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