Circuit Documentation

Summary

This circuit is designed to measure weight using load sensors and display the measured weight on a 16x2 I2C LCD. The circuit also includes a pushbutton to tare (zero) the scale and a buzzer that activates when the weight exceeds a certain limit. The ESP32 microcontroller is used to interface with the load sensors, LCD, pushbutton, and buzzer.

Component List

1. HX711 - Bridge Sensor Interface

   • Description: Interface for load sensors to measure weight.
   • Pins: E+, E-, A-, A+, B-, B+, GND - GROUND, DATA (OUT), SCK - CLOCK (IN), 3.3/3.5V Supply

2. Load Sensor - 50kg

   • Description: Sensor to measure weight.
   • Pins: W, R, B

3. 16x2 I2C LCD

   • Description: LCD display to show weight measurements.
   • Pins: GND, VCC, SDA, SCL

4. ESP32 (30 pin)

   • Description: Microcontroller to interface with sensors and display.
   • Pins: EN, VP, VN, D34, D35, D32, D33, D25, D26, D27, D14, D12, D13, GND, Vin, D23, D22, TX0, RX0, D21, D19, D18, D5, TX2, RX2, D4, D2, D15, 3V3

5. Pushbutton

   • Description: Button to tare (zero) the scale.
   • Pins: Pin 3 (out), Pin 4 (out), Pin 1 (in), Pin 2 (in)

6. Buzzer

   • Description: Buzzer to alert when weight exceeds a limit.
   • Pins: PIN, GND

Wiring Details

HX711 - Bridge Sensor Interface

• SCK - CLOCK (IN): Connected to ESP32 pin RX0
• DATA (OUT): Connected to ESP32 pin D2
• GND - GROUND: Connected to ESP32 pin GND
• 3.3/3.5V Supply: Connected to ESP32 pin 3V3
• E+: Connected to Load Sensor pin R
• E-: Connected to Load Sensor pin R
• A-: Connected to Load Sensor pin R
• A+: Connected to Load Sensor pin R

Load Sensor - 50kg

• W: Connected to other Load Sensor pins W
• R: Connected to HX711 pins E+, E-, A-, A+
• B: Connected to other Load Sensor pins B

16x2 I2C LCD

• GND: Connected to ESP32 pin GND
• VCC: Connected to ESP32 pin Vin
• SDA: Connected to ESP32 pin D21
• SCL: Connected to ESP32 pin D22

ESP32 (30 pin)

• D15: Connected to Pushbutton pin 2 (in)
• Vin: Connected to Pushbutton pin 3 (out)
• GND: Connected to HX711 pin GND - GROUND, 16x2 I2C LCD pin GND, and Buzzer pin GND
• D4: Connected to Buzzer pin PIN
• D2: Connected to HX711 pin DATA (OUT)
• RX0: Connected to HX711 pin SCK - CLOCK (IN)
• D21: Connected to 16x2 I2C LCD pin SDA
• D22: Connected to 16x2 I2C LCD pin SCL
• 3V3: Connected to HX711 pin 3.3/3.5V Supply

Pushbutton

• Pin 2 (in): Connected to ESP32 pin D15
• Pin 3 (out): Connected to ESP32 pin Vin

Buzzer

• PIN: Connected to ESP32 pin D4
• GND: Connected to ESP32 pin GND

Documented Code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "HX711.h"

// Definições de pinos
#define LOADCELL_DOUT_PIN 2
#define LOADCELL_SCK_PIN 16
#define BUTTON_PIN 15
#define BUZZER_PIN 4

// Inicialização do display LCD I2C
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Inicialização do HX711
HX711 scale;

void setup() {
  // Inicialização do display LCD
  lcd.begin();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Inicializando...");

  // Inicialização do HX711
  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
  scale.set_scale(); // Ajuste a escala conforme necessário
  scale.tare(); // Zera a balança

  // Configuração do pino do botão
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  // Configuração do pino do buzzer
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Pronto");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Leitura do peso
  float weight = scale.get_units(10);

  // Exibição do peso no display LCD
  lcd.setCursor(0, 0);
  lcd.print("Peso: ");
  lcd.print(weight, 2);
  lcd.print(" kg");

  // Verificação do botão
  if (digitalRead(BUTTON_PIN) == LOW) {
    scale.tare(); // Zera a balança
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Zerado");
    delay(1000);
    lcd.clear();
  }

  // Acionamento do buzzer se o peso for maior que um valor limite
  if (weight > 10.0) { // Ajuste o valor limite conforme necessário
    digitalWrite(BUZZER_PIN, HIGH);
  } else {
    digitalWrite(BUZZER_PIN, LOW);
  }

  delay(500);
}

This code initializes the LCD, HX711, pushbutton, and buzzer. It reads the weight from the load sensors, displays it on the LCD, and activates the buzzer if the weight exceeds a specified limit. The pushbutton is used to tare (zero) the scale.