TestaWDT.ino

#include <avr/wdt.h>
#define led 13 // pin 13 is connected to a led on Arduino Uno
//---------------------------------------
void setup()
{
  Serial.begin(115200);
  pinMode(led, OUTPUT);       // set pin mode
  digitalWrite(led, HIGH);    // turn the LED on (HIGH is the voltage level)
  delay(1000);                // wait for a tenth of a second
  digitalWrite(led, LOW);     // turn the LED off by making the voltage LOW
  delay(1000);                // wait for a tenth of a second
  wdt_enable(WDTO_4S);        // enable the watchdog 4 segundos
   Serial.println("WDT");
}
//---------------------------------------
void loop()
{
  //wdt_reset();                          // uncomment to avoid reboot
  digitalWrite(led, !digitalRead(led));   // turn the LED off by making the voltage LOW
  delay(1000);                            // wait for a tenth of a second
}