// reset modem by pressing and holding the button for 5 sec
// once reset initiated cannot reset for next 1 minute
unsigned long previousMillis = 0; 
unsigned long currentMillis = 0;
unsigned long resetStart = 0;
unsigned long resetHold = 0;
unsigned long resetStartedAt = 0;
bool rebooting = 0;
#define BLINK_INTERVAL 1000
#define RESET_TIME 5000 // 5 SEC RESET time

#define RESET_SWITCH 23
#define RESET_LED 26
#define RESET_BUTTON_PRESS 27
#define RESET_DISABLE_TIME 60000

void setup() {
  Serial.begin(9600);

pinMode(RESET_BUTTON_PRESS, OUTPUT);
pinMode(RESET_LED, OUTPUT);
pinMode(RESET_SWITCH, INPUT);

}

void loop() {
currentMillis = millis();

if(digitalRead(RESET_SWITCH)==HIGH)
  {
    digitalWrite(RESET_BUTTON_PRESS, HIGH);
  }
  else{
    digitalWrite(RESET_BUTTON_PRESS, LOW);
  }
  checkReset();
  reset5Sec();

}

void checkReset(){
// check if button is pressed for 5 sec
if(digitalRead(RESET_SWITCH)==HIGH && resetStartedAt == 0)
  {
    if(resetStart == 0){resetStart = millis();}
    resetHold = millis();
    if(resetHold-resetStart >= RESET_TIME)
    {
      resetStartedAt = millis();
      Serial.println("Reset started");
      digitalWrite(RESET_LED, HIGH);
    }

  }
  else{
    resetStart = 0;
    resetHold = 0;
  }
}

void reset5Sec()
{
  if(resetStartedAt > 0)
    {
      if(millis() - resetStartedAt>=RESET_TIME && !rebooting)
      {
        digitalWrite(RESET_LED, LOW);
        Serial.println("Reset Done");
        rebooting = 1;
      }
// clear reset
       if(millis() - resetStartedAt>=RESET_DISABLE_TIME)
      {
        resetStartedAt = 0;
        Serial.println("Reset clear");
        rebooting = 0;
      }
    }
}