//////////////////////////////////////////////////////////////////////////
////                               DS1302.C                           ////
////                     Driver for Real Time Clock                   ////
////                                                                  ////
////  rtc_init()                                   Call after power up////
////                                                                  ////
////  rtc_set_datetime(day,mth,year,dow,hour,min)  Set the date/time  ////
////                                                                  ////
////  rtc_get_date(day,mth,year,dow)               Get the date       ////
////                                                                  ////
////  rtc_get_time(hr,min,sec)                     Get the time       ////
////                                                                  ////
////  rtc_write_nvr(address,data)                  Write to NVR       ////
////                                                                  ////
////  data = rtc_read_nvr(address)                 Read from NVR      ////
////                                                                  ////
//////////////////////////////////////////////////////////////////////////
////        (C) Copyright 1996,1997 Custom Computer Services            ////
//// This source code may only be used by licensed users of the CCS C   ////
//// compiler.  This source code may only be distributed to other       ////
//// licensed users of the CCS C compiler.  No other use, reproduction  ////
//// or distribution is permitted without written permission.           ////
//// Derivative programs created using this software in object code     ////
//// form are not restricted in any way.                                ////
////////////////////////////////////////////////////////////////////////////

#ifndef RTC_SCLK

#define RTC_SCLK PIN_B1
#define RTC_IO   PIN_B3
#define RTC_RST  PIN_B2

#endif


void write_ds1302_byte(byte cmd) {
   byte i;

   for(i=0;i<=7;++i) {
      output_bit(RTC_IO, shift_right(&cmd,1,0) );
      output_high(RTC_SCLK);
      output_low(RTC_SCLK);
   }
}

void write_ds1302(byte cmd, byte data) {

   output_high(RTC_RST);
   write_ds1302_byte(cmd);
   write_ds1302_byte(data);
   output_low(RTC_RST);
}

byte read_ds1302(byte cmd) {
   byte i,data;

   output_high(RTC_RST);
   write_ds1302_byte(cmd);

   for(i=0;i<=7;++i) {
      shift_right(&data,1,input(RTC_IO));
      output_high(RTC_SCLK);
      delay_us(2);
      output_low(RTC_SCLK);
      delay_us(2);
   }
   output_low(RTC_RST);
   return(data);
}

void rtc_init() {
   byte x;
   output_low(RTC_RST);
   output_low(RTC_SCLK);
   write_ds1302(0x8e,0);
   write_ds1302(0x90,0xa6);
   x=read_ds1302(0x81);
   if((x & 0x80)!=0)
     write_ds1302(0x80,0);
}

void rtc_set_datetime(byte day,byte mth,byte year,byte dow,byte hr,byte min) {
   write_ds1302(0x86,day);
   write_ds1302(0x88,mth);
   write_ds1302(0x8c,year);
   write_ds1302(0x8a,dow);
   write_ds1302(0x84,hr);
   write_ds1302(0x82,min);
   write_ds1302(0x80,0);
}

void rtc_get_date(byte & day,byte & mth,byte & year,byte & dow) {
   day = read_ds1302(0x87);
   mth = read_ds1302(0x89);
   year = read_ds1302(0x8d);
   dow = read_ds1302(0x8b);
}


void rtc_get_time(byte & hr,byte & min,byte & sec) {
   hr = read_ds1302(0x85);
   min = read_ds1302(0x83);
   sec = read_ds1302(0x81);
}

void rtc_write_nvr(byte address,byte data) {
   write_ds1302(address|0xc0,data);
}

byte rtc_read_nvr(byte address) {
    return(read_ds1302(address|0xc1));
}