Arduino CHX711 Load Cell with LCD Display

Introduction

Creating a digital weighing scale at home is easier than ever with the CHX711 load cell amplifier, an Arduino, and a simple 16x2 LCD display. This combination allows you to accurately measure weight and display it in real-time, making it perfect for DIY kitchen scales, small robotics applications, or hobbyist electronics projects.

The CHX711 is a high-resolution 24-bit ADC (Analog-to-Digital Converter) specifically designed for load cells. It converts the tiny voltage changes from a load cell into digital values that the Arduino can process. When paired with an LCD, you can have a complete, functional digital scale with instant visual feedback.

Why CHX711?

Compared to older modules like the HX711, the CHX711 offers:

Faster readings and improved stability
Higher accuracy thanks to a 24-bit ADC
Support for multiple gain channels for different load cell sensitivities
Simple two-wire interface (DATA and CLOCK) to Arduino

These features make it ideal for projects that require precise weight measurements without relying on expensive commercial scales.

Hardware Required

Arduino Uno, Nano, or Mega
CHX711 Load Cell Amplifier
Load Cell (e.g., 5kg, 10kg, or 50kg depending on your application)
16x2 LCD Display with I2C
Jumper wires and breadboard

Wiring

CHX711 to Arduino

CHX711 Pin	Arduino Pin	Notes
VCC	5V	Power supply
GND	GND	Ground
DAT	D2	Data pin to read ADC values
SCK	D3	Clock pin for timing

LCD (I2C) to Arduino

LCD Pin	Arduino Pin	Notes
VCC	5V	Power
GND	GND	Ground
SDA	A4	I2C Data
SCL	A5	I2C Clock

Note: On different Arduino boards (Mega, Nano, etc.) SDA/SCL pins may vary. Check your board’s pinout.

Arduino Code Example

#include <CHX711.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define LOADCELL_DOUT_PIN 2
#define LOADCELL_SCK_PIN 3

CHX711 scale(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address might differ

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();

  scale.begin();
  scale.set_scale(2280.0); // Adjust this value to calibrate your load cell
  scale.tare();             // Reset the scale to zero
}

void loop() {
  long weight = scale.get_units(10); // Average 10 readings for stability
  lcd.setCursor(0, 0);
  lcd.print("Weight: ");
  lcd.print(weight);
  lcd.print(" g");

  Serial.print("Weight: ");
  Serial.println(weight);
  
  delay(500);
}

How the Code Works

Initialization – The LCD is initialized and the backlight is turned on. The CHX711 is started, and the scale is tared (zeroed).
Reading Weight – The get_units() function reads the load cell multiple times and averages the value to reduce noise.
Displaying – The weight is printed both on the LCD and the Serial Monitor.
Calibration – Adjust set_scale() using a known weight for accurate readings.

Practical Tips

Calibrate Properly – Always use a known weight to set the correct scale factor.
Stable Power – Avoid using USB power alone if the load cell is heavy; fluctuations can affect readings.
Mechanical Mounting – The load cell must be flat and firmly mounted; uneven pressure can skew results.
Noise Reduction – Averaging multiple readings smooths out small fluctuations.
Expandability – You can add a tare button, Bluetooth/Wi-Fi logging, or even store measurements to an SD card.

Applications

DIY kitchen or postal scales
Robotics for measuring payload
Science experiments needing weight measurement
Educational projects to learn about sensors, ADCs, and I2C communication