upd17225 Renesas Electronics Corporation., upd17225 Datasheet - Page 39

• Manufacturer Part Number: upd17225
• Description: 4-bit Single-chip Microcontroller For Small General-purpose Infrared Remote Control Transmitter
• Manufacturer: Renesas Electronics Corporation.

6.3
is reset. It is therefore necessary to reset through programming the watchdog timer with in a fixed time.
Cautions 1. The watchdog timer cannot be reset in the shaded range in Figure 6-2. Therefore, set
Note
The basic interval timer can be used as a watchdog timer.
Unless the watchdog timer is reset within a fixed time
The watchdog timer can be reset by setting WDTRES to 1.
Watchdog timer
reset signal
INTBTM (f
INTBTM (f
Operation Timing for Watchdog Timer
WDTRES
WDOUT
Fixed time: approx. 340 ms (at 4 MHz)
X
X
f
f
f
f
X
X
X
X
/2
/2
2. Refer to 9. RESET for the WDOUT pin function.
/2
/2
/2
/2
20
18
18
19
20
21
)
)
WDTRES before both the f
Figure 6-2. Watchdog Timer Operation Timing
Setting WDTRES at
this timing is invalid
Data Sheet U12643EJ2V0DS00
X
/2
21
and f
Note
, it judges that “the program has hung up”, and the PD17225
X
/2
20
signals go high.
PD17225, 17226, 17227, 17228
WDOUT output goes low
if WDTRES is not set
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