Post by thread:Rejected posting to PICLIST@MITVMA.MIT.EDU

Since this email was forwarded to me I do not know the original subject line, so I had to make one up, hopefully those interested in this thread picked up on it. This is in regards to Mark E'silva's message regarding the 12C509 vs 12C509A oscillator calibration, and his complaint that code written for the 12C509 runs "a LOT slower" on the 12C509A. This is a basic misunderstanding of the purpose of the OSCCAL register and calibration of the internal RC oscillator and of RC oscillators in general. The purpose of the OSCCAL register is to allow the user to move the value placed into the W register on reset by the MOVLW XX command placed at the reset vector (3FFh in the 12C509) by the factory. This is to reduce the effects of the silicon process variation on the final frequency of the internal oscillator, and to allow Microchip to provide a tighter specification for the oscillator and still maintain a reasonable yield (and thus provide a reasonable cost to you, the customer). It is NOT recommended that the customer place any value other that the factory programmed oscillator calibration value into the OSCCAL register. The reason for this is that if the customer designs his code to adjust the OSCCAL value up or down from that factory calibration value, there may not be any adjustment range left. For example if the customer is trying to adjust the value two counts faster, what if the factory had to program the cal value to FFh (there would be no adjustment range left)? If this is a high volume application, the customer could receive parts that he cannot use for many, many months until the process shifted back to a faster value. For this reason we recommend that customers use the factory programmed value and do any timing adjustments in software. Mr. E'silva doesn't say what voltage and temperature he is running at, so I will assume 25C and Vdd = 5.0V. If I further assume that the 12C509 is actually running at 4MHz and yields a 3.937KHz tone when set at mid range, the 12C509A must be running at 3.89MHz, well within the range of approx 3.71 to 4.22MHz shown in figure 14-1 of the data sheet (DS40139E), and really really within the spec given in table 13-3 of 3.65 to 4.28MHz over temperature (but still at 5V). Remember that this is a resistor-capacitor (RC) oscillator and so cannot be expected to have a tolerance anything like a crystal or even a resonator. If tight tolerances are needed over temperature and Vdd, you should use a crystal or resonator. I have been out of the office for a while and have not been watching the list, but I will get back on and see if there are any further questions about this, or you can directly email me. Best Regards, Scott Fink

You are not authorized to send mail to the PICLIST list from your spam_OUTPICTakeThisOuTMITVMA.MIT.EDU account. You might be authorized to send to the list from another of your accounts, or perhaps when using another mail program which generates slightly different addresses, but LISTSERV has no way to associate this other account or address with yours. If you need assistance or if you have any question regarding the policy of the PICLIST list, please contact the list owners: .....PICLIST-requestKILLspam@spam@MITVMA.MIT.EDU. ------------------------ Rejected message (45 lines) -------------------------- Return-Path: <picKILLspamMITVMA.MIT.EDU> Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 5858 for <pic@MITVMA>; Mon, 29 Jul 2002 05:24:44 -0400 Received: from *unknown [193.192.101.135] by mitvma.mit.edu (IBM VM SMTP Level 320) via TCP with SMTP ; Mon, 29 Jul 2002 05:24:42 EDT X-Warning: mitvma.mit.edu: Host *unknown claimed to be yahoo.com From: .....picKILLspam.....mitvma.mit.edu Received: from yahoo.com by 8ROI5.yahoo.com with SMTP for EraseMEpicspam_OUTTakeThisOuTmitvma.mit.edu; Mon, 29 Jul 2002 05:31:11 -0500 To: picspam_OUTmitvma.mit.edu Reply-To: @spam@picKILLspammitvma.mit.edu X-Priority: 3 Subject: Lowest Mortgage Rates Around Message-Id: <KILLspam0H6I6I8ILA5J.7OEGDHQBG13O7JG6VK71.picKILLspammitvma.mit.edu>> X-MSMail-Priority: Normal MIME-Version: 1.0 X-Encoding: MIME Date: Mon, 29 Jul 2002 05:31:11 -0500 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable We will help you get the mortgage loan you want! Only takes 2 minutes to fill out our form. http://xnet.123alias.com/index.php Whether a new home loan is what you seek or to refinance your current home = loan at a lower interest rate and payment, we can help! Mortgage rates haven't been this low in the last 12 months, take action now! Refinance your home with us and include all of those pesky credit card bills = or use the extra cash for that pool you've always wanted... Where others says NO, we say YES!!! Even if you have been turned down elsewhere, we can help! Easy terms! Our mortgage referral service combines the highest quality loans with most economical rates and the easiest = qualification! Click Here to fill out our form. http://xnet.123alias.com/index.php -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

You are not authorized to send mail to the PICLIST list from your spamBeGonePICspamBeGoneMITVMA.MIT.EDU account. You might be authorized to send to the list from another of your accounts, or perhaps when using another mail program which generates slightly different addresses, but LISTSERV has no way to associate this other account or address with yours. If you need assistance or if you have any question regarding the policy of the PICLIST list, please contact the list owners: TakeThisOuTPICLIST-requestEraseMEspam_OUTMITVMA.MIT.EDU. ------------------------ Rejected message (46 lines) -------------------------- Return-Path: <RemoveMEpicTakeThisOuTMITVMA.MIT.EDU> Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 8273 for <pic@MITVMA>; Sun, 4 Aug 2002 20:04:38 -0400 Received: from demeure.demon.co.uk [212.229.71.68] by mitvma.mit.edu (IBM VM SMTP Level 320) via TCP with SMTP ; Sun, 04 Aug 2002 20:04:28 EDT X-Warning: mitvma.mit.edu: Host demeure.demon.co.uk claimed to be yahoo.com From: picEraseME.....mitvma.mit.edu Received: from yahoo.com by 7MQW4DH18W.yahoo.com with SMTP for EraseMEpicmitvma.mit.edu; Sun, 04 Aug 2002 20:11:08 -0500 MIME-Version: 1.0 Date: Sun, 04 Aug 2002 20:11:08 -0500 Importance: Normal To: RemoveMEpicEraseMEEraseMEmitvma.mit.edu X-Sender: RemoveMEpicspam_OUTKILLspammitvma.mit.edu Reply-To: RemoveMEpicTakeThisOuTspammitvma.mit.edu X-Priority: 3 (Normal) X-Encoding: MIME Message-Id: <EraseME79AA9M7YT.I51R9U17LQ6U01.picspamspamBeGonemitvma.mit.edu>> Subject: Refinance and Save $$$ Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: Quoted-Printable We will help you get the mortgage loan you want! Only takes 2 minutes to fill out our form. http://xnet.123alias.com/index.php Whether a new home loan is what you seek or to refinance your current home = loan at a lower interest rate and payment, we can help! Mortgage rates haven't been this low in the last 12 months, take action now! Refinance your home with us and include all of those pesky credit card bills = or use the extra cash for that pool you've always wanted... Where others says NO, we say YES!!! Even if you have been turned down elsewhere, we can help! Easy terms! Our mortgage referral service combines the highest quality loans with most economical rates and the easiest = qualification! Click Here to fill out our form. http://xnet.123alias.com/index.php -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestKILLspammitvma.mit.edu

part 1 1448 bytes content-type:text/plain; (decoded 7bit) I tried to reply before, but the list server bounced it back because the message exceeded 1000 lines. Here it is again with the PICPRG.INS.PAS attachment omitted: {Quote hidden}> > > I don't remember exactly which chip it was, but I do remember that the > > > Vpp/Vdd order mattered for it. One of the symptoms was that > > > the ID word > > > would sometimes come back all zero. I experimented enough to > > > see positive > > > evidence that the Vpp/Vdd order can be important. > > > > Do you recall whether this applied to a flash or EPROM/OTP PIC? > > It was definitely a flash chip because that's all I've tested so far. I > think I was testing a 16F876 which requires Vdd before Vpp with an algorithm {Quote hidden}> that was the other way around. The result was flakiness. It would > sometimes not appear to respond to commands at all by not driving the data > line when expected. Other times is would drive the data line, but the ID > word would read back all zeros. > > This caused me to put a special check into the algorithm that tries to > identify the target chip. If the ID is 0, then switch to Vdd before Vpp > reset and try again. Attached is PICPRG_ID.PAS, which is the host source > code for the ID determination. I have also attached PICPRG.INS.PAS which > might help you guess what some of the calls do. part 2 9795 bytes content-type:application/octet-stream; (decode) part 3 310 bytes ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservSTOPspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body