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rtc.c

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//*****************************************************************************
//
// File Name    : 'rtc.c'
// Title                        : real-time clock function library
// Author               : Pascal Stang - Copyright (C) 2002
// Created              : 5/10/2002
// Revised              : 7/12/2002
// Version              : 0.5
// Target MCU   : Atmel AVR Series
// Editor Tabs  : 3
//
// NOTE: This code is currently below version 1.0, and therefore is considered
// to be lacking in some functionality or documentation, or may not be fully
// tested.  Nonetheless, you can expect most functions to work.
//
// This code is distributed under the GNU Public License
//              which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

//***Changes by MG
// line 87 changed [month-1] to [RtcTime.month-] (was causing compiler error)
#ifndef WIN32
        #include <io.h>
        #include <sig-avr.h>
        #include <interrupt.h>
        #include <progmem.h>
#endif

#include "global.h"
#include "timer.h"
#include "rtc.h"

// Program ROM constants
static char __attribute__ ((progmem)) MonthDayTable[] = {31,28,31,30,31,30,31,31,30,31,30,31};

// Global variables
// time registers
RtcTimeType RtcTime;

void rtcInit(void)
{
        // set up timer for RTC operation
        // initialize real-time registers
        RtcTime.totaltics = 0;
        RtcTime.tics = 0;
        RtcTime.seconds = 0;
        RtcTime.minutes = 0;
        RtcTime.hours = 0;
        RtcTime.day = 1;
        RtcTime.month = 1;
        RtcTime.year = 2000;

        // initialize timer 2
        timer2Init();
        // count with 32.768KHz/8
        timer2SetPrescaler(TIMER_CLK_DIV8);
        // switch to asynchronous input (32KHz crystal)
        sbi(ASSR, AS2);

        // attach service to real-time clock interrupt
        // rtcService() will be called at ((32768/8)/256) = 16Hz
        timerAttach(TIMER2OVERFLOW_INT, rtcService);
}

void rtcService(void)
{
        // update real-time clock registers
        RtcTime.totaltics++;
        RtcTime.tics++;
        // check for overflows
        if(RtcTime.tics == 16)                                                  // tics
        {
                RtcTime.tics = 0;
                RtcTime.seconds++;                                                      // increment seconds
                if(RtcTime.seconds > 59)                                        // check seconds overflow
                {
                        RtcTime.seconds -= 60;
                        RtcTime.minutes++;                                              // increment minutes
                        if(RtcTime.minutes > 59)                                // check minutes overflow
                        {
                                RtcTime.minutes -= 60;
                                RtcTime.hours++;                                                // increment hours
                                if(RtcTime.hours > 23)                          // check hours overflow
                                {
                                        RtcTime.hours -= 24;
                                        RtcTime.day++;                                          // increment days
                                        if(RtcTime.day == PRG_RDB(&MonthDayTable[RtcTime.month-1]))// check days overflow
                                        {
                                                RtcTime.day = 1;
                                                RtcTime.month++;                                // increment months
                                                if(RtcTime.month == 13)         // check months overflow
                                                {
                                                        RtcTime.month = 1;
                                                        RtcTime.year++;                 // increment years
                                                }
                                        }
                                }
                        }
                }
        }
}

RtcTimeType* rtcGetTime(void)
{
        // return the real-time clock data
        return &RtcTime;
}

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