SN8F2270B Series
USB 2.0 Low-Speed 8-Bit Micro-Controller
Watchdog timer application note is as following.
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Before clearing watchdog timer, check I/O status and check RAM contents can improve system error.
z
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Don’t clear watchdog timer in interrupt vector and interrupt service routine. That can improve main routine fail.
Clearing watchdog timer program is only at one part of the program. This way is the best structure to enhance the
watchdog timer function.
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Example: An operation of watchdog timer is as following. To clear the watchdog timer counter in the top
of the main routine of the program.
Main:
Err:
…
…
JMP $
; Check I/O.
; Check RAM
; I/O or RAM error. Program jump here and don’t
; clear watchdog. Wait watchdog timer overflow to reset IC.
Correct:
; I/O and RAM are correct. Clear watchdog timer and
; execute program.
MOV
B0MOV
CALL
CALL
…
A,#5AH
WDTR,A
SUB1
SUB2
…
…
JMP
MAIN
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