April 12, 2025 On April 6, 2025

HX711 Dual-Channel 24 Bit Precision A/D weight Pressure Sensor

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Ekostra Electronics

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HX711 Dual-Channel 24-Bit Precision A/D Converter

High-Precision Weight Measurement for Load Cells and Strain Gauges

Introduction

The HX711 is a precision 24-bit analog-to-digital converter (ADC) designed for weigh scales and industrial control applications. This module interfaces directly with load cells and strain gauges, providing accurate weight measurements with resolutions up to 1 in 16,777,216.

Key Features

⚖️ Ultra-High Resolution

24-bit ADC with 16,777,216 counts

📶 Dual-Channel

Channel A (128x gain) and Channel B (32x gain)

🔌 Simple Interface

Serial communication with Arduino

🔋 Low Power

Typical current: 1.3mA (active), <1μA (sleep)

Technical Specifications

Resolution	24-bit (16,777,216 counts)
Input Channels	2 differential (A: 128x, B: 32x gain)
Data Rate	10SPS or 80SPS (selectable)
Supply Voltage	2.6V – 5.5V (3.3V or 5V compatible)
Interface	Serial (Clock + Data)
Operating Temp	-40°C to +85°C

Pin Configuration

Pin	Label	Description	Arduino Connection
1	VCC	Power (2.6-5.5V)	5V
2	GND	Ground	GND
3	DT	Data Output	D3
4	SCK	Clock Input	D2
5	A+	Channel A Positive	Load Cell Red
6	A-	Channel A Negative	Load Cell Black
7	B+	Channel B Positive	Load Cell White
8	B-	Channel B Negative	Load Cell Green

Note: Standard load cell wire colors may vary – verify with manufacturer

Load Cell Wiring

// Typical Load Cell Connections:
// HX711 A+ → Load Cell Red
// HX711 A- → Load Cell Black
// HX711 B+ → Load Cell White
// HX711 B- → Load Cell Green
// E+ (Excitation+) → Load Cell Red (may vary)
// E- (Excitation-) → Load Cell Black (may vary)

Basic Weight Measurement

#include "HX711.h"

HX711 scale;
const int LOADCELL_DOUT_PIN = 3;
const int LOADCELL_SCK_PIN = 2;

void setup() {
  Serial.begin(9600);
  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
  
  // Calibration factor (adjust for your load cell)
  scale.set_scale(2280.f); 
  scale.tare(); // Reset to zero
}

void loop() {
  Serial.print("Weight: ");
  Serial.print(scale.get_units(), 1); // 1 decimal place
  Serial.println(" g");
  delay(200);
}

Library Required: Install “HX711 Arduino Library” by Bogdan Necula

Advanced Features

Calibration

// Calibration procedure
scale.set_scale(); // Reset scale
scale.tare(); // Reset to zero

Serial.println("Place known weight...");
delay(5000);
float reading = scale.get_units(10);
float known_weight = 100.0; // 100g test weight
float calibration_factor = reading/known_weight;

scale.set_scale(calibration_factor);

Data Rate Selection

// Set data rate (10SPS or 80SPS)
scale.set_gain(128); // Channel A, 128x gain, 10SPS
// scale.set_gain(64); // Channel A, 64x gain, 80SPS

Power Management

// Power saving modes
scale.power_down(); // Current drops to <1μA
delay(1000);
scale.power_up(); // Wake up and stabilize

Multiple Sensors

// Interface multiple HX711
HX711 scale1, scale2;
scale1.begin(D3, D2);
scale2.begin(D5, D4);

float weight1 = scale1.get_units();
float weight2 = scale2.get_units();