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Richard Erlacher
04/16/12 09:07
Read: 725 times
Denver, Co

#187174 - Are you willing to explore this in detail?
Responding to: Erik Malund's previous message
Erik Malund said:
What I mentioned was the anomalous behavior of the MCU during decay of Vcc while RESET is active . It did, in fact, occur when the supervisor had asserted RESET.
WRONG< DEAD WRONG you say "the MCU" but are talking about a specific MCU (probably Dallas). There is no Guarantee that all MCUs have a properly designed reset circuitry.

You're absolutely right. There is no guarantee. There's not even a good reason to believe that the manufacturer has faithfully replicated the circuitry in the licensed original Intel design. Unless the manufacturer provides specific information about this, you're on your own ... sadly ... and likely to remain so. I did observe similar run-on with DALLAS, PHILIPS, and INTEL MCU's. I'm not sure what, exactly, that implies, since their reset logic may be different.

I can't get inside the package any better than you can.
I know, then please, tell me how to get 'proof' of the inner workings of the chip

Quite frankly, I don't know that we can get solid "proof" of what's going on inside the MCU. However, it IS possible to get significantly persuasive evidence. It's not easy or likely to happen overnight, but with considerable thought, and some concerted effort, you can gain insight into what the chip's behavior is under controlled circumstances, including those under which the, in your case, "lost flash" occurs.

This is quite far removed from the "Has LINUX had its chips" topic, though, and I believe, if you, Erik, are willing to have a discussion, rather than a "food fight", it can be done, in an MCU-specific context, as well as a general one that's applicable to pretty much all 805x-core MCU's, though there will undoubtedly be some exceptions, but I believe it would be appropriate to do it in a separate thread.

Since I've finally, after many years, managed to assume a retired status, I have some time available, and have the hardware with which to do much of the "heavy lifting" in the sense of building the necessary hardware to perform rigorous testing over long time and many repetitions. Keep in mind, though, that this will wander into several sensitive areas, including the application of "reset circuitry", power supply bypass, and raw power supply, about which many people have expressed opinion. Oscillator startup is probably also a factor.

However, It's a bit of a stretch from "lost flash" to "RESET problem" which is what you concluded.
pray explain the 'stretch'
1) flash NEVER lost w/o power cycle
2) flash occasionally lost by power cycle
3) solid reset during power cycle = no lost flash.

There's no question that this line of reasoning would lead you to the conclusion you reached. However, in my own rather cursory testing, over long periods and with a few different MCU's, I found that my BBRAM was clobbered despite the assertion of RESET during Vcc decay, as there was a supervisor in the circuit. Now, this doesn't prove anything about your particular experience, but it does give me pause, as I observed activity on ALE, nRD, nPS, and nWR during the interval when RESET was active. This was, in my case, complicated by the fact that the supervisor, the BBRAM, and the MCU all had different ideas about where a "brownout" began and ended. I'm persuaded that if they all agreed, the problem might have been averted, but that's just a guess.

I'd guess it's just as likely your problem would have "gone away", mysteriously as that occurred, if you'd reduced the rise and fall times of Vcc, though that's not been tried at your end, has it?
I can, by sheer reasoning, guarantee you that with a fall time of ZERO, absolute zero, the problem would not exist. However the likely tolerance on fall times (Sure you can pay a fortune for low tolerance decoupling caps) makes it undesirable to base any design on it. another undesirable effect of relying on fall times will be a tendency to skip on decoupling and I would definitely not recommend that.

Well, I'm not sure that the problem's as severe as you suggest, but I do agree that it is potentially cost-sensitive. However, in this particular discussion, it's not about designing a cost effective solution. It's about finding out what the nature of the underlying problem actually is. What I'd point out is that the manufacturers may or may not have done this sort of thing already, but putting the information in front of potential users probably doesn't help them. It's much easier for them to suggest using one or another supervisor, particularly if it's one of theirs.

It may take some time for me to gather up the resources with which to perform thorough automated testing and documentation of the result, particularly as my wife will be coming around to make me go outside and work in the garden. I do however have the resources with which to perform automatic testing over a lengthy period and with which to record the result. I'd find that interesting, if only to show that the various manufacturers have been unkind in not doing this or at least releasing the results.


List of 92 messages in thread
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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