Datasheet

CHAPTER 5 CLOCK GENERATOR
User’s Manual U18698EJ1V0UD
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(9) Internal high-speed oscillation trimming register (HIOTRM)
This register corrects the accuracy of the internal high-speed oscillator. The accuracy can be corrected by self-
measuring the frequency of the internal high-speed oscillator, using a subsystem clock using a crystal resonator
or using a timer with high-accuracy external clock input, such as a real-time counter.
HIOTRM can be set by an 8-bit memory manipulation instruction.
Reset signal generation sets HIOTRM to 10H.
Caution If the temperature or V
DD pin voltage is changed after accuracy correction, the frequency will
fluctuate. Also, if a value other than the initial value (10H) is set to the HIOTRM register, the
oscillation accuracy of the internal high-speed oscillation clock may exceed the MIN. and MAX.
values described in CHAPTER 27 ELECTRICAL SPECIFICATIONS (STANDARD PRODUCTS)
due to the subsequent fluctuation in the temperature or V
DD voltage, or HIOTRM register
setting value. If the temperature or V
DD voltage fluctuates, accuracy correction must be
executed either before frequency accuracy will be required or regularly.