---- START NEW MESSAGE --- Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-8.05) id A9347299009A; Fri, 30 Jan 2004 09:49:40 -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 <5.00CC5026@cherry.ease.lsoft.com>; Fri, 30 Jan 2004 12:37:49 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8e) with spool id 2009 for PICLIST@MITVMA.MIT.EDU; Fri, 30 Jan 2004 12:37:44 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 4347; Fri, 30 Jan 2004 12:37:06 -0500 Received: from balin.rl.ac.uk [130.246.135.155] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with ESMTP ; Fri, 30 Jan 2004 12:37:06 EST X-Comment: mitvma.mit.edu: Mail was sent by balin.rl.ac.uk X-RAL-MFrom: X-RAL-Connect: Received: from sstdwkiwi (sstdwkiwi.ag.rl.ac.uk [130.246.189.231]) by balin.rl.ac.uk (8.12.8/8.12.8) with SMTP id i0UHQZVL014877 for ; Fri, 30 Jan 2004 17:26:35 GMT References: <401A9A93.20071.28A7C0C@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-CCLRC-SPAM-report: 0 : X-Scanned-By: MIMEDefang 2.39 Message-ID: <018601c3e756$343de0a0$e7bdf682@space.rl.ac.uk> Date: Fri, 30 Jan 2004 17:26:32 -0000 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: "Alan B. Pearce" Subject: Re: [EE]: Challenge for keen minds To: PICLIST@MITVMA.MIT.EDU Precedence: list X-RCPT-TO: Status: U X-UIDL: 371856533 ..> 1) It will be all enclosed in a box with no openings, time of day >> programming will be done with an IR remote, data will be collected >> from it the same way. Aside from these operations, battery consumption >> must be minimum. >> >> Any ideas to improve this number 1 ? > >IR is pretty power hungry. Any reason not to use a (gold) contact >method for data transfer ? Not to mention potentially hackable. However I guess if the receiver only is enabled then the power draw should not be too much until you enable the transmitter to transfer data. Using a non-standard protocol using a Palm or something similar to capture the data may allow you to make something secure enough to not be confused by someone else coming along with an IRDA device, such as another Palm and trying to foul it up. OTOH would a PCMCIA WIFI card do it for you? drive up to the gate and collect the data without getting out of the vehicle :))))) Again probably current drain may can this one, but you may be able to organise something where a headlight shone at it in (say) a one hour window during daylight causes the wifi to be turned on by the micro. Have a timeout to turn it off again if there is no wifi contact in half a minute (say), and then a half hour reset time before the next enable. >> 2) How to detect gate openings ? > >RFID - when the gate is closed, the tag is in range and when it's open, it >isn't. I would look at using one of those shop antitheft devices, the type that get a foil stuck over them to disable them rather than the type that get put on a magnet to disable them. Put the thing in a slot on the gate so that it is under the wood surface, and hence as invisible as you can get it. Putting it in a joint where a rail meets a vertical member of the gate may do. Essentially you have to hide it, what ever method of sensing you use, as the biggest part of bypassing one of these systems is knowing where the sensor is (ever tried to disable sensors on a laser printer?). Now your box can be mounted on the gate post beside the latch. The antitheft sticker I talk about above is really a tuned circuit, probably at 13.56MHz when you look at the size of the L & C in them. It should be possible to build a low power oscillator to detect the presence of the device in the gate from a handful of inches, even if in rain soaked wood (this will increase the path loss). Using a plastic box should mean you don't need the detector placed outside the box. You may also have the box placed right beside the bolt on the gate so that you can sense when the bolt is home in the latch, using hall effect or something. Now people may figure that you are using the bolt to detect the gate is shut, so if the antitheft device cannot be sensed when the bolt is sensed, then a warning LED could be flashed, and perhaps an audible warning sounded, to signify that the gate is not shut, to stop people trying to fool your box. Now an LED could be flashed at a slow low duty cycle when the sensor is detected and the bolt not home, to signify to the person that this state is detected. Between all these combinations, your users will have a real conundrum trying to work out how your box knows the gate is shut. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body . Return-Path: <> Received: from mitvma.mit.edu ([18.92.0.3]) by tomts38-srv.bellnexxia.net (InterMail vM.5.01.06.05 201-253-122-130-105-20030824) with ESMTP id <20040128024127.YJSP8311.tomts38-srv.bellnexxia.net@mitvma.mit.edu> for ; Tue, 27 Jan 2004 21:41:27 -0500 Received: by mitvma.mit.edu (IBM VM SMTP Level 430) via spool with SMTP id 6164 ; Tue, 27 Jan 2004 21:41:24 EST Received: from MITVMA.MIT.EDU (NJE origin LISTSERV@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 4339; Tue, 27 Jan 2004 21:41:24 -0500 Date: Tue, 27 Jan 2004 21:41:24 -0500 From: "L-Soft list server at MITVMA.MIT.EDU (1.8e)" Subject: PICLIST: error report from YAHOO.COM To: listsjosh@3MTMP.COM, piclist_errors@SYMPATICO.CA Message-ID: X-LSV-ListID: None The enclosed message has been identified as a delivery error for the PICLIST list because it was sent to 'owner-piclist@MITVMA.MIT.EDU'. ------------------------------ Message in error ------------------------------- Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 4337; Tue, 27 Jan 2004 21:41:24 -0500 Received: from mta200.mail.scd.yahoo.com [66.218.86.116] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with SMTP ; Tue, 27 Jan 2004 21:41:23 EST X-Comment: mitvma.mit.edu: Mail was sent by mta200.mail.scd.yahoo.com From: MAILER-DAEMON@yahoo.com To: owner-piclist@mitvma.mit.edu X-Loop: MAILER-DAEMON@yahoo.com Subject: Delivery failure Message from yahoo.com. Unable to deliver message to the following address(es). : Sorry, your message to hbarregrd@yahoo.com cannot be delivered. This account is over quota. --- Original message follows. Return-Path: Received: from 209.119.0.109 (EHLO cherry.ease.lsoft.com) (209.119.0.109) by mta200.mail.scd.yahoo.com with SMTP; Tue, 27 Jan 2004 13:45:50 -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 <12.00CBF756@cherry.ease.lsoft.com>; Tue, 27 Jan 2004 13:55:40 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8e) with spool id 0648 for PICLIST@MITVMA.MIT.EDU; Tue, 27 Jan 2004 13:55:30 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 1566; Tue, 27 Jan 2004 13:54:32 -0500 Received: from outbound03.telus.net [199.185.220.222] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with SMTP ; Tue, 27 Jan 2004 13:54:32 EST X-Warning: mitvma.mit.edu: Host outbound03.telus.net claimed to be priv-edtnes14-hme0.telusplanet.net Received: from DAR2.planet.eon.net ([198.53.251.69]) by priv-edtnes14-hme0.telusplanet.net (InterMail vM.6.00.05.02 201-2115-109-103-20031105) with ESMTP id <20040127185433.HCNM15680.priv-edtnes14-hme0.telusplanet.net@DAR2.planet.eon.net> for ; Tue, 27 Jan 2004 11:54:33 -0700 X-Sender: dwayner@pop.telusplanet.net X-Mailer: QUALCOMM Windows Eudora Version 6.0.1.1 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Message-ID: <6.0.1.1.2.20040127105028.02c501a8@pop.telusplanet.net> Date: Tue, 27 Jan 2004 11:40:31 -0700 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: Dwayne Reid Subject: [EE:] RTD transmitter To: PICLIST@MITVMA.MIT.EDU Precedence: list Good day to all. I'm re-visiting an existing project because the client is now asking for remote temperature readings. Their preferred temperature sensor is a 100R platinum RTD which they will supply. I need to condition those sensors and turn it into a serial bit stream and down a fiber. The complicating factor is that this will be operating in the presence of large AC magnetic magnetic fields generated by currents in the order of 250K Amps or so. The easiest solution is to purchase an off-the-shelf RTD transmitter with fiber output - and I'm starting a search as soon as I finish typing this. But I'm hoping that someone has a favorite unit they like and can offer up supplier names and model numbers. Expense is a consideration - I need 24 units for this particular project. If I can't find anything suitable, I have to build it. In that case, I'm looking for design hints. I've seen the ap notes offered by LT and the like - I'll be looking at those as well. I've got my choice of 2 power sources available: 12Vdc @ 30 mA sitting about 1000 Vdc above ground or 125 Vdc ground referenced. Neither is optimal but its what I've got. Any suggestions appreciated. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads *** MESSAGE TRUNCATED *** .. .