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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Operating Modes and System Clocks
W
atchdog T
imer
22
Watchdog Timer
The Watchdog Timer, also known as the WDT, is provided to inhibit program malfunctions caused
by the program jumping to unknown locations or entering endless program loops, due to certain
uncontrollable external events such as electrical noise. Its basic structure is a 16-bit timer which
when it overflows will execute an MCU reset operation. The accompanying diagram illustrates the
basic operational block diagram.
÷16
f
SYS
WDTCS
WDTL
÷16
WDTH
WDT
Softwa�e
Reset
Watchdog Co�nte� Registe�s
WDTREL
Latch
WDT
SWDT
LXT
LIRC
LSOSEL
Refresh
Control
Bits
Refresh
Value
Watchdog Timer