rtccsetcalibration.c

Mplab C30编译器

#if defined(__PIC24F__)
#include <p24Fxxxx.h>
#endif
#include "Rtcc.h"


#ifdef _TMR_RTCC_V1

/**********************************************************************************************
 Function:         void RtccSetCalibration(int drift)
 
 PreCondition:     drift has to fit into signed 8 bits representation 
 
 Input:            drift - value to be added/subtracted to perform calibration 
 
 Output:           None
 
 Side Effects:     None
 
 Overview:         The function updates the value that the RTCC uses in the
                   auto-adjust feature, once every minute.
                   The drift value acts as a signed value, [-128*4, +127*4], 0 not having
                   any effect.
                   
 Note:             Writes to the RCFGCAL.CAL[7:0] register should  only occur when the timer
                   is turned off or immediately or after the edge of the seconds pulse
                   (except when SECONDS=00 - due to the possibility of the auto-adjust event).
                   In order to speed-up the process, the API function performs the reading
                   of the HALFSEC field.
                   The function may block for half a second, worst case, when called
                   at the start of the minute.
                   Interrupts can not be disabled for such a long period. However, long 
                   interrupt routines can interfere with the proper functioning of the
                   device.Care must be taken.
 ***********************************************************************************************/
void RtccSetCalibration(int drift)
{
   if(mRtccIsOn())
   {
       UINT16  currSec;
       mRtccClearRtcPtr();     // make sure you read seconds
       if((currSec=RTCVAL)&0xff==00)
       {   // we're at second 00, wait auto-adjust to be performed
           while(!mRtccIs2ndHalfSecond()); // wait until second half...
       }
   }
   
   // update the CAL value
   RCFGCALbits.CAL=drift;
}

#else
#warning "Does not build on this target"
#endif