Datasheet

Section 5 Clock Pulse Generators
Rev. 1.50 Sep. 18, 2007 Page 72 of 584
REJ09B0240-0150
5.1 Features
• Choice of two clock sources
On-chip oscillator clock
External oscillator clock
• Choice of two frequencies of the on-chip oscillator by the user software
40 MHz
32 MHz
The signal generated by dividing the above clock by a value from 2 to 8 can be used as the
system clock and the above clock can be used as the clock source for timer RC or timer RD.
• Frequency trimming
The initial frequency of the on-chip oscillator is within the range shown above, so users do not
need to trim the frequency. If needed, users can adjust the on-chip oscillator frequency to the
range by rewriting the trimming registers.
• Interrupt can be requested to the CPU when the system clock is changed from the external
clock to the on-chip oscillator clock.
5.2 Register Descriptions
Clock oscillators are controlled by the following registers.
• RC control register (RCCR)
• RC trimming data protect register (RCTRMDPR)
• RC trimming data register (RCTRMDR)
• Clock control/status register (CKCSR)