File content as of revision 2:66dbf3ae0f89:

#include "ds1337.h"

#define TIME_LENGTH 8 //Length of buffer needed for time/date

DS1337::DS1337(PinName sda, PinName scl) : _i2c(sda, scl)
{
    _i2c.frequency(DS1337_I2C_FCY);
    memset(err, 0, ERR_BUFFER_LEN);
}

void DS1337::time2str(Time * t, char * str)
{
    sprintf(str, "%02d/%02d/%04d-%02d:%02d:%02d",t->tm_mon, t->tm_mday,(t->tm_year+1900), t->tm_hour,t->tm_min,t->tm_sec);
}

bool DS1337::now(Time * now)
{
    buffer[0] = 0x00; // memory address
    
    if (_i2c.write(DS1337_ADDR, &buffer[0], 1) != 0) 
    {
        sprintf(err, "RTC command write Failed");
        return false;
    }
    
    if (_i2c.read(DS1337_ADDR, buffer, DS1337_BUFFER_SIZE) != 0) 
    {
        sprintf(err, "RTC buffer read Failed");
        return false;
    }
   
    if (buffer[0] & 0x80) 
    {
        sprintf(err, "Clock Stopped");
        return false;
    }
    
    if (buffer[2] & 0x40) 
    {
        sprintf(err, "12hour not supported");
        return false;
    }
    
    now->tm_sec = bcdToDecimal(buffer[0] & 0x7F);
    now->tm_min = bcdToDecimal(buffer[1] & 0x7F);
    now->tm_hour = bcdToDecimal(buffer[2] & 0x3F);
    now->tm_wday = buffer[3] & 0x07;
    now->tm_mday = bcdToDecimal(buffer[4] & 0x3F);
    now->tm_mon = bcdToDecimal(buffer[5] & 0x1F);
    now->tm_year = bcdToDecimal(buffer[6] & 0xFF);
    
    return true;
}

bool DS1337::set_time(Time * now)
{
    buffer[0] = 0x00; // memory address
    buffer[1] = decimalToBcd(now->tm_sec) & 0x7F;
    buffer[2] = decimalToBcd(now->tm_min) & 0x7F;
    buffer[3] = decimalToBcd(now->tm_hour) & 0x3F; // 24-hour format
    buffer[4] = now->tm_wday & 0x07;
    buffer[5] = decimalToBcd(now->tm_mday) & 0x3F;
    buffer[6] = decimalToBcd(now->tm_mon) & 0x1F;
    buffer[7] = decimalToBcd(now->tm_year) & 0xFF;
    
    if (_i2c.write(DS1337_ADDR, buffer, TIME_LENGTH) != 0) 
    {
        sprintf(err, "RTC command write Failed");
        return false;
    }

    return true;
}