTW, special thanks to Russel ! -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body .