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???
08/10/07 08:00
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 		 #143036 - can you please be more precise...
Responding to: ???'s previous message
Richard Erlacher said:
I've done a little experimenting with RESET and with Vcc fall times. If I use a really hefty linear power supply, one which, with the on-board ~2750 uF of capacitance still produces a rise time on Vcc of about 140 microseconds, when switched on, I see no observable flaws in the RESET behavior. However, when I switch off the power, regardless of whether I use a DALLAS, Philips, Signetics, Siemens, or Intel MCU, it frequently (about one time in 6) corrupts my BBRAM, which is mapped into both data and program space. It does not exhibit this behavior on a pushbutton RESET.


Can you be please more precise in describing, what exactly you did, what was the circuit (especially the chipselect and power of the BB RAM - is it the type integrated with battery, or a standard SRAM and a battery?), and what were the results?


--

Or, do I understand it right, that you DID NOT use a proper reset IC with this experiments? And, do I understand it right, that you encountered NO BBRAM corruption when holding the reset input high by a pusbutton, while playing with VCC?

If this is the case, is this not enough evidence for you, that it IS the reset IC (which "holds" the "button" for you upon power failure) which is what you really need to prevent the BBRAM corruption, and NOT any sophisticated precise VCC control?

JW


List of 29 messages in thread
TopicAuthorDate
reset supervisors            01/01/70 00:00      
   two purposes of the IC (at least)            01/01/70 00:00      
      Unfortunately, they seem to fail at one of them            01/01/70 00:00      
         you are talking about the RC resets, I assume            01/01/70 00:00      
            No, I'm referring to the DS and Max 1232            01/01/70 00:00      
               and what            01/01/70 00:00      
                  It's just not that simple ...            01/01/70 00:00      
                     I am getting tired            01/01/70 00:00      
                        Reset chips do work properly and prevent damage!            01/01/70 00:00      
                           I never doubted that, Kai            01/01/70 00:00      
                              can you please be more precise...            01/01/70 00:00      
                                 Yes            01/01/70 00:00      
                              It is a black box and you will never find out...            01/01/70 00:00      
                                 It\'s the power supply, and probably not the reset.            01/01/70 00:00      
                                    That's not what the bible states...            01/01/70 00:00      
                                       Isn't that the same thing with different syntax?            01/01/70 00:00      
                                          No, is not. Look at INTEL's original C51 manual!            01/01/70 00:00      
                                             Vcc rise time            01/01/70 00:00      
                                                It can, I believe, be done simply.            01/01/70 00:00      
                                             Brown-out Bug Chasing            01/01/70 00:00      
                                                Seems reasonable            01/01/70 00:00      
                                             There's been nothing specific enough to test.            01/01/70 00:00      
                                                Some hints            01/01/70 00:00      
                                                   it's a thorny problem            01/01/70 00:00      
                                                      Add a monoflop            01/01/70 00:00      
                                                         I\'ve got to be careful ...            01/01/70 00:00      
                        Jan, you\'re missing my point!            01/01/70 00:00      
                           that's too easy to answer            01/01/70 00:00      
                              You have stories, but no specifics            01/01/70 00:00      

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