How to Use Load Cell HX711 with Arduino: Simple Guide

To use a load cell with the HX711 amplifier on Arduino, connect the load cell wires to the HX711, then connect HX711 to Arduino pins. Use the HX711 library to read weight values by initializing the module and calling read() or get_units() functions.

Syntax

The basic syntax to use the HX711 with Arduino involves including the HX711.h library, creating an HX711 object with data and clock pins, and then reading values.

• HX711 scale; - creates the scale object.
• scale.begin(dataPin, clockPin); - initializes communication with HX711.
• scale.read(); - reads raw data from the load cell.
• scale.get_units(n); - reads averaged weight values over n samples.

arduino

#include "HX711.h"

HX711 scale;

void setup() {
  scale.begin(dataPin, clockPin); // Initialize pins
}

void loop() {
  long reading = scale.read(); // Raw reading
  float weight = scale.get_units(10); // Average of 10 readings
}

Example

This example shows how to connect the HX711 to Arduino pins 3 (data) and 2 (clock), initialize the scale, and print the weight in grams to the serial monitor.

arduino

#include "HX711.h"

#define DOUT  3
#define CLK   2

HX711 scale;

void setup() {
  Serial.begin(9600);
  scale.begin(DOUT, CLK);
  scale.set_scale(2280.f); // Adjust this value to calibrate
  scale.tare(); // Reset the scale to 0
}

void loop() {
  float weight = scale.get_units(10); // Average 10 readings
  Serial.print("Weight: ");
  Serial.print(weight);
  Serial.println(" g");
  delay(500);
}

Output

Weight: 0.00 g
Weight: 0.00 g
Weight: 5.23 g
Weight: 5.10 g
Weight: 0.00 g
...

Common Pitfalls

• Incorrect wiring: Mixing up data and clock pins or load cell wires causes no or wrong readings.
• Not calibrating: Without set_scale() and tare(), readings won't match actual weight.
• Insufficient power: HX711 and load cell need stable 5V or 3.3V supply.
• Ignoring noise: Use averaging (get_units(n)) to reduce fluctuations.

arduino

// Wrong wiring example (data and clock swapped):
// scale.begin(CLK, DOUT); // Wrong

// Correct wiring:
scale.begin(DOUT, CLK);

Quick Reference

Function	Description
HX711.begin(dataPin, clockPin)	Initialize HX711 with Arduino pins
HX711.read()	Get raw data from load cell
HX711.get_units(n)	Get averaged weight over n samples
HX711.set_scale(scale)	Set calibration factor for weight conversion
HX711.tare()	Reset scale to zero

Key Takeaways

Connect load cell wires correctly to HX711 and HX711 to Arduino pins.

Use the HX711 library to read and average weight values.

Calibrate your scale with set_scale() and tare() for accurate readings.

Ensure stable power supply and correct wiring to avoid errors.

Use get_units(n) to reduce noise by averaging multiple readings.