Datasheet

Section 5 Clock Pulse Generator
Rev. 3.00 Sep. 10, 2007 Page 86 of 528
REJ09B0216-0300
5.4 Trimming of On-Chip Oscillator Frequency
Users can trim the on-chip oscillator clock, supplying the external reference pulses with the input
capture function in internal timer Z. An example of trimming flow and a timing chart are shown in
figures 5.9 and 5.10, respectively. Because RCTRMDR is initialized by a reset, when users have
trimmed the frequencies, some operations after a reset are necessary, such as trimming it again or
saving the trimming value in an external device for later reloading.
Yes
No
Note: * Comparing the difference between the measured frequency and the desired frequency,
individual bits of RCTRMDR are decided from the MSB bit by bit.
Start
Setting timer Z
GRA: Input capture
GRC: Buffer of GRA
Set RCTRMDR to H'00
Input reference pulses to
pin P60/FTIOA0
Capture 1
Capture 2
Frequency calculation
Within
desired frequency
range?
End
Modify RCTRMDR*
Figure 5.9 Example of Trimming Flow for On-Chip Oscillator Clock