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Richard Erlacher
03/20/12 01:56
Read: 417 times
Denver, Co
USA


 
#186789 - Where you sit determines what you see ...
Responding to: Erik Malund's previous message
Erik Malund said:
I've found that, in my own experience, those brownout bugaboos relating to program-store-content-loss that trouble the 805x community at large, don't make themselves apparent when the Vcc supply rise and fall times are very short.
probably correct. If the fall time is so short that the period of "who knows what it does" is short enough the likelyhood of 'bugaboos' will be less. Will they be zero, I'm not too sure

Since there are different levels at which various devices perceive "out-of-spec" Vcc, the behaviors of MCU's, supervisors, BBRAM's, and other devices can be very hard to predict as Vcc wanders around the 4.5-volt level. Some devices will respond as though it's a brownout, while others will not.
all arguments for supervisors are based on the selection of a supervisor with the right "activation voltage" if you choose a supervisor with the "activation voltage" of 1V for a 5V system, you will, of course, see no improvement. BTW this is the reason that some circuits can not use the uC's reset output for everything and thus need an external supervisor

What? Did anyone mention the uC's RESET output? The supervisor can't do anything but assert its own RESET output. Not every uC has a bidirectional RESET, and those that do only serve to confuse the situation in this context.

Additionally, I've observed that supervisors do absolutely nothing useful during the power-down transient, aside from activating the RESET. My argument is, once again, that nothing guarantees what happens when RESET is active but Vcc is below the acceptable level.
Well, if you consider statements in the datasheet 'nothing'

In the face of physical evidence, I've concluded that it is, indeed, nothing. They say what active RESET input is supposed to do when Vcc is within specified limits. They say nothing about what happens once Vcc is outside of those limits.

While I'm forced by circumstance to respect the general opinion that a supervisor will, in general, make these problems "go away," I know that nobody has made the assertion that they've spent any time testing that notion. Consequently it's just an unproven hypothesis.
the FDA bases approval on "statistical data" you have the same re this. There are countless posts that after the suggestion of using a supervisor (or in the case of SILabs adding a pullup to the internal super) states "this fixed the problem"

The FDA uses statistics based on what their people can see through a microscope. I've read lots of posts indicating that the "reset problem" went away, without a single indication of how it was determined that there was a "reset problem" at all. Though I've asked you to show indication of a RESET problem, you've never been able to show any evidence, or, for that matter, that you've even tried to find one. You, and others, simply added a supervisor and declared the problem, whatever it was, solved. Now, I can't say there was no RESET problem, since I didn't observe the situation, I have not seen any indication that the "problem", whatever it was, was solved. You simply didn't see itany longer, and that was "good enough" for you. Without firm and rigorous methodology, you simply can't declare a problem "fixed," particularly when you haven't even tracked the problem down to a RESET=related issue.

I'm still convinced that the guys at Intel couldn't get their oscillator to start reliably, so they used a RESET time-constant long enough to convince their boss that it would start most of the time, rather than figuring out how to do it properly.
except for "antique collectors" like you I doubt many care about "the guys at Intel" re the '51

I mention this detail only because nearly every manufacturer has used the crappy old RESET design from Intel in their own examples of "how to do it." It doesn't make sense, even when they do specify a minimal duration of RESET since the RC values produce a pulse many times longer.

The FLASH-corruption issue didn't come about until FLASH-based program store became a reality. This makes the supervisor look more like a fig-leaf rather than a solution. Maybe someone with a real motivation will actually spend the time and resources to perform rigorous testing on the function of the supervisor in this environment rather than allowing it to continue to float in the fog.
repeat/rewording of a statement above, the same answer applies

Erik

PS Richard, do you see how easy it is to follow a post when there is references to what it replies to


Do you, Erik, see how easy it is to follow a post when there is reference to the original?

RE



List of 66 messages in thread
TopicAuthorDate
Sine wave detection on microcontroller      Yagnesh Mehta      03/07/12 04:59      
   Detect or measure?      Per Westermark      03/07/12 05:25      
      not detection, measurement of sine wave signal      Yagnesh Mehta      03/07/12 06:14      
         What are you measuring?      Andy Peters      03/07/12 10:05      
            RMS and Average - 1st Priority      Yagnesh Mehta      03/07/12 20:59      
               415 v      Mahmood Elnasser      03/08/12 22:07      
                  I have to do using MCU      Yagnesh Mehta      03/08/12 22:48      
                     Start simple      Mahmood Elnasser      03/08/12 23:17      
                        if time is major isssue than.....      Yagnesh Mehta      03/08/12 23:31      
                           People responding to specific questions      Per Westermark      03/09/12 02:14      
                              Same Technique....      Yagnesh Mehta      03/09/12 04:32      
                                 RMS      Maarten Brock      03/09/12 05:49      
                                    Sorry for my laziness        Yagnesh Mehta      03/09/12 20:50      
                                 So what have you done?      Per Westermark      03/09/12 06:19      
                                    Require more work...      Yagnesh Mehta      03/10/12 00:50      
                                    Working on that      Yagnesh Mehta      03/10/12 06:12      
                                       options, options      Per Westermark      03/10/12 06:49      
   Help me      Yagnesh Mehta      03/08/12 21:31      
      Okay      Joseph Hebert      03/09/12 06:13      
         Are many threads available      Per Westermark      03/09/12 06:29      
      when you save a char ...        Erik Malund      03/09/12 08:09      
      Why don't you specify your problem COMPLETELY?      Richard Erlacher      03/09/12 11:36      
         Already specify it      Yagnesh Mehta      03/10/12 02:07      
            there are some details?      Richard Erlacher      03/10/12 07:51      
               comparisions      Yagnesh Mehta      03/12/12 01:16      
                  How are you calculating your needed sample rate?      Per Westermark      03/12/12 01:54      
                     start with simple one....      Yagnesh Mehta      03/12/12 08:02      
                        You do know sin(90+angle)? Or 2-log computations?      Per Westermark      03/12/12 08:48      
                           ADC resolution............      Yagnesh Mehta      03/12/12 12:27      
                              impossible or wrong      Erik Malund      03/12/12 13:30      
                              double post, ignore      Erik Malund      03/12/12 13:30      
                  Precision Rectify:      Erik Malund      03/12/12 06:44      
                     SCR Chopped Wave      Yagnesh Mehta      03/12/12 07:48      
                        What accuracy do you need?      Kalpak Dabir      03/12/12 08:43      
                           CT accuracy      Yagnesh Mehta      03/12/12 12:58      
                              the fundamental      Erik Malund      03/12/12 13:41      
                              50Hz      Per Westermark      03/12/12 14:27      
                              Precision rectifier is suitable for any waveform      Kalpak Dabir      03/13/12 01:47      
                                 are u sure??      Yagnesh Mehta      03/13/12 08:03      
                                    Depends      Per Westermark      03/13/12 09:08      
                                    must be severely bandwidth limited      Erik Malund      03/13/12 09:11      
                                       Maybe was circuit with top-voltage capacitor      Per Westermark      03/13/12 09:17      
                                       Sorry for confusion      Yagnesh Mehta      03/14/12 00:18      
                                          What accuracy do you need?      Kalpak Dabir      03/14/12 01:23      
                                             360/1024      Yagnesh Mehta      03/14/12 01:41      
                                                Not what he (or me) have asked      Per Westermark      03/14/12 04:39      
                                                   you are right....      Yagnesh Mehta      03/14/12 11:51      
                                                Do you believe you can protect your circuit from noise?      Richard Erlacher      03/14/12 08:19      
                                                   Very Noisy environment      Yagnesh Mehta      03/14/12 11:57      
                                                      re Very Noisy environment      Erik Malund      03/14/12 12:23      
                                                         Some of those rules are showing their age      Richard Erlacher      03/14/12 20:00      
                                                            here we go again      Erik Malund      03/15/12 08:15      
                                                               think about this for a minute      Richard Erlacher      03/15/12 17:10      
                                                                  when discussing a FAQ      Erik Malund      03/16/12 06:49      
                                                                     Well, when were those cap sizes determined?      Richard Erlacher      03/16/12 09:53      
                                                                        Technology      Per Westermark      03/16/12 10:13      
                                                                           Steady state currents do not need decaps      Kalpak Dabir      03/16/12 22:48      
                                                                              Often low capacitance so limited charge. But remember load.      Per Westermark      03/17/12 06:41      
                                                                        fixations      Erik Malund      03/16/12 10:40      
                                                                           Nothing. has been proven yet.      Richard Erlacher      03/18/12 13:15      
                                                                              once more for the peanut gallery      Erik Malund      03/19/12 07:23      
                                                                                 Where you sit determines what you see ...      Richard Erlacher      03/20/12 01:56      
                                                                                    Off-topic        Per Westermark      03/20/12 02:01      
                                                                                       difficult when ...      Erik Malund      03/20/12 06:59      
                                                                                       Yes ... I don't know how we got here either      Richard Erlacher      03/20/12 09:32      
                                                                                          i do      Erik Malund      03/20/12 09:45      

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