AN1216

4/11

DocID007016 Rev 2

For example, to set a period of 1 hour 49 minutes 35 seconds, the procedure is as follows:

RPT4 = 1

RPT3 = RPT2 = RPT1 = 0

alarm_second = 0x35

alarm_minute = 0x49

alarm_hour = 0x01

Or, to set a period of 49 minutes 35 seconds, the procedure is as follows:

RPT4 = RPT3 = 1

RPT2 = RPT1 = 0

alarm_second = 0x35

alarm_minute = 0x49

alarm_hour = Don’t care

Software implementation

TIMEKEEPER data is held as BCD (binary coded decimal). This is handled in the C

programming language using the ‘unsigned char’ data type. This can be converted within

the C program to other data types, such as ‘integer’, for numeric processing. Two functions

are provided in the program at the end of this document for making this conversion.



Char_To_Int: to take a BCD parameter, and to return the equivalent integer value



Int_To_Char: to take an integer parameter, and to return the equivalent BCD value.

The valid ranges for the alarm fields are summarized in Table 4.

Table 3. Bit setting to control the period of the repeated alarm

RPT4 RPT3 RPT2 RPT1

Periodic alarm activated every

1111

1 second

1

1

1

0

alarm_second seconds (less than 1 minute)

1

1

0

0

alarm_minute minutes alarm_second seconds (less than 1 hour)

1

0

0

0

alarm_hour hours alarm_minute minutes alarm_second seconds (less than 1 day)

Data C language type

Int (integer)

decimal

Char (character)

hexadecimal

Char (character)

BCD

Alarm second

0-59

00-3B

0-59