Hello everyone,
TL;DR (I want my photoresistor value A0 pin to update on the webpage without hustle of manually refreshing the page. How do I do it with this code?)
I am fairly new user to Arduino, and just recently got myself UNO R4 with Wifi feature, so I've been studying up IoT part of arduino, and had a question on how to make the values refresh without the need to actually refresh the "webpage". This is the code that I've been working with, which is mostly copy/paste from the arduino's example:
#include <WiFiS3.h>
char ssid[] = "WIFI NAME"; //self explanatory
char pass[] = "WIFI PASSWORD"; //self explanatory
int keyIndex = 0; // should I delete it?
int status = WL_IDLE_STATUS; //connection status
WiFiServer server(80); //server socket
WiFiClient client = server.available();
int ledPin = 2;
const int photoPin = A0;
void setup() {
Serial.begin(9600);
pinMode(ledPin, OUTPUT); //FOR LED
pinMode(photoPin, INPUT); //FOR PHOTORESISTOR
while (!Serial);
enable_WiFi();
connect_WiFi();
server.begin();
printWifiStatus();
}
void loop() {
client = server.available();
if (client) {
printWEB();
}
}
void printWifiStatus() {
// print the SSID of the network you're attached to:
Serial.print("SSID: ");
Serial.println(WiFi.SSID());
// print your board's IP address:
IPAddress ip = WiFi.localIP();
Serial.print("IP Address: ");
Serial.println(ip);
// print the received signal strength:
long rssi = WiFi.RSSI();
Serial.print("signal strength (RSSI):");
Serial.print(rssi);
Serial.println(" dBm");
Serial.print("To see this page in action, open a browser to http://");
Serial.println(ip);
}
void enable_WiFi() {
// check for the WiFi module:
if (WiFi.status() == WL_NO_MODULE) {
Serial.println("Communication with WiFi module failed!");
// don't continue
while (true);
}
String fv = WiFi.firmwareVersion();
if (fv < "1.0.0") {
Serial.println("Please upgrade the firmware");
}
}
void connect_WiFi() {
// attempt to connect to Wifi network:
while (status != WL_CONNECTED) {
Serial.print("Attempting to connect to SSID: ");
Serial.println(ssid);
// Connect to WPA/WPA2 network. Change this line if using open or WEP network:
status = WiFi.begin(ssid, pass);
// wait 10 seconds for connection:
delay(10000);
}
}
void printWEB() {
if (client) { // if you get a client,
Serial.println("new client"); // print a message out the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected()) { // loop while the client's connected
if (client.available()) { // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println();
if (currentLine.endsWith("GET /value")) {
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/plain");
client.println();
client.print(analogRead(photoPin));
break;
}
//create the buttons
client.print("Click <a href=\"/H\">here</a> turn the LED on<br>"); //HERE WE CREATE A SIGNAL /H
client.print("Click <a href=\"/L\">here</a> turn the LED off<br><br>"); //HERE WE CREATE A SIGNAL /L
int photoValue = analogRead(photoPin);
client.print("Readings from photoresistor: ");
client.print(photoValue);
// The HTTP response ends with another blank line:
client.println();
// break out of the while loop:
break;
}
else { // if you got a newline, then clear currentLine:
currentLine = "";
}
}
else if (c != '\r') { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
if (currentLine.endsWith("GET /H")) {
digitalWrite(2, HIGH);
}
if (currentLine.endsWith("GET /L")) {
digitalWrite(2, LOW);
}
}
}
// close the connection:
client.stop();
Serial.println("client disconnected");
}
}
In raspberry pi I know that you can embed the HTML file separately, and have the JS mainly running, so you dont have to do the "dirty refresh"...but I am not sure how it works in arduino 
teaching myself from internet. And I am not sure what you mean by POST vs GET. Can you clarify it for me a bit more? Im feeling lost in WiFi and Bluetooth territory of arduinos. And thank you for your response!
