//////////////////////////////////////////////////////////////////////////
////                              NJU6355.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       ////
////                                                                  ////
//////////////////////////////////////////////////////////////////////////
////        (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_CE

#define RTC_IO    PIN_B3
#define RTC_CE    PIN_B2
#define RTC_CLK   PIN_B1
#define RTC_DATA  PIN_B0

#endif


void rtc_init() {
   output_low(RTC_CE);
   output_low(RTC_IO);
}


void write_rtc_byte(byte data_byte, byte number_of_bits) {
   byte i;

   for(i=0; i<number_of_bits; ++i) {
      if((data_byte & 1)==0)
        output_low(RTC_DATA);
      else
        output_high(RTC_DATA);
      data_byte=data_byte>>1;
      output_high(RTC_CLK);
      output_low(RTC_CLK);
   }
}


byte read_rtc_byte(byte number_of_bits) {
   byte i,data;

   for(i=0;i<number_of_bits;++i) {
      output_high(RTC_CLK);
      shift_right(&data,1,input(RTC_DATA));
      output_low(RTC_CLK);
   }
   return(data);
}


void rtc_set_datetime(byte day,byte mth,byte year,byte dow,
                      byte hour,byte min) {

   output_low(RTC_CLK);
   output_high(RTC_IO);
   output_high(RTC_CE);
   write_rtc_byte(year,8);
   write_rtc_byte(mth,8);
   write_rtc_byte(day,8);
   write_rtc_byte(dow,4);
   write_rtc_byte(hour,8);
   write_rtc_byte(min,8);
   output_low(RTC_CE);
   output_low(RTC_IO);
}


void rtc_get_date(byte & day,byte & mth,byte & year,byte & dow) {
   byte i;

   output_low(RTC_CLK);
   output_low(RTC_IO);
   output_high(RTC_CE);
   year=read_rtc_byte(8);
   mth=read_rtc_byte(8);
   day=read_rtc_byte(8);
   dow=read_rtc_byte(4)>>4;

   read_rtc_byte(8*3);
   output_low(RTC_CE);
   output_low(RTC_IO);
}


void rtc_get_time(byte & hr,byte & min,byte & sec) {
   byte i;

   output_low(RTC_CLK);
   output_low(RTC_IO);
   output_high(RTC_CE);
   read_rtc_byte(8*3+4);
   hr=read_rtc_byte(8);
   min=read_rtc_byte(8);
   sec=read_rtc_byte(8);

   output_low(RTC_CE);
   output_low(RTC_IO);
}