/*
    HOW TO RESET AN ARDUUINO USING CODE: HARDWARE RESET
    By: TheGeekPub.com
    More Arduino Tutorials: https://www.thegeekpub.com/arduino-tutorials/
*/

// https://www.instructables.com/two-ways-to-reset-arduino-in-software/
// https://www.mysensors.org/apidocs/group__avr__watchdog.html

/*
  int ResetPin = 4;

  void setup() {
  digitalWrite(ResetPin, HIGH); // Set digital pin to 5V
  pinMode(ResetPin, OUTPUT); // Set the digital pin to an OUTPUT pin
  Serial.begin(115200);
  while(!Serial);
  Serial.println("Arduino Nano Ready");
  }

  void loop() {
  // A little fun countdown!  3..2..1
  Serial.print("3... ");
  delay(1000);
  Serial.print("2... ");
  delay(1000);
  Serial.print("1... ");
  delay(1000);
  Serial.println("We are now resetting Arduino programmatically");
  Serial.println();
  delay(1000);
  digitalWrite(ResetPin, LOW); // This command grouunds the reset pin and reboots the Arduino
  Serial.println("If it worked, the Arduino will never output this line!");
  }
*/

#include <avr/wdt.h> //should be in any adruino IDE
// https://passionelectronique.fr/watchdog-arduino/
// WDTO_15MS	16ms
// WDTO_30MS	32ms
// WDTO_60MS	64ms
// WDTO_120MS	128ms
// WDTO_250MS	256ms
// WDTO_500MS	512ms
// WDTO_1S	1,024s
// WDTO_2S	2,048s
// WDTO_4S	4,096s
// WDTO_8S

void setup() {
  wdt_disable(); //always good to disable it, if it was left 'on' or you need init time
  //do some stuff here
  Serial.begin(115200);
  while (!Serial);
  if (bitRead(MCUSR, WDRF)) {
    Serial.println("System was reset due to watchdog timeout!");
  }
  Serial.println("Arduino Nano Ready");
  wdt_enable(WDTO_8S); //enable it, and set it to 8s
  wdt_reset();
}

void loop() {
  //do some stuff here
  if (Serial.available() && Serial.read() == 'r') {
    char wdtString[4];
    uint16_t wdtDelay;
    if (Serial.available()) {
      int bytesRead = Serial.readBytes(wdtString, 3);
      wdtString[bytesRead] = '\0';  // Null-terminate the string
      wdtDelay = atoi(wdtString);
      Serial.print("Received: r");
      Serial.println(wdtDelay);
    }
    wdt_overflow(wdtDelay);
  }
  wdt_delay(5000); //instead of delay, i made my own delay to reset the WDT
}

//this makes sure the WDT is reset immediately when entering the
//function, but we can still benefit from a real 'delay'.
//upon leaving the function, we reset it again.
//i realize timing will be loose, you can always do something with
//millies() if you need strict timing.
//you might also need to adjust the '1000' if you WDT is shorter

void wdt_delay(unsigned long msec) {
  wdt_reset();

  while (msec > 1000) {
    wdt_reset();
    delay(1000);
    msec -= 1000;
    Serial.print(msec / 1000);
    Serial.print("... ");
  }
  delay(msec);
  Serial.println("0");
  wdt_reset();
}

//to reload the board, you only have to delay > WDT
//another option is to set the WDT very short, and do a short delay

void wdt_overflow(uint16_t wdtDelay) {
  Serial.println("Reseting Now!");
  Serial.println();
  Serial.flush();
  wdt_enable(WDTO_15MS); //enable WDT, and set it to 15ms
  wdt_reset();
  // delay(8001);
  delay(wdtDelay); // while(true); should be safer
  Serial.println("Didn't work!!!");
  wdt_enable(WDTO_8S); //enable WDT, and set it to 8s
}