hx711-pico

C++ driver for the hx711 24-bit ADC using the Raspberry Pi Pico (RP2350) and the Pico SDK.
The hx711 is commonly used with load cells to build digital scales.
This repository provides a modern C++ class for the Pico, plus calibration examples.

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✨ Features

• Supports the HX711 24-bit ADC for load cells
• Fixed configuration: Gain = 128, Output Rate = 10 samples per second (SPS)
• Simple calibration routine with tare and scale factor
• Example applications included:
  • Calibration
  • Raw sensor value reading
  • Saving the calibration to flash memory enablig weighin without new calibratin after powering back on.
• Compatible with Raspberry Pi RP2350 and Pico SDK (CMake build system)
• Uses RP2350’s Programmable I/O (PIO) for efficient sampling
• Parallel reads: Each RP2350 PIO block can run four state machines, allowing up to four HX711 load cells to be read in parallel
• Optional trimmed moving average filter: removes the highest and lowest values in a window to smooth noisy readings while maintaining 10 SPS output rate

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📜 License

This project is licensed under the MIT License.

• Parts of this code are derived from Rob Tillaart’s hx711 library,
  Copyright (c) 2019-2025 Rob Tillaart, MIT License.
• Parts of this code are derived from Daniel Robertons hx711 PIO,
  Copyright (c) 2020 Daniel Robertson, MIT License.
• Additions and Pico-specific code
  Copyright (c) 2025 Max Penfold, MIT License.

Info

cpg is counts per gram. grams = (raw - offset) / cpg