HD64F2149 Datasheet, PDF (415/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

IVI signal
IHI signal
divided
waveform
ICRB(1)
FRC
ICRB
ICRB(2)
ICRB(3)
ICRB(4)
Figure 13.5 Timing Chart for Measurement of IVI Signal and
IHI Signal Divided Waveform Periods
13.3.4 IHI Signal and 2fH Modification
By using the timer connection FRT, even if there is a part of the IHI signal with twice the
frequency, this can be eliminated. In order for this function to operate properly, the duty cycle of
the IHI signal must be approximately 30% or less, or approximately 70% or above.
The 8-bit OCRDM contents or twice the OCRDM contents can be added automatically to the data
captured in ICRD in the FRT, and compare-matches generated at these points. The interval
between the two compare-matches is called a mask interval. A value equivalent to approximately
1/3 the IHI signal period is written in OCRDM. ICRD is set so that capture is performed on the
rise of the IHI signal.
Since the IHI signal supplied to the IHO signal selection circuit is normally set on the rise of the
IHI signal and reset on the fall, its waveform is the same as that of the original IHI signal. When
2fH modification is selected, IHI signal edge detection is disabled during mask intervals. Capture
is also disabled during these intervals.
Examples of FRT TCR settings are shown in table 13.6, and the 2fH modification timing chart is
shown in figure 13.6.
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