File content as of revision 0:1377bcf1455e:

/*
 *  PCF2127 library
 *
 *  @author     Akifumi (Tedd) OKANO, NXP Semiconductors
 *  @version    1.5
 *  @date       04-Dec-2014
 *
 *  PCF2127 is a "real time clock (RTC)" module which is including a Xtal and TCXO
 *  http://www.nxp.com/products/interface_and_connectivity/real_time_clocks/rtcs_with_temp_compensation/series/PCF2127.html
 *
 *  RTC initializing part is ported from..
 *    http://mbed.org/users/roen/notebook/real-time/
 *
 *  This code is refined version of..
 *    http://developer.mbed.org/users/okano/code/NXP_PCF2127A/
 */

#include    "mbed.h"
#include    "PCF2127.h"

#define     PCF2127_I2C_SLAVE_ADDRESS   0xA2

PCF2127::PCF2127( PinName sda, PinName sdl, char vControl_1, char vControl_2, char vControl_3 )
    : i2c( sda, sdl ), device_address( PCF2127_I2C_SLAVE_ADDRESS )
{
    set_register( Control_1, vControl_1 );
    set_register( Control_2, vControl_2 );
    set_register( Control_3, vControl_3 );
}

PCF2127::~PCF2127()
{
}

int PCF2127::is_init_required( void )
{
    return ( read_register( Seconds ) & 0x80 ? true : false );
}

void PCF2127::set_time( struct tm *dtp )
{
    char        buf[ 8 ];
    char        c;

    buf[ 0 ]    = Seconds;
    buf[ 1 ]    = i2bcd( dtp->tm_sec  );
    buf[ 2 ]    = i2bcd( dtp->tm_min  );
    buf[ 3 ]    = i2bcd( dtp->tm_hour );
    buf[ 4 ]    = i2bcd( dtp->tm_mday );
    buf[ 5 ]    = i2bcd( dtp->tm_wday );
    buf[ 6 ]    = i2bcd( dtp->tm_mon  + 1   );
    buf[ 7 ]    = i2bcd( dtp->tm_year - 100 );

    c    = read_register( Seconds );
    while ( c == read_register( Seconds ) )
        ;

    i2c.write( device_address, buf, 8 );
}

void PCF2127::set_time( char *s )
{
    //  The time information should be given in format of "YYYY MM DD HH MM SS"

    struct tm   dt, *dtp;

    dtp = &dt;

    sscanf( s, "%d %d %d %d %d %d", &(dtp->tm_year), &(dtp->tm_mon), &(dtp->tm_mday), &(dtp->tm_hour), &(dtp->tm_min), &(dtp->tm_sec) );
    printf( "%d/%d/%d - %d:%d:%d\r\n", (dtp->tm_year), (dtp->tm_mon), (dtp->tm_mday), (dtp->tm_hour), (dtp->tm_min), (dtp->tm_sec) );

    // adjust for tm structure required values
    dtp->tm_year = dtp->tm_year - 1900;
    dtp->tm_mon  = dtp->tm_mon - 1;

    set_time( dtp );
}

time_t PCF2127::time( time_t *tp )
{
    struct tm   dt, *dtp;
    time_t      t;
    char        buf[ 8 ]    = { Seconds };

    dtp = &dt;

    i2c.write( device_address, buf, 1 );
    i2c.read( device_address, buf, 7 );

    dtp->tm_sec     = bcd2i( buf[ 0 ] );
    dtp->tm_min     = bcd2i( buf[ 1 ] );
    dtp->tm_hour    = bcd2i( buf[ 2 ] );
    dtp->tm_mday    = bcd2i( buf[ 3 ] );
    dtp->tm_wday    = bcd2i( buf[ 4 ] );
    dtp->tm_mon     = bcd2i( buf[ 5 ] ) - 1;
    dtp->tm_year    = bcd2i( buf[ 6 ] ) + 100;

    t   = mktime( dtp );

    if ( tp )
        *tp  = t;

    return( t );
}

void PCF2127::set_alarm( char addr, char s )
{
    char    v;

    v   = i2bcd( s );
    set_register( addr, v );
}

void PCF2127::clear_intr( void )
{
    set_register( Control_2, 0x00 );
}

void PCF2127::set_register( char addr, char data )
{
    char    b[ 2 ];

    b[ 0 ]    = addr;
    b[ 1 ]    = data;

    i2c.write( device_address, b, 2 );
}

char PCF2127::read_register( char addr )
{
    char    data;

    data    = addr;
    i2c.write( device_address, &data, 1 );
    i2c.read( device_address, &data, 1 );

    return ( data );
}

char PCF2127::i2bcd( char n )
{
    return ( ((n / 10) << 4) | (n % 10) );
}

char PCF2127::bcd2i( char bcd )
{
    return ( ((bcd >> 4) * 10) + (bcd & 0x0F) );
}