Arduino Nano 33 IoT - Solenoid Lock

The Solenoid Lock, also called the Electric Strike Lock, is a device that locks or unlocks cabinets, drawers, or doors. This guide shows you how to use an Arduino Nano 33 IoT to control the solenoid lock.

Another option for a solenoid lock is the electromagnetic lock. You can find more information in the Arduino Nano 33 IoT Electromagnetic Lock tutorial.

Hardware Preparation

1	×	Arduino Nano 33 IoT
1	×	Micro USB Cable
1	×	Solenoid Lock
1	×	Relay
1	×	12V Power Adapter
1	×	Breadboard
1	×	Jumper Wires
1	×	Optionally, DC Power Jack
1	×	Recommended: Screw Terminal Expansion Board for Arduino Nano
1	×	Recommended: Breakout Expansion Board for Arduino Nano
1	×	Recommended: Power Splitter for Arduino Nano

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

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Additionally, some of these links are for products from our own brand, DIYables .

Overview of Solenoid Lock

Pinout

The solenoid lock has two wires:

Red wire (+): Connect to the 12V output of the DC power supply.
Black wire (-): Connect to the ground (GND) of the DC power supply.

How It Works

When the solenoid lock receives power, the metal piece moves out, and the door becomes locked.
When the solenoid lock does not receive power, the metal piece moves in, and the door becomes unlocked.

※ NOTE THAT:

The solenoid lock normally works with a 12V, 24V, or 48V power supply. This means you should not connect the solenoid lock directly to an Arduino Nano 33 IoT pin. Instead, you need to use a relay to make the connection.

If we attach the solenoid lock to a relay that stays open by default:

When the relay is turned off, the door is unlocked.
When the relay is turned on, the door is locked.

Connect the Arduino Nano 33 IoT to the relay, and then you can write a program to control the solenoid lock. Learn more about the relay in the Arduino Nano 33 IoT - Relay tutorial.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

You can also build this circuit without a breadboard. Here is the same wiring:

The wiring diagram between Arduino Nano and 33 IoT Solenoid Lock (No Breadboard)

This image is created using Fritzing. Click to enlarge image

A screw terminal keeps each wire tight, even when the board shakes. To do that, mount the Arduino Nano 33 IoT on a Screw Terminal Expansion Board for Arduino Nano. Here is the same circuit wired through the screw terminal board:

The wiring diagram between Arduino Nano and 33 IoT Solenoid Lock Screw Terminal

This image is created using Fritzing. Click to enlarge image

Note: on the Arduino Nano 33 IoT, the 5V pin is the VUSB pin. It gives 5V only after you close the VUSB solder jumper on the bottom of the board, and only when the board runs on USB power.

Arduino Nano 33 IoT Code

The code below locks and unlocks the door every five seconds.

/* * This Arduino Nano 33 IoT code was developed by newbiely.com * * This Arduino Nano 33 IoT code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-iot/arduino-nano-33-iot-solenoid-lock */ #define RELAY_PIN 2 // The Arduino Nano 33 IoT pin connected to the solenoid lock via the relay // The setup function runs once on reset or power-up void setup() { // initialize digital pin as an output. pinMode(RELAY_PIN, OUTPUT); } // The loop function repeats indefinitely void loop() { digitalWrite(RELAY_PIN, HIGH); // unlock the door delay(5000); digitalWrite(RELAY_PIN, LOW); // lock the door delay(5000); }

Detailed Instructions

If you are new to the Arduino Nano 33 IoT, be sure to check out our Getting Started with Arduino Nano 33 IoT tutorial. Then, follow these steps:

Connect the components to the Arduino Nano 33 IoT board as depicted in the diagram.
Use a USB cable to connect the Arduino Nano 33 IoT board to your computer.
Launch the Arduino IDE on your computer.
Select the Arduino Nano 33 IoT board and choose its corresponding COM port.
Copy the code above and paste it into the Arduino IDE.
Click the Upload button in the Arduino IDE to compile the code and send it to the Arduino Nano 33 IoT board.
Check the status of the lock tongue.

Arduino Nano 33 IoT - Button Controls Solenoid Lock

See the Arduino Nano 33 IoT project that shows how to use a button to control a solenoid lock: Arduino Nano 33 IoT - Button Controls Solenoid Lock guide

※ NOTE THAT:

In the code above, we used the delay function, so we don't need to debounce the button. However, we've still added code with debouncing in case you want to do more tasks without using the delay function. See this link for more details: How to use millis() instead of delay().

Relay vs MOSFET Module for the Solenoid Lock

This tutorial uses a relay to switch the solenoid lock. A 12V solenoid lock runs on DC, so a MOSFET module can also switch it.

	Relay	MOSFET Module
Lock control	lock or unlock	lock or unlock
Switching sound	a click every time	no sound
Switching time	slow (milliseconds)	very fast
Wear	the contacts get old with use	no moving parts to wear
Works with	AC and DC locks	DC locks only
Flyback diode	most relay modules do not need one	must add one (1N4007 or 1N5819)
Isolation	yes	yes, with a PC817 optocoupler
Choose it for	a simple, common setup	a silent lock, or a door that opens many times a day

A solenoid lock is only locked or unlocked, so the MOSFET module does not give extra control here. Its gains are: no click, and nothing wears out. Both turn on when the pin is HIGH, so the code stays the same. Do not keep the lock unlocked for a long time, or it gets hot. This is the same with a relay. The 3.3V pin of the Arduino Nano 33 IoT is enough to drive the module.

A solenoid valve works the same way as a solenoid lock. To see how to wire and code one with both a relay and a MOSFET module, see the Arduino Nano 33 IoT - Water/Liquid Valve tutorial. The wiring for a solenoid lock is in the Arduino Nano 33 IoT - MOSFET Module tutorial.

Video Tutorial

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