SN8P2602B Datasheet, PDF (70/95 Pages) SONiX Technology Company – 8-Bit Micro-Controller

8 _TIMERS
SN8P2602B
8-Bit Micro-Controller
8.1 WATCHDOG TIMER
The watchdog timer (WDT) is a binary up counter designed for monitoring program execution. If the program goes into
the unknown status by noise interference, WDT overflow signal raises and resets MCU. Watchdog clock controlled by
code option and the clock source is internal low-speed oscillator (16KHz @3V, 32KHz @5V).
Watchdog overflow time = 8192 / Internal Low-Speed oscillator (sec).
VDD
3V
5V
Internal Low RC Freq.
16KHz
32KHz
Watchdog Overflow Time
512ms
256ms
’ Note: If watchdog is “Always_On” mode, it keeps running event under power down mode or green
mode.
Watchdog clear is controlled by WDTR register. Moving 0x5A data into WDTR is to reset watchdog timer.
0CCH
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
WDTR
WDTR7 WDTR6 WDTR5 WDTR4 WDTR3 WDTR2 WDTR1
Read/Write
W
W
W
W
W
W
W
After reset
0
0
0
0
0
0
0
Bit 0
WDTR0
W
0
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:
MOV
B0MOV
…
CALL
CALL
…
…
…
JMP
A,#5AH
WDTR,A
SUB1
SUB2
MAIN
; Clear the watchdog timer.
SONiX TECHNOLOGY CO., LTD
Page 70
Preliminary Version 0.4