Arduino guide

Guide for Relay Module with Arduino

click here:-https://amzn.to/3cbH9et

This article shows how to control mains voltage with the Arduino

using a relay module. We make a brief introduction to the relay module

and build a simple project example with the Arduino. The example we’ll build

shows how to control a relay module with an Arduino and a PIR motion sensor.

Introducing the 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.

Controlling a relay module with the Arduino is as simple as controlling any

other output as we’ll see later on.

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 3.3V, which is ideal for ESP32,

ESP8266, and other microcontrollers

Mains voltage connections

The high-voltage side has two connectors, each with three sockets: common

(COM), normally closed (NC), and normally open (NO).

COM: common pin
NC (Normally Closed): the normally closed configuration is used when

you want the relay to be closed by default, meaning the current is flowing

unless you send a signal from the Arduino to the relay module to open the

circuit and stop the current.

NO (Normally Open): the normally open configuration works the other

 way around: the relay is always open, so the circuit is broken unless you send a signal from the Arduino to close the circuit.

If you just want to light up a lamp occasionally, it is better to use a normally-open circuit configuration.

Example: Controlling a Lamp with a Relay Module and PIR Motion Sensor

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 If you are not familiar with the PIR

motion sensor, you can read the following post:

To control the lamp with mains voltage we’ll use a in normally-open

configuration.

Safety warning

Before proceeding with this project, I want to let you know that you’re dealing with mains

voltage. 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. If you’re not 100% sure what you are doing,

do yourself a favor and don’t touch anything. Ask someone who knows!

Parts required

Here’s the needed parts for this example:

clike here:-https://amzn.to/2AiUu7G

arduno uno https://amzn.to/3cbH9et

clike here :-https://amzn.to/2ZJ686j

clike here:-https://amzn.to/2AhKKKA

Code

// Relay pin is controlled with D8. The active wire is connected to Normally Closed and common

int relay = 8;

volatile byte relayState = LOW;

// PIR Motion Sensor is connected to D2.

int PIRInterrupt = 2;

// Timer Variables

long lastDebounceTime = 0;

long debounceDelay = 10000;

void setup() {

// Pin for relay module set as output

pinMode(relay, OUTPUT);

digitalWrite(relay, HIGH);

// PIR motion sensor set as an input

pinMode(PIRInterrupt, INPUT);

// Triggers detectMotion function on rising mode to turn the relay on, if the condition is met

attachInterrupt(digitalPinToInterrupt(PIRInterrupt), detectMotion, RISING);

// Serial communication for debugging purposes

Serial.begin(9600);

}

void loop() {

// If 10 seconds have passed, the relay is turned off

if((millis() - lastDebounceTime) > debounceDelay && relayState == HIGH){

digitalWrite(relay, HIGH);

relayState = LOW;

Serial.println("OFF");

}

delay(50);

}

void detectMotion() {

Serial.println("Motion");

if(relayState == LOW){

digitalWrite(relay, LOW);

}

relayState = HIGH;

Serial.println("ON");

lastDebounceTime = millis();

}