Sanjeev Kumar's Blog

Turn on LED or Solenoid with push button and turn off after 10 seconds

1/12/2017

Much of it is same how to turn on LED on using a push button tutorials you might have come across on the internet, however I have used millis function to turn off the solenoid after 10 seconds. You can choose for how much time you want.

What you need

hook up

Once you have all hooked up as shown in above fritzing,
Upload the below code to your UNO. I have set 10 seconds represented by interval variable which in code is showing set to 10000 milli seconds.

//Constants
const int buttonPin = 3;
const int ledPin =  7;

//Variables
int buttonState = 0;
int flag = 0;


// the interval in mS
unsigned long interval = 10000; // the time we need to wait to finish watering the plant.
unsigned long currentMillis = 0;    // stores the value of millis() in each iteration of loop()
unsigned long previousMillis = 0; // millis() returns an unsigned long.

void setup() {
  //Input or output?
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  currentMillis = millis();   // capture the latest value of millis()
  //Read button state (pressed or not pressed?)
  buttonState = digitalRead(buttonPin);

  //If button pressed...
  if (buttonState == LOW) {
    //...ones, turn led on!
    if ( flag == 0) {
      digitalWrite(ledPin, HIGH);
      flag = 1; //change flag variable
    }
    //...twice, turn led off!
    else if ( flag == 1) {
      digitalWrite(ledPin, LOW);
      flag = 0; //change flag variable again
    }
  }
  if ((unsigned long)(currentMillis - previousMillis) >= interval) {
    flag = 0; //change flag variable again
    digitalWrite(ledPin, LOW);
    // save the "current" time
    previousMillis = millis();
  }

}