PCF8523 Class Reference

Interface to the PCF8523 Real Time Clock (RTC). More...

#include <pcf8523.h>

Public Member Functions
	PCF8523 ()
	Create a PCF8523 instance. More...
bool	Init (I2C *newbus)
	Initialize a PCF8523 instance. More...
bool	GetStatus ()
	Test to see if the device is present and readable. More...
bool	SetClock (const int year, const int month, const int day, const int hour, const int minute, const int second, const int weekday=0)
	Sets the time on the RTC. More...
bool	GetClock (int &year, int &month, int &day, int &hour, int &minute, int &second, int &weekday)
	Get the current time from the RTC chip. More...
bool	GetClock (int &year, int &month, int &day, int &hour, int &minute, int &second)
	Get the current time from the RTC chip. More...

Detailed Description

Interface to the PCF8523 Real Time Clock (RTC).

Hardware connections: The PCF8523 should be connected to an I2C bus. If you want the clock to keep ticking after power is removed, make sure to attach a battery to the batt pin. The SQW pin can optionally be connected. At this time, this class does not use that pin for any purpose.

Possible improvements:

• Use the OS bit to keep track of oscillator state.
• Make use of the SQW pin.

Author

SRLM

Constructor & Destructor Documentation

PCF8523::PCF8523 ( )

inline

Create a PCF8523 instance.

Member Function Documentation

bool PCF8523::GetClock ( int &  year, int &  month, int &  day, int &  hour, int &  minute, int &  second, int &  weekday  )

inline

Get the current time from the RTC chip.

Note that the parameters are passed by reference.

Parameters

year	The current year, in the range 0 to 99.
month	The current month, in the range 1 to 12.
day	The current day, in the range 1 to 31.
hour	The current hour, in the range 0 to 23.
minute	The current second, in the range 0 to 59.
second	The current second, in the range 0 to 59.
weekday	The current weekday, in the range 0 to 6.

Returns

true if the RTC chip was successfully read, and false otherwise.

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bool PCF8523::GetClock ( int &  year, int &  month, int &  day, int &  hour, int &  minute, int &  second  )

inline

Get the current time from the RTC chip.

Note that the parameters are passed by reference.

Parameters

year	The current year, in the range 0 to 99.
month	The current month, in the range 1 to 12.
day	The current day, in the range 1 to 31.
hour	The current hour, in the range 0 to 23.
minute	The current second, in the range 0 to 59.
second	The current second, in the range 0 to 59.

Returns

true if the RTC chip was successfully read, and false otherwise.

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bool PCF8523::GetStatus ( void  )

inline

Test to see if the device is present and readable.

Sends a ping on the i2c bus.

Returns

present (true) or missing (false).

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bool PCF8523::Init ( I2C *  newbus)

inline

Initialize a PCF8523 instance.

Set the control registers of the device:

• CONTROL_1 (set to 0b10000000):
  • Set to 12.5pF capacitor (matches crystal)
  • 0 (no functionality)
  • Set to RTC time circuits running
  • No software reset
  • 24 Hour mode
  • second interrupt disabled
  • alrarm interrupt disabled
  • no correction input generated
• CONTROL_2 (set to 0b00000000):
  • 0 (no functionality on write)
  • 0 (no functionality on write)
  • 0 (no functionality on write)
  • 0 (no functionality on write)
  • 0 (no functionality on write)
  • Disable watchdog timer A interrupt.
  • Disable countdown timer A interrupt.
  • Disable countdown timer B interrupt.
• CONTROL_3 (set to 0b00000000):
  • Battery switch over (standard mode), battery low detection enabled
  • 0 (no functionality)
  • Reset battery switchover interrupt (whether set or not)
  • 0 (no functionality on write)
  • Set to no interrupt when battery switch over flag is set
  • Set to no interrupt when battery low flag is set

Parameters

newbus

The i2c bus to use.

Returns

true if successfully initialized, false otherwise

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bool PCF8523::SetClock ( const int  year, const int  month, const int  day, const int  hour, const int  minute, const int  second, const int  weekday = 0  )

inline

Sets the time on the RTC.

The various limits (ie, month less than 12) are not checked.

If the RTC chip has a battery backup, then the time will persist across power cycles.

Parameters

year	The year to set, in the range 0 to 99.
month	The month to set, in the range 1 to 12.
day	The day to set, in the range 1 to 31.
hour	The hour to set, in the range 0 to 23.
minute	The minute to set, in the range 0 to 59.
second	The second to set, in the range 0 to 59.
weekday	The weekday to set, in the range of 0 to 6. You can set and interpret this anyway that you want: it's simply incremented when the day changes.

Returns

true if the clock was successfully set, false otherwise.

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The documentation for this class was generated from the following file:

• pcf8523.h