Hitachi H8/3048 Hardware Manual page 375

— Buffer transfer at transition from down-counting to up-counting
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If the general register value is in the range from H'0000 to T – 1, do not transfer a buffer
register value outside this range. Conversely, when a general register value is outside this
range, do not transfer a value within this range. See figure 10-41.
TCNT3
TCNT4
T
T – 1
Illegal changes
H'0000
H'FFFF
Figure 10-41 Changing a General Register Setting by Buffer Transfer (Caution 2)
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