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CHAPTER 6 WATCHDOG TIMER
6.6 Program Example for Watchdog Timer
Programming examples for the watchdog timer are provided below.
■ Programming Examples of Watchdog Timer
● Processing specification
• Activate the watchdog timer immediately after the program starts.
• Clear the watchdog timer whenever the loop of the main program is run.
• Ensure that the time necessary for running the main loop once, including interrupt handling, is shorter
than the minimum time interval (approximately 335.5 ms: operating at 12.5 MHz) of the watchdog
timer.
● Coding example
WDTC EQU 0009H ; Address of watchdog control register
WDT_CLR EQU 00000101B
VECT DSEG ABS ; [DATA SEGMENT]
ORG 0FFFEH
RST_V DW PROG ; Setting reset vector
VECT ENDS
;------------------------Main program---------------------------------------------------------------------------------
CSEG ; [CODE SEGMENT]
PROG ; Initialization routine upon reset
MOVW SP,#0280H ; Setting initial value of stack pointer (for interrupt)
:
Initializing interrupt or other peripheral functions
:
INIT MOV WDTC,#WDT_CLR ; Activating watchdog timer
MAIN MOV WDTC,#WDT_CLR ; Clearing watchdog timer
:
User processing (interrupt may occur in this processing.)
:
JMP MAIN ; Ensure that the time necessary for running the loop is
shorter than the minimum time interval of the watchdog
timer.
ENDS
;---------------------------------------------------------------------------------------------------------------------
END