Output to operate as (and in parallel with) momentary pushbutton

So my project is a simple one:
Use sensors on side of interior garage to detect vehicle entering or leaving, then give the garage door opener a momentary button push just like the remote. SIMPLE.

The problem I am facing is, using the example Debouncer code, instead of toggling the output I would like to send a momentary pulse to then close the garage door.

I tried:
digitalWrite(ledPin, !ledState);
digitalWrite(ledPin, ledState);

...to "push" the button than release it. No worky.


I am using the Example Debouncer code with the above change replacing the "toggle output" command at the end.

The easier you make it to read and copy your code the more likely it is that you will get help

Please follow the advice given in the link below when posting code , use code tags and post the full code of your project here

If you get errors when compiling please copy them from the IDE using the "Copy error messages" button and paste the clipboard here in code tags

Read the forum guidelines.

Post a schematic of the project.

Post the whole code.

What does that mean? That conveys no actual information that we can use to help you.

Well,I guess this is not a simple job.
At least you need a button-manager, a timer and eventuel a small FSM.

Below is the code (example with modification to output), sorry for the lack of information here. First post.
I have also attached a schematic of what I am trying to accomplish.

Let me know if anything else is needed for clarity.


  Each time the input pin goes from LOW to HIGH (e.g. because of a push-button
  press), the output pin is toggled from LOW to HIGH or HIGH to LOW. There's a
  minimum delay between toggles to debounce the circuit (i.e. to ignore noise).

  The circuit:
  - LED attached from pin 13 to ground through 220 ohm resistor
  - pushbutton attached from pin 2 to +5V
  - 10 kilohm resistor attached from pin 2 to ground

  - Note: On most Arduino boards, there is already an LED on the board connected
    to pin 13, so you don't need any extra components for this example.

  created 21 Nov 2006
  by David A. Mellis
  modified 30 Aug 2011
  by Limor Fried
  modified 28 Dec 2012
  by Mike Walters
  modified 30 Aug 2016
  by Arturo Guadalupi

  This example code is in the public domain.


// constants won't change. They're used here to set pin numbers:
const int buttonPin = 2;    // the number of the pushbutton pin
const int ledPin = 13;      // the number of the LED pin

// Variables will change:
int ledState = HIGH;         // the current state of the output pin
int buttonState;             // the current reading from the input pin
int lastButtonState = LOW;   // the previous reading from the input pin

// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastDebounceTime = 0;  // the last time the output pin was toggled
unsigned long debounceDelay = 50;    // the debounce time; increase if the output flickers

void setup() {
  pinMode(buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);

  // set initial LED state
  digitalWrite(ledPin, ledState);

void loop() {
  // read the state of the switch into a local variable:
  int reading = digitalRead(buttonPin);

  // check to see if you just pressed the button
  // (i.e. the input went from LOW to HIGH), and you've waited long enough
  // since the last press to ignore any noise:

  // If the switch changed, due to noise or pressing:
  if (reading != lastButtonState) {
    // reset the debouncing timer
    lastDebounceTime = millis();

  if ((millis() - lastDebounceTime) > debounceDelay) {
    // whatever the reading is at, it's been there for longer than the debounce
    // delay, so take it as the actual current state:

    // if the button state has changed:
    if (reading != buttonState) {
      buttonState = reading;

      // only toggle the LED if the new button state is HIGH
      if (buttonState == HIGH) {
        ledState = !ledState;

  // set the LED:
  digitalWrite(ledPin, !ledState);
  digitalWrite(ledPin, ledState);

  // save the reading. Next time through the loop, it'll be the lastButtonState:
  lastButtonState = reading;

You don't have to use ledState; that part just toggles the led, something you don't need and don't want. Just place your pulse code inside the if block.

if (buttonState == HIGH)
  digitalWrite(ledPin, HIGH);
  digitalWrite(ledPin, LOW);

And remove

1 Like

I knew there was a simple fix i was missing. Thank you !!

Are you sure this is correct circuit config?

Pin2 of the Arduino will be pulled to 11.3V, it can only tolerate 5V.
At the moment the impedance of the B-E junction and the internal protection diodes of the UNO must be saving Pin2 from destruction.
Not even sure why you used a transistor, a simple potential divide would suffice.

Do you have a DMM?

Measure the volts in Pin2 when unobstructed?
Measure the 5V pin of the Arduino?
ALL with reference to the Arduino gnd.

Can you please post link to data/specs of your sensor Emitter and Receiver?

Thanks.. Tom.. :grinning: :+1: :coffee: :australia:

Used a multimeter to measure pin 2 of Arduino... 4.98v.

What about the 5v Pin of the Arduino?
Does pin2 go to 0V when obstructed?
Please post link to data/specs of IR units, or a picture of them?

A potential divider will be safer.

Tom... :grinning: :+1: :coffee: :australia:

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