HX711 is a precision 24-bit analog-to-digital converter (ADC) designed for weighing scale and industrial control applications to interface directly with a bridge sensor. The HX711 amplifier is used to amplify the low-level output signal from a load cell or strain gauge, making it possible to accurately measure weight or pressure. The HX711 provides a high-precision and low-cost solution for load cell amplification and data conversion.

Package Includes:

• 1 x HX711 is a Precision 24-Bit Analog-To-Digital Converter (ADC) Module

Features:

• 24-bit analog-to-digital conversion: The HX711 provides high-precision 24-bit A/D conversion, ensuring accurate and stable readings even in demanding applications.
• Precision amplification: The HX711 amplifies the low-level output signals from load cells or strain gauges, making it possible to measure weight or pressure accurately.
• Low noise amplifier: The amplifier is designed with a low noise floor, minimizing the effects of interference and improving measurement accuracy.
• Programmable gain amplifier: The gain of the amplifier can be programmed, allowing for flexible adjustment based on the specific requirements of each application.
• Onboard A/D converter: The onboard A/D converter in the HX711 provides stable and accurate measurements without the need for external components.
• Single power supply operation: The HX711 operates on a single power supply, making it easy to integrate into a wide range of systems.
• Simple serial interface: The HX711 can be controlled using a simple serial interface, reducing the complexity of system integration.
• Adjustable offset and gain: The HX711 includes adjustable offset and gain, allowing users to calibrate their system to meet their specific requirements.
• Ideal for weigh scale and industrial control applications: The HX711 is specifically designed for weigh scale and industrial control applications, making it an ideal solution for a variety of use cases.

Description:

The HX711 is a precision 24-bit analog-to-digital converter (ADC) created for use directly with a bridge sensor in weigh scale and industrial control applications. The HX711 amplifier is used to enhance the low-level output signal from a load cell or strain gauge, allowing for accurate weight or pressure measurement. The HX711 is a low-cost, high-precision solution for load cell amplification and data conversion.
This device has a low-noise amplifier, a configurable gain amplifier, and an inbuilt A/D converter for accurate and steady measurements. The HX711 uses a single power supply and is operated by a simple serial interface, making it simple to integrate into a wide range of applications. The HX711 has an adjustable offset and gain, allowing customers to fine-tune their system to match their individual needs. Overall, the HX711 load cell amplifier is a must-have for anyone who needs to reliably detect weight or pressure in industrial or laboratory applications.

Principle of Work:

The HX711 load cell amplifier operates on the principle of bridge sense. A load cell or strain gauge is used to measure weight or pressure, and the HX711 amplifies the low-level output signal from the load cell. The load cell works by deforming under an applied load, and this deformation changes the electrical resistance of the strain gauge. The HX711 measures the change in electrical resistance and converts it into a digital signal, which can be easily read and processed by a microcontroller or computer. The HX711 includes a programmable gain amplifier (PGA), which allows the gain of the amplifier to be set according to the specific requirements of the application. The PGA is used to amplify the small output signal from the load cell, making it possible to accurately measure weight or pressure. The HX711 also includes an adjustable offset, which can be used to compensate for any residual offset in the system. This offset is added to the digital signal produced by the HX711 and can be used to correct any measurement errors.

In summary, the HX711 works by amplifying the low-level output signal from a load cell or strain gauge, converting the signal into a digital signal, and then providing the digital signal to a microcontroller or computer for further processing. The programmable gain amplifier, adjustable offset, and onboard A/D converter make the HX711 a versatile and accurate solution for load cell amplification and data conversion.

Pinout of the Module:

• VCC: Power supply pin, typically connected to a 5V supply.
• GND: Ground pin, used to connect the HX711 to the ground of the system.
• SCK: Serial clock input pin, used to clock in data from the load cell.
• DT: Data output pin, used to output the digital data from the HX711.
• E+: Positive excitation input pin, used to provide power to the load cell.
• E-: Negative excitation input pin used to return current from the load cell.
• E+ (A channel): Positive excitation input pin for the A channel, used to provide power to the load cell.
• E- (A channel): Negative excitation input pin for the A channel, used to return current from the load cell.
• E+ (B channel): Positive excitation input pin for the B channel, used to provide power to the load cell.
• E- (B channel): Negative excitation input pin for the B channel, used to return current from the load cell.

These pins provide the interface to the HX711 and allow it to communicate with a microcontroller or computer, receive power, and receive signals from the load cell. The HX711 is designed to be easy to integrate into a wide range of systems, making it a versatile solution for load cell amplification and data conversion.

Applications: 

• Weighing scales: The HX711 is commonly used in digital weighing scales, providing amplification and conversion of the signals from
• Force measurement: The HX711 can be used to measure forces in various applications, such as load testing, compression testing, and tension testing.
• Pressure measurement: The HX711 can be used to measure pressures in various applications, such as tire pressure monitoring systems, pressure sensors, and fluid pressure sensors.
• Load cell calibration: The HX711 can be used as a calibration tool for load cells, providing precise measurement of the output of the load cell.
• Other sensor interfaces: The HX711 can be used to interface with a variety of other sensors, such as potentiometers, force-sensitive resistors (FSRs), and strain gauges.
• Data acquisition: The HX711 can be used as a component in a data acquisition system, providing digitization of analog signals from sensors for further processing or storage.

Circuit:

Library:

1. Open the Arduino IDE.
2. Go to Sketch > Include Library > Manage Libraries.
3. Search for HX711 in the search bar.
4. Find the HX711 Load Cell Amplifier library in the list and click Install.
5. Wait for the library to be installed, then close the library manager.
6. You should now be able to include the HX711.h library in your sketches and use it to communicate with the HX711 load cell amplifier.

Code:  

example code in C++ for using the PCF8591 with a potentiometer connected to input channel A0, and the module connected to the I2C bus on A5 (SDA) and A4 (SCL) pins of an Arduino Uno:

#include "HX711.h"

HX711 scale;

void setup() {
  Serial.begin(9600);
  scale.begin(2, 3);
  scale.set_scale(1000);  // set the scale factor to 1000 for a 1k load cell
  scale.tare();
}

void loop() {
  float weight = scale.get_units();
  Serial.println(weight);
}

1. The code starts by including the HX711.h library, which provides the necessary functions and definitions for using the HX711 load cell amplifier with an Arduino.
2. The HX711 scale the object is declared, which represents the HX711 device and provides access to its functions and properties.
3. In the setup function, the serial communication is initialized with a baud rate of 9600, and the scale.begin function is called with the digital pins 2 and 3 specified as the DT and SCK pins, respectively.
4. The scale.set_scale the function is called with a parameter of 1000, which sets the scale factor for the 1k load cell. This value is used to convert the raw ADC values from the HX711 into units of weight.
5. The scale.tare the function is called, which sets the current weight reading as the zero point, effectively subtracting the weight of any containers or other components connected to the load cell.
6. In the loop function, the scale.get_units the function is called, which returns the current weight reading in units of weight (determined by the scale factor set earlier). The weight value is then printed to the serial port using the Serial.println function

Technical Details:

• Operating voltage: 2.7V to 5.5V DC
• Input impedance: greater than 10MΩ
• ADC resolution: 24-bit
• Conversion rate: 10 samples per second (default), up to 80 samples per second (maximum)
• Channel selection: automatic, via external pin or via software command
• Load cell excitation voltage: 5V DC
• Load cell input voltage range: ±15mV
• Load cell input resistance: 350Ω to 700Ω
• Load cell input current: less than 60μA
• Load cell input capacitance: less than 15pF
• Operating temperature range: -40°C to +85°C
• Dimensions: 24mm x 20mm x 14mm
• Weight: 2.1g

Resources:

• Tutorial

Comparisons: