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???
05/03/10 15:47
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#175625 - Modifying design
Responding to: ???'s previous message
Hi Michael and Jez,

Michael wrote:
You could modify your design ...


Actually, that would be (in this case) Arun's job. Actually, in this case, I did not offer a design. I offered an idea. I leave it to the implementor to do his/her own engineering.

(Actually, the reason I keep starting sentences with the word "Actually" is as much because I really enjoyed that A-Team cartoon someone posted as for rhetorical effect.)

Here's my position. Every design choice we make is always a judgement call. But every solution is not necessarily more code. If you have a µ-controller doing nothing but monitoring a thermocouple and a pushbutton, then a firmware debouncing routine is the obvious choice for the pushbutton. But at some point the µ-controller will become sufficiently tasked and taxed that you will have to start asking yourself whether it's worth the compute cycles to debounce the pushbutton. At some point you need to think about using a Schmidt trigger device to debounce the pushbutton.

Unfortunately, I get the impression that a lot of embedded people are starting to get like software people, piling on more and more code and leaving it to the chip designers to make it all fast enough. Basically, unless you know how to do something in hardware, then as a designer it's no longer your choice because you have no choice. It is, IMHO, always best to know how to accomplish a task both ways if possible. Only then can you make an educated choice.

And now Arun, thanks to my initial idea and your added comments, at least has the basis of how he can detect edges in hardware, assuming he can do the requisite engineering to make it sufficiently reliable for his purpose.

Joe

List of 86 messages in thread
TopicAuthorDate
External Interrupt on both Falling edge & rising edge            01/01/70 00:00      
   ABORT!, ABORT!, ABORT!            01/01/70 00:00      
      Better circuits exists            01/01/70 00:00      
      one more            01/01/70 00:00      
   DANGER!! Don't Try This At Home!            01/01/70 00:00      
      Its not just Atmel            01/01/70 00:00      
   interrupts on both edges            01/01/70 00:00      
      Thank you All            01/01/70 00:00      
         Read about external Gate for Timer            01/01/70 00:00      
            gate for timer            01/01/70 00:00      
               Jan, will you Shhhhh!!!            01/01/70 00:00      
               Great Idea !            01/01/70 00:00      
                  But i've used up INT0 and INT1 pins            01/01/70 00:00      
                     int0 is gate for timer0            01/01/70 00:00      
                     T1(T0) pin is not use here            01/01/70 00:00      
                        so only one Ext.int pin will do            01/01/70 00:00      
                           i think so            01/01/70 00:00      
                              I haven't tried it yet            01/01/70 00:00      
                                 is a Zener that costly?            01/01/70 00:00      
                                 so try something safely            01/01/70 00:00      
                                    That the most exhaustive reply i got so far !            01/01/70 00:00      
                                       You are wellcome            01/01/70 00:00      
                                          Here's what i have done            01/01/70 00:00      
                                             simulation is partial            01/01/70 00:00      
                                                I'll try writing a sample code            01/01/70 00:00      
                                                   Dimmer            01/01/70 00:00      
                                                      its a dimmer for commercial sale            01/01/70 00:00      
                                                         Dimmer            01/01/70 00:00      
   Its in my Profile            01/01/70 00:00      
      is 8051/2 I/O similar to Zilog Z8            01/01/70 00:00      
         Cease and Desist            01/01/70 00:00      
         It's DANGEROUS - It's not about the IOs!!            01/01/70 00:00      
         Either you are NOT listening...or you don't want to listen            01/01/70 00:00      
            It's worse than that!            01/01/70 00:00      
               Its like openning Pandora's box            01/01/70 00:00      
                  chip A != chip B != chip C            01/01/70 00:00      
                  Consider these points...            01/01/70 00:00      
                     not a newbie to electronics            01/01/70 00:00      
                        What results do you really get from an experiment?            01/01/70 00:00      
                        Reply to Arun Kumar V            01/01/70 00:00      
                  what if the result is death?            01/01/70 00:00      
                     very positive opinion            01/01/70 00:00      
                     Thanks for the pointer            01/01/70 00:00      
   A generic approach to dual edge detection            01/01/70 00:00      
      Here is the method I have been using...            01/01/70 00:00      
      Oh Noes!!!!!!            01/01/70 00:00      
      4 -> 10 nsec Pulse Does Not Work for MCU            01/01/70 00:00      
         No additional logic gates            01/01/70 00:00      
         Modifying design            01/01/70 00:00      
            Yeah But...            01/01/70 00:00      
               If you say so            01/01/70 00:00      
                  Poppycock            01/01/70 00:00      
   Why you should not do this...            01/01/70 00:00      
      Galvanic isolation            01/01/70 00:00      
         Can't we use single AC optocoupler            01/01/70 00:00      
            not 1,8V            01/01/70 00:00      
            can be wrong circuit below            01/01/70 00:00      
               Critical again...            01/01/70 00:00      
                  varistor?            01/01/70 00:00      
                     Yes, but...            01/01/70 00:00      
            You can do a lot of things...            01/01/70 00:00      
               25V is too coarse            01/01/70 00:00      
                  use tha appnote I gave you the link to            01/01/70 00:00      
                  25V is not bad            01/01/70 00:00      
                     You still don't know what my product is?            01/01/70 00:00      
                        sorry            01/01/70 00:00      
                           Its O.K - this thread has crossed 65 replies            01/01/70 00:00      
                              npn            01/01/70 00:00      
                        no, I do not know what your product is            01/01/70 00:00      
                           Answers            01/01/70 00:00      
                              OK, then            01/01/70 00:00      
                                 No headphones            01/01/70 00:00      
                  Then take a better opto!            01/01/70 00:00      
                     he wants to build a Yogo, not a Mercedes            01/01/70 00:00      
                        which makes the lamp flicker when the fridge turns-off            01/01/70 00:00      
                           it (probably) does that anyhow            01/01/70 00:00      
                              No body wants to buy a Mercedez            01/01/70 00:00      
                                 What do you expect??            01/01/70 00:00      
                                    What is there to be ashamed of ?            01/01/70 00:00      
                                       Thread began with ....            01/01/70 00:00      
                                          Dead Horse is Alive and Kicking            01/01/70 00:00      
                                             obviously a comparator is a better solution            01/01/70 00:00      
                                                Oh My God...you having sleepless nights???            01/01/70 00:00      
                                             Then share it with us...            01/01/70 00:00      
                                             to Arun PLEASE get ...            01/01/70 00:00      
                                 what did you expect            01/01/70 00:00      

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