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DS1340 RTC driver

 
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gs



Joined: 22 Aug 2005
Posts: 30
Location: Ioannina - Greece

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DS1340 RTC driver
PostPosted: Sun Dec 17, 2006 9:32 am     Reply with quote

Hello, I finally got a DS1340 and played with it the last few days, I post here the results.

The driver checks for the OSF (Oscillator Stop Flag) to check data validity so if you are reading all zeros, you have to re-adjust the time.

Please post any comments for improvements.
Smile


Code:

///////////////////////////////////////////////////////////////////////////////////
///                               DS1340.C                                     ///
///                   Driver for Real Time Clock                      ///
///      For Dallas/Maxim DS1340 RTC (I2C, trickle charge, etc)      ///
///         Based on DS1307 driver.             ///
///                                                                            ///
///    rtc_init()    -Call once at start-up. To Set trickle charge state   ///
///         uncomment the line you want below. No Calibration    ///
///         used here Control byte is set to all 0's      ///
///                                             ///
///                                                                            ///
///    rtc_set_date_time(day,mth,year,dow,hour,min,sec)  Set the date/time     ///
///                                                                           ///
///    rtc_get_date(day,mth,year,dow)               Get the date*      ///
///                                                                        ///
///   rtc_get_time(hr,min,sec)                     Get the time*                ///
///                              ///
///      *(if returned value's are all zeros this means that the clock   ///
///      stopped for some reason and the time is invalid)      ///
///                                                                         ///
///////////////////////////////////////////////////////////////////////////////////

//#define RTC_SDA  PIN_C4
//#define RTC_SCL  PIN_C3

//#use i2c(master, sda=RTC_SDA, scl=RTC_SCL, FORCE_HW)

BYTE bin2bcd(BYTE binary_value);
BYTE bcd2bin(BYTE bcd_value);
void rtc_check_valid();


void rtc_init(void)
{
   BYTE seconds = 0;
   
   i2c_start();
   i2c_write(0xD0);      // WR to RTC
   i2c_write(0x00);      // REG 0
   i2c_start();
   i2c_write(0xD1);            // RD from RTC
   seconds = bcd2bin(i2c_read(0)); // Read current "seconds" in DS1340
   i2c_stop();
   seconds &= 0x7F;

   delay_us(3);

   i2c_start();
   i2c_write(0xD0);            // WR to RTC
   i2c_write(0x00);            // REG 0
   i2c_write(bin2bcd(seconds));    // Start oscillator with current "seconds value

   i2c_start();
   i2c_write(0xD0);   // WR to RTC
   i2c_write(0x07);   // goto Control reg
   i2c_write(0);      // Set control byte to zer0s

   i2c_start();
   i2c_write(0xD0);   // WR to RTC
   i2c_write(0x08);   // goto trickle address

      // Set Trickle Charger byte (uncomment ONLY one of the following)*****************
//   i2c_write(0b00100101);      //  disabled
//   i2c_write(0b10100101);      //  No diode,   250Ω resistor
//   i2c_write(0b10101001);      //  One diode,   250Ω resistor
//   i2c_write(0b10100110);      //  No diode,   2kΩ resistor
//   i2c_write(0b10101010);      //  One diode,   2kΩ resistor
   i2c_write(0b10100111);      //  No diode,   4kΩ resistor
//   i2c_write(0b10101011);      //  One diode,   4kΩ resistor
      // Set Trickle Charger byte

   i2c_stop();
}

void rtc_set_date_time(BYTE day, BYTE mth, BYTE year, BYTE dow, BYTE hr, BYTE min, BYTE sec)
{
  sec &= 0x7F;
  hr &= 0x3F;

   i2c_start();
   i2c_write(0xD0);      // I2C write address
   i2c_write(0x00);      // Start at REG 0 - Seconds
   i2c_write(bin2bcd(sec));   // REG 0
   i2c_write(bin2bcd(min));   // REG 1
   i2c_write(bin2bcd(hr));      // REG 2
   i2c_write(bin2bcd(dow));   // REG 3
   i2c_write(bin2bcd(day));   // REG 4
   i2c_write(bin2bcd(mth));   // REG 5
   i2c_write(bin2bcd(year));   // REG 6

   i2c_start();
   i2c_write(0xD0);   // WR to RTC
   i2c_write(0x09);   // Set OSF address
   i2c_write(0);      // Clear OSF
   i2c_stop();
}

void rtc_get_date(BYTE &day, BYTE &mth, BYTE &year, BYTE &dow)
{
  i2c_start();
  i2c_write(0xD0);
  i2c_write(0x03);            // Start at REG 3 - Day of week
  i2c_start();
  i2c_write(0xD1);
  dow  = bcd2bin(i2c_read() & 0x7f);   // REG 3
  day  = bcd2bin(i2c_read() & 0x3f);   // REG 4
  mth  = bcd2bin(i2c_read() & 0x1f);   // REG 5
  year = bcd2bin(i2c_read(0));      // REG 6
  i2c_stop();

rtc_check_valid();
}

void rtc_get_time(BYTE &hr, BYTE &min, BYTE &sec)
{
  i2c_start();
  i2c_write(0xD0);
  i2c_write(0x00);            // Start at REG 0 - Seconds
  i2c_start();
  i2c_write(0xD1);
  sec = bcd2bin(i2c_read() & 0x7f);
  min = bcd2bin(i2c_read() & 0x7f);
  hr  = bcd2bin(i2c_read(0) & 0x3f);
  i2c_stop();


rtc_check_valid();
}


void rtc_check_valid()
{
int   validity;
   i2c_start();      //read OSF bit to check data validity
    i2c_write(0xD0);
   i2c_write(0x09);
   i2c_start();
   i2c_write(0xD1);
   validity=i2c_read(0);
   i2c_stop();

   if (validity!=0)   //if data not valid make them zeros
   {
   sec=0;
   min=0;
   hour=0;
   dow=0;      
   year=0;
   mth=0;
   day=0;
   }
}



BYTE bin2bcd(BYTE binary_value)
{
  BYTE temp;
  BYTE retval;

  temp = binary_value;
  retval = 0;

  while(1)
  {
    // Get the tens digit by doing multiple subtraction
    // of 10 from the binary value.
    if(temp >= 10)
    {
      temp -= 10;
      retval += 0x10;
    }
    else // Get the ones digit by adding the remainder.
    {
      retval += temp;
      break;
    }
  }

  return(retval);
}


// Input range - 00 to 99.
BYTE bcd2bin(BYTE bcd_value)
{
  BYTE temp;

  temp = bcd_value;
  // Shifting upper digit right by 1 is same as multiplying by 8.
  temp >>= 1;
  // Isolate the bits for the upper digit.
  temp &= 0x78;

  // Now return: (Tens * 8) + (Tens * 2) + Ones

  return(temp + (temp >> 2) + (bcd_value & 0x0f));
}



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YARGICH



Joined: 19 Jan 2007
Posts: 8

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PostPosted: Wed Mar 18, 2009 7:56 pm     Reply with quote

Hi,

I tried to use your ds1340 driver. But when I read hour, minute and second, I always read hour=0x2D, minute=0x55, and second=0x55. what do you think about my problem ?

I am using ds1340c model. You know that, ds1340 have internal xtal in its ds1340c model. Should I define to use this xtal to my ds1340c?

best regards.
gs



Joined: 22 Aug 2005
Posts: 30
Location: Ioannina - Greece

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PostPosted: Thu Mar 19, 2009 4:26 pm     Reply with quote

I don't see any settings on the datasheet specifically for the C version, but I noticed this:
Quote:
All N.C. (no connect) pins must be connected
to ground.


I did not read thorougly the datasheet and the last time I used this chip is some years ago.
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YARGICH



Joined: 19 Jan 2007
Posts: 8

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PostPosted: Thu Mar 19, 2009 6:16 pm     Reply with quote

Thx for your research. I solved this problem. When I read hour, minute, and second data serially, It gave me wrong datas. after that I wrote separate routines to read these datas. Now, It gives me true datas. But in this wise, I must call different routines to take all datas.

Actually it is not important for me. Thanks a lot for DS1340 CCS driver.

Best Regards.
sajjadonline



Joined: 07 Sep 2011
Posts: 2

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tnx for ds1307 library
PostPosted: Wed Feb 27, 2013 3:22 am     Reply with quote

very nice this library gs Smile
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