Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI Data Sheet

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ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]

Atmel-8271H-AVR- ATmega-Datasheet_08/2014

Note:

1.

Note: If the Watchdog is accidentally enabled, for example by a runaway pointer or brown-out condition, the 
device will be reset and the Watchdog Timer will stay enabled. If the code is not set up to handle the Watchdog, 
this might lead to an eternal loop of time-out resets. To avoid this situation, the application software should 
always clear the Watchdog System Reset Flag (WDRF) and the WDE control bit in the initialization routine, 
even if the Watchdog is not in use.

Assembly Code Example

WDT_off:

; Turn off global interrupt

; Reset Watchdog Timer

; Clear WDRF in MCUSR

in    r16, MCUSR

andi  r16, ~(1<<WDRF)

out   MCUSR, r16

; Write logical one to WDCE and WDE

; Keep old prescaler setting to prevent unintentional 

time-out

lds r16, WDTCSR

ori   r16, (1<<WDCE) | (1<<WDE)

sts WDTCSR, r16

; Turn off WDT

ldi   r16, (0<<WDE)

sts WDTCSR, r16

; Turn on global interrupt

C Code Example

void WDT_off(void)

{

__disable_interrupt();

__watchdog_reset();

/* Clear WDRF in MCUSR */

MCUSR &= ~(1<<WDRF);

/* Write logical one to WDCE and WDE */

/* Keep old prescaler setting to prevent unintentional 

time-out */

WDTCSR |= (1<<WDCE) | (1<<WDE);

/* Turn off WDT */

WDTCSR = 0x00;

__enable_interrupt();

}