We make a brief introduction to the relay module and build a simple project example with the Arduino. By the end of this tutorial, you should be able to control any electronics appliances with your Arduino using a relay module. A relay is an electrically operated switch that can be turned on or off, letting the current go through or not, and can be controlled with low voltages, like the 5V provided by the Arduino pins.
This relay module has two channels those blue cubes. There are other models with one, four and eight channels. This module should be powered with 5V, which is appropriate to use with an Arduino. There are other relay modules that are powered using 3. The six pins on the left side of the relay module connect high voltage, and the pins on the right side connect the component that requires low voltage—the Arduino pins.
If you just want to light up a lamp occasionally, it is better to use a normally-open circuit configuration. The jumper cap allows you to choose whether the circuit is physically connected to the Arduino circuit or not, and you can choose to have it on or not. In this example, we create a motion sensitive lamp.
A lamp lights up for 10 seconds every time motion is detected. Motion will be detected using a PIR motion sensor. If you are not familiar with the PIR motion sensor, you can read the following post:. Please read the safety warning below carefully. Warning: when you are making projects that are connected to mains voltage, you really need to know what you are doing, otherwise you may shock yourself. This is a serious topic, and we want you to be safe.
Ask someone who knows! You can use the preceding links or go directly to MakerAdvisor. View raw code. First, we create variables to hold the pin the relay IN1 pin is connected to and to save the relay state:. We need to create some auxiliary variables to handle timers with the PIR motion sensor.
The lastDebounceTime variable saves the last time motion was detected. The relay is triggered when the input goes below about 2 V. That means if you send a LOW signal from the Arduino, the relay turns on, and if you send a HIGH signal, the relay turns off; it works with inverted logic. Whenever the PIR motion sensor is triggered, it calls the detectMotion function declared at the end of the code to turn the relay on:. In the loop , we check whether 10 seconds have passed since the relay is on.
If that condition is true, we can turn the relay off. Warning: do not touch any wires that are connected to mains voltage. Also make sure you have tighten all screws of the relay module. The lamp is connected to the relay using a normally open configuration. The Arduino controls the relay through pin 8 pin 8 is connected to the relay IN1 pin. Finally, the PIR motion sensor is connected to pin 2.
When motion is detected, your lamp lights up. With the relay module you can control almost any AC electronics appliances not just lamps. If you like this project, you may also like our premium Arduino course:. We have more than 60 free tutorials and projects with the Arduino. Finally, you can also get access to our FREE resources here.
Arduino Step-by-Step Projects » Build 25 Arduino projects with our course, even with no prior experience! Oi Rui! Any way we can omit the use of another 5V power adapter? Because doing so will waste sockets. Can we, say, draw the power from the same wire that powers the light, and feed that same mains power into Arduino with a bit of circuits to drop the power to 5V before feeding to Arduino? You can do that, but you need to have a proper circuit to have an output of 5V to power the Arduino.
Regards, Sara. This look as opening doors by shot from canone. Definitely, but this is just an example for beginners. Would love to see you write a tutorial demonstrating how to use more than 1 different type of sensor at a time, for example a distance sensor and say a tilt sensor that could be combined for use on a wheeled robot that could detect objects in front as well as if it has been picked up or knocked over.
I have made many of these without an Arduino, but I guess the lesson here is how to control a relay with the Arduino. OK, I get it …. Did you simulate the circuit first on a computer program like Proteus? I tried to simulate the circuit in this project with Proteus but when I ran it, the light was always on regardless whether I changed the PIR sensor logic from 0 to 1.
I hope this helps. I am planning to use an ESP and this is 3. Hi Chris. To power the relay module you need to supply 5V in the Vin pin of the relay board. To control the relay, you can send a 3. May i know how come the subfunction detectmotion was not included in the loop function still the project progress as if detectmotion keeps looping? Interrupts are useful for making things happen automatically in microcontroller programs, and can help solve timing problems.
I have a question though. My observation is that you only need as many relays as devices you wish to control with your Arduino. Am I right? Yes, you are right. You can use a 1-channel relay module if you just want to control an output. It would be possible to keep the lamp turned on for a larger period of time, like minutes, without damaging the relay or the arduino board? Do you have any idea what this means? Thanks for the tutorial! I followed the instructions and everything worked fine.
That was my first arduino project! I hope you had fun with it! You can try other of our Arduino projects. You should really have done this in this demo. It helped me understand the code and how to connect it. I thought you may want to add in your box about Jd-vcc , that most of the generic boards are not idiot-proof because the GND and VCC are right next to each other so make sure you put that jumper in the right place! Hello, The 20mA current output for the relay is not enough.
It is a bridge between Arduino and high voltage devices. WARNING When you are making projects that are connected to mains voltage, you need to know what you are doing, otherwise, you may shock yourself. Pins in the high voltage group are connected to the high voltage device, including three pins usually in screw terminal :.
COM pin: is the common pin. It is used in both normally open mode and normally closed mode. NO pin: is normally open pin. It is used in the normally open mode. NC pin: is normally closed pin. It is used in the normally closed mode.
Some relay module only has two pin in high voltage group. The device is OFF or inactive. The device is ON or active. Wiring Diagram Image is developed using Fritzing. How To Program For Relay. Configure an Arduino's pin to the digital output mode by using pinMode function.
For example, pin Video Tutorial We are considering to make the video tutorials. Challenge Yourself. Automatically turn on the light when you enter into your room and turn off the light after you leave 30 seconds. Hint : Refer to Arduino - Motion Sensor. Alternative Relays The above code also works with the following relays:.
Relay on Commercial Products. Function References. The Best Arduino Starter Kit. See the best Arduino kit for beginner. See Also. Arduino - Relay Shield. Arduino - 4-Channel Relay Module. Arduino - Controls Fan. Arduino - Controls Heating Element. Arduino - Button - Relay. Arduino - Button Toggle Relay. Arduino - Potentiometer Triggers Relay. Arduino - Light Sensor Triggers Relay. Arduino - Ultrasonic Sensor - Relay. Arduino - Motion Sensor - Relay.
Arduino - Keypad - Relay. Arduino - Heating System. Arduino - Touch Sensor - Relay. Arduino - Touch Sensor Toggle Relay. Arduino - Door Sensor - Relay. Arduino - Door Sensor Toggle Relay.
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This post shows how to use a relay module with an Arduino board. A relay is an electrically operated switch that you can use to control mains voltage. The relay module is an electrically operated switch that can be turned on or off deciding to let current flow through or not. They are designed. A relay is a programmable electrical switch, which can be controlled by Arduino or any micro-controller. It is used to programmatically control on/off the.