HD64336900G Datasheet, PDF (106/408 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Tiny Series

5.4 Trimming of Internal RC Oscillator Frequency
Users can trim the internal RC oscillator frequency, supplying the external reference pulses with
the input capture function in internal timer W. 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 oscillators, 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 W
GRA: Input capture
GRC: Buffer of GRA
Set RCTRMD to H'00
Input reference pulses to
pin P81/FTIOA
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 Internal RC Oscillator Frequency
Rev. 1.00, 11/03, page 78 of 376