How do I pause a loop just once?

Question

I ́m trying to make a pause in a loop, but just for the first time it loops. The next loops i would like the program to NOT do the pause. Just once time, each time a button is pressed. Does anybody knows how to do it? Thanks! This is the code i want to pause just once:

void loop() {
 if(digitalRead(switch_pin) == LOW){
 digitalWrite(led_green_pin,LOW);
 digitalWrite(led_red_pin,HIGH);
 lastMotionState = currentMotionState; 
 currentMotionState = digitalRead(MOTION_SENSOR_PIN); //
 if (currentMotionState == LOW && lastMotionState == HIGH) { 
 servo.write(90);
 }
 else
 if (currentMotionState == HIGH && lastMotionState == LOW) { // pin state change: HIGH -> LOW
 servo.write(0);
 }
 }

• jsotola: Does anybody knows how to do it? is not a question that asks how to do it ... it is not a question about the arduino
• jsotola: what do you mean by pause? ... that implies that the code would somehow start up again, but you said nothing about what would stop it and what would start it again and where it should "pause"
• Juraj: Juan, stackoverflow.com/help/merging-accounts

Answer 1

The following code will pause (Give some delay) when it runs for the first time and also when you press the button.

void loop() {
 static int status = true;
 if(status){
 //Pause
 delay(15);
 status=false;
 return;
 }
 
 if(digitalRead(switch_pin) == LOW){
 digitalWrite(led_green_pin,LOW);
 digitalWrite(led_red_pin,HIGH);
 lastMotionState = currentMotionState; 
 currentMotionState = digitalRead(MOTION_SENSOR_PIN); //
 if (currentMotionState == LOW && lastMotionState == HIGH) { 
 servo.write(90);
 }
 else if (currentMotionState == HIGH && lastMotionState == LOW) { // pin state change: HIGH -> LOW
 servo.write(0);
 }
 }
 else{
 status = true;
 }
}

Give delay according to your need.

• Gerben: I don't know what that continue; line does when there isn't a for/while/do-loop.
• lurker: Better would be void loop() { static int status = true; ... } keeping the scope of status inside of loop() instead of global.
• HARSH MITTAL: @Gerben and lurker thanks for pointing that out. I have made the changes accordingly. Instead of continue I have added return which will work as desired.

Answer 2

This is pretty simple, although you shouldn't see any difference, because loop() is running a lots of times in one second. But:

bool firstrun = true;
void loop() {
 if(firstrun == true){};
 else{
 if(digitalRead(switch_pin) == LOW){
 digitalWrite(led_green_pin,LOW);
 digitalWrite(led_red_pin,HIGH);
 lastMotionState = currentMotionState; 
 currentMotionState = digitalRead(MOTION_SENSOR_PIN); //
 if (currentMotionState == LOW && lastMotionState == HIGH) { 
 servo.write(90);
 }
 else if (currentMotionState == HIGH && lastMotionState == LOW) { // pin state change: HIGH -> LOW
 servo.write(0);
 }
 }
 }
 firstrun = false;
}