Fujitsu FR81S User Manual
CHAPTER 18: WATCHDOG TIMER
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : WATCHDOG TIMER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
24
5.2.3. Operation
This section explains operation of the hardware watchdog function.
The operation of the watchdog timer 1 after activation is explained.
Counting conditions
The watchdog timer 1 counts the rising edges of the CR oscillation.
When the watchdog timer 1 is connected with ICE, the timer stops counting under the following conditions:
-In emulator mode
- In the debug interface functions, if the watchdog reset suppression function is enabled.
The watchdog timer 1 stops counting in sleep mode, watch mode, stop mode, and during the oscillation
stabilization wait time recovering from standby mode.
Clearing the timer
Once the watchdog timer 1 is activated, the timer must be cleared before the timer period has elapses.
The watchdog timer 1 is cleared when the value "0xA5" is written to the register WDTCPR1.
Reset Request Generation
The watchdog timer 1 generates a watchdog rest request under the following conditions:
⋅
⋅
An overflow of the watchdog timer cycle occurs.
⋅
A value other than "0xA5" is written to the register WDTCPR1.
MB91520 Series
MN705-00010-1v0-E
633