//Needs Updating

The original idea was to make a master plug for each room and several slave plugs connected to the master through a WiFi access point created using the master plug. But due to Network Stack issues and issues pertaining to maintain time in all the smart plugs, I'm dropping this idea dor the time being.

Description of libraries Used

servertext.h

Contains the required HTML for the WiFi Connection feature The Master acts as a HTML Server and is used to connect to the required Network using a web interface.

ESP8266WiFi.h

Library used by ESP8266 module to give WiFi functionality to the Board.

ESP8266WebServer.h

Library required to bring the web server functionality for the Module.

EmonLib.h

Used to calculate the current drawn

NTPClient.h

Uses UDP protocol to connect to a NTP Server. IS used to sync time with the master plug. Currently having Issues with syncing time with a server. The issue is resolved when the flexible WiFi Connection feature isnt used, i.e. when I preset the WiFi SSID and password. Cannot seem to make it work otherwise. Suspected problem is with the UDP Connection

WiFiUDP.h

Used for setting up the udp connection required for the NTPClient Server Commuincation.

PROGRAM DESCRIPTION

Preprocessing and Declarations

The NodeMCU has two WiFi Modes, the Station Mode and the Access Point Mode Station mode is used to connect to our home network and the Access Point mode makes the master an Access Point through which the WebServer will be accessed. The following code describes the basic config of the access point and other constants that are used in the later functions

//Constants Declarations
#define wifi_led D4

const char *softSSID = "Master";    //Credentials for Master Access Point
const char *softPASS = "password";  //For the function to work, the password should be more than 8 chars and should begin with a char too

IPAddress softAP_ip(192,168,0,1);         //IP config for the soft Access Point
IPAddress softAP_gateway(192,168,0,1);
IPAddress softAP_subnet(255,255,255,0);

int sflag = 0;
int cflag = 0;

const long int offset = 19800;

int voltage = 230;

Objects that will be used are declared as follows

//Class Object Declarations
//ESP8266WifiMulti WiFimulti_Object;
ESP8266WebServer server(80);

EnergyMonitor curr;

WiFiUDP ntp_udp_client;
NTPClient time_object(ntp_udp_client, "asia.pool.ntp.org", offset);
//

ESP8266WebServer class is used for the methods of the webserver. 80 declares the network port used for the webserver, which is default for HTML

EnergyMonitor class contains the methods used to calculate the RMS value of Current

WiFiUDP class declares an object used for the UDP connection

NTPClient class uses a constructor taking in the UDP object, NTPServer and the Time Offset that is declred in the constants above

Function Descriptions The Following Functions are used in the Program:

//Function Prototypes
void sta_setup(char*, char*);

void handle_root();
void handle_notfound();
void handle_disconnect_wifi();
void handle_connect_wifi();
void handle_wifi_login();
//

Other than this, the void setup and loop do the same thing as in an Arduino

void sta_setup()

This function is used to dynamically connect to a home wifi network using the WebServer.

void handle_root ...... handle_wifi_login()

Used for the behavior of the webserver and redirecting webpages There is an Outstanding Issue with this. When Incorrect Login info is passed throught the server, the webpage isn't returned soon enough and the browser considers it a time out and hence an error is produced. Haven't figured out a way to delay the redirection as of now

The Setup function is described below:

//Setup
void setup() {

  //Pin Setup
  pinMode(wifi_led, OUTPUT);      //LED Indication for WiFi Connection
  digitalWrite(wifi_led, HIGH);
  pinMode(A0, INPUT);
  
  // Variables
  int flag = 0;
  
  // Begin Serial Communication
  Serial.begin(115200);
  Serial.println("\nBegin Serial Communication With NodeMCU");

  //Begin WiFi Connections
  WiFi.mode(WIFI_AP_STA);   //Declares the WiFi Mode as Station plus Access Point
  
  //Begin WiFi Access Point Mode
  WiFi.softAPConfig(softAP_ip, softAP_gateway, softAP_subnet);
  bool ret = WiFi.softAP(softSSID, softPASS, 1, false, 6);
  if (ret == true)
  {
    Serial.print("\nSoft Access Point Started with IP: ");
    Serial.print(WiFi.softAPIP());
  }
  //Attempts WiFi Connection to the last connected network
  -----------------
  WiFi.begin();       //NTP Sync Issue
  -----------------
  //HTML Server and Handles
  server.begin();
  Serial.print("\nHTTPS Server Started");
  server.on("/", HTTP_GET, handle_root);
  server.on("/disconnect_wifi", HTTP_POST, handle_disconnect_wifi);
  server.on("/connect_wifi", HTTP_POST, handle_connect_wifi);
  server.on("/wifi_login", handle_wifi_login);
  server.onNotFound(handle_notfound);

  //Current Measurement Setup
  curr.current(1, 4.8);
  
  time_object.begin();
}
//

pinModes are used to declare the I/O pins on the NodeMCU as Input or output The digital pin D4 is connected to a status LED that indicates the Status of the station mode connection i.e connection to the Home Network. The Analog pin A0 is used to read the output from the current sensor and it's sensed value is used to calculate the RMS current.

Serial.begin is used begin serial communication with our Arduino IDE.

softApConfig configures the soft access point with the given IP config details declared before if the method returns true then it prints so on the serial monitor

After the soft Access Point is started the WiFi.begin() statement attempts STA mode connection to the last known WiFi network

Next, the HTML server is started and handles are defined using server.on method

curr.current confiures the sapling cycles and calibration factor based off the hardware.

//Main Loop
void loop() {
  server.handleClient();            //Handle Incoming HTTP requests from Clients
  
  double curr_raw;
  if(WiFi.status() == WL_CONNECTED) //WiFi connection LED Indication
      digitalWrite(D4, LOW);
  else
    digitalWrite(D4, HIGH);
  if(time_object.getSeconds() % 10 == 0 && cflag == 0)
  {  
    curr_raw = analogRead(A0);
    curr_raw = curr.calcIrms(1480);
    Serial.println();
    Serial.print(time_object.getFormattedTime());
    Serial.println();
    Serial.print(curr_raw);
    Serial.print("\nNo. of Station Connected to AP: ");
    Serial.print(WiFi.softAPgetStationNum());
    cflag = 1;
  }
  else if(time_object.getSeconds() % 10 != 0)
    cflag = 0;
}
//

server.handleClient() handles all the incoming HTTP requests from the Clients if WiFi successfully connects using the last known creds then tis is indicated using the pin D4 else it's turned off.

Using if statement, every 10 seconds, the value through the current sensor is read and RMS Current is calculated using which the apparent power is calculated taking V = 230V.
Assuming P.F. ~ 1 gives us the active power which is a reasonable assumption in most cases.

void handle_root() : Home Page hosted on the WebServer

void handle_disconnect_wifi() : disconnects WiFi on disconnect button press on home page

void handle_connect_wifi() : handles new wifi connection landing

void handle_wifi_logon() : handles wifi connection when creds are passed on This handle uses the void sta_setup() method to connect to the WiFi Network once the network creds has been received from the user.

Once Pub Sub Topics have been added to this, The Appliance control will be done through a Relay for which one more Digital Pin will be used as Output Pin. Power will be stored Interval wise and averaged over a single cloud transmission inverval eg. 5 minutes. The control value will be obtained from Sub topic and power values will be uploaded via a Pub topic