W681308DG Datasheet, PDF (27/64 Pages) Nuvotem Talema – W681308 USB Audio Controller from Nuvoton integrates fast 8051 Microcontroller Unit (MCU)

W681308
XXXX PRODUCT DESCRIPTION
Control Bit
EWT
RWT
Name
Enable Watchdog
timer Reset
Reset Watchdog
Timer
Function
Setting this bit will enable the Watchdog timer Reset function.
This bit helps in putting the watchdog timer into a know state. It also helps in
resetting the watchdog timer before a time-out occurs. Failing to set the EWT before
time-out will cause an interrupt, if EWDI (EIE.4) is set, and 512 clocks after that a
watchdog timer reset will be generated if EWT is set. This bit is self-clearing.
Table 8 Watchdog Control Bits
WTRF is set to a 1 on a Watchdog timer reset, set to 0 on power on/down resets. WTRF is not altered by an external reset.
POR is set to 1 by a power-on reset. EWT is cleared to 0 on a Power-on reset and unaffected by other resets.
To prevent software from accidentally enabling or disabling the watch dog reset function, the bit of WDCON requires Time
Access (TA) procedure to write.
Example:
mov TA, #0AAH
mov TA, #055H
clr WDIF
WD1, WD0 are Time-out bits for Watchdog Timer located at CKCON.7 and CKCON.6. These bits determine the time-out
period of the watchdog timer. The reset time-out period is 512 clocks longer than the watchdog time-out.
WD1
0
0
1
1
WD0
0
1
0
1
Interrupt time-out
2²³
2²⁵
2²⁶
2²⁸
Table 9 Watchdog Timer Timeout Control
Reset time-out
2²³ + 512
2²⁵ + 512
2²⁶ + 512
2²⁸ + 512
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Rev1.2