HD64336901G Renesas Technology, HD64336901G Datasheet - Page 106

• Manufacturer Part Number: HD64336901G
• Description: (HD64xxx Series) 16-BIT MICROCONTROLLER
• Manufacturer: Renesas Technology

5.4
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.
Rev. 1.00, 11/03, page 78 of 376
Note: * Comparing the difference between the measured frequency and the desired frequency,
Figure 5.9 Example of Trimming Flow for Internal RC Oscillator Frequency
Trimming of Internal RC Oscillator Frequency
individual bits of RCTRMDR are decided from the MSB bit by bit.
Input reference pulses to
Frequency calculation
Set RCTRMD to H'00
GRC: Buffer of GRA
GRA: Input capture
desired frequency
Setting timer W
pin P81/FTIOA
Capture 1
Capture 2
Within
range?
Start
End
Yes
No
Modify RCTRMDR*