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10/10/05 13:14
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#102168 - Software Based RTC
Hello,
IN the article published in this website about designing a software based RTC I have a confusion on the statements put forth. Cut and pasting the same for everyone's understanding here ...

" In the tutorial published in the 8052 website I found the following sentences which are contradicting
"This means we can't simply count the number of overflows from it counting from 0 to 65536. We'll be introducing even more inaccuracy. In the case of an 11.0592Mhz crystal, this inaccuracy will be about 0.44%, but if we were to use this same program with a 12.000Mhz crystal, the inaccuracy would be 1.70% which is much worse. Other crystal frequencies could result in even less accuracy. Generally, the slower the crystal, the more pronounced the error will be-and the error can easily become significant."

So here I am unable to understand whether using higher frequency will reduce the error or using lower frequency and also how is this percentage derived?

Thanks,


List of 19 messages in thread
TopicAuthorDate
Software Based RTC            01/01/70 00:00      
   Context            01/01/70 00:00      
      Link to my RTC - sftware crystal freq.            01/01/70 00:00      
   The precision is depending on the fracti            01/01/70 00:00      
   How to count seconds            01/01/70 00:00      
      How to decide count for a 3.5795Mhz,            01/01/70 00:00      
         the frequency range does not matter            01/01/70 00:00      
            the "tricks"            01/01/70 00:00      
         3.93216MHz is better            01/01/70 00:00      
            4.915200            01/01/70 00:00      
            3.93216 ??            01/01/70 00:00      
               3.93216 is standard frequency            01/01/70 00:00      
                  Can i have some clarifications on XTALS            01/01/70 00:00      
                     manufacturing tolerances            01/01/70 00:00      
                        low frequencies Crystals are bigger ?            01/01/70 00:00      
                     32.768kHz means low current consumption            01/01/70 00:00      
                        so higher Frequeny crystals are accurate            01/01/70 00:00      
                           Yes!            01/01/70 00:00      
   The Right Frequency            01/01/70 00:00      

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