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Arduino UNO and HX711-Based Bluetooth Weight Measurement System with I2C LCD Display

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Circuit Documentation

Summary

This circuit is designed to measure weight using load sensors and an HX711 bridge sensor interface. The measured weight is displayed on a 16x2 I2C LCD and transmitted via an HC-06 Bluetooth module. The circuit is controlled by an Arduino UNO microcontroller.

Component List

  1. Load Sensor - 50kg

    • Description: Measures weight up to 50kg.
    • Pins: W, R, B

  2. HX711 - Bridge Sensor Interface

    • Description: Amplifies and converts the signal from the load sensors.
    • Pins: E+, E-, A-, A+, B-, B+, GND, DATA (OUT), SCK (IN), 3.3/3.5V Supply

  3. Resistor

    • Description: Provides resistance in the circuit.
    • Pins: pin1, pin2
    • Properties: 2000 Ohms

  4. Arduino UNO

    • Description: Microcontroller used to control the circuit.
    • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

  5. HC-06

    • Description: Bluetooth module for wireless communication.
    • Pins: RXD, TXD, GND, VCC

  6. 16x2 I2C LCD

    • Description: Displays weight data.
    • Pins: GND, VCC, SDA, SCL

  7. HC-SR04 Ultrasonic Sensor

    • Description: Measures distance using ultrasonic waves.
    • Pins: VCC, TRIG, ECHO, GND

  8. rp2040 zero

    • Description: Microcontroller used for additional processing.
    • Pins: 5V, GND, 3V3, 29, 28, 27, 26, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

  9. 9V Battery

    • Description: Provides power to the circuit.
    • Pins: +, -

  10. 5V Battery

    • Description: Provides power to the circuit.
    • Pins: +, -

Wiring Details

Load Sensor - 50kg

HX711 - Bridge Sensor Interface

Resistor

Arduino UNO

HC-06

16x2 I2C LCD

HC-SR04 Ultrasonic Sensor

rp2040 zero

9V Battery

5V Battery

Code Documentation

/*
 * Arduino Sketch for interfacing with HX711, HC-06, and 16x2 I2C LCD
 * - Reads weight data from load cells via HX711
 * - Displays weight on 16x2 I2C LCD
 * - Sends weight data via HC-06 Bluetooth module
 */

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

// Pin definitions
const int LOADCELL_DOUT_PIN = 3;
const int LOADCELL_SCK_PIN = 2;
const int BLUETOOTH_TX_PIN = 9;
const int BLUETOOTH_RX_PIN = 10;

// HX711 initialization
HX711 scale;

// LCD initialization
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  // Initialize serial communication for Bluetooth
  Serial.begin(9600);
  // Initialize HX711
  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
  // Initialize LCD
  lcd.begin(16, 2); // Corrected line
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Weight: ");
}

void loop() {
  // Read weight from HX711
  float weight = scale.get_units(10);
  // Display weight on LCD
  lcd.setCursor(0, 1);
  lcd.print(weight);
  lcd.print(" kg");
  // Send weight data via Bluetooth
  Serial.print("Weight: ");