Hitachi H8/3006 Hardware Manual page 359

Note on Writes in Synchronized Operation: When channels are synchronized, if a 16TCNT
value is modified by byte write access, all 16 bits of all synchronized counters assume the same
value as the counter that was addressed.
(Example) When channels 1 and 2 are synchronized
• Byte write to channel 1 or byte write to channel 2
16TCNT1 W
16TCNT2 Y
Upper byte Lower byte
• Word write to channel 1 or word write to channel 2
16TCNT1 W
16TCNT2 Y
Upper byte Lower byte
Write A to upper byte
of channel 1
X
Z
Write A to lower byte
of channel 2
X
Write AB word to
Z
channel 1 or 2
16TCNT1 A
16TCNT2 A
Upper byte Lower byte
16TCNT1 Y
16TCNT2 Y
Upper byte Lower byte
16TCNT1 A
16TCNT2 A
Upper byte Lower byte
X
X
A
A
B
B
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