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Richard Erlacher
04/12/12 10:52
Read: 628 times
Denver, Co
USA


 
#187114 - when you're wrong, you're wrong
Responding to: Erik Malund's previous message
Erik Malund said:
I've challenged you on many occasions to show, just as one example, that the "reset problem" that you've apparently encountered more than once, was, in fact, a reset problem. All you've ever said is that your customer stopped complaining after you did whatever you did.
here we go again Richard just will not believe that a supervisor is essential, that is hios problem and I am getting darn tired of him bring it up every time he does not know what else to post

here is the documentation:
since there is no way of knowing what the processor does when outside its specified voltages, it is essential that when such is the case the processor is held in reset. Thus a supervisor (chip) is essential for good design.

This is where you're wrong.

When you believe your circuit is misbehaving, you should try to determine WHY it is misbehaving and in what way it is misbehaving. One thing you can do is to attach your logic analyzer to the parts of the circuit that you suspect, and then monitor its behavior through the perceived malfunction.

That's how I discovered the MCU running on during decay of Vcc, despite the presence and apparently normal function of the supervisor and it's active RESET signal to the MCU. That was years ago, but I did write about it, though you didn't really understand what it was that I'd discovered.

In the days when Richard liked how things were the effect was minimal since the brief time during power down from 'undefined behaviour' to 'no behaviour' rearely did anything long enough to show any ill effects. Now that most of us have moved forward and use flash based designs there is a possibility that a flash write/erase occur during the "power down window" and thus it is essential to grab the processor by the balls during this time.

Since the circuit in which I discovered the anomalous behavior was one with external BBRAM, I was very interested in the behavior during active RESET while the Vcc was decaying, since that's where the BBRAM corruption apparently occurred. I also was able to make the problem go away by reducing the Vcc capacitance, hence, reducing the decay time. A later experiment showed that by limiting the rise and fall time of Vcc to much less than 1 ms, I could avoid the occurrence of the BBRAM corruption. Now, I used a DALLAS supervisor, since I was using a DALLAS MCU and a DALLAS BBRAM. IIRC, Kai didn't approve of the use of that Dallas supervisor. However, when I substituted a different manufacturer's MCU, including Intel, AMD, and Philips, I found the same effects. I wrote about all that back in the day. I believe the first truly acrimonious "debate" you and I had resulted from my assertion that this problem went away with the change in Vcc rise and fall time, regardless of the presence of a supervisor.

I have made no investigation of the effects of power up, but the reset functionality is essential during power down

Erik


I found it confusing that the supervisor, MCU, which had a built-in brownout detector, and BBRAM, all had different notions of what a brownout was, which made it hard to guess what was really going on. However, there was no doubt that the MCUs' continuing to generate nWR signal after the assertion of RESET was probably a problem. The bidirectional RESET on some MCU's can also create some confusion.

Some day, perhaps I'll get the hardware that I used to experiment with this stuff back out of storage and play with it some more. the hardware I used for this experiment certainly wasn't what one would want to deploy in a commercial application. As I mentioned back when I originally played with this "problem", I find it odd that manufacturers who've got the necessary resources on hand haven't spend a few hours on this problem, preferring instead to replicate, at least in publication, the inane slow-rise-and-fall RC RESET that Intel cooked up back in the '70's when it didn't matter. I also find it odd that so many designers are simply willing to change their circuitry without pursuing the actual cause of a given malfunction.

RE



List of 92 messages in thread
TopicAuthorDate
has linux had its chips?      Jez Smith      04/06/12 05:09      
   some weirdo in sandals a ponytail        Andy Neil      04/06/12 05:38      
      Problem is      Jez Smith      04/06/12 06:16      
      possibly, but not only      Erik Malund      04/06/12 08:11      
      It's all in the history ... and "read the code" doesn't work      Richard Erlacher      04/06/12 16:39      
         Good points!      Andy Neil      04/07/12 14:48      
            Why not a firm objective?      Richard Erlacher      04/08/12 00:32      
               Lots of projects have a large percentage research        Per Westermark      04/08/12 14:58      
                  I knew you'd have to come in with something irrelevant      Richard Erlacher      04/08/12 19:29      
                     Try document an invention before it's invented...      Per Westermark      04/08/12 20:16      
                        Here's some research for you, Per      Richard Erlacher      04/09/12 13:03      
                           Richard to give an example      Erik Malund      04/09/12 13:16      
                              I'd like YOU, Erik, to come up with one example ...      Richard Erlacher      04/09/12 13:42      
                                 Always prejudice from Richard      Per Westermark      04/09/12 23:14      
                                 'documenting' means many things      Jim Granville      04/10/12 01:11      
                                 here we go again      Erik Malund      04/10/12 08:00      
                                    when you're wrong, you're wrong      Richard Erlacher      04/12/12 10:52      
                                       I do not have a microscope and probes that small      Erik Malund      04/12/12 12:30      
                                          So you've made no observations ... you just guessed ...      Richard Erlacher      04/15/12 02:22      
                                             and that irks you immensely      Erik Malund      04/15/12 06:33      
                                                What did you do, aside from guessing?      Richard Erlacher      04/15/12 09:04      
                                                   then please, tell me      Erik Malund      04/15/12 15:45      
                                                      Are you willing to explore this in detail?      Richard Erlacher      04/16/12 09:07      
                                                         now you are jumping      Erik Malund      04/16/12 09:38      
                           Your references aren't exactly backing your view      Per Westermark      04/09/12 23:39      
                              It's not about me ... it's about process      Richard Erlacher      04/10/12 00:08      
                                 But processes contains feedback loops      Per Westermark      04/10/12 00:56      
                                    I believe you've gone off-the-rails, Per      Richard Erlacher      04/12/12 11:04      
                                       But getty isn't Linux      Per Westermark      04/12/12 11:28      
                                          it's a small piece, but it's an example      Richard Erlacher      04/15/12 02:10      
                                             But not of Linux      Per Westermark      04/15/12 07:08      
                                                It was part of the distribution.      Richard Erlacher      04/15/12 09:06      
                                 'Research' can mean many things      Jim Granville      04/10/12 01:00      
                                    Yes, but that's in a different context      Richard Erlacher      04/12/12 11:11      
                                       You still haven't told what Linux documentation you miss      Per Westermark      04/12/12 11:44      
                                          I don't know what you mean      Richard Erlacher      04/15/12 02:28      
                                             Still claims based on assumptions and not facts      Per Westermark      04/15/12 07:19      
                                                Not everyone is completely stupid      Richard Erlacher      04/15/12 08:28      
                                                   But what is the relevance today?      Per Westermark      04/15/12 10:08      
                                                      I've no opinion about the current LINUX      Richard Erlacher      04/16/12 09:16      
                                                         and, you Richard, who loves living in the past      Erik Malund      04/16/12 09:40      
                                                            just a minute, Erik      Richard Erlacher      04/17/12 09:36      
                                                               Examples?      Per Westermark      04/17/12 10:42      
                                                                  Nothing has changed since 15 years ago ...      Richard Erlacher      04/17/12 23:03      
                                                                     at least not Richards opinions :)      Erik Malund      04/18/12 07:42      
                                                                     Still lots of assumptions and unbacked claims      Per Westermark      04/18/12 11:59      
                                 Oh, Richard, I have a job for you      Erik Malund      04/10/12 08:14      
                           I had Yourdons first book as manuscript and ...      Erik Malund      04/10/12 08:11      
                              be careful ...      Richard Erlacher      04/12/12 10:23      
                                 were you once a bartender ...      Erik Malund      04/12/12 10:47      
                                    You have to accept the difference ...      Richard Erlacher      04/12/12 11:14      
                                 We are careful      Per Westermark      04/12/12 11:01      
                     Hog Wash.....        Michael Karas      04/08/12 21:57      
                        Odd that you see it that way ...      Richard Erlacher      04/09/12 11:24      
                     I just documented fully      Erik Malund      04/09/12 06:43      
               Because an "Objective" is not a final product specification        Andy Neil      04/09/12 02:36      
                  I have to disagree ... the objective specification is step 1      Richard Erlacher      04/09/12 11:36      
            documentation        Andy Peters      04/09/12 11:02      
               Definitely not the "usual response"      Per Westermark      04/09/12 22:47      
   Android      Joseph Hebert      04/06/12 09:31      
      I don't think so      Jez Smith      04/06/12 12:58      
         Don't agree      Per Westermark      04/07/12 07:05      
      all due respect, no.      Andy Peters      04/09/12 11:11      
         Apple may have a price match on the superluxourious      Erik Malund      04/09/12 11:40      
            re: Apple may have a price match on the superluxourious      Andy Peters      04/11/12 18:31      
               but 95% of the population does not need....      Erik Malund      04/12/12 07:35      
                  Web browsing normally the most power-hungry you can do      Per Westermark      04/12/12 10:32      
                  re: 95%      Andy Peters      04/12/12 10:40      
               So how exactly am I wrong?      Joseph Hebert      04/12/12 08:11      
                  But Android is Linux      Per Westermark      04/12/12 10:41      
                     Just the opposite        Joseph Hebert      04/12/12 12:11      
                        {sigh}      Andy Peters      04/13/12 10:42      
                           just like the preacher said to the atheist      Erik Malund      04/13/12 11:13      
                  re: How exactly?      Andy Peters      04/12/12 11:51      
      850000 Android phones activated per day, linux video      Frieder Ferlemann      04/09/12 11:25      
   anecdotes...      Jim Granville      04/06/12 15:29      
      These guys...      Jez Smith      04/07/12 01:40      
         digital audio consoles      Andy Peters      04/09/12 11:13      
   The Rasperry Pi Foundation clearly doesn't think so!      Andy Neil      04/09/12 02:41      
      The world isn't just a few companies      Per Westermark      04/09/12 06:47      
   the basic problem with free software is...      Erik Malund      04/10/12 08:33      
      Careful with the use of "Linux". Most things "Linux" aren't!      Per Westermark      04/10/12 08:53      
         I did refer to linux itself      Erik Malund      04/10/12 09:06      
            Wrong hw selected, or just big lack of platform knowledge?      Per Westermark      04/10/12 12:54      
               a port      Erik Malund      04/10/12 13:10      
                  Always danger with low-level code for platform      Per Westermark      04/10/12 14:32      
      True - but "paid-for" is not necessarily any better!      Andy Neil      04/10/12 13:31      
         when selecting any tool      Erik Malund      04/10/12 13:44      
      As Stallman said.....      Steve M. Taylor      04/11/12 15:59      
         free      Erik Malund      04/12/12 08:11      
            All about volume or already existing knowledge/experience      Per Westermark      04/12/12 10:37      
   Well...say what you like about me, and many people do.        Jez Smith      04/11/12 14:43      

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