Components

ARDUINO_NANO

x 1

Description

Electronic scale with Arduino with HX711 module and tare function

More info and updates in https://rogerbit.com/wprb/2024/03/balanza-electronica/

In this tutorial, you will learn step by step how to use an HX711 module with a load cell to make accurate weight measurements using an Arduino development board and an SH1106 OLED display. Load cells are sensors widely used in industrial weighing applications, and the HX711 module provides a convenient interface for connecting these load cells to the Arduino.

The HX711 module is a high-precision ADC (Analog to Digital Converter) amplifier and converter designed especially for weighing and load sensing applications. This module is commonly used in DIY electronics projects and in industrial applications where accurate reading of load sensors is required, such as in scales and force measurement systems.

The HX711 is capable of reading small analog signals from voltage bridge sensors, such as those used in load cells, and amplifying them to obtain an accurate reading using a microcontroller. It is compatible with a variety of common development boards, such as Arduino, Raspberry Pi and other development devices.

The HX711 module usually comes on a small printed circuit board that includes the HX711 chip and connectors for the load sensor cables. Some modules also include additional components, such as resistors and capacitors, to aid in measurement stability and accuracy.

Electronic components of the project

Arduino Nano

A socket for arduino

female pins

Male female dupont cables

sh1106 oled display

It is a 128x64 dot monochrome OLED display module with I2C interface. It has several advantages compared to LCD screens, and we can highlight its high brightness, very good contrast, a wider viewing angle, and low consumption. of energy. It is compatible with Arduino Rasberry Pi and PIC microcontrollers among others. It works with logic levels from 3.3V to 5V and has a viewing angle greater than 160 degrees. Screen Size is 1.3 inches. It is powered with a voltage of 3.3V to 5V. It can be used in applications such as smart watches, MP3s, thermometers, instruments, and various projects, etc.

Characteristics

Interface: I2C (3.3V / 5V logic level)

Resolution: 128 x 64

Angle of view: >160 degree

Display color: Blue

Display size: 1.3 inch

Driver IC: SH1106

Power supply: DC 3.3V~5V

Operating temperature: -20~70'C

Application: smart watch, MP3, thermometer, instruments, DIY projects, etc.

ky-004 module

The KY-004 module is a mechanical limit switch used to detect the status of a button or switch. This module connects to a development board (such as Arduino) via the input and output pins and can be programmed to detect when the switch is turned on or off. It also has an LED that lights up when the switch is activated. It is a common part in robotics and automation projects for event detection.

One HX711 Module

This module is an interface between the load cells and the microcontroller, allowing the weight to be read easily. Internally, it is responsible for reading the wheatstone bridge formed by the load cell, converting the analog reading to digital with its internal 24-bit A/D converter. It communicates with the microcontroller through 2 pins (Clock and Data) serially.

The HX711 amplifier module is a transmitter between the load cells and a microcontroller such as Arduino, allowing the weight in the cell to be read easily. It is compatible with 5kg, 20kg and 50kg load cells. Used in automated measurement systems, industrial processes, medical industry.

The HX711 chip has internally the electronics for reading the Wheatstone bridge formed by the load cell and also a 24-bit ADC converter. It communicates with the microcontroller through a serial protocol through 2 pins (Clock and Data).

The load cells are made up of strain gauges in a Wheatstone bridge configuration. To connect the cell to the HX711 module, 4 cables are necessary, the colors usually used are Red, Black, White and Green. Each color corresponds to a signal as shown below:

Red: Excitation voltage +, E+, VCC

Black: Excitation voltage -, E-, GND

White: Amplifier +, Signal +, A+

Green: Amplifier -, Signal -, A-

HX711 Cell Amplifier Module Specifications

Supply voltage: 2.7V – 5V

Operating current: < 1.5 mA

Standby current: <1 uA

Complete digitization on the HX711 chip

Connection to breadboard or card with standard header

2 differential input channels

Serial digital output interface

With holes to hold

With 10-pin header

On-chip regulator for analog source

Selectable operation: 80 and 10 samples per second

Works with Arduino, PIC Microcontrollers and other brands

Dimensions: 34mm X 20mm

Model: HX711

One YZC-131 load cell

Load cells are used to measure forces. This cell consists of a resistive bridge coupled to an aluminum bar. The assembly of this cell allows it to be anchored at one end with two screws, supporting the force on the other. Thus, the deformation that occurs in the aluminum bar when the force is applied will be reflected in the value of the bridge resistances and, in turn, in the output voltage. The output voltage varies linearly with the applied force, so an adequate measurement of this allows us to obtain a force value

3Kg load cell

Power: 5-10V

Rated output: 1 mV/V ± 150 μV/V

Material: Aluminum

Connection of the measurement bridge:

Power: Red-Black

Signal: Green-White

PCB

Download the PCB

electronic pcb diagram

Circuit

Code

Source code

C/C++

#include "HX711.h"//Librería para el módulo HX711
#include <U8g2lib.h>//Librería para el control del display oled
#define DAT  4 // Pin DAT del módulo HX711 conectado a Arduino
#define CLK   5 // Pin CLK del módulo HX711 conectado a Arduino
const int d12 = 12;//Pulsador para calibrar la tara
HX711 scale;
U8G2_SH1106_128X64_NONAME_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ SCL, /* data=*/ SDA, /* reset=*/ U8X8_PIN_NONE);
void setup() {
  Serial.begin(9600);//Velocidad del puerto serial
  pinMode(d12, INPUT);//Se configura este pin como entrada para el pulsador
  scale.begin(DAT, CLK);
  scale.set_scale(731.0);//Calibración. Cambia este valor para ajustarlo a tu celda de carga.
  scale.tare();// Pone el valor actual como tara
  u8g2.begin();//Inicializa el display oled
}
void loop() {
float peso = scale.get_units(10);//Toma 10 muestras para mayor presición
Serial.print("Peso: ");
Serial.println(peso, 1);//Vemos el valos del peso en el terminal serial
u8g2.clearBuffer(); // Limpiar el buffer de la pantalla
  u8g2.setFont(u8g2_font_ncenB14_tr); // Establecer la fuente
  // Muestra Peso: en la pantalla
  u8g2.setCursor(0, 15);
  u8g2.print("Peso:");
  u8g2.setCursor(0, 35);
  u8g2.print(peso, 1);//Muestra el valor del peso en el display
  u8g2.print(" gramos");//Muestra gramos en el display
  int boton12= digitalRead(d12);//Lee el estado del pulsador
  if(boton12==LOW){//Si se pulsa el pulsador se cumple esta condición
  scale.tare();//Pone el valor actual como tara
  u8g2.clearBuffer(); // Limpiar el buffer de la pantalla
  u8g2.setFont(u8g2_font_ncenB14_tr); // Establece la fuente
  u8g2.setCursor(0, 15);
  u8g2.print("Tara calibrada");//Muestra en el display Tara Calibrada
  Serial.println("Tara calibrada");
  }  
  u8g2.sendBuffer();  // Enviar la información del buffer a la pantalla
  delay(100);        // Esperar un tiempo antes de la siguiente lectura
}

Download Gerbers

Jun 20,2024

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Electronic scale with Arduino with HX711 module and tare function

In this tutorial, you will learn step by step how to use an HX711 module with a load cell to make accurate weight measurements using an Ardu

310

Published: Jun 20,2024

Download Gerber file 1

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