HX-711

The HX711 is a precision 24-bit analog-to-digital converter (ADC) designed specifically for weigh scales and industrial control applications to interface directly with a bridge sensor. It is a popular choice for projects involving load cells due to its high resolution and ease of use.

Overview

The HX711 is a small breakout board that allows you to easily read load cells to measure weight. By connecting the load cell to the HX711, you can get a digital reading of the weight applied to the load cell. The HX711 is capable of measuring very small changes in resistance, making it ideal for applications requiring high precision.

Features

• 24-bit ADC: Provides high resolution for precise measurements.
• Two differential input channels: Allows for multiple load cells to be connected.
• Selectable gain: Gain of 32, 64, and 128, which allows for different load cell sensitivities.
• Low noise: Ensures stable and accurate readings.
• Simple interface: Communicates with microcontrollers via a two-wire interface (clock and data).

Applications

The HX711 is commonly used in:

• Weighing scales
• Industrial control systems
• Load cell applications
• Force measurement

Pin Configuration

The HX711 has a total of 16 pins, but only a few are typically used in most applications:

• VCC: Power supply (2.6V to 5.5V)
• GND: Ground
• DT: Data output
• SCK: Clock input
• VFB: Feedback voltage
• VBG: Bandgap voltage

Working Principle

The HX711 works by converting the small analog voltage changes from a load cell into a digital signal that can be read by a microcontroller. The load cell is a transducer that converts force into an electrical signal. The HX711 amplifies this signal and converts it into a digital value using its 24-bit ADC.

Interfacing with Microcontrollers

The HX711 can be easily interfaced with microcontrollers such as Arduino, Raspberry Pi, and others. The communication is done using a simple two-wire interface, where the microcontroller sends clock pulses to the HX711 and reads the data bits.

Advantages

• High precision: The 24-bit ADC provides a high level of precision, making it suitable for applications requiring accurate weight measurements.
• Cost-effective: The HX711 is an affordable solution for weight measurement applications.
• Ease of use: The simple interface and availability of libraries for popular microcontrollers make it easy to integrate into projects.

Limitations

• Temperature sensitivity: The HX711 can be affected by temperature changes, which may require calibration.
• Limited input range: The input range is limited by the gain settings, which may not be suitable for all load cells.

Also see

• Load cell
• Analog-to-digital converter
• Weighing scale
• Microcontroller

External links

• [HX711 Datasheet](https://www.sparkfun.com/datasheets/Sensors/ForceFlex/hx711_english.pdf)
• [HX711 Arduino Library](https://github.com/bogde/HX711)