Fujitsu FR81S User Manual
CHAPTER 29: RTC/WDT1 CALIBRATION
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : RTC/WDT1 CALIBRATION
FUJITSU SEMICONDUCTOR CONFIDENTIAL
17
5.2. Measurement of Errors in CR Clock
This section shows measurement of errors in the CR clock.
The procedure for measuring errors in the CR clock is as follows:
1. Setting CUTD1
2. Setting CUCR1.INTEN
3. Setting CUCR0.STRT
4. Loop waiting for interrupt
5. Occurrence of interrupt
6. Reading CUTR1
7. Comparison of CUTR1 and CUTD1 can be used to calculate the ratio between the main clock
frequency and the sub clock frequency.
MB91520 Series
MN705-00010-1v0-E
1086