Ezzel probaltam (kissebb-nagyobb modositasokkal):

 

#include <Arduino.h>
#include <wdt.h>
/*
watchdog timer example code.

flashes LED three times quickly on boot up. Then goes thru a loop delaying
an additional 250ms on each iteration. The LED is on during each delay.
Once the delay is long enough, the WDT will reboot the MCU.
*/

const int onboardLED = 13;

void setup() {

int k;

// immediately disable watchdog timer so set will not get interrupted

wdt_disable();

// I often do serial i/o at startup to allow the user to make config changes of
// various constants. This is often using fgets which will wait for user input.
// any such 'slow' activity needs to be completed before enabling the watchdog timer.

// the following forces a pause before enabling WDT. This gives the IDE a chance to
// call the bootloader in case something dumb happens during development and the WDT
// resets the MCU too quickly. Once the code is solid, remove this.

delay(2L * 1000L);

// enable the watchdog timer. There are a finite number of timeouts allowed (see wdt.h).
// Notes I have seen say it is unwise to go below 250ms as you may get the WDT stuck in a
// loop rebooting.
// The timeouts I'm most likely to use are:
// WDTO_1S
// WDTO_2S
// WDTO_4S
// WDTO_8S

wdt_enable(WDTO_4S);

// initialize the digital pin as an output.
// Pin 13 has an LED connected on most Arduino boards:

pinMode(onboardLED, OUTPUT);

// at bootup, flash LED 3 times quick so I know the reboot has occurred.

for (k = 1; k <= 3; k = k + 1) {
digitalWrite(onboardLED, HIGH);
delay(250L);
digitalWrite(onboardLED, LOW);
delay(250L);
}
// delay a bit more so it is clear we are done with setup
delay(750L);
}

void loop() {

int k;

// this loop simply turns the LED on and then waits k*250ms. As k increases, the amount of time
// increases. Until finally the watch dog timer doesn't get reset quickly enough.
for (k = 1; k<= 10000; k = k + 1) {
// at the top of this infinite loop, reset the watchdog timer
wdt_reset();
digitalWrite(onboardLED, HIGH);
delay(k*250L);
digitalWrite(onboardLED, LOW);
delay(250L);
}
}