SparkFun Load Cell Amplifier - HX711

The SparkFun HX711 Load Cell Amplifier acts as the bridge between your microcontroller and a load cell, allowing you to measure weight with high accuracy. By reading subtle changes in resistance, this board enables you to create everything from industrial scales to simple process control systems (even a dog treat dispenser). We’ve updated this version specifically based on your feedback to ensure the cleanest possible data:

• Separated Supply Lines: Analogue and digital supply lines have been decoupled to significantly reduce noise interference.
• Enhanced Filtering: A 3.3μH inductor and a 0.1μF filter capacitor have been added to the digital supply to stabilize measurements.

Simple Interface & Wiring

The HX711 uses a simple two-wire interface (Clock and Data) that works with the GPIO pins of almost any microcontroller, supported by widely available libraries (special thanks to Bodge!). The board is designed to accept the standard four-wire Wheatstone Bridge Configuration found on most load cells:

• Standard Pinout: Clearly labelled to match standard load cells:
  • Red (Excitation+ or VCC)
  • Black (Excitation- or GND)
  • White (Amplifier-, Signal- or Output-)
  • Green (A+, S+ or O+)
  • Yellow (Shield)
• EMI Protection: The YLW pin is an optional input that is not connected to the strain gauge and is used to ground and shield against external EMI (electromagnetic interference).

With its user-refined circuit design and library support, this amplifier simplifies weight-sensing projects.

Need a Solderless Solution?

If you need an even faster setup, check out the SparkFun Qwiic Scale. It offers all the features of the HX711, with a true I²C interface via our solder-free Qwiic Connect System and MicroPython Libraries.

• Schematic
• Eagle Files
• Hookup Guide
• Getting Started with Load Cells
• Datasheet (HX711)
• GitHub (Design Files & Example Code)
• GitHub (Library)