Published November 18, 2025

Doorknob Sensor

A sensor connected to a Particle Photon which sends notifications to your phone when movement detected.

BeginnerFull instructions provided93

Things used in this project

Hardware components

Particle Photon 2

Tilt Switch Sensor

Jumper wires (generic)

Female/Female Jumper Wires

Software apps and online services

NTFY.sh

Particle Build Web IDE

Story

Have you ever had an annoying cousin that enters your room without asking? If so, knowing when they enter without your approval is now possible.

How It Works

A tilt sensor contains a small metal ball that completes a circuit when tilted. The photon reads this as either a "high" or "low" input. When the sensor closes, we know the door has moved, which sends a notification to my phone through a webhook. For this project, it will only read it when it detects a "low" input.

Webhook and NTFY Setup

Download NTFY App on your mobile device. Once clicked on the app, a menu like this will pop up. Afterwards click the "+" button in the top right corner.

NTFY Homescreen

Once done so, a prompt like this will pop up.

NTFY Topic Creation Screen

Once here, create a topic name that is not easily acessible or guessable by any circumstances so the server is mainly and only for you. Making a generic topic name will allow others to potentially use the same server as you allowing you to get unnecessary notifications.

Once you successfully create a topic name, the url would look something around "https://ntfy.sh/" After the url for your ntfy has been created, you need to connect it to a webhook.

In the Particle Console, go to "Cloud Services, " then click on "Integrations." Afterwards proceed to "+AddNewIntegration."

A new page will open up with various types of integrations, but ignore them and scroll all the way to the bottom and click on "CustomWebhook."

Afterwards, fill out the section with a name for your webhook, the event name within your code to call the webhook, aswell as the request type and url link to connect to ntfy.

For Example:

Integration Info page

Make sure that the "Event name" within the webhook is the same as the name within your code. In this case it would be "push-notification."

After setting your request format to CustomBody, scroll down to ExtraSettings then in the box for CustomRequestBody insert:

This code allows it so when the photon detects movement, it sends the message "Door Opened" to your phone through ntfy.

After that is done, click EnableIntegration then you are finished!

You have made your own doorknob sensor. Congratulations!

Final Video

Video

Code

Doorknob Sensor

SYSTEM_MODE(AUTOMATIC);

int tiltPin = D2;

void setup() {
  pinMode(tiltPin, INPUT_PULLUP);
}

void loop() {
  // If tilt switch closes (door opens)
  if (digitalRead(tiltPin) == LOW) {
    if (Particle.connected()) {
      Particle.publish("push-notification", "Door opened", PRIVATE);
    }
    // Wait until the tilt switch is released to avoid spamming
    while (digitalRead(tiltPin) == LOW) {
      delay(100);
    }
  }
  delay(100);
}

Credits

Joel D

1 project • 0 followers

Doorknob Sensor

Things used in this project

Hardware components

Software apps and online services

Story

How It Works

Webhook and NTFY Setup

Schematics

Breadboard Wiring

Elegoo Sensor Wire Setup

Code

Doorknob Sensor

Credits

Joel D

Comments

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Doorknob Sensor

Doorknob Sensor

Things used in this project

Hardware components

Software apps and online services

Story

How It Works

Webhook and NTFY Setup

Schematics

Breadboard Wiring

Elegoo Sensor Wire Setup

Code

Doorknob Sensor

Credits

Joel D

Comments

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