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???
02/05/06 19:04
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 		 #109245 - Define Immediately
Responding to: ???'s previous message
Peter Chatterton said:
If a PB is pressed you want to immediately update the displays.

Although Erik may opine otherwise, there is no such thing as immediately. There will always be a finite delay between pressing the button and and the system recognising it. Even if the PB is connected directly to an interrupt, the current instruction will complete before the ISR is called and only after it has done its work will the display be updated. I make this point just to illustrate there is no such thing as immediately in software terms.

Using a 10mS poll it takes at most 20mS to recognise and debounce the button which for a human is unrecognisable from immediately.

Ian



List of 41 messages in thread
TopicAuthorDate
Polling vs interrupts in a chess clock.            01/01/70 00:00      
   Polling            01/01/70 00:00      
      Debounce            01/01/70 00:00      
   Either            01/01/70 00:00      
      debounce?            01/01/70 00:00      
         Yes            01/01/70 00:00      
      Alternatively            01/01/70 00:00      
         but PBs update clocks asynchronously            01/01/70 00:00      
            micro time vs real time            01/01/70 00:00      
               One second is a long time in Blitz chess            01/01/70 00:00      
            Use a fast main loop            01/01/70 00:00      
               but this won't let us power-down            01/01/70 00:00      
                  Do what Ian says            01/01/70 00:00      
                     I don't understand            01/01/70 00:00      
                        set a flag in the PB ISR right?            01/01/70 00:00      
                           No pb isr as such.            01/01/70 00:00      
                              The PB INTs wake up the cpu also            01/01/70 00:00      
                                 re: The PB INTs wake up the cpu also            01/01/70 00:00      
                                    Still LCD            01/01/70 00:00      
                              Isn't PB bouncing going to be a problem?            01/01/70 00:00      
                                 No            01/01/70 00:00      
                                    OK, I get it now, thanks            01/01/70 00:00      
                                       In the timer loop            01/01/70 00:00      
                                          Is it?            01/01/70 00:00      
                                             No            01/01/70 00:00      
                                                ISR capability?            01/01/70 00:00      
                                                   Pick a way            01/01/70 00:00      
                                                   ISR reources            01/01/70 00:00      
               Debounce            01/01/70 00:00      
            Define Immediately            01/01/70 00:00      
               No if the debounce is post delay            01/01/70 00:00      
                  Granted            01/01/70 00:00      
               naah and to the question bu the OP            01/01/70 00:00      
   The smartest thing ...            01/01/70 00:00      
      Re the smartest thing            01/01/70 00:00      
         Re Re the smartest thing            01/01/70 00:00      
         as for the character LCD ...            01/01/70 00:00      
            There are several IC to do this            01/01/70 00:00      
               Perhaps it's cheaper ...            01/01/70 00:00      
                  DigiKey has them            01/01/70 00:00      
      Saving Power            01/01/70 00:00      

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