FUJITSU MB91460 SERIES FR60 - Manual (Page 979)

963
Chapter 50 Subclock Calibration Unit
1.Overview
Chapter 50 Subclock Calibration Unit
1. Overview
The Clock Calibration Module provides possibilities to calibrate the 32kHz oscillation clock or
100kHz RC oscillation clock with respect to the 4MHz oscillation clock. This chapter gives an
overview of the calibration unit, describes the registers and provides some application notes.
1.1 Description
This hardware allows the software to measure time generated by the 32kHz clock (or 100kHz RC clock) with
the 4MHz clock.
By utilizing this hardware in conjunction with software processing, the accuracy of the 32kHz clock (or 100kHz
RC clock) can come closer to that of the 4MHz clock. The measurement result from the Clock Calibration
Module can be processed by the software and the setting required for the Real Time Clock Module can be
obtained.
This module consists of two timers, one operating with the 32kHz clock (or 100kHz RC clock) and the other
operating with the 4MHz clock. The 32kHz (100kHz) timer triggers the 4MHz timer and resulting 4MHz timer
value is stored in a register. The value stored in this register can be used for the subsequent software
processing to calculate the desired Real Time Clock module’s setting.