So Im having trouble trying to figure this out. My project needs a valve to stay shut and when an event is triggered, 3 seconds into that event the valve opens for 2 seconds, then remain shut till it's triggered again. I was just treating it like an LED in the code. I was trying to code it to jump from one if-statement to the next with the appropriate delays but it doesn't work the way i thought it would. Any help would be great. Thanks

//the event does ventGo0 = true;
 if(((millis() - previousVenting) > offoffDuration)&&(ventGo0==true)){ 
        previousVenting1 = millis();


     if(((millis() - previousVenting1) > onDuration)&&(ventGo1==true)){ 
       digitalWrite(ventPin, HIGH);
       previousVenting2 = millis();
       if(((millis() - previousVenting2) > offDuration)&&(ventGo2==true)){  
         digitalWrite(ventPin, LOW);
  • just a note ... if (ventGo1==true) is same as if (ventGo1)
    – jsotola
    May 8 at 20:55

You could use two millis() based timers.

// Sketch uses 1066 bytes (3%) of program storage space.
// Global variables use 27 bytes (1%) of dynamic memory.
// Arduino Uno, IDE 1.8.9
class MillisTimer{


    unsigned long m_timeInMilliSeconds;
    unsigned long m_previousMillis;
    byte m_timerActive;


    MillisTimer(unsigned long timeInMilliSeconds):
      m_timerActive = 0;
      m_previousMillis = 0;

    bool Update(){
      if(m_timerActive && (millis() - m_previousMillis >= m_timeInMilliSeconds)){
        m_previousMillis += m_timeInMilliSeconds;
        return 1;
        return 0;

    void Start(){
      m_timerActive = 1;

    void Stop(){
      m_timerActive = 0;

    void ReStart(){
      m_timerActive = 1;
      m_previousMillis = millis();

    byte IsActive(){
      return m_timerActive;


// Make copies of the object to work with.
MillisTimer TwoSecondTimer(2000);
MillisTimer ThreeSecondTimer(3000);

void setup(){

  // Call this function when an event is triggered.

  // Timer status indicator.
  digitalWrite(LED_BUILTIN, LOW);


void loop(){

  // Call the update function as fast as possible.
    digitalWrite(LED_BUILTIN, HIGH);

  // Call the update function as fast as possible.
  if(TwoSecondTimer.Update() && !ThreeSecondTimer.IsActive()){
    digitalWrite(LED_BUILTIN, LOW);

  • Great thanks Ve7jro. I put your code in my project and it works great, just what I needed. When the arduino is booted up for the first time, it does tigger the the led or in my case the valve. Is there a way to stop that from happening? Thanks
    – Jason8899
    May 8 at 23:24
  • @Jason8899 _ If you update your question with the complete "sketch", I'll take a look at it for you. Keep in mind that, ThreeSecondTimer.ReStart(); in setup() starts the timer immediately, so you should remove it from setup() and add it to your code, the "event driven" part of your code.
    – VE7JRO
    May 8 at 23:44
  • I found the issue, thanks again.
    – Jason8899
    May 9 at 15:32

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