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 project i will explain how to interface SR04 ultrasonic sensor module with Arduino and display result on OLED display.




Components:

Arduino

SR04 Ultrasonic sensor module

OLED display i2c

Wires and basic tools




Circuit Diagram:

Description: 

1. Connect SR04 ultrasonic sensor power to arduino +5v and GND also connect Trigger and Echo pin to arduino pin 9 and pin 8 as shown in above circuit diagram.
2. In same way connect OLED power to arduino and connect SCL & SDA of oled display to arduino pin A5 and pin A4.
3. Download arduino code and all libraries form download section, compile the code and upload it to your arduino.
4. If you are new to ultrasonic sensors, do visit this post for basic study “SR04 Ultrasonic Sensor Module Basics”

Code:

/******************************************************************
 * Project: Printing utrasonic sensor data on OLED display
 * Author: Pranay Sawarkar
 * Website: www.etechpath.com
 *
 * This example is for a 128x32 pixel monocrome display using i2c
 *
 *****************************************************************/
#include <Ultrasonic.h>
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
Ultrasonic ultrasonic(9, 8);
#define OLED_RESET 4   //(optional)
Adafruit_SSD1306 display(OLED_RESET);
#if (SSD1306_LCDHEIGHT != 32)     // change it to 64 if you are using 128x64 pixel OLED
#error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif
void setup()
{
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  //display.display();
  //delay(2000);
  display.clearDisplay();
}
void loop ()
{
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.print("Distance: ");
  display.println(ultrasonic.distanceRead());
  display.setCursor(80,0);
  display.print("cm");
  display.display();
  delay(1000);
  display.clearDisplay();
}

 



Downloads:

SR04 Ultrasonic Sensor Module Basics

SR04 Ultrasonic Module Library 

Adafruit GFX Library

Adafruit_SSD1306 OLED Library

Arduino Code