Code

gistfile1.txt

/*
 * ds1302.c:
 *	Real Time clock
 *
 * Copyright (c) 2013 Gordon Henderson.
 ***********************************************************************
 * This file is part of wiringPi:
 *	https://projects.drogon.net/raspberry-pi/wiringpi/
 *
 *    wiringPi is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    wiringPi is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the GNU Lesser General Public License
 *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
 ***********************************************************************
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <time.h>

#include <wiringPi.h>
#include <ds1302.h>

// Register defines

#define	RTC_SECS	 0
#define	RTC_MINS	 1
#define	RTC_HOURS	 2
#define	RTC_DATE	 3
#define	RTC_MONTH	 4
#define	RTC_DAY		 5
#define	RTC_YEAR	 6
#define	RTC_WP		 7
#define	RTC_TC		 8
#define	RTC_BM		31


static unsigned int masks [] = { 0x7F, 0x7F, 0x3F, 0x3F, 0x1F, 0x07, 0xFF } ;


/*
 * bcdToD: dToBCD:
 *	BCD decode/encode
 *********************************************************************************
 */

static int bcdToD (unsigned int byte, unsigned int mask)
{
  unsigned int b1, b2 ;
  byte &= mask ;
  b1 = byte & 0x0F ;
  b2 = ((byte >> 4) & 0x0F) * 10 ;
  return b1 + b2 ;
}

static unsigned int dToBcd (unsigned int byte)
{
  return ((byte / 10) << 4) + (byte % 10) ;
}


/*
 * ramTest:
 *	Simple test of the 31 bytes of RAM inside the DS1302 chip
 *********************************************************************************
 */

static int ramTestValues [] =
  { 0x00, 0xFF, 0xAA, 0x55, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x00, 0xF0, 0x0F, -1 } ;

static int ramTest (void)
{
  int addr ;
  int got ;
  int i = 0 ;
  int errors = 0 ;
  int testVal ;

  printf ("DS1302 RAM TEST\n") ;

  testVal = ramTestValues [i] ;

  while (testVal != -1)
  {
    for (addr = 0 ; addr < 31 ; ++addr)
      ds1302ramWrite (addr, testVal) ;

    for (addr = 0 ; addr < 31 ; ++addr)
      if ((got = ds1302ramRead (addr)) != testVal)
      {
	printf ("DS1302 RAM Failure: Address: %2d, Expected: 0x%02X, Got: 0x%02X\n",
		addr, testVal, got) ;
	++errors ;
      }
    testVal = ramTestValues [++i] ;
  }

  for (addr = 0 ; addr < 31 ; ++addr)
    ds1302ramWrite (addr, addr) ;

  for (addr = 0 ; addr < 31 ; ++addr)
    if ((got = ds1302ramRead (addr)) != addr)
    {
      printf ("DS1302 RAM Failure: Address: %2d, Expected: 0x%02X, Got: 0x%02X\n",
	      addr, addr, got) ;
      ++errors ;
    }

  if (errors == 0)
    printf ("-- DS1302 RAM TEST: OK\n") ;
  else
    printf ("-- DS1302 RAM TEST FAILURE. %d errors.\n", errors) ;

  return 0 ;
}

/*
 * setLinuxClock:
 *	Set the Linux clock from the hardware
 *********************************************************************************
 */

static int setLinuxClock (void)
{
  char dateTime [20] ;
  char command [64] ;
  int  clock [8] ;


  printf ("Setting the Linux Clock from the DS1302... ") ; fflush (stdout) ;

  ds1302clockRead (clock) ;

// [MMDDhhmm[[CC]YY][.ss]]

  sprintf (dateTime, "%02d%02d%02d%02d%02d%02d.%02d",
	bcdToD (clock [RTC_MONTH], masks [RTC_MONTH]),
	bcdToD (clock [RTC_DATE],  masks [RTC_DATE]),
	bcdToD (clock [RTC_HOURS], masks [RTC_HOURS]),
	bcdToD (clock [RTC_MINS],  masks [RTC_MINS]),
	20,
	bcdToD (clock [RTC_YEAR],  masks [RTC_YEAR]),
	bcdToD (clock [RTC_SECS],  masks [RTC_SECS])) ;

  sprintf (command, "/bin/date %s", dateTime) ;
  system (command) ;

  return 0 ;
}


/*
 * setDSclock:
 *	Set the DS1302 block from Linux time
 *********************************************************************************
 */

static int setDSclock (void)
{
  struct tm t ;
  time_t now ;
  int clock [8] ;

  printf ("Setting the clock in the DS1302 from Linux time... ") ;

  now = time (NULL) ;
  gmtime_r (&now, &t) ;

  clock [ 0] = dToBcd (t.tm_sec) ;	// seconds
  clock [ 1] = dToBcd (t.tm_min) ;	// mins
  clock [ 2] = dToBcd (t.tm_hour) ;	// hours
  clock [ 3] = dToBcd (t.tm_mday) ;	// date
  clock [ 4] = dToBcd (t.tm_mon + 1) ;	// months 0-11 --> 1-12
  clock [ 5] = dToBcd (t.tm_wday + 1) ;	// weekdays (sun 0)
  clock [ 6] = dToBcd (t.tm_year - 100) ;       // years
  clock [ 7] = 0 ;			// W-Protect off

  ds1302clockWrite (clock) ;

  printf ("OK\n") ;

  return 0 ;
}




int main (int argc, char *argv [])
{
  int i ;
  int clock [8] ;

  wiringPiSetup () ;
  ds1302setup   (0, 1, 2) ;

  if (argc == 2)
  {
    /**/ if (strcmp (argv [1], "-slc") == 0)
      return setLinuxClock () ;
    else if (strcmp (argv [1], "-sdsc") == 0)
      return setDSclock () ;
    else if (strcmp (argv [1], "-rtest") == 0)
      return ramTest () ;
    else
    {
      printf ("Usage: ds1302 [-slc | -sdsc | -rtest]\n") ;
      return EXIT_FAILURE ;
    }
  }

  for (i = 0 ;; ++i)
  {
    printf ("%5d:  ", i) ;

    ds1302clockRead (clock) ;
    printf (" %2d:%02d:%02d",
	bcdToD (clock [2], masks [2]), bcdToD (clock [1], masks [1]), bcdToD (clock [0], masks [0])) ;

    printf (" %2d/%02d/%04d",
	bcdToD (clock [3], masks [3]), bcdToD (clock [4], masks [4]), bcdToD (clock [6], masks [6]) + 2000) ;
      
    printf ("\n") ;

    delay (200) ;
  }
 
  return 0 ;
}