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FUJITSU MB91460 SERIES FR60 User Manual

Page 986

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970

Chapter 50 Subclock Calibration Unit

5.Register Description

5.2 32 kHz / 100 kHz Timer Data Register (16 bit) (CUTD)

The 32kHz/100kHz Timer Data Register (CUTD) holds the value which determines the duration of calibration
(32kHz/100kHz reload value)

Default value is 0x8000 which corresponds to a measurement duration of 1 second, if a 32.768
kHz crystal is used.

This register should be written only when the calibration is inactive (STRT=0).

The 32kHz/100kHz Timer Register stores the value to specify the duration of the calibration.
When the calibration is started, the stored value is loaded into the 32kHz/100kHz Timer and the
timer starts counting down until it reaches zero.

If CUTD is initialized with 0000 an underflow will occur and the measurement will take (FFFF hex
+ 1) * T

osc32/osc100

The 32kHz/100kHz timer operates with the 32kHz or with the 100kHz oscillation clock (see
chapter “

4.4

CSCFG: Clock Source Configuration Register (Page No.196)

how to select

between those clocks.

In order to achieve a measurement duration of 1 second at a 32kHz oscillation, the CUTD register
has to be load with 0x8000 = 32768 dec. This number results from the exact oscillation frequency
of the crystal, which is F

osc

=32768 Hz. The ideal values of the measurement results (if a 4.00

MHz crystal is used) are shown in the following table.

In order to achieve a measurement duration of half a second at a 100kHz oscillation, the CUTD
register has to be load with 0xC350 = 50000 dec. This number results from the exact oscillation
frequency of the crystal, which is F

osc

=100000 Hz. The ideal values of the measurement results

(if a 4.00 MHz crystal is used) are shown in the following table.

TDD15TDD14 TDD13 TDD12 TDD11TDD10

TDD9 TDD8

Bit no.

Read/write

(R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W)

Default value

(1)

(0)

(0)

(0)

(0)

(0)

(0)

(0)

32/100kHz Timer Register high byte

Address : 0004B2

H

15

14

13

12

11

10

9

8

CUTDH

TDD7 TDD6 TDD5 TDD4 TDD3 TDD2 TDD1 TDD0

Bit no.

Read/write

(R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W)

Default value

(0)

(0)

(0)

(0)

(0)

(0)

(0)

(0)

Address : 0004B3

H

7

6

5

4

3

2

1

0

CUTDL

32/100kHz Timer

Register low byte