From PICLIST@MITVMA.MIT.EDU Fri Nov 15 05:49:08 2002 Received: from LIME.EASE.LSOFT.COM [209.119.1.41] by dpmail10.doteasy.com with ESMTP (SMTPD32-7.13) id AB54149E00DA; Fri, 15 Nov 2002 05:49:08 -0800 Received: from PEAR.EASE.LSOFT.COM (209.119.0.19) by LIME.EASE.LSOFT.COM (LSMTP for Digital Unix v1.1b) with SMTP id <10.005A9ADB@LIME.EASE.LSOFT.COM>; Fri, 15 Nov 2002 8:36:09 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8d) with spool id 2316 for PICLIST@MITVMA.MIT.EDU; Fri, 15 Nov 2002 08:34:58 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 9320; Fri, 15 Nov 2002 08:33:18 -0500 Received: from nameserv.rl.ac.uk [130.246.135.129] by mitvma.mit.edu (IBM VM SMTP Level 320) via TCP with ESMTP ; Fri, 15 Nov 2002 08:33:17 EST X-Comment: mitvma.mit.edu: Mail was sent by nameserv.rl.ac.uk Received: from sstdwkiwi (sstdwkiwi.ag.rl.ac.uk [130.246.189.231]) by nameserv.rl.ac.uk (8.8.8/8.8.8) with SMTP id NAA00198 for ; Fri, 15 Nov 2002 13:33:16 GMT References: <012301c28c8f$f3b25d80$e7bdf682@sstdwkiwi> <010001c28ca5$f6ce4180$b64aa40a@a7m7h6> X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4807.1700 X-MIMEOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 Message-ID: <01f501c28cab$8e62efa0$e7bdf682@sstdwkiwi> Date: Fri, 15 Nov 2002 13:33:17 -0000 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: "Alan B. Pearce" Subject: Re: [PIC]: Detecting SRAM and eeprom To: PICLIST@MITVMA.MIT.EDU X-RCPT-TO: Status: R X-UIDL: 277600647 X-Evolution-Source: pop://mailinglist%40farcite.net@mail.farcite.net/ Mime-Version: 1.0 X-Evolution: 0000075c-0000 >Do I detect a hint on the topic of TTL , pullups and >pulldowns as seen in an old post! No, in this case pull ups or pull downs are used to ensure that the capacitive charge on the lines is discharged so you know when you try and read a non-existent location, you will get a known value. That is surely good engineering practice. The value of the resistors can be quite high, and still achieve the desired condition, often without creating problems with current draw, if one is careful in how the drivers are programmed. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.