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'[PIC] Long power supply fall time SOLVED!'
2005\05\05@162230 by Mauricio Jancic

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Hi,
       Here was the problem:

       [SNIP]

       get_time();                                // Get time from RTC

       if(time[SEGUNDOS] & 0x80)        // If the RTC oscillator is off
       {
               time[SEGUNDOS] = (time[SEGUNDOS]+1) & 0x3F;        // Get the
actual second and clear the 8th bit to
       
// enable the oscillator
               save_time();                                                //
Save time -> saves hour, mins and secs
       }

       [SNIP]

       As you can see, one the RTC was powering down, one should read
FF:FF:FF as the time, so the program will interpret that the oscillator was
off and then re-write the time (recently read) which was off course
incorrect.

       This was solved eliminating that part of the code and adding a piece
of code that detects when the PIC reads an incorrect time, like FF hours...
Then, print "E" as an error message on the display. Approximately 200ms
before the display is off (when the board is unplugged) is shows that E...
Just tested 230 cycles successfully-

       Thank to all of you guys!!


Mauricio

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