casova konstanta

[Libor]

Nejak mi to nepocita.....
Krystal jsem dal 4096
program takovyto

 void interrupt() { 
   timeticks++; 
   INTCON = 0x20;           // Set T0IE, clear T0IF 
 
 
 } 
 
 
 main 
   OPTION_REG = 0x00; 
   INTCON = 0xA0;           // Enable TMRO interrupt 
 


jedna sekunda by mela byt  timeticks=4000 , ale zati m mi 4000 casove 
vychazi pres 2 sekundy.
Diky za radu...

LK


Marek Pavlu wrote:
> Nepouzivejte 4,000MHz, ale 4,096MHz krystal. 
>
> Delicku k TMR0 vypnete, tim ziskate preruseni kazdych: 
>
>
> 4,096 * 10^6 / 4 / 256  = 4000 
>
> Preruseni kazdych 0.25 ms, coz uz staci napocitat do ctyr a mate presne 1ms.
>
> Nicmene kondiky u krystalu Vam lehce ovlivni vysledny kmitocet tez... 
>
>
> M. Pavlu 
>                 
>
>
>   
>>>  -----Original Message----- 
>>>  From: hw-list-bounces@list.hw.cz [mailto:hw-list-bounces@list.hw.cz] 
>>>  On Behalf Of Libor 
>>>  Sent: Saturday, June 16, 2007 8:03 PM 
>>>  To: HW-news 
>>>  Subject: casova konstanta 
>>>  
>>>  Zdravim 
>>>  Mel bych dotaz jestli by mi nekdo nezkontroloval tento kod pro 
>>>  microchoip 16f627 
>>>  
>>>  Clock je 4MHZ crystal a potreboval bych aby promenna timeticks 
>>>  ukazovala 
>>>  co nejpresneji milisekundy cili timeticks = 1000   => 1 sekunda 
>>>  
>>>  void interrupt() { 
>>>    timeticks++; 
>>>    TMR0   = 101; 
>>>    INTCON = 0x20;           // Set T0IE, clear T0IF 
>>>  
>>>  
>>>  } 
>>>  
>>>  
>>>  main 
>>>    OPTION_REG = 0x01; 
>>>    TMR0  = 101; 
>>>    INTCON = 0xA0;           // Enable TMRO interrupt 
>>>  
>>>  Mockrat diky 
>>>  
>>>  LK 
>>>  _______________________________________________ 
>>>  HW-list mailing list  -  sponsored by www.HW.cz 
>>>  Hw-list@list.hw.cz 
>>>  http://list.hw.cz/mailman/listinfo/hw-list 
>>>       
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