Datasheet

Section 14 Timer Z
Rev. 3.00 Mar. 15, 2006 Page 283 of 526
REJ09B0060-0300
4. Contention between TCNT Write and Overflow/Underflow: If overflow/underflow occurs in
the T
2
state of a TCNT write cycle, TCNT write has priority without an increment operation.
At this time, the OVF flag is set to 1. Figure 14.55 shows the timing in this case.
T
1
T
2
TCNT
H'FFFF
M
OVF
TCNT address
WTCNT
(internal write signal)
TCNT input clock
Overflow signal
TCNT write data
TCNT write cycle
φ
Figure 14.55 Contention between TCNT Write and Overflow