In this tutorial you will learn how to interface HX711 loadcell amplifier module with ESP8266 NodeMCU board and getting output on i2c OLED display. Also, we will learn how to add zero push button function to adjust scale offset.

Loadcell:

Load cell is a sensor which converts mechanical force into electronic signal. Where the mechanical force can be tension, pressure, compression or torque. There are many types of load cells are available in the market which can be used as per required application. In this example we are going to use strain gauge load cell for converting mechanical force into electrical signal.

Loadcell consist of several resistive strain gauge sensor elements which changes its resistance when the load is applied and gives output in milli volts when input or excitation voltage is applied to it.
This milli volt output is then amplified to voltage signal to make it compatible with controllers to read and convert to load units.

Things You Will Need:

• ESP8266 NodeMCU
• HX711 Amplifier Board
• 10kg Loadcell
• i2c OLED Display
• Connecting Cables

Circuit Diagram:

Code:

Example 1: ln this example we will use Arduino IDE serial monitor window to get output values from the loadcell.

/**
 *
 * Interfacing 10kg loadcell and HX711 amplifier board with ESP8266 NodeMCU
 * Author: Pranay Sawarkar
 * Website: www.eTechPath.com
 * Link: https://blog.etechpath.com/diy-weighing-scale-using-hx711-oled-i2c-display-and-esp8266-nodemcu-with-zero-calibration-function/
 * 
 *
**/

#include <Arduino.h>
#include "HX711.h"

// HX711 circuit wiring
const int Dout_Pin = 14;
const int SCK_Pin = 12;
const int pb1 = 13;            //push button input 
int tarepb = 0;
int newread = 0;
#define CalFactor 235.5    //enter your calibration factor here

HX711 scale;

void setup() {
  Serial.begin(115200);
  scale.begin(Dout_Pin, SCK_Pin);
  pinMode(pb1, INPUT_PULLUP);
  
  Serial.println("Initialization..."); 
  
  scale.set_scale(CalFactor);
  scale.tare();
  delay (200);
  Serial.println("Ready");
  delay (100);
}

void loop() {
  
  tarepb = digitalRead(pb1);
  delay(10);
  if (tarepb == LOW) 
  {
    scale.tare();
    Serial.println("TareDONE");
  }
  else
  { 
  newread = scale.get_units(5);
  Serial.println("Weight: ");
  Serial.println(newread);
  delay(10);
   }
}

Circuit Diagram:

Example 2: In this example we will interface oled display with the existing circuit and print loadcell output values on display.

/**
 *
 * DIY Weighing Scale using HX711, OLED i2c display and ESP8266 NodeMCU with Zero Calibration Function
 * Author: Pranay Sawarkar
 * Website: www.eTechPath.com
 * Link: https://blog.etechpath.com/diy-weighing-scale-using-hx711-oled-i2c-display-and-esp8266-nodemcu-with-zero-calibration-function/
 * 
 *
**/

#include <Arduino.h>
#include <U8g2lib.h>
#include "HX711.h"

#ifdef U8X8_HAVE_HW_SPI
#include <SPI.h>
#endif
#ifdef U8X8_HAVE_HW_I2C
#include <Wire.h>
#endif

//select your oled display size
U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
//U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);

// HX711 circuit wiring
const int Dout_Pin = 14;
const int SCK_Pin = 12;
const int pb1 = 13;
//const int pb2 = 5;
int tarepb = 0;
int newread = 0;
#define CalFactor 235.5

//235.5


HX711 scale;

void setup() {
  Serial.begin(115200);
  u8g2.begin();
  scale.begin(Dout_Pin, SCK_Pin);
  pinMode(pb1, INPUT_PULLUP);
  
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_6x10_tf);
  u8g2.drawStr(0, 20, "Initializing...");
  u8g2.sendBuffer();
  
  scale.set_scale(CalFactor);
  scale.tare();
  delay (500);
  u8g2.clearBuffer();
  u8g2.drawStr(0, 20, "Ready");
  u8g2.sendBuffer();
  delay (100);
 
}

void loop() {
  
  tarepb = digitalRead(pb1);
  delay(10);
  if (tarepb == LOW) 
  {
    scale.tare();
    u8g2.clearBuffer();
    u8g2.drawStr(0, 20, "Tare Done");
    Serial.println("TareDONE");
    u8g2.sendBuffer();
  }
  else
  {
  
  newread = scale.get_units(5);
  Serial.println(newread);
  delay(10);

      u8g2.clearBuffer();
      u8g2.setFont(u8g2_font_6x10_tf);
      u8g2.drawStr(0, 20, "Weight: ");
      u8g2.setCursor(45, 20);
      u8g2.print(newread);
      u8g2.sendBuffer();
      delay(10);
    
   }
}

Prototype:

About:

In this tutorial, we will learn how to interface hc-sr04 ultrasonic sensor with ESP8266 module and display the water tank level on mobile browser.

Table of Contents:

• HC-SR04 Module
• How Ultrasonic sensor works
• Interfacing sensor module with NodeMCU
• Programming NodeMCU with ArduinoIDE

HC-SR04 Module and How it works

HC-SR04 is an Ultrasonic sensor module which includes ultrasonic transmitter, receiver and control circuit in single compact PCB.  HC-SR04 has distance measurement ability ranging from 2cm to 400cm. These small units are very accurate, and its accuracy can be reach up to 3mm.

Ultrasonic modules work on the principle similar to radar or sonar- sensors. It generates high frequency signals from the transmitter of about 40kHz towards the sensing object and receives echo signal back to the receiver. Then we can calculate object distance using time interval between the sending of signal and the receiving of echo pulse.

Circuit Diagram:

Libraries:

• ESP8266 board manager  Follow this simple tutorial
• HC-SR04 GitHub link (zip)
• ESPAsyncWebServer  GitHub link (zip)
• ESPAsyncTCP GitHub link (zip)

Code:

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <Hash.h>
#include <ESPAsyncTCP.h>
#include <ESPAsyncWebServer.h>
#include <HCSR04.h>

const char* ssid     = "WaterLevel"; //Access point ssid
const char* password = "12341234";   //Access point password

float l = 0.0;
float per = 0.0;
float fcm = 0;
//Rectangular Tank dimentions in cm
float lcm = 200;  //Length
float bcm = 200;    // width
float hcm = 130;  // Height, from Sensor to tank bottom

HCSR04 ultrasonicSensor(D6, D5, 20, 300);
AsyncWebServer server(80);
unsigned long previousMillis = 0;
const long interval = 1000;  

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;
     margin: 0px auto;
     text-align: center;
    }
    h2 { font-size: 3.0rem; Color:DodgerBlue; }
    h3 { font-size: 1.5rem; Color:Tomato; }
    p { font-size: 3.0rem; }
    .units { font-size: 1.2rem; }
    .temp-labels{
      font-size: 1.5rem;
      vertical-align:middle;
      padding-bottom: 10px;
    }
  </style>
</head>
<body>
  <h2>Water Tank Level</h2>
  <h3>www.eTechPath.com</h3>
  <p>
    <span id="permap">%PERMAP%</span>
    <sup class="units">%</sup> 
  </p>
   <p>
   <span id="liter">%LITER%</span>
    <sup class="units">Liters</sup>
  </p>
      <p>
    <span id="distance">%DISTANCE%</span>
    <sup class="units">Cm</sup>
  </p>
</body>
<script>
setInterval(function ( ) {
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("permap").innerHTML = this.responseText;
    }
  };
  xhttp.open("GET", "/permap", true);
  xhttp.send();
}, 1000 ) ;
setInterval(function ( ) {
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("liter").innerHTML = this.responseText;
    }
  };
  xhttp.open("GET", "/liter", true);
  xhttp.send();
}, 1000 ) ;
setInterval(function ( ) {
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("distance").innerHTML = this.responseText;
    }
  };
  xhttp.open("GET", "/distance", true);
  xhttp.send();
}, 1000 ) ;
</script>
</html>)rawliteral";

// Replaces placeholders with sensor values
String processor(const String& var){
 
  if(var == "DISTANCE"){
    return String(fcm);
  }
  else if(var == "LITER"){
    return String(l);
  }
  else if(var == "PERMAP"){
    return String(per);
  }
  return String();
}
void setup(){
  Serial.begin(115200);  
  ultrasonicSensor.begin(); 
  Serial.print("Setting AP (Access Point)…");
  WiFi.softAP(ssid, password);

  IPAddress IP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(IP);
  Serial.println(WiFi.localIP());

  // Route for root
  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/html", index_html, processor);
  });
  server.on("/permap", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/plain", String(per).c_str());
  });
  server.on("/liter", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/plain", String(l).c_str());
  });
  server.on("/distance", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/plain", String(fcm).c_str());
  });
  server.begin();
} 
void loop()
{  
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) 
  {
    previousMillis = currentMillis;
     float newdistance = ultrasonicSensor.getMedianFilterDistance(); //pass 3 measurements through median filter, better result on moving obstacles
    if (newdistance != HCSR04_OUT_OF_RANGE)
    {
      Serial.print("sensor raw value:");
      Serial.println(newdistance);
      fcm = hcm - newdistance;
      float v = fcm * lcm * bcm ;
      l = v / 1000;
      per = map(fcm, 0, hcm, 0, 100);
      Serial.println(per);
      Serial.println(l);
      Serial.println(fcm);     
    }
    else 
    {
      Serial.println(F("out of range"));
    }     
  }
}

Video:

Table of Contents:

• Types of temperature sensors
• MAX6675 HW-550 Module
• Interfacing MAX6675 with ESP
• Installing libraries
• Examples to read temperature from MAX6675

Types of temperature sensors.

There are four measure types of temperature sensors that are commonly used in the industry: RTD, Thermocouples, Thermistor and semiconductor based IC’s. From these four types, we will talk about the Thermocouple temperature sensors in this tutorial.

Thermocouple is a temperature sensor which contains two wires and gives output in millivoltage with respect to junction temperature. This temperature sensor wires also has fixed polarity, So you can not reverse it.

Sensor element of thermocouple is made up of two different types of metals which is joint together at one point. When this point gets heated or cooled, a voltage is created that can be use as reference for temperature calculation.

Max6675 Module:

MAX6675 is k-type thermocouple to digital converter which provides output in SPI serial interface with 12-bit resolution. MAX6675 can measure temperature range from 0°C to 1024°C with the accuracy of 0.25°C

• Supply Voltage: 3.0V to 6.0V DC
• Current: 50mA
• Operating temperature : -20°C to +80°C

Schematic Diagram:

Installing Arduino Libraries:

• First you will have to install ESP8266 board manager into Arduino IDE, if you have not installed it yet. Follow this simple tutorial
• Install MAX6675 library in Arduino IDE. GitHub link to download library. (ZIP)
• Install ESPAsyncWebServer library in Arduino IDE. GitHub link to download library. (ZIP)

Examples:

Interfacing MAX6675 with ESP8266 and monitoring temperature in serial monitoring.

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include "max6675.h"

int thermoDO = 12;
int thermoCS = 15;
int thermoCLK = 14;

MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);

void setup() {
  Serial.begin(115200);

  Serial.println("MAX6675 test");
  // Stabilisation delay for MAX6675 chip
  delay(500);
}

void loop() {
   Serial.print("C = "); 
   Serial.println(thermocouple.readCelsius());
   Serial.print("F = ");
   Serial.println(thermocouple.readFahrenheit());
 
   // There should be at-least 250ms delay between reeds from MAX 6675 
   delay(1500);
}

Interfacing MAX6675 with ESP8266 and monitoring temperature in ESP local webserver.

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <Hash.h>
#include <ESPAsyncTCP.h>
#include <ESPAsyncWebServer.h>
#include "max6675.h"

const char* ssid     = "MAX6675-Server";
const char* password = "12341234";

int thermoDO = 12;
int thermoCS = 15;
int thermoCLK = 14;

MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);

float t = 0.0;
float f = 0.0;

AsyncWebServer server(80);

unsigned long previousMillis = 0; //will store last time temp was updated

const long interval = 1000;  

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;
     margin: 0px auto;
     text-align: center;
    }
    h2 { font-size: 3.0rem; }
    p { font-size: 3.0rem; }
    .units { font-size: 1.2rem; }
    .temp-labels{
      font-size: 1.5rem;
      vertical-align:middle;
      padding-bottom: 10px;
    }
  </style>
</head>
<body>
  <h2>Max6675 Thermocouple Server</h2>
  <h3>www.eTechPath.com</h3>
  <p>
    <span class="temp-labels">Temperature</span> 
  </p>
   <p>
    <span id="temperature">%TEMPERATURE%</span>
    <sup class="units">&deg;C</sup>
  </p>
  <p>
    <span id="fahrenheit">%FAHRENHEIT%</span>
    <sup class="units">&deg;F</sup>
  </p>
</body>
<script>
setInterval(function ( ) {
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("temperature").innerHTML = this.responseText;
    }
  };
  xhttp.open("GET", "/temperature", true);
  xhttp.send();
}, 1000 ) ;

setInterval(function ( ) {
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("fahrenheit").innerHTML = this.responseText;
    }
  };
  xhttp.open("GET", "/fahrenheit", true);
  xhttp.send();
}, 10000 ) ;
</script>
</html>)rawliteral";

// Replaces placeholder with sensor values
String processor(const String& var){
 
  if(var == "TEMPERATURE"){
    return String(t);
  }
  else if(var == "FAHRENHEIT"){
    return String(f);
  }
  return String();
}
void setup(){
  Serial.begin(115200);  
  Serial.print("Setting AP (Access Point)…");
  WiFi.softAP(ssid, password);

  IPAddress IP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(IP);

  Serial.println(WiFi.localIP());

  // Route for root
  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/html", index_html, processor);
  });
  server.on("/temperature", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/plain", String(t).c_str());
  });
  server.on("/fahrenheit", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/plain", String(f).c_str());
  });
  server.begin();
} 
void loop()
{  
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) 
  {
    previousMillis = currentMillis;
    // Read Celsius
     float newT = thermocouple.readCelsius();
    if (isnan(newT))
    {
      Serial.println("Failed to read from Thermocouple Sensor!");
    }
    else 
    {
      t = newT;
      Serial.println(t);
    }
      // Read Fahrenheit
      float newF = thermocouple.readFahrenheit();
     if (isnan(newF)) 
     {
      Serial.println("Failed to read from Thermocouple Sensor!");
    }
    else 
    {
      f = newF;
      Serial.println(f);
      Serial.println(WiFi.softAPIP());
    }  
  }
}

Prototype:

Ticker is basically a display which connects with your local WiFi router or access-point and fetch online crypto currency data from api and displays on its screen. In this ticker we are going to use esp8266 nodeMCU and 0.98” OLED display for demonstration.

Things you will need:

• Node MCU or any ESP8266
• 0.98 inch OLED display
• Lipo battery
• 100k resistors
• TP4056 module
• USB to serial programmer in case of standalone Esp8266
• Arduino IDE – Software
• Breadboard and connection cables

Circuit Diagram:

Code:

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <ArduinoJson.h>
#include <NTPClient.h>
#include <WiFiUdp.h>
#include <Wire.h>
#include <U8g2lib.h>

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);

const char* ssid     = "username";
const char* password = "password";

int analogInPin  = A0;    
int sensorValue;   
float calibration = 0.36; 
int bat_percentage;

WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP, "0.in.pool.ntp.org", 5.5*3600, 60000);

#define CG_URL "https://api.coingecko.com/api/v3/simple/price?ids=bitcoin%2Cethereum%2Cdogecoin%2Cshiba-inu%2Cpolkadot&vs_currencies=inr%2Cusd&include_last_updated_at=true&include_24hr_change=true"
const char *fingerprint  = "33 C5 7B 69 E6 3B 76 5C 39 3D F1 19 3B 17 68 B8 1B 0A 1F D9";

String payload = "{}";

void setup()
{
  Serial.begin(115200);
  Serial.setDebugOutput(false);
  delay(10);

  u8g2.begin();
  u8g2.enableUTF8Print();

  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_helvB08_tf);

  u8g2.setCursor(1, 15);
  u8g2.print("Connecting to WiFi ");
  u8g2.setCursor(1, 25);
  u8g2.sendBuffer();

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
    u8g2.print(".");
    u8g2.sendBuffer();
  }
  timeClient.begin();

 Serial.println("");
 Serial.println("WiFi connected");
 Serial.print("IP address: ");
 Serial.println(WiFi.localIP());
 u8g2.setCursor(1, 45);
    u8g2.print("Connected to ");
    u8g2.print(ssid);
    u8g2.setCursor(1, 55);
    u8g2.print("IP Address ");
    u8g2.print(WiFi.localIP());
    u8g2.sendBuffer();
    delay(5000);
}

void loop()
{ 
  if (WiFi.status() == WL_CONNECTED)
  {  
    WiFiClientSecure client;
    client.setFingerprint(fingerprint);
    HTTPClient http; 
    delay(200);

    while (!timeClient.update()) {
      timeClient.forceUpdate();
    }
    Serial.println();
    Serial.print("Time     - ");
    Serial.println(timeClient.getFormattedTime());
    
    u8g2.clearBuffer();
    u8g2.setFont(u8g2_font_helvB18_tf);
    u8g2.setCursor(23, 40);
    u8g2.print(timeClient.getFormattedTime());
    u8g2.drawFrame(110,1,13,6);
    u8g2.drawFrame(123,3,1,2);
    u8g2.drawBox(111,2,bat_percentage,4);
    u8g2.sendBuffer();
    delay (1000);
    
    sensorValue = analogRead(analogInPin);
    float voltage = (((sensorValue * 3.3) / 1024) * 2 + calibration); //multiply by two as voltage divider network is 100K & 100K Resistor

    bat_percentage = mapfloat(voltage, 2.8, 4.2, 0, 11); //2.8V as Battery Cut off Voltage & 4.2V as Maximum Voltage
 
  if (bat_percentage >= 11)
  {
    bat_percentage = 11;
  }
  if (bat_percentage <= 0)
  {
    bat_percentage = 1;
  }
  Serial.print("Analog Value = ");
  Serial.print(sensorValue);
  Serial.print("\t Output Voltage = ");
  Serial.print(voltage);
  Serial.print("\t Battery Percentage = ");
  Serial.println(bat_percentage);
  delay(1000);
  delay (20);
  
    payload = "{}";

    http.begin(client, CG_URL);
    Serial.println();
    Serial.print("Coingecko URL - ");
    Serial.println(CG_URL);

    int httpCode = http.GET();
    
    if (httpCode > 0) { 
      payload = http.getString();
      DynamicJsonDocument doc(800);
      DeserializationError error = deserializeJson(doc, payload);
      if (error) 
      {
        Serial.print(F("deserializeJson() failed: "));
        Serial.println(error.f_str());
        delay(5000);
        return;
      }
     JsonObject bitcoin = doc["bitcoin"];
      double bitcoin_inr = bitcoin["inr"]; 
      double bitcoin_usd_24h_change = bitcoin["usd_24h_change"]; 
      double bitcoin_usd = bitcoin["usd"]; 
     
      JsonObject ethereum = doc["ethereum"];
      double ethereum_inr = ethereum["inr"];
      double ethereum_usd_24h_change = ethereum["usd_24h_change"]; 
      double ethereum_usd = ethereum["usd"]; 
      
      JsonObject dogecoin = doc["dogecoin"];
      double dogecoin_inr = dogecoin["inr"];
      double dogecoin_usd = dogecoin["usd"];
      double dogecoin_usd_24h_change = dogecoin["usd_24h_change"]; 
      long dogecoin_last_updated_at = dogecoin["last_updated_at"]; 

      JsonObject shibainu = doc["shiba-inu"];
      double shibainu_inr = shibainu["inr"]; 
      double shibainu_usd_24h_change = shibainu["usd_24h_change"]; 
      double shibainu_usd = shibainu["usd"]; 

      JsonObject polkadot = doc["polkadot"];
      double polkadot_inr = polkadot["inr"];
      double polkadot_usd_24h_change = polkadot["usd_24h_change"]; 
      double polkadot_usd = polkadot["usd"]; 

      // Edit below your coin holdings here
     double holdings_ethereum  =  0.555;
      double holdings_bitcoin  =  0;
      double holdings_dogecoin =  0.5443;
      double holdings_polkadot    =  0.0324;
      double holdings_shibainu   =  4800000;

      Serial.print("Bitcoin  - $");
      Serial.print("   $");
      Serial.print(bitcoin_usd);
      Serial.println();
      Serial.print("Ethereum  - $");
      Serial.print("   $");
      Serial.print(ethereum_usd);
      Serial.println();
      Serial.print("Dogecoin  - $");
      Serial.print("   $");
      Serial.print(dogecoin_usd);
      Serial.println();
      Serial.print("Polkadot  - $");
      Serial.print("   $");
      Serial.print(polkadot_usd);
      Serial.println();
      Serial.print("shibainu  - $");
      Serial.print("   $");
      Serial.print(shibainu_usd);
      Serial.println();

      double holdings =
        (ethereum_usd   * holdings_ethereum) +
        (bitcoin_usd   * holdings_bitcoin) +
        (dogecoin_usd  * holdings_dogecoin) +
        (polkadot_usd * holdings_polkadot) +
        (shibainu_usd    * holdings_shibainu);

      Serial.println(holdings);
      Serial.println();
      Serial.println();
      Serial.println();
      Serial.println();
  
      draw("BITCOIN - BTC",    bitcoin_usd,   2,  bitcoin_usd_24h_change,   "$");
      draw("ETHEREUM - ETH",   ethereum_usd,  2,  ethereum_usd_24h_change,  "$");
      draw("SHIBA-INU - SHIB", shibainu_usd, 6,  shibainu_usd_24h_change, "$");
      draw("DOGECOIN - DOGE", dogecoin_usd, 4,  dogecoin_usd_24h_change, "$");
      draw("POLKADOT - DOT",     polkadot_usd,  2,  polkadot_usd_24h_change,    "$");
      draw("HOLDINGS  ",       holdings,      0,  0,                        "$");
    }
    http.end();  
  }
}
float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
void drawScrollString(int16_t offset, const char *s)
{
  static char buf[36];  // should for screen with up to 256 pixel width
  size_t len;
  size_t char_offset = 0;
  u8g2_uint_t dx = 0;
  size_t visible = 0;
  len = strlen(s);
  if ( offset < 0 )
  {
    char_offset = (-offset) / 8;
    dx = offset + char_offset * 8;
    if ( char_offset >= u8g2.getDisplayWidth() / 8 )
      return;
    visible = u8g2.getDisplayWidth() / 8 - char_offset + 1;
    strncpy(buf, s, visible);
    buf[visible] = '\0';
    u8g2.setFont(u8g2_font_8x13_mf);
    u8g2.drawStr(char_offset * 8 - dx, 62, buf);
  }
  else
  {
    char_offset = offset / 8;
    if ( char_offset >= len )
      return; // nothing visible
    dx = offset - char_offset * 8;
    visible = len - char_offset;
    if ( visible > u8g2.getDisplayWidth() / 8 + 1 )
      visible = u8g2.getDisplayWidth() / 8 + 1;
    strncpy(buf, s + char_offset, visible);
    buf[visible] = '\0';
    u8g2.setFont(u8g2_font_8x13_mf);
    u8g2.drawStr(-dx, 62, buf);
  }
}
void draw(char *s, double coinprice, int prec, double change, String currency)
{
  int16_t offset = -(int16_t)u8g2.getDisplayWidth();
  int16_t len = strlen(s);

  char pricelen[10];
  dtostrf(coinprice, 4, prec, pricelen);
  int xPos = 64 - (((strlen(pricelen)) * 11) / 2);

  for (;;)
  {
    u8g2.clearBuffer();
    u8g2.setFont(u8g2_font_helvB18_tf);
    u8g2.setCursor(xPos - 11, 30);
    u8g2.print(currency);
    u8g2.print(coinprice, prec);

    if (change != 0) {
      u8g2.setFont(u8g2_font_helvB10_tf);
      u8g2.setCursor(38, 47);
      if (change > 0) {
        u8g2.print("+");
      }
      u8g2.print(change, 2);
      u8g2.print("%");
    }

    drawScrollString(offset, s);
     u8g2.drawFrame(110,1,13,6);
    u8g2.drawFrame(123,3,1,2);
    u8g2.drawBox(111,2,bat_percentage,4);
    u8g2.sendBuffer();
    delay(10);
    offset += 2;
    if ( offset > len * 8 + 1 )
      break;
  }
}

Code Explanation:

Edit your router WiFi username and password here

const char* ssid     = "username";
const char* password = "password";

Replace bellow line with your OLED model from u8g2 library if needed

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);

Calibration factor need to be adjusted as per resistors value and final output in below line

int analogInPin  = A0;    
int sensorValue;   
float calibration = 0.36; 
int bat_percentage;

Replace multiplication factor value for ntp client as per your local time zone. (GMT+5.5 is for India time)

NTPClient timeClient(ntpUDP, "0.in.pool.ntp.org", 5.5*3600, 60000);

You can change ticker Crypto currencies as per your choice in bellow URL link

#define CG_URL "https://api.coingecko.com/api/v3/simple/price?ids=bitcoin%2Cethereum%2Cdogecoin%2Cshiba-inu%2Cpolkadot&vs_currencies=inr%2Cusd&include_last_updated_at=true&include_24hr_change=true"

If your ticker is not working, do check if this is updated fingerprint for coingencko.com. Or you can get updated fingerprint from GRC | SSL TLS HTTPS Web Server Certificate Fingerprints .

const char *fingerprint  = "33 C5 7B 69 E6 3B 76 5C 39 3D F1 19 3B 17 68 B8 1B 0A 1F D9";

Edit your crypt holdings here to get total holdings on crypto-ticker screen.

      double holdings_ethereum  =  0.555;
      double holdings_bitcoin  =  0;
      double holdings_dogecoin =  0.5443;
      double holdings_polkadot    =  0.0324;
      double holdings_shibainu   =  4800000;

Prototype :

.

Downloads:

• U8g2 OLED Library
• NTP-Client Library
• Circuit Diagram

Video:

In this post i will explain you how to program your ESP8266 board using Arduino IDE software.

Things you will need:

1. ESP8266 Node MCU or any Generic ESP8266
2. USB to Serial TTL adapter. (CH340, CP2102, FTDI )
3. 3.3v voltage source.
4. A computer with Arduino IDE

Procedure:

Part 1 : Make your Arduino IDE ready for ESP boards

1. Install Arduino IDE in your computer if you are using it for first time. (Arduino IDE)
2. Open Arduino IDE, go to File – Preferences – find Additional board manager URL input box and copy paste below link to it and hit OK button.
   http://arduino.esp8266.com/stable/package_esp8266com_index.json
3. Then go to Tools – Board – Board Manager and search for ESP8266, select latest version form the drop-down list and hit install button.
4. You are done with setting Arduino IDE now, here is a simple video tutorial if you have any doubt with the above procedure..

Part 2 : Installing USB driver for your USB to Serial/TTL adapter

Depending on what adapter you are using for connecting ESP8266 serially with your computer, download and install respective drivers in your computer. Here i am linking some address of widely used programming adapters.

1. CH340
2. FTDI
3. CP2102 

If you are unsure about the present driver ic on your ESP8266 or adapter board, then you can conform it visually form bellow picture.

Part 3 : Connection and uploading your first code to ESP8266

Connect esp8266 board to USB port of your computer and check its COM port (here’s how to) in device manager. Then select your ESP board type and COM port in Arduino IDE, that’s it you are ready to upload your first code.

1. MAX7219 8×8 LED Matrix
2. ESP8266 Node MCU
3. USB Cable for programming and power

Circuit Diagram:

Steps: 

1. 1. 1. Connect the circuit as shown above.
      2. Install Arduino IDE form arduino website. After that install ESP8266 board and library in Arduino IDE.
      3. Download and install MD_MAX7219 Library from download section for driving MAX7219 matrix. For using this library you will need to edit MAX72xx.h file for configure the type of LED matrix you are using. In this project we are using FC-16 Chinese module.
      4. Download code ino file from download section and open it with Arduino IDE.
      5. You will need to edit WiFi network SSID and Password inside your code before flashing it in ESP module.

         const char* ssid = "your SSID";                   // edit your wifi SSID here
         const char* password = "your Password";            // edit your wifi password here

      6. Select board to NodeMCU and flash the code in ESP module.
      7. Power up the circuit and you will see IP address of your ESP module allocated by your WiFi network on Matrix display. (watch video)

   
   
   

   1. Now open that IP address in any browser connected in same network. And you will see web user interface to enter text.
   2. For detailed procedure of configuring WiFi module with your home network and using web interface, please watch embedded YouTube video linked at the bottom of this page.

Code:

//Link: https://blog.etechpath.com

#include <ESP8266WiFi.h>
#include <MD_MAX72xx.h>
#include <SPI.h>

#define	PRINT_CALLBACK	0
#define DEBUG 0
#define LED_HEARTBEAT 0

#if DEBUG
#define	PRINT(s, v)	{ Serial.print(F(s)); Serial.print(v); }
#define PRINTS(s)   { Serial.print(F(s)); }
#else
#define	PRINT(s, v)
#define PRINTS(s)
#endif

#if LED_HEARTBEAT
#define HB_LED  D2
#define HB_LED_TIME 500 // in milliseconds
#endif

#define	MAX_DEVICES	4

#define	CLK_PIN		D5 // or SCK
#define	DATA_PIN	D7 // or MOSI
#define	CS_PIN		D8 // or SS

// SPI hardware interface
//MD_MAX72XX mx = MD_MAX72XX(CS_PIN, MAX_DEVICES);
#define HARDWARE_TYPE MD_MAX72XX::PAROLA_HW  //edit this as per your LED matrix hardware type
MD_MAX72XX mx = MD_MAX72XX(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);
// Arbitrary pins
//MD_MAX72XX mx = MD_MAX72XX(DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);

// WiFi login parameters - network name and password
const char* ssid = "your SSID";                   // edit your wifi SSID here
const char* password = "your Password";            // edit your wifi password here

// WiFi Server object and parameters
WiFiServer server(80);

// Global message buffers shared by Wifi and Scrolling functions
const uint8_t MESG_SIZE = 255;
const uint8_t CHAR_SPACING = 1;
const uint8_t SCROLL_DELAY = 75;

char curMessage[MESG_SIZE];
char newMessage[MESG_SIZE];
bool newMessageAvailable = false;

char WebResponse[] = "HTTP/1.1 200 OK\nContent-Type: text/html\n\n";

char WebPage[] =
"<!DOCTYPE html>" \
"<html>" \
"<head>" \
"<title>eTechPath MAX7219 ESP8266</title>" \
"<style>" \
"html, body" \ 
"{" \
"width: 600px;" \
"height: 400px;" \
"margin: 0px;" \
"border: 0px;" \
"padding: 10px;" \
"background-color: white;" \
"}" \
"#container " \
"{" \
"width: 100%;" \
"height: 100%;" \
"margin-left: 200px;" \
"border: solid 2px;" \
"padding: 10px;" \
"background-color: #b3cbf2;" \
"}" \          
"</style>"\
"<script>" \
"strLine = \"\";" \
"function SendText()" \
"{" \
"  nocache = \"/&nocache=\" + Math.random() * 1000000;" \
"  var request = new XMLHttpRequest();" \
"  strLine = \"&MSG=\" + document.getElementById(\"txt_form\").Message.value;" \
"  request.open(\"GET\", strLine + nocache, false);" \
"  request.send(null);" \
"}" \
"</script>" \
"</head>" \
"<body>" \
"<div id=\"container\">"\
"<H1><b>WiFi MAX7219 LED Matrix Display</b></H1>" \ 
"<form id=\"txt_form\" name=\"frmText\">" \
"<label>Msg:<input type=\"text\" name=\"Message\" maxlength=\"255\"></label><br><br>" \
"</form>" \
"<br>" \
"<input type=\"submit\" value=\"Send Text\" onclick=\"SendText()\">" \
"<p><b>Visit Us at</b></p>" \ 
"<a href=\"http://www.eTechPath.com\">www.eTechPath.com</a>" \
"</div>" \
"</body>" \
"</html>";

char *err2Str(wl_status_t code)
{
  switch (code)
  {
  case WL_IDLE_STATUS:    return("IDLE");           break; // WiFi is in process of changing between statuses
  case WL_NO_SSID_AVAIL:  return("NO_SSID_AVAIL");  break; // case configured SSID cannot be reached
  case WL_CONNECTED:      return("CONNECTED");      break; // successful connection is established
  case WL_CONNECT_FAILED: return("CONNECT_FAILED"); break; // password is incorrect
  case WL_DISCONNECTED:   return("CONNECT_FAILED"); break; // module is not configured in station mode
  default: return("??");
  }
}
uint8_t htoi(char c)
{
  c = toupper(c);
  if ((c >= '0') && (c <= '9')) return(c - '0');
  if ((c >= 'A') && (c <= 'F')) return(c - 'A' + 0xa);
  return(0);
}
boolean getText(char *szMesg, char *psz, uint8_t len)
{
  boolean isValid = false;  // text received flag
  char *pStart, *pEnd;      // pointer to start and end of text
  // get pointer to the beginning of the text
  pStart = strstr(szMesg, "/&MSG=");
  if (pStart != NULL)
  {
    pStart += 6;  // skip to start of data
    pEnd = strstr(pStart, "/&");
    if (pEnd != NULL)
    {
      while (pStart != pEnd)
      {
        if ((*pStart == '%') && isdigit(*(pStart+1)))
        {
          // replace %xx hex code with the ASCII character
          char c = 0;
          pStart++;
          c += (htoi(*pStart++) << 4);
          c += htoi(*pStart++);
          *psz++ = c;
        }
        else
          *psz++ = *pStart++;
      }
      *psz = '\0'; // terminate the string
      isValid = true;
    }
  }
  return(isValid);
}
void handleWiFi(void)
{
  static enum { S_IDLE, S_WAIT_CONN, S_READ, S_EXTRACT, S_RESPONSE, S_DISCONN } state = S_IDLE;
  static char szBuf[1024];
  static uint16_t idxBuf = 0;
  static WiFiClient client;
  static uint32_t timeStart;

  switch (state)
  {
  case S_IDLE:   // initialise
    PRINTS("\nS_IDLE");
    idxBuf = 0;
    state = S_WAIT_CONN;
    break;
  case S_WAIT_CONN:   // waiting for connection
    {
      client = server.available();
      if (!client) break;
      if (!client.connected()) break;
#if DEBUG
      char szTxt[20];
      sprintf(szTxt, "%03d:%03d:%03d:%03d", client.remoteIP()[0], client.remoteIP()[1], client.remoteIP()[2], client.remoteIP()[3]);
      PRINT("\nNew client @ ", szTxt);
#endif
      timeStart = millis();
      state = S_READ;
    }
    break;
  case S_READ: // get the first line of data
    PRINTS("\nS_READ");
    while (client.available())
    {
      char c = client.read();
      if ((c == '\r') || (c == '\n'))
      {
        szBuf[idxBuf] = '\0';
        client.flush();
        PRINT("\nRecv: ", szBuf);
        state = S_EXTRACT;
      }
      else
        szBuf[idxBuf++] = (char)c;
    }
    if (millis() - timeStart > 1000)
    {
      PRINTS("\nWait timeout");
      state = S_DISCONN;
    }
    break;
  case S_EXTRACT: // extract data
    PRINTS("\nS_EXTRACT");
    // Extract the string from the message if there is one
    newMessageAvailable = getText(szBuf, newMessage, MESG_SIZE);
    PRINT("\nNew Msg: ", newMessage);
    state = S_RESPONSE;
    break;
  case S_RESPONSE: // send the response to the client
    PRINTS("\nS_RESPONSE");
    // Return the response to the client (web page)
    client.print(WebResponse);
    client.print(WebPage);
    state = S_DISCONN;
    break;
  case S_DISCONN: // disconnect client
    PRINTS("\nS_DISCONN");
    client.flush();
    client.stop();
    state = S_IDLE;
    break;

  default:  state = S_IDLE;
  }
}
void scrollDataSink(uint8_t dev, MD_MAX72XX::transformType_t t, uint8_t col)
// Callback function for data that is being scrolled off the display
{
#if PRINT_CALLBACK
  Serial.print("\n cb ");
  Serial.print(dev);
  Serial.print(' ');
  Serial.print(t);
  Serial.print(' ');
  Serial.println(col);
#endif
}
uint8_t scrollDataSource(uint8_t dev, MD_MAX72XX::transformType_t t)
// Callback function for data that is required for scrolling into the display
{
  static enum { S_IDLE, S_NEXT_CHAR, S_SHOW_CHAR, S_SHOW_SPACE } state = S_IDLE;
  static char		*p;
  static uint16_t	curLen, showLen;
  static uint8_t	cBuf[8];
  uint8_t colData = 0;
  // finite state machine to control what we do on the callback
  switch (state)
  {
  case S_IDLE: // reset the message pointer and check for new message to load
    PRINTS("\nS_IDLE");
    p = curMessage;      // reset the pointer to start of message
    if (newMessageAvailable)  // there is a new message waiting
    {
      strcpy(curMessage, newMessage); // copy it in
      newMessageAvailable = false;
    }
    state = S_NEXT_CHAR;
    break;
  case S_NEXT_CHAR: // Load the next character from the font table
    PRINTS("\nS_NEXT_CHAR");
    if (*p == '\0')
      state = S_IDLE;
    else
    {
      showLen = mx.getChar(*p++, sizeof(cBuf) / sizeof(cBuf[0]), cBuf);
      curLen = 0;
      state = S_SHOW_CHAR;
    }
    break;
  case S_SHOW_CHAR:	// display the next part of the character
    PRINTS("\nS_SHOW_CHAR");
    colData = cBuf[curLen++];
    if (curLen < showLen)
      break;
    // set up the inter character spacing
    showLen = (*p != '\0' ? CHAR_SPACING : (MAX_DEVICES*COL_SIZE)/2);
    curLen = 0;
    state = S_SHOW_SPACE;
    // fall through
  case S_SHOW_SPACE:	// display inter-character spacing (blank column)
    PRINT("\nS_ICSPACE: ", curLen);
    PRINT("/", showLen);
    curLen++;
    if (curLen == showLen)
      state = S_NEXT_CHAR;
    break;
  default:
    state = S_IDLE;
  }
  return(colData);
}
void scrollText(void)
{
  static uint32_t	prevTime = 0;
  // Is it time to scroll the text?
  if (millis() - prevTime >= SCROLL_DELAY)
  {
    mx.transform(MD_MAX72XX::TSL);	// scroll along - the callback will load all the data
    prevTime = millis();			// starting point for next time
  }
}
void setup()
{
#if DEBUG
  Serial.begin(115200);
  PRINTS("\n[MD_MAX72XX WiFi Message Display]\nType a message for the scrolling display from your internet browser");
#endif
#if LED_HEARTBEAT
  pinMode(HB_LED, OUTPUT);
  digitalWrite(HB_LED, LOW);
#endif
  // Display initialisation
  mx.begin();
  mx.setShiftDataInCallback(scrollDataSource);
  mx.setShiftDataOutCallback(scrollDataSink);
  curMessage[0] = newMessage[0] = '\0';
  // Connect to and initialise WiFi network
  PRINT("\nConnecting to ", ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED)
  {
    PRINT("\n", err2Str(WiFi.status()));
    delay(500);
  }
  PRINTS("\nWiFi connected");
  // Start the server
  server.begin();
  PRINTS("\nServer started");
  // Set up first message as the IP address
  sprintf(curMessage, "%03d:%03d:%03d:%03d", WiFi.localIP()[0], WiFi.localIP()[1], WiFi.localIP()[2], WiFi.localIP()[3]);
  PRINT("\nAssigned IP ", curMessage);
}
void loop()
{
#if LED_HEARTBEAT
  static uint32_t timeLast = 0;
  if (millis() - timeLast >= HB_LED_TIME)
  {
    digitalWrite(HB_LED, digitalRead(HB_LED) == LOW ? HIGH : LOW);
    timeLast = millis();
  }
#endif
  handleWiFi();
  scrollText();
}

Downloads:

1. Arduino IDE
2. ESP8266 Arduino Library
3. MajicDesigns MD_MAX7219 Library
4. Code.ino

Video:

How to solve mirror image and orientation problems of matrix display if you are using old MD_MAX72xx library.

In this project we are going to control 1 watt RGB full color LED diode using WiFi module ESP8266-01. You can use any WiFi enabled device to access web interface to control this RGB LED. Watch video at the bottom of this page.




Things you will need: 

• 1W RGB LED
• ESP-01  WiFi module
• 10Ω Resistance
• ASM1117 3.3v  (or any 3.3v voltage source)
• USB to TTL converter (for programming esp-01)
• Momentary push button (optional)
• Android / Apple / Windows  Phone or any WiFi enabled Laptop / Desktop (to control RGB LED)

Circuit Diagram for programming ESP-01 : 

Steps :

1. 1. Connect the circuit on breadboard as shown in above circuit diagram for programming ESP-01 WiFi module. You must use only 3.3v logic setting in TTL device.
   2. In this tutorial we will used Arduino IDE to download code into ESP module. So, install Arduino IDE and add supporting board manager and ESP library into it. (Download links are given in download section)

1. Download and save source code on your computer and open it up using Arduino IDE.
2. Connect USB to TTL module to your computer.
3. Open Arduino IDE – Select board ‘Generic ESP8266 Module’ – Select Port of your TTL device (Here’s How to)
4. Open downloaded code.ino file into arduino and upload the code into ESP module by pressing upload button.
5. After uploading, Disconnect the ESP module from USB-TTL module and connect it to RGB LED as shown in bellow diagram.

Circuit Diagram for connecting RGB LED:

Steps: 

1. 1. Connect the final circuit as shown in above diagram and power it up using 5v battery or wall adapter.
   2. ESP module will boot up and LED light will show fade effect in all three colors at startup.

1. Then open your device WiFi in discovery mode and you will see a new WiFi access point, named as RGB in discovery list.
2. Connect that WiFi access point, Open any web browser in that device and open ip address 192.168.1.1 , thats it, you will see a colorful RGB control screen to control your wireless RGB LED.

        Note: Do not feed more than 3.3v to ESP-01 module

Source Code : 

/* RGB web server with ESP8266-01 (ESP-01)
* There are only 2 GPIOs available in ESP-01: 0 and 2
* but RX and TX can also be used as: 3 and 1
* Wiring Circuit 
* 0=Red (GPIO0) D3
* 2=Green (GPIO2) D4
* 3=Blue (GPIO3) Rx
* www.etechpath.com
*/

#include <ESP8266WiFi.h>
#include <DNSServer.h>
#include <ESP8266WebServer.h>

const char *ssid = "RGB";
//Uncomment below line if you wish to set a password for ESP wifi network...
// const char *password = "87654321";  

const byte DNS_PORT = 53;
IPAddress apIP(192, 168, 1, 1);   //IP address of your ESP 
DNSServer dnsServer;
ESP8266WebServer webServer(80);

//Webpage html Code
String webpage = ""
"<!DOCTYPE html><html><head><title>RGB control eTechPath.com</title><meta name='mobile-web-app-capable' content='yes' />"
"<meta name='viewport' content='width=device-width' /></head><body style='margin: 0px; padding: 0px;'>"
"<canvas id='colorspace'></canvas>"
"</body>"
"<script type='text/javascript'>"
"(function () {"
" var canvas = document.getElementById('colorspace');"
" var ctx = canvas.getContext('2d');"
" function drawCanvas() {"
" var colours = ctx.createLinearGradient(0, 0, window.innerWidth, 0);"
" for(var i=0; i <= 360; i+=10) {"
" colours.addColorStop(i/360, 'hsl(' + i + ', 100%, 50%)');"
" }"
" ctx.fillStyle = colours;"
" ctx.fillRect(0, 0, window.innerWidth, window.innerHeight);"
" var luminance = ctx.createLinearGradient(0, 0, 0, ctx.canvas.height);"
" luminance.addColorStop(0, '#ffffff');"
" luminance.addColorStop(0.05, '#ffffff');"
" luminance.addColorStop(0.5, 'rgba(0,0,0,0)');"
" luminance.addColorStop(0.95, '#000000');"
" luminance.addColorStop(1, '#000000');"
" ctx.fillStyle = luminance;"
" ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);"
" }"
" var eventLocked = false;"
" function handleEvent(clientX, clientY) {"
" if(eventLocked) {"
" return;"
" }"
" function colourCorrect(v) {"
" return Math.round(1023-(v*v)/64);"
" }"
" var data = ctx.getImageData(clientX, clientY, 1, 1).data;"
" var params = ["
" 'r=' + colourCorrect(data[0]),"
" 'g=' + colourCorrect(data[1]),"
" 'b=' + colourCorrect(data[2])"
" ].join('&');"
" var req = new XMLHttpRequest();"
" req.open('POST', '?' + params, true);"
" req.send();"
" eventLocked = true;"
" req.onreadystatechange = function() {"
" if(req.readyState == 4) {"
" eventLocked = false;"
" }"
" }"
" }"
" canvas.addEventListener('click', function(event) {"
" handleEvent(event.clientX, event.clientY, true);"
" }, false);"
" canvas.addEventListener('touchmove', function(event){"
" handleEvent(event.touches[0].clientX, event.touches[0].clientY);"
"}, false);"
" function resizeCanvas() {"
" canvas.width = window.innerWidth;"
" canvas.height = window.innerHeight;"
" drawCanvas();"
" }"
" window.addEventListener('resize', resizeCanvas, false);"
" resizeCanvas();"
" drawCanvas();"
" document.ontouchmove = function(e) {e.preventDefault()};"
" })();"
"</script></html>";
void handleRoot() 
{
// Serial.println("handle root..");
String red = webServer.arg(0); // read RGB arguments
String green = webServer.arg(1);  // read RGB arguments
String blue = webServer.arg(2);  // read RGB arguments

//for common anode
analogWrite(0, red.toInt());
analogWrite(2, green.toInt());
analogWrite(3, blue.toInt());
//for common cathode
//analogWrite(0,1023 - red.toInt());
//analogWrite(2,1023 - green.toInt());
//analogWrite(3,1023 - blue.toInt());
webServer.send(200, "text/html", webpage);
}
void setup() 
{
pinMode(0, OUTPUT);
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);

analogWrite(0, 1023);
analogWrite(2, 1023);
analogWrite(3, 1023);
delay(1000);
WiFi.mode(WIFI_AP);
WiFi.softAPConfig(apIP, apIP, IPAddress(255, 255, 255, 0));
WiFi.softAP(ssid);
dnsServer.start(DNS_PORT, "rgb", apIP);
webServer.on("/", handleRoot);
webServer.begin();
testRGB();
}
void loop() 
{
dnsServer.processNextRequest();
webServer.handleClient();
}
void testRGB() 
{ 
// fade in and out of Red, Green, Blue
analogWrite(0, 1023); // Red off
analogWrite(2, 1023); // Green off
analogWrite(3, 1023); // Blue off

fade(0); // Red fade effect
fade(2); // Green fade effect
fade(3); // Blue fade effect
}
void fade(int pin) 
{
for (int u = 0; u < 1024; u++) 
{
analogWrite(pin, 1023 - u);
delay(1);
}
for (int u = 0; u < 1024; u++) 
{
analogWrite(pin, u);
delay(1);
}
}

Downloads:

1. Code.ino
2. Arduino IDE
3. ESP8266 Board link for IDE board manager
4. ESP8266 Arduino Library

1. NodeMCU or any ESP8266
2. Relay Module
3. 128×64 OLED display (Optional)
4. Android Phone

Circuit Diagram :

Source Code:

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <Adafruit_GFX.h>
#include <ESP_Adafruit_SSD1306.h>

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

 

#if (SSD1306_LCDHEIGHT != 64)
#error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif

const char* ssid = "xxxxxxx"; //replace xxxxxxx with your wifi ssid
const char* password = "xxxxxxx"; //replace xxxxxxx with your wifi password

ESP8266WebServer server(80);

const int output1 = 14;
const int output2 = 12;
const int output3 = 13;
const int output4 = 15;

boolean device1 = false;
boolean device2 = false;
boolean device3 = false;
boolean device4 = false;

void handleRoot() {
//digitalWrite(led, 1);
//server.send(200, "text/plain", "hello from esp8266!");
//digitalWrite(led, 0);

String cmd;
cmd += "<!DOCTYPE HTML>\r\n";
cmd += "<html>\r\n";
//cmd += "<header><title>ESP8266 Webserver</title><h1>\"ESP8266 Web Server Control\"</h1></header>";
cmd += "<head>";
cmd += "<meta http-equiv='refresh' content='5'/>";
cmd += "</head>";

if(device1){
cmd +=("<br/>Device1 : ON");
}
else{
cmd +=("<br/>Device1 : OFF");
}

if(device2){
cmd +=("<br/>Device2 : ON");
}
else{
cmd +=("<br/>Device2 : OFF");
}

if(device3){
cmd +=("<br/>Device3 : ON");
}
else{
cmd +=("<br/>Device3 : OFF");
}

if(device4){
cmd +=("<br/>Device4 : ON");
}
else{
cmd +=("<br/>Device4 : OFF");
}

cmd += "<html>\r\n";
server.send(200, "text/html", cmd);
}

void handleNotFound(){

String message = "File Not Found\n\n";
message += "URI: ";
message += server.uri();
message += "\nMethod: ";
message += (server.method() == HTTP_GET)?"GET":"POST";
message += "\nArguments: ";
message += server.args();
message += "\n";
for (uint8_t i=0; i<server.args(); i++){
message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
}
server.send(404, "text/plain", message);

}

void setup(void){
pinMode(output1, OUTPUT);
pinMode(output2, OUTPUT);
pinMode(output3, OUTPUT);
pinMode(output4, OUTPUT);

digitalWrite(output1, LOW);
digitalWrite(output2, LOW);
digitalWrite(output3, LOW);
digitalWrite(output4, LOW);

Serial.begin(115200);
WiFi.begin(ssid, password);
Serial.println("");

 

// by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
//display.begin(SSD1306_SWITCHCAPVCC, 0x3D); // initialize with the I2C addr 0x3D (for the 128x64)
display.begin(SSD1306_SWITCHCAPVCC, 0x78>>1); // init done

display.clearDisplay(); // Clear the buffer.

display.setTextSize(2);
display.setTextColor(WHITE);
//display.setTextColor(BLACK, WHITE); // 'inverted' text
display.setCursor(0,0);
display.println(" ESP8266");

display.setTextSize(3); //Size4 = 5 digit , size3 = 7 digits
//display.setTextColor(BLACK, WHITE); // 'inverted' text
display.setTextColor(WHITE);
display.setCursor(0,18);
display.println("Control");

display.setTextSize(1);
display.setTextColor(WHITE);
//display.setTextColor(BLACK, WHITE); // 'inverted' text
display.setCursor(0,52);
display.println("Version 0.1");

display.display();
delay(2000);

display.clearDisplay();

display.setTextSize(2);
display.setTextColor(WHITE);
//display.setTextColor(BLACK, WHITE); // 'inverted' text
display.setCursor(0,0);
display.println("Connecting");

// Wait for connection
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");

display.print(".");
display.display();
}
Serial.println("");
Serial.print("Connected to ");
Serial.println(ssid);
Serial.print("IP address: ");
Serial.println(WiFi.localIP());

display.clearDisplay();
display.setTextSize(1); display.setTextColor(WHITE);
display.setCursor(0,0); display.println(ssid);
display.setTextSize(2); display.setTextColor(WHITE);
display.setCursor(0,18); display.println(WiFi.localIP());
//display.setCursor(0,36); display.println(WiFi.localIP());

display.display();

if (MDNS.begin("esp8266")) {
Serial.println("MDNS responder started");
}

server.on("/", handleRoot);

server.on("/status1=1", [](){
server.send(200, "text/plain", "device1 = ON");
digitalWrite(output1, HIGH);
device1 = true;
});

server.on("/status1=0", [](){
server.send(200, "text/plain", "device1 = OFF");
digitalWrite(output1, LOW);
device1 = false;
});

server.on("/status2=1", [](){
server.send(200, "text/plain", "device2 = ON");
digitalWrite(output2, HIGH);
device2 = true;
});

server.on("/status2=0", [](){
server.send(200, "text/plain", "device2 = OFF");
digitalWrite(output2, LOW);
device2 = false;
});

server.on("/status3=1", [](){
server.send(200, "text/plain", "device3 = ON");
digitalWrite(output3, HIGH);
device3 = true;
});

server.on("/status3=0", [](){
server.send(200, "text/plain", "device3 = OFF");
digitalWrite(output3, LOW);
device3 = false;
});

server.on("/status4=1", [](){
server.send(200, "text/plain", "device4 = ON");
digitalWrite(output4, HIGH);
device4 = true;
});

server.on("/status4=0", [](){
server.send(200, "text/plain", "device4 = OFF");
digitalWrite(output4, LOW);
device4 = false;
});

server.onNotFound(handleNotFound);
server.begin();
Serial.println("HTTP server started");
}

void loop(void){
server.handleClient();
}

Steps:

1. 1. Build up the circuit as shown in circuit diagram.
   2. Download source code from download section, edit downloaded code and input your home router’s SSID and Password in the code.

      const char* ssid = "xxxxxxx"; //replace xxxxxxx with your wifi ssid
      const char* password = "xxxxxxx"; //replace xxxxxxx with your wifi password

   3. Compile and upload the source code in NodeMCU or any ESP8266 you are using. You can use Arduino IDE to upload the code.

1. Once your uploading process is completed, power up the circuit and reset the ESP once.
2. Now ESP will connect to your router and it will show IP address of your ESP in OLED display.
3. Install android application in your phone and open it, application link is given bellow in download section.
4. Input IP address shown in OLED display and port i.e 80 in application page and hit connect button.
5. Now you can operate relay from your phone and can connect any appliances to these relays. (consider relay amps rating )

Note: You can not use direct 5v relay in this project, because NodeMCU control output is only 3.3v which is not enough to trigger 5v relay. That is- why we are using relay  module to work on this project.

Downloads:

esp8266_relay_control.ino

Android application

Circuit diagram

ESP8266 is advance WiFi chip with complete and standalone networking capabilities. This can be use ether as a standalone or the slave to a host microcontroller. ESP8266 is integrated with advance Tensilica’s L106 diamond series 32 bit micro-processor and on-chip SRAM with CPU clock speed 80MHz. We can also interface external input devices with this chip though provided GPIO’s (general purpose input/output).

For detailed information you can download ESP8266 datasheet here.

ESP8266 Modules:

There are several esp8266 modules available in market but only some of them are famous and commonly used. The most commonly used esp modules are ESP-01, ESP-07, ESP-12  & ESP-32. Nowadays  ESP-32 is most famous module amongs all of them because ESP-32 is the only version  of ESP which combines WiFi and Bluetooth in single module. You can download datasheets of these modules from attachments.

ESP-01 Basic Circuit:

ESP-01 Pinout

How to flash ESP-01 using Flash tools:

1. Gather all component shown in above circuit and wire your esp to serial module as shown.
2. Download ESP flash download tool from  the link given at the bottom of the page. You will not need to install this tool in your system, this tool will run directly without installation.
3. Extract the rar file which we have downloaded in last step and run application file in it and select ESP8266 form selection buttons.

   

4. After selecting ESP8266 download tool button, Flash tool screen will appear like bellow picture.

   

5. Now go back to your circuit and put jumper JP1 on. For setting ESP-01 into programming mode, you have to short GPIO0 to ground terminal of connected source.
6. Connect serial module to your computer USB port and check the COM port for this device in device manger. You will need the correct COM port number of the connected device which you want to flash.   ( learn how to check COM port )
7. That’s it, You are ready to go. Now select the bin files you want to burn into your ESP, select com port at the bottom of the flash tool and hit START. Ongoing process and success message will show in download panel dialog box.
8. For beginner level you can burn NodeMCU firmware in your ESP-01 for general use.

How to Flash NodeMCU firmware in ESP-01:

1. Download ESP8266 Flasher form the link given bellow at the bottom of this page.
2. Run the flasher application file. You will see the tool as shown in bellow picture,

   

3. Now setup your ESP-01 in programming mode as i described in previous steps. and select the COM port of your serial module.
4. Do not change any other settings in flasher, setting right port is enough.
5. Now hit Flash button provided just beside com port and your ESP will start receiving data from flasher. At the same time  AP MAC and STA MAC will appears on flasher as shown in picture bellow,

   

6.  After successfully completing flashing process green indication will appear at the bottom, This means your ESP is programmed successfully and ready to use.

Downloads:

1. ESP Flash Download Tools
2. ESP Flasher win32
3. ESP Flasher win6