AN1216

2/11

DocID007016 Rev 2

The TIMEKEEPER register mapping is shown in Table 2. This is divided in two parts: the

clock registers and the alarm registers.

Clock registers

The clock registers can be configured in the C language computer program as follows:

*TIMEKEEPER_CAL |= 0x80

*TIMEKEEPER_SEC= 00 //user clock setting : seconds parameter

*TIMEKEEPER_MIN= 00 //user clock setting : minutes parameter

*TIMEKEEPER_HOUR= 00 //user clock setting : hours parameter

*TIMEKEEPER_CAL&= 0x7F

The process for starting the clock and making the calibration adjustments are described in

the M48T37V/Y datasheet, and in application notes AN925 and AN934.

Alarm registers

For TIMEKEEPER devices it is necessary to set the Write bit, W, at the top of the control

register (at address offset 7FF8h) before proceeding to any clock modification. Modifications

Address

Data

Function

Range

(in BCD format)

D7

D6

D5

D4

D3

D2

D1

D0

7FFFh

10 Years

Year

Year

00-99

7FFEh

0

0

0

10M

Month

Month

01-12

7FFDh

0

0

10 date

Date

Date

01-31

7FFCh

0

FT

0

0

0

Day

Day

01-7

7FFBh

0

0

10 hours

Hours

Hour

00-23

7FFAh

0

10 Minutes

10 Minutes

Minute

00-59

7FF9h

ST

10 Seconds

Seconds

Second

00-59

7FF8h

W

R

S

Calibration

Control

7FF7h

WDS

BMB4

BMB3

BMB2 BMB1 BMB0 RB1

RB0

Watchdog

7FF6h

AFE

0

ABE

0

0

0

0

0

Interrupt

7FF5h

RPT4

0

Al 10 Date

Alarm Date

A Date

01-31

7FF4h

RPT3

0

Al 10 Hour

Alarm Hour

A Hour

00-23

7FF3h

RPT2

Alarm 10 Minutes

Alarm Minutes

A Minute

00-59

7FF2h

RPT1

Alarm 10 Seconds

Alarm Seconds

A Second

00-59

7FF1h

1000 Years

100 Years

Century

00-99

7FF0h

WDF

AF

Z

BL

Z

Z

Z

Z

Flags