In This tutorial to build a standalone ESP8266 NodeMCU Web Server that controls any relay module. We’ll create an ESP8266 Web Server and it can be accessed with any device with a Web browser in your local network.
Circuit Diagram
Components Required
ESP8266 12E
4 Channel Relay Module
Jumper wires
4 Channel Isolated 5A or 10A Relay HW-316
The 4 Channel Relay Breakout is an easy way to use your Arduino, Raspberry Pi, or other microcontroller to switch high voltages and high current loads. ... Each relay has the common, normally open, and normally closed pin broken out to a convenient 5.0mm pitch screw terminal.
While this board can be used to switch mains power, it should be done so using extreme caution. This should not be done without the aid of an experienced electrician.
Equiped with high-current relay, AC250V 10A ; DC30V 10A
5V 4-Channel Relay interface board, and each one needs 50-60mA Driver Current
Be able to control various appliances, and other equipments with large current
Application：Supports all MCU control, The industrial field, PLC control, Smart home control
Indication LED's for Relay output status
Installing the ESP8266_Arduino_Library
Click here to download the ESPAsyncWebServer library
Click here to download the AsyncTCP library (ESP32)
Click here to download the ESPAsyncTCP library (ESP8266 NodeMCU)
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In your Arduino IDE, to install the libraries go to Sketch > Include Library > Add .ZIP library… and select the library you’ve just downloaded.
After installing the required libraries, copy the following code to your Arduino IDE.
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Arduino Code
#include "ESP8266WiFi.h"
#include "ESPAsyncWebServer.h"
// Set to true to define Relay as Normally Open (NO)
#define RELAY_NO true
// Set number of relays
#define NUM_RELAYS 4
// Assign each GPIO to a relay
int relayGPIOs[NUM_RELAYS] = {5, 4, 14, 12};
// WiFi login parameters - network name and password
const char* ssid = "TP-Link_3200"; // your SSID
const char* password = "9500112137"; // your WIFi Password
const char* PARAM_INPUT_1 = "relay";
const char* PARAM_INPUT_2 = "state";
// Create AsyncWebServer object on port 80
AsyncWebServer server(80);
const char index_html[] PROGMEM = R"rawliteral(
<!DOCTYPE HTML><html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
html {font-family: Arial; display: inline-block; text-align: center;}
h2 {font-size: 2.0rem;}
p {font-size: 2.0rem;}
body {max-width: 900px; margin:0px auto; padding-bottom: 25px;}
.switch {position: relative; display: inline-block; width: 120px; height: 68px}
.switch input { opacity: 0; width: 0; height: 0;}
.slider {position: absolute; top: 0; left: 0; right: 0; bottom: 0; background-color: #ff3737; -webkit-transition: .4s; transition: .4s;}
.slider:before {position: absolute; content: ""; height: 52px; width: 52px; left: 8px; bottom: 8px; background-color: #e6e6e6; -webkit-transition: .4s; transition: .4s; }
input:checked+.slider {background-color: #21f37e}
input:checked+.slider {box-shadow: 0 0 1px #21f37e}
input:checked+.slider:before {-webkit-transform: translateX(52px); -ms-transform: translateX(52px); transform: translateX(52px)}
</style>
</head>
<body>
<h2>ESP8266 Home Automation Web Sever</h2>
%BUTTONPLACEHOLDER%
<script>function toggleCheckbox(element) {
var xhr = new XMLHttpRequest();
if(element.checked){ xhr.open("GET", "/update?relay="+element.id+"&state=1", true); }
else { xhr.open("GET", "/update?relay="+element.id+"&state=0", true); }
xhr.send();
}</script>
</body>
</html>
)rawliteral";
// Replaces placeholder with button section in your web page
String processor(const String& var){
//Serial.println(var);
if(var == "BUTTONPLACEHOLDER"){
String buttons ="";
for(int i=1; i<=NUM_RELAYS; i++){
String relayStateValue = relayState(i);
buttons+= "<h4>Device : " + String(i) + "</h4><label class=\"switch\"><input type=\"checkbox\" onchange=\"toggleCheckbox(this)\" id=\"" + String(i) + "\" "+ relayStateValue +"><span class=\"slider\"></span></label>";
}
return buttons;
}
return String();
}
String relayState(int numRelay){
if(RELAY_NO){
if(digitalRead(relayGPIOs[numRelay-1])){
return "";
}
else {
return "checked";
}
}
else {
if(digitalRead(relayGPIOs[numRelay-1])){
return "checked";
}
else {
return "";
}
}
return "";
}
void setup(){
// Serial port for debugging purposes
Serial.begin(115200);
// Set all relays to off when the program starts - if set to Normally Open (NO), the relay is off when you set the relay to HIGH
for(int i=1; i<=NUM_RELAYS; i++){
pinMode(relayGPIOs[i-1], OUTPUT);
if(RELAY_NO){
digitalWrite(relayGPIOs[i-1], HIGH);
}
else{
digitalWrite(relayGPIOs[i-1], LOW);
}
}
// Connect to Wi-Fi
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("Connecting to WiFi..");
}
// Print ESP8266 Local IP Address
Serial.println(WiFi.localIP());
// Route for root / web page
server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
request->send_P(200, "text/html", index_html, processor);
});
// Send a GET request to <ESP_IP>/update?relay=<inputMessage>&state=<inputMessage2>
server.on("/update", HTTP_GET, [] (AsyncWebServerRequest *request) {
String inputMessage;
String inputParam;
String inputMessage2;
String inputParam2;
// GET input1 value on <ESP_IP>/update?relay=<inputMessage>
if (request->hasParam(PARAM_INPUT_1) & request->hasParam(PARAM_INPUT_2)) {
inputMessage = request->getParam(PARAM_INPUT_1)->value();
inputParam = PARAM_INPUT_1;
inputMessage2 = request->getParam(PARAM_INPUT_2)->value();
inputParam2 = PARAM_INPUT_2;
if(RELAY_NO){
Serial.print("NO ");
digitalWrite(relayGPIOs[inputMessage.toInt()-1], !inputMessage2.toInt());
}
else{
Serial.print("NC ");
digitalWrite(relayGPIOs[inputMessage.toInt()-1], inputMessage2.toInt());
}
}
else {
inputMessage = "No message sent";
inputParam = "none";
}
Serial.println(inputMessage + inputMessage2);
request->send(200, "text/plain", "OK");
});
// Start server
server.begin();
}
void loop() {
}
After a successful upload, open the Serial Monitor at a baud rate of 115200. Press the “EN/RST” button on the ESP8266 board. Now it should print its IP address.
