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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