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Application note, 32khz, 100khz – FUJITSU MB91460 SERIES FR60 User Manual

Page 989

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973

Chapter 50 Subclock Calibration Unit

6.Application Note

6. Application Note

This section lists application notes concerning accuracy of the calibration, power dissipation and
measurement duration.

32kHz

The setting of the 32KHz Timer Data Register can be calculated in the following way.

If the duration of 1 second is desired for the calibration, 8000Hex = 32768Dec should be set in
the 32kHz Timer Data Register and it represents 32,768 pulses of the 32.768kHz oscillation
clock.

This setting should result in the stored value of approximately 3D0900Hex in the 4MHz Time Data
Register. This value represents 4,000,000 pulses of the 4MHz oscillator.

100kHz

The setting of the 100KHz Timer Data Register can be calculated in the following way.

If the duration of 0.5 second is desired for the calibration, C350Hex = 50000Dec should be set in
the 100kHz Timer Data Register and it represents 50,000 pulses of the 100kHz oscillation clock.

This setting should result in the stored value of approximately 1E8480Hex in the 4MHz Time Data
Register. This value represents 2,000,000 pulses of the 4MHz oscillator.

Table 6-1 Ideal measurement results (CUTR) with 32.768kHz and 4.0MHz oscillators

The key to the use of the calibration module is power dissipation as well as accuracy of the
calibration.

Table 6-2 Ideal measurement results (CUTR) with 100kHz and 4.0MHz oscillators

The key to the use of the calibration module is power dissipation as well as accuracy of the
calibration.

duration of

calibration

CUTD

value

CUTR

value

2 sec

0x0000

0x7A1200

1.75 sec

0xE000

0x6ACFC0

1.5 sec

0xC000

0x5B8D80

1.25 sec

0xA000

0x4C4B40

1 sec

0x8000

0x3D0900

0.75 sec

0x6000

0x2DC6C0

0.5 sec

0x4000

0x1E8480

0.25 sec

0x2000

0x0F4240

duration of

calibration

CUTD

value

CUTR

value

0.5 sec

0xC350

0x1E8480

0.25 sec

0x61A8

0x0F4240

0.125 sec

0x30D4

0x07A120

0.1 sec

0x2710

0x061A80