Fujitsu MB96300 series Hardware Manual page 671

F2mc-16fx 16-bit

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MB96300 Super Series Hardware Manual

If CUTD is initialized with 0x0000 an underflow will occur and the measurement will take (0xFFFF + 1) *

In order to achieve a measurement duration of 1 second at a 32kHz oscillation, the CUTD register has to be

loaded with 0x8000 = 32768 dec. This number results from the exact oscillation frequency of the crystal,

shown in the following table.

32kHz: Ideal measurement results depending on measurement duration

In order to achieve a measurement duration of half a second at a 100kHz oscillation, the CUTD register has

to be loaded with 0xC350 = 50000 dec. This number results from the exact oscillation frequency of

=100000 Hz. The ideal values of the measurement results (if a 4.00 MHz crystal is used) are shown in the

following table.

100kHz: Ideal measurement results depending on measurement duration

The duration of the whole process from writing a 1 into the STRT bit until STRT is reset by hardware is

longer than the actual calibration measurement time, due to synchronization between the different clock

domains. Process Duration < (CUTD + 3) * T

The calibration measurement time is CUTD * T

■ Clock Calibration Unit Calibration Timer Data Register (24 bits) (CUTR)

The Clock Calibration Unit Calibration Timer Data Register stores the result of the calibration. When the

calibration is started, the Calibration Timer starts counting up from zero. When the Duration Timer reaches

zero, the Calibration Timer stops counting and the register holds the calibration result until the next

calibration is triggered by software.

Reading this register during calibration results in random values. The end of calibration is indicated by

the INT-bit and the STRT-bit in the CUCR-register.

=32768 Hz. The ideal values of the measurement results (if a 4.00 MHz crystal is used) are

CHAPTER 25 CLOCK CALIBRATION UNIT