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???
03/26/08 16:19
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 		 #152568 - Have you seen the pulse?
Responding to: ???'s previous message
Also, read the datasheet chapter "WDT during power down and idle". There you will find the passage: "Exiting power-down with an interrupt is significantly different. The interrupt is held low long enough for the oscillator to stabilize. When the interrupt is brought high, the interrupt is serviced."

So, this

Seemanta said:
However upon consulting the DS12C887 datasheet I found that the /IRQ line is kept low as long as the /IRQ bit does not get read by the micro.


will not work!

You could use the /IRQ output of DS12C887 to trigger a monoflop and feed a suited low pulse to the /INT line of AT89S52.

Kai

List of 42 messages in thread
TopicAuthorDate
Problem waking up from power down mode:AT89S52            01/01/70 00:00      
   Have you seen the pulse?            01/01/70 00:00      
      Saw tthat            01/01/70 00:00      
         I agree!            01/01/70 00:00      
      monoflop IC number?            01/01/70 00:00      
         also know as one shot (in the foot)            01/01/70 00:00      
            Supervisor chip?            01/01/70 00:00      
               try digikey            01/01/70 00:00      
                  Can you explain how that would help?            01/01/70 00:00      
         how about 4538?            01/01/70 00:00      
         You can, but also read this...            01/01/70 00:00      
      Maybe rather than a monoflop....            01/01/70 00:00      
         Ehem...            01/01/70 00:00      
            Ehem....Hmmm            01/01/70 00:00      
               Why messy?            01/01/70 00:00      
               Remember that the oscillator is turned off            01/01/70 00:00      
                  So using a one-shot seems the best idea..right?            01/01/70 00:00      
                     a one shot should always ...            01/01/70 00:00      
                        I tried using an RC circuit...but it did not work            01/01/70 00:00      
                           sorry, I was wrong            01/01/70 00:00      
                              If one shot is a close second...            01/01/70 00:00      
                                 I'd rather not            01/01/70 00:00      
                                    but problem with FF is that            01/01/70 00:00      
                                       ah, Arghmel            01/01/70 00:00      
                           Not same part            01/01/70 00:00      
                     If You Use PCF8563 RTC...            01/01/70 00:00      
                        555 vs '121? Which is better?            01/01/70 00:00      
                           121 ..            01/01/70 00:00      
                              I used a 74LS121 and...            01/01/70 00:00      
                                 yes it will, but            01/01/70 00:00      
                                    HC and HCT?            01/01/70 00:00      
                                       there is this fancy newfangled thing ....            01/01/70 00:00      
                                    There is no 74HC121, but HC123 and HC221            01/01/70 00:00      
                                 Should really consider....            01/01/70 00:00      
                                    I really would consider PCF8563 but...            01/01/70 00:00      
                           Digital pulse is still better            01/01/70 00:00      
                     I would try this            01/01/70 00:00      
                        elegant, but why ....            01/01/70 00:00      
                           You can, of course, but...            01/01/70 00:00      
                              reg power consumtption...            01/01/70 00:00      
                                 Have you seen my circuit?            01/01/70 00:00      
                                    Pulse Mode from RTC,,,,            01/01/70 00:00      

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