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R01UH0336EJ0102 Rev.1.02
Page 389 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 12 Window Watchdog Timer A (WDTA)
WDTA start timing
The WDTA start timing and the changes to the WDTA settings are illustrated in
the following figure.
Figure 12-2
Timing Diagram of WDTA Start
The timing diagram above shows the following.
1. After reset release, the counter value remains 0000
H
until the first trigger is
generated.
2. WDTAnMD should be written before the first trigger is generated. However,
the settings are not applied immediately.
3. The counter starts at the first trigger.
The overflow value and other settings specified in WDTAnMD are applied.
12.3.2
WDTA Trigger
The WDTA trigger has the following functions.
• Starting the WDTA by the first trigger after release from reset (i.e. the first
software trigger to start counting).
• Counter re-start trigger to keep the counter from overflowing.
The WDTA can be triggered by writing a fixed activation code to the trigger
register (see Table 12-5, Trigger Register and Activation Code).
FFFFH
(2)
(1)
(3)
0000 H
Counter value
Reset
release
WDTAnMD
write
First
trigger
Overflow value
Table 12-5
Trigger Register and Activation Code
Type of Activation
Code
Trigger Register
Activation Code
Fixed
WDTAnWDTE
AC
H
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