PCF2127 and PCF2129 are high accuracy real-time-clock (RTC) module. This library provides simple interface to accessing clock information.

Dependents:   PCF2127_Demo PCF2127_Hello

PCF2127 and PCF2129

PCF2127T PCF2127T is in SO16 package

The PCF2127 and the PCF2129 are a CMOS Real Time Clock (RTC) and calendar with an integrated Temperature Compensated Crystal (Xtal) Oscillator (TCXO) and a 32.768 kHz quartz crystal optimized for very high accuracy and very low power consumption.
Both of PCF2127 and PCF2129 have a selectable I2C-bus or SPI-bus, a backup battery switch-over circuit, a programmable watchdog function, a timestamp function, and many other features.
On addition to this, the PCF2127 has 512 bytes of general-purpose static RAM.

These 4 types of RTC modules are software compatible. So this library "PCF2127" can be used all of those.
This library only supports I2C to communicate with the PCF2127/PCF2129.

Type variations

Main feature difference

type+/-3ppm accuracy range512 bytes RAMpackage
PCF2127T-30℃ to +80℃yesSO16
PCF2127AT-30℃ to +60℃yesSO20
PCF2129T-30℃ to +80℃not availableSO16
PCF2129AT-15℃ to +60℃not availableSO20

Pin assign

/media/uploads/nxp_ip/pcf2127_pcf2129_pin_assign.png

PCF2127T
PCF2127T

Connection between MCU and PCF2127/PCF2129

These examples show how the RTC module can be connected via I2C bus.

http://developer.mbed.org/media/components/pinouts/both_types_connection3.png

References

Revision:
0:1377bcf1455e
Child:
1:700e0285cfd8
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCF2127.cpp	Thu Dec 04 04:58:24 2014 +0000
@@ -0,0 +1,148 @@
+/*
+ *  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) );
+}