Hitachi H8/3032 Series Hardware Manual page 253

Output pin
Output pin
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— General register settings outside the counting range (H'0000 to GRA3)
Waveforms with a duty cycle of 0% or 100% can be output by setting a general register to
a value outside the counting range. When a buffer register is set to a value outside the
counting range, then later restored to a value within the counting range, the counting
direction (up or down) must be the same both times. See figure 8-42.
GRA3
GR
H'0000
BR
GR
Write during down-counting
Figure 8-42 Changing a General Register Setting by Buffer Transfer (Example 2)
Settings can be made in this way by detecting GRA3 compare match or TCNT4
underflow before writing to the buffer register.
0% duty cycle 100% duty cycle
Write during up-counting
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