HD64F3687GHV Datasheet, PDF (120/566 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 5 Clock Pulse Generator
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.
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
Modify RCTRMDR*
Within
No
desired frequency
range?
Yes
End
Note: * Comparing the difference between the measured frequency and the desired frequency,
individual bits of RCTRMDR are decided from the MSB bit by bit.
Figure 5.9 Example of Trimming Flow for On-Chip Oscillator Clock
Rev. 3.00 Sep. 10, 2007 Page 86 of 528
REJ09B0216-0300