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:

In this tutorial you will learn how to interface HX711 loadcell amplifier board with Arduino uno and getting output on i2c oled display. Also, we will learn how to add calibration push button to zeroing the scale.

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:

• Arduino Uno
• 10kg Loadcell
• HX711 ADC amplifier board
• i2c OLED display

Circuit Diagram:

Code:

Example 1: In this example we will use arduino serial window to get output values from the loadcell.

/**
 *
 * Interfacing 10kg loadcell and HX711 amplifier board with Arduino Uno
 * Author: Pranay Sawarkar
 * Website: www.eTechPath.com
 * Link: https://blog.etechpath.com/diy-oled-weighing-scale-using-10kg-loadcell-with-hx711-and-arduino-uno/
 * 
 *
**/

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

// HX711 circuit wiring
const int Dout_Pin = 2;
const int SCK_Pin = 3;
const int pb1 = 4;
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 it.

/**
 *
 * DIY Weighing scale using 10kg loadcell and HX711 amplifier board with Arduino Uno and OLED display
 * Author: Pranay Sawarkar
 * Website: www.eTechPath.com
 * Link: https://blog.etechpath.com/diy-oled-weighing-scale-using-10kg-loadcell-with-hx711-and-arduino-uno/
 * 
 *
**/

#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 type and 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 = 2;
const int SCK_Pin = 3;
const int pb1 = 4;
int tarepb = 0;
int newread = 0;
#define CalFactor 235.5   //enter your calibration factor here

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:

In this tutorial, I will explain how to interface SHARP 2Y0A21 infrared distance sensor with Arduino board and display the output in serial monitor.

SHARP 2Y0A21

SHARP 2Y0A21 sensor works on infrared technology, it consists of a transmitter and a receiver diode which calculates the distance between the sensor and the target by measuring time interval between transmitted and received wave.

SHARP 2Y0A21 Sensor Specifications:

1. Working voltage: 4.5 – 5.5 Vdc
2. Distance measuring range: 10cm – 80cm (10cm dead band)
3. Output type: Analog (voltage)
4. Output: 0 to 3.1v (3.1v at 10cm to 0.3v at 80cm)
5. Operating Temperature: -10 to +60 °C (Storage: -40 to +70 °C)

Circuit Diagram:

Code:

//SHARP 2Y0A21 IR Distance Sensor Test (10-80cm) 
// Author: Pranay Sawarkar
// www.eTechPath.com

#define sensor A2 

void setup() 
{
  Serial.begin(9600);
}

void loop() 
{
  float volts = analogRead(sensor)*0.0048828125;
  int distance = 30*pow(volts, -1.173);
  delay(1000); 
  
  if ((distance >=10)&&(distance <=80))
  {
    Serial.print("Distance:");
    Serial.println(distance);
    Serial.print("Volts:");
    Serial.println(volts);   
  }
  else
  Serial.println("Out of range");
}

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

PAM8610 is a duel channel stereo class D audio amplifier with 15w power output per channel. This chip equipped with 32 steps DC volume control which provides +32db to -75db of frequency range. Known for its low EMI , low noise and high sound quality reproduction.

Features :

Working voltage range : 7v to 15v

Protection : over current, thermal and short circuit protection

Provides 15w per channel into 4Ohm load at 12v & 10w per channel into 8Ohm load at 13v.

Provides on chip Mute function.

Circuit Diagram :

• IC1           :     ATtiny2313P
• LED1-8  :     Diffused LED  (use any color of your choice )
• R1-R8     :     200Ω
• R10         :     10KΩ
• VCC        :      5V Power Supply

Circuit Diagram :

( Note: In circuit diagram, programming pins are not shown. Take out ISP pins for ATtiny2313 and flash the code using ISP programmer. or simply make your own ISP programmer.   USB ASP AVR universal USB programmer  )

Downloads :

Firmware files    ( .c  | .hex  |  make )

Image to hex Converter tool

USB ASP is stand alone USB programmer for Atmel AVR microcontrollers, It mainly consist of atmega8 micro controller and some supportive components. Works with multiple platforms including linux, MacOS, & windows. This programmer is originally build by Thomas Fischl under GNU GPL 2 licence.

In this post, we will see how to make this programmer using atmega8. You can also use atmega88 or atmega48 instead of atmega8, firmware files for both is attached at download section at the bottom.

Components List: 

•  IC :             Atmega8
• C1, C2 :      18 pF
• C3:              100 nF
• Q2:             12MHz  cristal
• R1 :             10K
• R6, R2 :     68 Ω
• R3:             270 Ω
• R4, R5  :    390 Ω
• R7 :             1.5 KΩ
• J1, J2, J3 :       Jumper
• D1 :                   3mm Red LED
• D2 :                  3mm Green LED
• K4 :                  USB male pcb mount

Circuit Diagram :

Steps: 

1. Download firmware rar file form download section and unrar the files in folder, it consist of three hex files for atmega8, atmega48 & atmega88. Select one hex file for your microcontroller and flash it in using another working programmer.
2. You have to change the fuse bits for external crystal as bellow,
   atmega8  HFUSE=0xc9   LFUSE=0xef
   atmega48  HFUSE=0xdd  LFUSE=0xff
   atmega88  HFUSE=0xdd    LFUSE=0xff

   ---

   (Note: Put jumper J2 ON, at the time of programming firmware in ASP microcontroller  )

   ---

3. once you are done with the flashing and fuse bit setting, install the USB drivers for your windows. (Drivers are attached at download section)
4. For installing drivers, Connect USB ASP to your computer (Put jumper J2 OFF ). When windows ask for a driver, choose downloaded win-drivers folder. And it will install drivers to your computer automatically.
5. Unplug USB asp and plug it again and windows will detect it. Now you can use ASP programmer to program AVR microcontrollers. AVRDUDE or eXtreme Burner GUI are easy to use software’s for USB ASP, Download it from the links given bellow.

Software: 

• AVRDUDE
• Khazama AVR Programmer       ( Windows XP/Vista GUI application for USBasp and avrdude )
• eXtreme Burner – AVR         ( Windows GUI Software for USBasp based USB AVR programmers )

Downloads:

• Firmware
• USB Drivers (windows)
• USB Drivers (linux)

In this project i am going to explain you how to build your own WiFi repeater to extend your home WiFi signal strength. This device is very easy to make and very handy to use. You can use this device at school, college, office or Cafe to extend the WiFi signal without buying expensive WiFi modems from the market.




Components you will need:

1. ESP-01 or NodeMCU
2. ASM1117 3.3V voltage converter IC
3. Male USB connector
4. USB-UART adapter for programming ESP-01
5. Android or iOS phone to configure settings.

Circuit Diagram for Programming ESP-01 : 

Steps: 

1. 1. Connect ESP-01 to UART adapter as shown in above diagram.
   2. Download firmware files form the bottom of the page, We will flash these files to ESP-01 using ESP flash tools.
   3. Firmware files are in rar folder, So unrar firmware files first and then open ESP flash download tools.
   4. Browse downloaded firmware files into given location as shown in bellow picture and write down where do you want flash the particular file, i.e select 0x00000.bin file and then write location to flash @0x00000 after that select 0x10000.bin file and locate it to 0x10000. (refer bellow screenshot for example)
   5. select COM port and hit START button. (If you dont know how to use flash tool, Check this link on Getting started with ESP8266 to flash ESP-01)
   6. After flashing firmware to esp-01, disconnect the circuit and connect USB male port to ESP-01 as given in bellow circuit diagram.
   7. Now you can power this circuit using any 5v USB wall adapter. So power up this circuit and follow the further steps for configuring WiFi AP settings.
   8. Download Telnet Client Terminal application in your phone. Download links are given in download section at the bottom of this page.

1. Power up the circuit, default device will create open access point with name MyAP without any password and default IP will be 192.168.4.1, Open WiFi settings in your phone and connect this open access point.
2. Open Telnet Client Terminal in your phone and add two fields as IP: 192.168.4.1 and Port: 7777, hit connect button.
3. If everything is ok, terminal will show connected. write command show and hit enter. It will show the current name and password of device STA and AP as shown in bellow screenshot.
4. Use these commands to update the username and password of your STA and AP.

• set ssid XXXXXXXX    (your home router SSID)
• set password XXXXXXXX   (your home router password)
• set ap_ssid  XXXXXXXX   (new access point name)
• set ap_password  XXXXXXXX   (new access point password)
• save    (save configuration)
• reset   (reset device)
• show     (this will show updated setting of your device, i.e your routers and access point  username and password)
• quit     (terminates current remote session)

You are now done with the repeater configuration, reset the ESP once and it will connect your home router with updated ssid and password at the same time it will create an access point with your new access point name and password.

Downloads:

Firmware

ESP Flash Download Tools v3.4.4

Telnet Client Terminal  (Android) (iOS)

1. XS-3868 Bluetooth module.
2. Good quality Headphones (wired).
3. 10k resistor.
4. 47uF capacitor.
5. 3mm LED.
6. 3.7v  Lithium ion battery.

Tools:

1. Soldering ion
2. Soldering paste
3. Soldering tin wire

Wiring Diagram:

My Prototype: