4-CH Web Controlled Ethernet relay

In this article i will give the basic steps to build a 4 channels Ethernet relay that can be used as a network power switch for many purposes. the importance of this project resides in having the ability to control those relay “wirelessly” from your smart phone through WiFi or even from outside your house through the internet.

That relay board is a LAN based, you need to attach it to your network through a network cable. i.e. you will need a WiFi Access point with at least one Ethernet port.

Below is the final assembled project:

The software image on the left is for the Android application that i built to controls the 4 Relays. Of course you can build the application you want, any application that can send HTTP requests can be used with this project, i will describe this later in this article.

The Ethernet Module:

The project has two main “hearts”, the ATMEL Atmega328P as the brain, and the Ethernet module ENC28J60 which saved lots and lots of work, otherwise you will have to build the TCP/IP stack in your microcontroller code. believe me it’s not an easy task. This module communicates with the microcontroller through SPI, typically, 6 pins is only required to work with this little thing.

The Microcontroller:

One of the challenges that i had in this project is to find a good library for the ENC28J60 Ethernet module. initially i started with the PIC microcontrollers, although that are very efficient but i found that writing a native C to handle the communication with the Ethernet module is a time consuming task which can be easily solved by using Arduino based microcontroller like Atmega328P which is the heart of Arduino Uno board. the idea is to use the Arduino libraries built for that module which give you the ability to build a “tiny” web server to receive and analyse the HTTP requests, then accordingly send orders to the relays through the output ports.

You will need to have at least one Arduino Uno board, write the code and save it to the microcontroller then pull it and insert it into your circuit.

Circuit Diagram

I used the famous CadSoft Eagle to build the PCB and circuit diagram, please contact me if you want the Eagle files.

PCB Artwork

Arduino Code

Make sure that both ETHER_28J60 and etherShield libraries are included in your Arduino project
I will add them later to this post

Note that the code was configured to have a fixed IP 192.168.2.100, you need to change it before compiling the project to have the same network address of you network.

You can invoke this small webserver directly from the browser, ex: http://192.168.2.100?d1=on to turn ON  the first relay and http://192.168.2.100?d1=off to turn it off. Invoking the server with the status parameters will send the realys’ ex: http://192.168.2.100?status will print the following:

d1=ond2=offd3=ond4=on

you will need to parse those values in your program and change the layout accordingly.
I have built an Android application to control this device. It was built using MIT App Inventor, the application was built as a sound system controller for my house, below is a screenshot of that App.
App Inventor source will be uploaded soon …

 

// A simple web server to turn 5 LED on or off
#include <Arduino.h>
#include "etherShield.h"
#include "ETHER_28J60.h"
#include <EEPROM.h>

int outPin0 = 0; // relay1 to pin 4
int outPin1 = 1; // relay2 to pin 3
int outPin2 = 2; // relay3 to pin 2
int outPin3 = 3; // relay4 to pin 1
int outPin4 = 4; // relay5 to pin 0

const int ledPin = 9; // led status pin 9

byte value0;
byte value1;
byte value2;
byte value3;
byte value4;

//int ledState = LOW;
//long previousMillis = 0;
//long interval = 1000;


static uint8_t mac[6] = {
 0x54, 0x55, 0x58, 0x10, 0x12, 0x24}; // this just needs to be unique for your network,

static uint8_t ip[4] = {192, 168, 2, 100}; // IP address for the webserver
static uint16_t port = 80; // Use port 80 - the standard for HTTP
String myip="";

ETHER_28J60 e;

void current_status() {
 int val = 0;

 val = digitalRead(outPin0);
 if (val == LOW)
 e.print("d1=off");
 else
 e.print("d1=on");

 val = digitalRead(outPin1);
 if (val == LOW)
 e.print("d2=off");
 else
 e.print("d2=on");


 val = digitalRead(outPin2);
 if (val == LOW)
 e.print("d3=off");
 else
 e.print("d3=on");


 val = digitalRead(outPin3);
 if (val == LOW)
 e.print("d4=off");
 else
 e.print("d4=on");
}


void LoadLastSettings() {
 value0 = EEPROM.read(0x00);
 value1 = EEPROM.read(0x01);
 value2 = EEPROM.read(0x02);
 value3 = EEPROM.read(0x03);
 value4 = EEPROM.read(0x04);

 if (value0==0)
 {
 digitalWrite(outPin0, LOW);
 }
 else if (value0==1)
 {
 digitalWrite(outPin0, HIGH);
 }


 if (value1==0)
 {
 digitalWrite(outPin1, LOW);
 }
 else if (value1==1)
 {
 digitalWrite(outPin1, HIGH);
 }


 if (value2==0)
 {
 digitalWrite(outPin2, LOW);
 }
 else if (value2==1)
 {
 digitalWrite(outPin2, HIGH);
 }


 if (value3==0)
 {
 digitalWrite(outPin3, LOW);
 }
 else if (value3==1)
 {
 digitalWrite(outPin3, HIGH);
 }


 if (value4==0)
 {
 digitalWrite(outPin4, LOW);
 }
 else if (value4==1)
 {
 digitalWrite(outPin4, HIGH);
 }
}//End



void setup()
{
 e.setup(mac, ip, port);

 pinMode(outPin0, OUTPUT);
 pinMode(outPin1, OUTPUT);
 pinMode(outPin2, OUTPUT);
 pinMode(outPin3, OUTPUT);
 pinMode(outPin4, OUTPUT);
 pinMode(ledPin, OUTPUT);


 LoadLastSettings();


} // End Setup


void loop()
{
 char* params;
 if (params = e.serviceRequest())
 {

 if (strcmp(params, "?status") == 0)
 {
 current_status();
 }

// to be implemented
// else if (strcmp(params, "?ipchange") == 0) { // ?ipchange192.168.1.250
// myip = substr(params,9,3);
// }


 e.print("<h1>Ethernet Relay Control<h1>");
 e.print("<h2><a href='/?d1=off'>Relay1OFF</a></h2>");
 e.print("<h2><a href='/?d1=on'>Relay1ON</a></h2>");
 e.print("<h2><a href='/?d2=off'>Relay2OFF</a></h2>");
 e.print("<h2><a href='/?d2=on'>Relay2ON</a></h2>");
 e.print("<h2><a href='/?d3=off'>Relay3OFF</a></h2>");
 e.print("<h2><a href='/?d3=on'>Relay3ON</a></h2>");
 e.print("<h2><a href='/?d4=off'>Relay4OFF</a></h2>");
 e.print("<h2><a href='/?d4=on'>Relay4ON</a></h2>");
 e.print("<h2><a href='/?d5=off'>out5off</a></h2>");
 e.print("<h2><a href='/?d5=on'>out5on</a></h2>");

 if (strcmp(params, "?d1=on") == 0)
 {
 value0=1;
 digitalWrite(outPin0, HIGH);
 e.print("<h1>d1=on</h1>");
 }
 else if (strcmp(params, "?d1=off") == 0)
 {
 value0=0;
 digitalWrite(outPin0, LOW);
 e.print("<h1>d1=off</h1>");
 }

 if (strcmp(params, "?d2=on") == 0)
 {
 value1=1;
 digitalWrite(outPin1, HIGH);
 e.print("<h1>d2=on</h1>");
 }
 else if (strcmp(params, "?d2=off") == 0)
 {
 value1=0;
 digitalWrite(outPin1, LOW);
 e.print("<h1>d2=off</h1>");
 }


 if (strcmp(params, "?d3=on") == 0)
 {
 value2=1;
 digitalWrite(outPin2, HIGH);
 e.print("<h1>d3=on</h1>");
 }
 else if (strcmp(params, "?d3=off") == 0)
 {
 value2=0;
 digitalWrite(outPin2, LOW);
 e.print("<h1>d3=off</h1>");
 }
 if (strcmp(params, "?d4=on") == 0)
 {
 value3=1;
 digitalWrite(outPin3, HIGH);
 e.print("<h1>d4=on</h1>");
 }
 else if (strcmp(params, "?d4=off") == 0)
 {
 value3=0;
 digitalWrite(outPin3, LOW);
 e.print("<h1>d4=off</h1>");
 }
 if (strcmp(params, "?d5=on") == 0)
 {
 value4=1;
 digitalWrite(outPin4, HIGH);
 e.print("<h1>d5=on</h1>");
 }
 else if (strcmp(params, "?d5=off") == 0)
 {
 value4=0;
 digitalWrite(outPin4, LOW);
 e.print("<h1>d5=off</h1>");
 }
 e.respond();

 EEPROM.write(0x00, value0);
 EEPROM.write(0x01, value1);
 EEPROM.write(0x02, value2);
 EEPROM.write(0x03, value3);
 EEPROM.write(0x04, value4);

 }
}

Testing the project