Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
03/01/07 21:03
Modified:
  03/01/07 21:44
Read: times


 
Msg Score: +1
 +1 Good Answer/Helpful		 #134050 - So long post...
Responding to: ???'s previous message
Richard,

I tried to read the whole text you posted but at some line I lost the idea in the whole due my English, sorry.

The OP, here: Kai said:
Just finished a testing to analyze how the AT89S52
[skip]
The testing showed, that the internal Pierce oscillator (quartz crystal oscillator) starts at V=2.0V with rising supply voltage. And, to my surpise, keeps running down to Vcc=1.3V with falling supply voltage!

(bold made by me)

The all post is about that oscillator keeps run for some time when the power falls down - which causes undefined bahaviour of MCU.
So:
RC reset may help when power-on (not always: it depends on off-then-on pause duration);
RC reset cannot help with power-off. As Erik said: it does nothing in this case! Well, modifyed sñheme with diode across resistor may help - but this is separate question, sure.

Finalize: the topic is not about how flash memory accepts power-off but about that MCU may destroy its content due this time.

On old mask/OTP MCU it may cause just malfunction; on "modern" MCU it may cause permanent system failure. Because, select yourself:
- flash utilization;
- absense of power/reset supervisor.

Regards,
Oleg

[Edited] no, even diode cannot help due positive reset - sorry.

List of 147 messages in thread
TopicAuthorDate
Pierce oscillator runs down to Vcc=1.3V!            01/01/70 00:00      
   you should get a probing set...            01/01/70 00:00      
      I keep the micro always reseted, ...            01/01/70 00:00      
      we already know            01/01/70 00:00      
   Low voltage operation            01/01/70 00:00      
      What puzzles me ...            01/01/70 00:00      
         True Reset            01/01/70 00:00      
            Thanks, Lynn, for giving us this deep insight!            01/01/70 00:00      
               Scary warnings            01/01/70 00:00      
               do you not know ...            01/01/70 00:00      
         What I know about this...            01/01/70 00:00      
            I didn't hear complaints about reset back then            01/01/70 00:00      
               MAY???            01/01/70 00:00      
                  Those were different times            01/01/70 00:00      
                     which troubles?            01/01/70 00:00      
                        I don\'t understand your question, Oleg.            01/01/70 00:00      
                           If I could do that, I would be a millionaire from            01/01/70 00:00      
                           There is an overwhelming evidence!            01/01/70 00:00      
                              Conjecture, not Evidence            01/01/70 00:00      
                                 already answered            01/01/70 00:00      
                                    HORSEFEATHERS! ... Read the question            01/01/70 00:00      
                                       Do you put in question, that...            01/01/70 00:00      
                                          Comments on Vdd and Flash            01/01/70 00:00      
                                             not quite true            01/01/70 00:00      
                                                I agree...            01/01/70 00:00      
                                                   by the way            01/01/70 00:00      
                                                      state machine decoding...            01/01/70 00:00      
                                          well Richard did not read it            01/01/70 00:00      
                                             No, I did read it ... in fact, I read it long ago            01/01/70 00:00      
                                                of course you are not            01/01/70 00:00      
                                          reset etc.            01/01/70 00:00      
                                          stories-part II            01/01/70 00:00      
                                             aka experience            01/01/70 00:00      
                                                Another Low VDD Story            01/01/70 00:00      
                                                   That's how many reset chips work            01/01/70 00:00      
                                          about that I have no doubt ...            01/01/70 00:00      
                                       You, even less like to read the answers            01/01/70 00:00      
                                          As I said before ... HORSEFEATHERS!            01/01/70 00:00      
                                             a horse of a different color            01/01/70 00:00      
                                                Flogging a dead (reset?) horse            01/01/70 00:00      
                                                   would that not be the case of            01/01/70 00:00      
                                                      Not defective, just powered down            01/01/70 00:00      
                                                         then where is the difference            01/01/70 00:00      
                                                            Good chips and state machine failures            01/01/70 00:00      
                                                               Reset seems to be different with static 8052            01/01/70 00:00      
                                                                  What do you think about my lines, Lynn?            01/01/70 00:00      
                                                                     Static and Dynamic Reset, and Lines            01/01/70 00:00      
                                                                        Thanks, the hope dies last...            01/01/70 00:00      
                                                                        why?            01/01/70 00:00      
                                                                           Isn't it shocking...            01/01/70 00:00      
                                                                              I know a lot ...            01/01/70 00:00      
                                                                              ...partially...            01/01/70 00:00      
                                                                                 The names and functions            01/01/70 00:00      
                                                                                    the analogy            01/01/70 00:00      
                                                                     Flash and Lines            01/01/70 00:00      
                                                                        So, what the hell is the remedy, then??            01/01/70 00:00      
                                       So long post...            01/01/70 00:00      
                                          Kai's remarks are germane to the issue            01/01/70 00:00      
                                             Stoping the oscillator            01/01/70 00:00      
                                                Lynn, pray explain            01/01/70 00:00      
                                                   Stopped clocks and reset            01/01/70 00:00      
                                                      waitaminute....            01/01/70 00:00      
                                                         This leads to the conclusion that ...            01/01/70 00:00      
                                                            Some further reading            01/01/70 00:00      
                                                   Let's be general            01/01/70 00:00      
                                                      General Reset            01/01/70 00:00      
                                                         So ... how do we fix it?            01/01/70 00:00      
                                                            one thing you could do would be to ..            01/01/70 00:00      
                                                               Tying reset ot crystal enable            01/01/70 00:00      
                                                it's already there... well in some form...            01/01/70 00:00      
                                                   Clock stopping on power-up            01/01/70 00:00      
                                                      we have alternatives...            01/01/70 00:00      
                                             comments            01/01/70 00:00      
                                             reset (and diode)            01/01/70 00:00      
   trying to conclude            01/01/70 00:00      
      Total agree!            01/01/70 00:00      
         That's not quite been my experience            01/01/70 00:00      
      Erik ... That proves nothing!            01/01/70 00:00      
         what else do you want 'proven'            01/01/70 00:00      
            suggestion vs. proof            01/01/70 00:00      
               I need a link            01/01/70 00:00      
                  well, you do not need tp prove it            01/01/70 00:00      
                     I had not considered these ATMEL (yechh) parts            01/01/70 00:00      
                        is there no end?            01/01/70 00:00      
                           coincidence is not proof            01/01/70 00:00      
                              Why on earth would I do that?            01/01/70 00:00      
                                 I would make me do something            01/01/70 00:00      
                                    Sadly, few who are in a position to do something            01/01/70 00:00      
                                 I am not demanding proof because is isn't there.            01/01/70 00:00      
                                    Maybe you can get support from Silabs?            01/01/70 00:00      
                        All manufacturers have problems            01/01/70 00:00      
                           function, not the device            01/01/70 00:00      
                              I like the way you go into the details!            01/01/70 00:00      
                                 It puzzles me that no chip maker has done this.            01/01/70 00:00      
                                    Vdd slew rate as a factor.            01/01/70 00:00      
                                       I have looked, but since it is not one of 'my' der            01/01/70 00:00      
                                          1 ms Vdd slew rates            01/01/70 00:00      
                                             I'd be afraid...            01/01/70 00:00      
                                                nope            01/01/70 00:00      
                                                   if I specify the slew rate for powerdown...            01/01/70 00:00      
                                                No ... I see this as limiting board capcitance            01/01/70 00:00      
                                                   I know...            01/01/70 00:00      
                                                      they get what they deserve!            01/01/70 00:00      
                                                         be realistic            01/01/70 00:00      
                                                            it takes more than a supervisor            01/01/70 00:00      
                                                               shooting sparrows with RPGs            01/01/70 00:00      
                                                                  it's not a sparrow, Erik ... it's a vulture            01/01/70 00:00      
                                                                     as it does not, then why worry            01/01/70 00:00      
                                                                        Erik, I don't know where your head's wedged ...            01/01/70 00:00      
                                                                           An almost off-topic comment on Xilinx JTAG            01/01/70 00:00      
                                                                           there is no problem, so why do you state there is            01/01/70 00:00      
                                                                              ?            01/01/70 00:00      
                                                                                 calrification            01/01/70 00:00      
                                                                              If you would get your head out of your ...            01/01/70 00:00      
                                                                                 well, if you do not want to 'test' the derivatives            01/01/70 00:00      
                                                                                    If you want yours tested, YOU test 'em            01/01/70 00:00      
                                                                                       I did not            01/01/70 00:00      
                                                                                          It's like breaking off the Vcc pin            01/01/70 00:00      
                                                                                             the datasheet states..            01/01/70 00:00      
                                                                                                It's probably ATMEL (yechhh!) that said that            01/01/70 00:00      
                                                                                                rephrased to match this subject            01/01/70 00:00      
                                                               the bulletproof '51            01/01/70 00:00      
                                                                  Custom 8051!            01/01/70 00:00      
                                                                  That is not the goal.            01/01/70 00:00      
                                             very true ...            01/01/70 00:00      
                                          I don't understand, Erik ...            01/01/70 00:00      
                                             READ!!!!!!!!!!!!!!!!!!!!!            01/01/70 00:00      
                                                when SiLabs builds a DIP-40 or PLCC-44 805x            01/01/70 00:00      
                                                   what does the package have to do with slew rate            01/01/70 00:00      
                                                      Erik ... it has to do with what I'll test.            01/01/70 00:00      
                                                         well, if you restrict your test to ancients, then            01/01/70 00:00      
                                                            current parts, but in DIP40 or PLCC44            01/01/70 00:00      
                                                               well you may find that someone sinned but did            01/01/70 00:00      
                                       No manufacturer warns about slew rates!!            01/01/70 00:00      
                                          actually I recall one            01/01/70 00:00      
                           I reread the whole link and            01/01/70 00:00      
                              To Richard            01/01/70 00:00      
                              it's just "lip-service" and means nothing            01/01/70 00:00      
               Please, Richard, only facts            01/01/70 00:00      
                  Kai, you can\'t compare the two environments            01/01/70 00:00      
   re 'lip service'            01/01/70 00:00      
      there you go again ...            01/01/70 00:00      
         unless the chairman of the board confess his sin            01/01/70 00:00      
            What you\'re spewing is nonsense            01/01/70 00:00      
               show what nonsesne you are communicating            01/01/70 00:00      
   what is this still about?            01/01/70 00:00      
      Times change, and so do IC's...            01/01/70 00:00      

Back to Subject List