Datasheet

Section 12 Timer Z
Rev. 4.00 Mar. 15, 2006 Page 238 of 556
REJ09B0026-0400
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 12.55 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 12.55 Contention between TCNT Write and Overflow