Arduino project · Smart doors and home · Medium
Door Opening Counter with Memory
A reed switch and magnet on a door count every opening. The total is kept in EEPROM and a button clears it.
What you will learn
- How a reed switch detects a door opening
- How to count events for days or weeks
- How to clear a counter with a button
How it works
When the door opens the reed contact changes, the count goes up and is saved. The program waits for the door to close before counting again. Real EEPROM survives about 100,000 writes, so a real program should save only when the number changes, as this one does.
Try this next
- Show the count on an OLED.
- Add a buzzer after 100 openings.
- Log the time of each opening with an RTC.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
A door that reports when it opens
Open the door contact in the simulator. The real door opens and, with the GSM module, a text message appears on the phone.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- Reed switch = the door
- GSM module = sends the SMS