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What is HX711 Load Cell Amplifier Module with Load Sensor?
The HX711 is a precision 24-bit analog-to-digital converter (ADC) module designed specifically for weigh scales and load cells. Consequently, it is widely used in Arduino and microcontroller projects to build digital weighing scales, force gauges, and weight-based automation systems. The load cell (often a strain gauge bar) converts mechanical force into a tiny electrical signal (mV range). Therefore, the HX711 amplifies and digitizes this signal with high resolution. Additionally, common kits include a 4-wire load cell (typically 5kg, 10kg, or 50kg capacity) for immediate use.
Working Principles of HX711 and Load Cell?
Load Cell Operation: First, a load cell contains strain gauges arranged in a Wheatstone bridge configuration. When weight is applied, the metal bar deforms slightly, changing the resistance of the gauges. As a result, this creates a differential voltage proportional to the applied force (typically 1-2 mV/V).
Amplification and Conversion: Moreover, the HX711 provides excitation voltage to the bridge, amplifies the tiny differential signal (gain 128 or 64), and converts it to a 24-bit digital value using a delta-sigma ADC. Consequently, it achieves very high resolution (noise-free bits around 20-21).
Data Communication: In addition, it uses a simple two-wire serial interface (DT and SCK) to send data to the microcontroller on demand.
Hardware Overview of HX711 and Load Cell?
The HX711 module is a small green board with the HX711 IC, while the load cell is an aluminum or steel bar with four color-coded wires (Red=E+, Black=E-, Green=A+, White=A-). The module includes voltage regulator, noise filtering, and pin headers. As a result, it works reliably with 5V or 3.3V systems.
Supporting Circuitry: Additionally, an onboard reference and oscillator ensure stable operation.
Consequently, setup requires only wiring the load cell to E+/E-/A+/A- and connecting DT/SCK to digital pins.
Technical Specifications of HX711 and Load Cell?
- Function: High-precision weight/force measurement.
- ADC Resolution: 24-bit (effective ~20-21 bits noise-free).
- Gain: 128 (Channel A) or 64 (Channel B).
- Load Cell Excitation: 5V (from module).
- Data Rate: 10 SPS or 80 SPS (selectable).
- Operating Voltage: 2.7V to 5.5V.
- Current Consumption: ~1.5 mA.
- Load Cell Capacity: Varies (common 5kg, 10kg, 20kg, 50kg).
- Sensitivity: Typically 1 mV/V or 2 mV/V.
- Pinout (HX711): VCC, GND, DT (data), SCK (clock).
HX711 Load Cell Amplifier Module Pinout?
- VCC: Power supply (5V or 3.3V)
- GND: Ground
- DT (DOUT): Data output to microcontroller
- SCK: Clock input from microcontroller
- E+, E-, A+, A-: Load cell connections (Red, Black, Green, White)
Basic Connections to Arduino:
- VCC: Connect to 5V on Arduino
- GND: Connect to Arduino GND
- DT: Connect to digital pin (e.g., 3)
- SCK: Connect to digital pin (e.g., 2)
Real Life Uses and Applications of HX711 with Load Cell?
The HX711 + load cell combination is perfect for accurate weight measurement projects.
- Digital Kitchen Scales: Precise ingredient weighing.
- Smart Bathroom Scales: Body weight tracking with app integration.
- Inventory Systems: Monitors stock levels by weight.
- Industrial Weighing: Small-scale batching or portion control.
- Robotics: Load sensing on grippers or legs.
- Pet Feeders: Dispenses exact food amounts.
- Postal Scales: Calculates shipping costs by weight.
Using HX711 Load Cell Amplifier with Arduino
In this part, we will learn how you can use HX711 with a load cell and Arduino Uno, Nano, or Mega to measure weight in just a few minutes – even if you’re a beginner.
What You Need:
- Any Arduino board (Uno recommended)
- HX711 Module
- Load Cell (e.g., 5kg)
- Jumper wires
- Known weights for calibration
Wiring Diagram:
Wire load cell to E+/E-/A+/A- on HX711.
Code:
Install “HX711” library by bogde via Arduino IDE Library Manager before uploading. Here’s a tested calibration and reading code – just copy-paste into your Arduino IDE.
#include <HX711.h>
#define DT_PIN 3
#define SCK_PIN 2
HX711 scale;
float calibration_factor = -7050; // Adjust this after calibration
void setup() {
Serial.begin(9600);
Serial.println("HX711 Load Cell Ready!");
scale.begin(DT_PIN, SCK_PIN);
scale.set_scale();
scale.tare(); // Reset to 0
Serial.println("Place known weight for calibration...");
}
void loop() {
scale.set_scale(calibration_factor);
Serial.print("Weight: ");
Serial.print(scale.get_units(), 1);
Serial.println(" kg");
delay(500);
}
Credit: This example code is adapted from the official examples in the HX711 library by bogde. Library available here: https://github.com/bogde/HX711
After uploading, place a known weight and adjust calibration_factor until reading matches. Open Serial Monitor (9600 baud) – you’ll see stable weight in kg!
Note: Tare with no load first. Calibration factor varies per load cell – fine-tune with known weights. Moreover, mount load cell properly (fixed one end, load on the other) for accurate results.
Wrapping up
In this post, we’ve covered all the fundamental aspects of the HX711 Load Cell Amplifier Module with Load Sensor. We trust that the information provided has been clear and insightful. Feel free to ask any questions you may have about this topic in the comment section below. We are here to help and provide additional clarification as needed.
