Freescale Semiconductor MPC5200B ユーザーズマニュアル

Freescale Semiconductor

7-73

This register is used during manufacturing test to expedite RTC testing and is not intended to be a user register. However, no protection from 
software access is provided.

 

16:22

—

Reserved

23

Int_min

Periodic interrupt at each minute rollover. High indicates interrupt has occurred.

Cleared by writing 1 to this bit position.

24:30

—

Reserved

31

Int_sec

Periodic interrupt at each second rollover. High indicates interrupt has occurred.

Cleared by writing 1 to this bit position.

msb  0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

R

Rsvd

PTERM

ETERM

W

RESET:

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31 lsb

R

Reserved

W

RESET:

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

—

Reserved

1:7

PTERM

Prescale Termination value, the number of 32KHz clocks per 7-bit prescale counter.

Default at reset is the maximum (and proper) value of 128 decimal. Any value lower than 
this causes the RTC to run fast.

8:15

ETERM

External Termination value, the number of prescaled counts per 8-bit external counter.

Default at reset is the maximum (and proper) value of 256 decimal. Any value lower than 
this causes the RTC to run fast.

16:31

—

Reserved

Note:  The 32.768KHz crystal frequency is divided by PTERM, which is then divided by ETERM to produce a 1 second 
time interval. It is conceivable that a system might wish to adjust these values to produce a more locally accurate clock 
rate. However, be aware that these values are affected by reset. Therefore, any adjustment value must be stored and 
retrieved from non-volatile memory. Further, the adjustment could only increase the clock rate, not decrease it.