CHAPTER 5 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U13850EJ6V0UD
166
5.3.7 Watchdog timer mode register (WDTM)
This register can be read/written in 8-bit or 1-bit units (for details, refer to
CHAPTER 9 WATCHDOG TIMER
).
After reset: 00H
R/W
Address: FFFFF384H
Symbol
<7>
6
5
4
3
2
1
0
WDTM
RUN
0
0
WDTM4
0
0
0
0
RUN
Watchdog timer operation control
0
Count operation stopped
1
Count start after clearing
WDTM4
Timer mode selection/interrupt control by WDT
0
Interval timer mode
1
WDT mode
Caution
If the RUN or WDTM4 bit is set to 1, it cannot be cleared other than by reset input.
5.3.8 Noise elimination
(1) Noise elimination of INTP0 to INTP3 pins
The INTP0 to INTP3 pins incorporate a noise eliminator that functions using analog delay. Therefore, a signal
input to each pin is not detected as an edge, unless it maintains its input level for a certain period.
An edge is detected after a certain period has elapsed.
(2) Noise elimination of INTP4 and INTP5 pins
The INTP4 and INTP5 pins incorporate a digital noise eliminator. If the input level of the INTP pin is detected by
the sampling clock (f
XX
) and the same level is not detected three successive times, the input pulse is eliminated
as a noise. Note the following.
•
If the input pulse width is between 2 and 3 clocks, whether the input pulse is detected as a valid edge or
eliminated as noise is undefined.
•
To securely detect the valid edge, the same level input of 3 clocks
or more is required.
•
When noise is generated in synchronization with the sampling clock, this may not be recognized as noise. In
this case, eliminate the noise by adding a filter to the input pin.
Содержание V850/SB1
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